Caveat Change of Strong Thunderstorms Late Afternoon-Evening South Half of Florida

CONDITIONAL-CAST TODAY: EXPLANATION OF IMAGE BELOW

SOUTH OF BLUE LINES IS WHERE STRONG STORMS COULD OCCUR AFTER 4pm  unitl just after dark
RED ARROW SHOWS DIRECTION OF ANVIL BLOWOFF
PURPLE: SUSPECT SATELLITE IMAGE. Not sure what those clouds are yet
NOTE THE STORM NEAR TAMPA BAY RELATED TO TROUGH NUMBER 1

LASTLY: YELLOW ARROW: STRONG WINDS ALOFT OF 100-120kts AFTER  3PM to DARK

TODAY: Interesting day today that could amount to a whole lot of nothing. Model guidance continues to be very inconsistent in the precipitation fields. Then again, I used to NEVER use them, other than to see if they broke any out. Sometimes they are almost right on the mark, whereas other times you wonder if the model has the right day. Today, none of the models agree much on where or even IF rain will fall today. And when it does, it is at different times. Per once model, it should be raining right on my roof as I type. Not even remotely close.

This forecast discussion addresses the best case scenario for rain over much of the areas that really need it due to on going drought. However, if this does occur after 4-5pm, the storms could be very strong with 1/4-3/4" inch hail in the very strongest of storms (1 or 2 storms some where), with 'hefty, 'hefty' gusty winds.  I would not expect storms before 4pm to be very strong. Storms are not expected to be officially bonafide severe though due to lack of instability and stronger winds in the mid-levels even though higher up they are about as stronng as we ever see here, even in the winter! .NOW: What I'm calling 850mb trough number 1 moved  in on the west coast during the early morning ..and is now starting to lift off to the NNE. In its wake of showers and a decaying thunderstorm over South Tampa Bay.. is a lot of anvil debris  which is being caught up in the strong jet stream winds  overhead  and spreading to the east coast.

 However, these should thin out during the next few hours heading toward latter portions of the afternoon. Additionally, toward the west side of the state clearing is already in progress, and as such, so is increasing instability.  Meanwhile, on the east side of the state near the coast is where coastal helicities will continue until late afternoon as long as the wind remains from the SE-SSE. These winds penetrate about as far inland as I-95 (at most) with any strength.

IN TROUGH ONE THUNDER STORMS HAVE OCCURRED. ONE IS NEAR TAMPA BAY. THIS TROUGH IS FORECAST TO LIFT NNE QUICKLY AND BEGIN TO BE REPLACED BY TROUGH 2.

MEANWHILE, EAST OF THE TROUGH THE ENVIRONMENT IS CAPPED AT 700MB. THIS IS FOR NOON TIME. AS YOU CAN SEE, NO RAIN ON THE EAST SIDE OF THE STATE. See the placement of TROUGH 2 in the second image after 6pm. TROUGH 2 is way up there in Virgina, and will generate some strong storms there.

Here on the left is 6pm. Trough 1 is well to the north and Trough 2 has moved in. In thinking of the best chance for rain or storms, by this time the high clouds will be cleared, and more important, height falls at the 850 and 700mb levels will break the cap which would permit storms to form rapidly toward 5pm on the east half of the state where the clouds might have begun to clear. At this time is when winds aloft will be the strongest as it so happens..up to nearly 120 kts at 200 mb. 

Additionally, temperatures will begin to fall to meet the dew points and precipitable water values will rise and lift north a bit in response to height falls. Temperatures aloft are quite cold at 700mb and 500mb...cold enough to support hail and strong wind gusts of 40-50mph. If the mid level winds were any stronger we would be dealing with big time severe storms today. 

Strongest storms, if they form will be within 6 miles of the East Coast where the strongest onshore component wind is found and as such, low level coastal helicities that feed into the storm along the storm relative wind fields . Any storm that does form ,and strongly, is likely to move right on offshore to the east and into the Atlantic.

NOW FOR THE CAVEAT: The high clouds have to clear for the atmosphere to destabilize. At least on the west half of the state.  And that is just the beginning. All in all, confidence is low today of anything to materialize of note worthy record keeping, but the above is something to keep in mind. Wouldn't hurt to watch the 3pm  onward time frame...just to see what might be brewing in your neck of the woods. Could be that activity will start before that time if it does. Also expecting some frequent lightning with any strong storm.

BEYOND: Weekend is looking nice, with only a marginal chance of thunderstorms sometime well into next week. Become warm by Sunday or Monday.

Chance of Showers/ Isolated Strong/Marginal Severe Storm East Coast Friday??

GFS Just Stream Forecast For Early Friday Afternoon. Area in Green Shows where the best chance of there being  a few isolated strong/marginally severe storm during the morning or  mid-afternoon hours

TODAY: No question at this time as to where the richest atmospheric resides this afternoon; that being over South Florida. It is rounding the ridge over NE Florida and trying to work up the west coast, as well as lifting slowly north everywhere as the high starts to move out late this afternoon.  In viewing the latest visible satellite image, we can see the more extensive cloudiness over South Florida with the expanding cloud field to the north as moisture tries to work north but can't with the ridge continue to be in place, but pulling off to the east this afternoon. As such, circulation around the high is creating some easterly winds this afternoon.   


Lower Clouds are interesting this afternoon if you happened to catch them just right. The low clouds are trying to form at the that level but are capping off with their tops making little curly tufts breaking off to the east...as if catching stronger mid level west winds at that level, yet models are showing little in the way of winds up there. Could be they are simply hitting dryer air.  In the satellite image we see what looks a bit like a 'mackerel sky' pattern from the top down, with little north/south stretched bands of clouds such as in the red circle and over West Central Florida. This would indicate wind shear.

In close inspection the red circled area (for instance) is showing scalloped cloud patterns. Also, but hard to tell unless in animation, thin cirrus clouds are pushing quickly across from west to east in the increasing winds from 20,000 to 35,000 '

TODAY: Winds will continue from the ENE-NE this afternoon becoming more easterly and decreasing some tonight as the veer toward the SE overnight into the early morning hours. Shower activity should start to let up and shift more toward the West Coast up toward Tampa toward sunset and there after until around 8-9pm. Skies will remain partly cloudy over Central and South Florida, with a occasional mostly cloudy periods under either the cirrus clouds or increasing low - mid level clouds, especially heading toward sunset.  There is a slight chance of a few isolated coastal rain showers well after dark through early morning, but only worth a hint of mention.


EARLY FRIDAY: Virtually every model is painting a different picture just to set the record straight right from the get go. Therefore, confidence level is low.  With that said, I'll paint the two extremes of possibilities first.


1) Chance of showers and coastal thunderstorms as moisture returns north up the east coast, namely after 5-6am Friday. Best chance of showers is from Brevard County and south. One model is indicating a prelude to a prefrontal boundary to approach in the early afternoon to generate this activity, which would include thunder near South Brevard to Vero Beach - my take? I think the model is over done, and would leave it as a chance of showers along and east of I-95 during this transitional period, mainly from Volusia County and South.  Otherwise, day should break under partly cloudy to most cloudy skies, perhaps clearing a bit after mid-morning with heating of the day.


2) Noon time. Meanwhile, a weak low pressure circulation is expected to form roughly 150 miles west of West Central Florida in the Gulf underneath the lift provided by approaching very strong jet stream level winds of nearly 110 kts.  This circulation could be briefly closed, but not expecting the strength of the circulation as it stands now to make too great an impact in the overall scheme of things.  This circulation will cross Central Florida during the early - mid afternoon and likely lose its characteristics as it interacts with daytime heating over the land mass, of which I don't expect to be much (in the heating category).


By noon this area is expected to approach West Florida with showers and some isolated thunder perhaps and then enter and cross the spine of the state around noon-1pm, accompanied by showers and thunderstorms. Some of which could be strong. Over the past 36 hours the favored areas for a strong storm have been near Daytona,  Cocoa Beach/Cape Canaveral, and Vero/Ft. Pierce areas.


**However: If one looks at the Topsy-turvy NAM model, which for two days has showed variables such as favorable wind fields for tornadogenesis near St. Augustine (last night), to a strong storm at Cape Canaveral (in two previous runs)..it has now gone to the opposite extreme and shows barely any rain at all over the state tomorrow other than a few showers THE ENTIRE DAY.  This might be because of two reasons : 1) too much cloud cover in the upper levels associated with the jet streak cutting off instability potential below combined with a near uniform vertical  moisture profile throughout the boundary layer with no dry slots in an otherwise favorable one with  the cold temperatures aloft department for strong storms. In short, not enough heating to get anything going in the absence of a trigger (earlier, it showed numerous triggers) such as liitle vorticity maxima and vertical velocity pockets at various levels.


On the other hand, the GFS is the same with the timing of rain from west to east after noon time..but more generous with more showery type rains.  Even with cold air aloft which would favor strong/severe storms, accompanied by the strong upper level winds..the mid-level winds (in both cases) do not change much in strength with height and are fairly uniform in direction as well.  This leaves us with just cloudy skies and some rain showers with lack of instability at the low levels.


And on the third hand (should you have one), we have the local WRF model which, like the SPC one, is showing early morning (even before sunrise) thunderstorms/showers near the East coast between Daytona to Vero Beach. This is what I'm thinking might just be some showers if anything.


Both models then bring in the second wave in the afternoon associated with the weak surface low and the main 850-700mb short wave trough axis which actually is mainly to the north of the state  when again, there could be some thunderstorms.


To add to the post, numerical guidance is showing anything from  a 20% chance of rain to as much as 50% percent (The Weather Channel for my location reads 40%). Most of what we are hearing, I think, is just a best guest' ruf-estimate mish-mash' of all the available information, none of which will be close to reality in all likelihood.


  I do have a problem with believing there will be ample moisture for storms in the low-mid level state wid..and like an older version of the GFS which had the best moisture return limited to Central and South Florida, namely from Brevard County -Tampa and South, then favoring up the east side of the state toward at least Ormond Beach if not St. Augustine for an isolated storm, which could be strong if it holds of until mid-afternoon. Guidance hints at moisture north of Brevard but varies on when it will be there, and as such, whether it will just be showers or a strong/severe storm.  On model shows something very strong up there in fact...that is in the afternoon associated with the mid-level trough axis.


SPC is NOT making any mention of strong or severe storms. In fact, they don't even MENTION the state at all in their discussion (but do mention the mid-Atlantic region and somewhere else that i don't even recall where now though..but it wasn't Florida) despite the near favorable credentials for as said storms.


  In the world of weather though, the sum total of 'near favorable conditions and parameters' ...now mater how many variables are 'close', does not add up to a sum total of 'severe' or 'strong". Often, everything  being "almost good enought' ends up with nothing other than clouds...that is, the NAM solution.  BTW: The RUC model today has been out to lunch. It did not even initialize the rains over Southeast this morning, and is not initializing them yet in successive runs since early in the morning. This means neither here nor there though in regard to tomorrow, since it does not run out that far in time.


I'll add just as an observation which is likely only 'in my mind' since I'm looking for answers;  that all of the NWS offices and SPC seem to be strangely 'mute' about tomorrow..sounding a bit in-definitive. But the point is, despite the strong winds aloft tomorrow (limited to the upper most levels and not the mid levels) and cold air aloft, weak instability seems to be the factor that would limit to some extent if not entirely an active weather day. Perhaps the NAM has it correct with almost nothing at all?  Only later model runs and closer scrutiny of satellite imagery will reveal what is to come.


In closure, as written in the prelude of today's post, should thunderstorms develop tomorrow, they could be strong to severe..most likely on the East Side of the state. Best chance of said will be from 1:30pm - 5pm from near Ormond Beach to Ft. Pierce. Other thunder storms could form just about anywhere, but would most favor the east coast. It will be interesting though to see what moves in on the West Coast earlier in the day. That, and how it trends as it pushes east (assuming something does move in)..will dictate how the end result of the day on the east side of the state.


Expect most if not all activity everywhere to end by sunset or shortly thereafter with a few stragglers, if there is anything to 'straggle'.


BEYOND: Quiet through the weekend as NW flow moves in. This might actually be a warm, dry NW flow..but it is way to sketchy to say for sure until after tomorrow is through. It does look to be dry though. Only exception would be continued shower chances far South Florida, possibly another shot at thunder close to Miami Metro area on Saturday, perhaps on Sunday if they play their cards right.

Isolated Showers and Some Thunder Possible, A Storm or Two Strong Interior/West Late

Greens: Showers possible (thunder audible mainly west of I-95) Red: Better chance of mid-afternoon to early evening thunder-one might be strong, Blue: beast chance of one or two strong storms

TODAY: As of 1pm I think a  much weakened surface front which is becoming close to non-existent is almost right over my head as I type.  Winds are near calm and it feels warm out there. Some puffy cumulus are visible just to the N-NW along the leading edge of the boundary.  Otherwise, a surface high building in  from the WSW-SW is cutting right thru the constructs in the vertical profile of the approaching front, leaving the mid-upper level portions well over head, but separated from just a surface boundary moving into Central Florida at the surface. The wind shift is due more from high pressure building in across the Panhandle rather than down from the North.  Be that as it may..


Instability this hour is building near the Sarasota even this hour..with the axis running from near that location to Central Brevard County. Additional instability will mount through the mid afternoon, mostly toward West Central and West Florida.  Behind the boundary, winds become ENE up to 3500 feet, then near calm in the ridge axis, with  westerly wind (and quite brisk) in the upper levels. Precipitable water values per the SPC latest analysis are only running about 1.3" inches..just barely enough to sustain a thing. In fact, there is little to be found on radar. Not much more to say about the surface boundary, as today's weather will be more of a function of sea breeze convergence coupled with the steering flow and ample moisture to generate some convective activity beginning pretty soon now, but mostly after 3-4pm.


Showers could be felt or be near by about anywhere within the 'green' above..and in some locations, most likely west of I-95, thunder might be heard from a distance if not directly overhead the close to the spine of the state one is located.  The best chance for a strong storm (if there is one) will be toward the West Side of state after 5-6pm when dewpoints begin to rise after peak heating.  A strong storm could put down some frequent lightning, strong winds gusts, and pea hail at its worst in one or two select locations if the timing is right. Not expecting severe storms today. The strongest activity looks to occur over an open, rural area.


THURSDAY: The moisture associated with the wind field boundary will settle toward Miami Metro and the Keys. Showers could be found throughout the night toward Palm Beach County into mid-morning as the moisture field sinks south, favoring Palm Beach to Boynton Beach into late morning.  Best chance of thunder tomorrow appears will be over Broward, Dade,and Collier Counties beginning early afternoon. By late in the date the high pressure responsible for the developing NE winds today further north will be crossing the state and into the Atlantic all evening. Winds will become ESE-SE over night with a return of atmospheric moisture to the more northern counterparts of the state.


FRIDAY: High pressure well to the east, and SE-SSE winds harvest moisture return to nearly all of the state. Another mid-upper level trough will be passing to the north of the state on Friday with the cold pool reaching into the north 1/2 half  of the state, but not forgetting the South as well.  On Friday, should the above materialize as forecast since yesterday but now more amplified, showers and thunderstorms could develop by early afternoon, some strong to marginally severe over the East Half of the state...any very isolated  severe category storm will most likely be along and east of I-95 from Ft Pierce Beach to St. Augustine or JAX...but this is a new evolution (for example, two previous model runs favored solely (and might add strongly so) the Brevard County area). It looks guaranteed that cold air (the forecast 850mb temperatures are almost obscene) under a nearly uncapped environment would get the show rolling early and would therefore put a significant damper on the potential strength of storms should they hold off until late in the day.  Winds aloft in the jet stream over Central are forecast to be in the 90-110 kt range...with Central in the right entrance region of the southern branch of the split-flow pattern that has been developing over the CONUS, adding in upper level divergence which is favorable for rising air currents in the mid-levels.


SATURDAY/SUNDAY: So far, looks like Friday will scour the atmosphere out. However, per my post 2 or 3 days ago...it was stated that thunder chances could exist Friday through Tuesday. The Weather Channel was showing this to be the case this morning (3 days later now)...but I'm not so sure about that now. Looks like it could be nearly a week before rain chances return beyond Friday as of this morning.

Partly to Mostly Cloudy Wednesday, Isolated Showers and Some Thunder Possible

Author's "Weather Station" recently installed. Not too excited yet.  It lacks one critical asset, namely accuracy.  But THANKS to the "Unpredictable WeatherGuys" on Facebook. This gem was won in a drawing which they conduct. It has a remote reader/sensor , wireless, to access observations from the comfort of my TV remote, snacks in hand while watching The Weather Channel.

TODAY: Relatively dry easterly breezes reign supreme today through tonight as a frontal boundary approaches the Western Florida Panhandle. Skies are mostly clear to partly cloudy across the state other than the panhandle where some showers are developing closer to the approaching front.


WEDNESDAY: The front will be located across NW Florida at sunrise.  This boundary will progress east-southeastward during the late morning into North Central Florida by mid-late morning. Meanwhile aloft, the supporting  mid-upper level trough will pass on east to ENE ward toward the mid-Atlantic coast (well North of Florida), leaving the sprawling surface front to enter all of North Central Florida between 9-11AM with the greatest moisture convergence right on and behind the boundary.  The front is expected to be roughly across Volusia County at 9AM and into North Brevard by 11AM.  Accompanying the boundary will be some light showers earlier in the day, transitioning to some moderate showers and isolated thunder after 11AM - noon time over North Brevard, Seminole, far Southern Volusia, and Northern Orange Counties.  Most of this activity it appears could be accompanied by more extensive cloud cover.


If we take the 'union' of GFS and NAM forecast precipitation subsets...the best chance of thunder tomorrow will occur near West Osceola and Polk Counties after 1pm- 5pm where greater surface heating/instability will be permitted to mount;however, the previous NAM and the latest GFS place the better chances of thunder over North Brevard from near Cape Canaveral to Mims into Seminole County after 1pm.  Given the wind fields portrayed by all models, severe weather is not likely.


The models do agree though that at the lowest levels the immediate surface front will reach into South Central Florida by early afternoon, but is nothing more than a wind shift, whereas just above the surface the mid-upper level troughs lag by a good 6-12 hours. Not sure what the net affect will be, but given that surface winds will be NE behind the front, rain chances on the East Side of the state beyond 1pm should be simply showers, with the better thermodynamics further south and west toward Western portions of South Central Florida. It does not appear that South Florida will receive any rain tomorrow from the front.  Rain chances could continue as late as sunset over the East Side of the state south of Daytona if the GFS verifies, but this will likely end up being simply cloud cover.


THURSDAY: The remaining surface boundary will skirt the east coast as high pressure over laps from the the west and north...all features...similar to the previous front, become non-entities over far South Florida. The best chance of Storms on Thursday and Friday look to be far SW Florida, Broward, Dade Counties, and the Keys, with mainly Dade and the Keys highlighted into Friday as moisture beings to return to the north overnight into Saturday.


SATURDAY: Model disagreement abounds per the author's observation and backed up by NWS forecast discussions. Saturday could end up being a bit like a modified summer day type pattern favoring inland showers and isolated thunder for South Central and South Florida as surface winds begin to swing around to the gradient SE-SSE  direction but with sea breezes generated from both coasts and moisture lifts back to the north.  Very typical for mid-Spring/pre-thunderstorm season (for Central/South), and more in line with the earlier onset of thunderstorms over South Florida, although it might be one or two more fronts before the full onset becomes even more evident.


In Summary, it's starting to look more and more since the previous system that the Thunderstorm season is starting right where it left off in 2010, over SW Florida at some point in time during the next two weeks. On the far far out there.  The GFS is starting to show very high Precipitable water values of 2"+ down in the Caribbean and trying to approach the southern Gulf going into mid portions of May.  This would be the missing ingredient needed to get the Florida Storm Season underway going into June...and potential act to ignite the Southern Plains State's Severe Weather activity from that perspective going later into May (outside of other moisture sources that region draws from).

Conway, Arkansas Photographer of the F4 Tornado of April 1965

The F4 tornado that hit Conway late on Saturday afternoon, April 10, 1965, is still vivid in the memories of many.

Six people were killed, 75 homes were destroyed, 200 people were injured, some severely. The dollar damage to homes, businesses and industries was estimated at $25 million (about $171 million in today's dollars

HISTORY/THE STORY:  Severe months ago  3 day running post concerning the account of a tornado in Texas was written here. Excerpts were taken from the book "Weather Made Clear", with permission granted from where the original text had appeared, which was in the magazine "Weatherwise". The above image appeared in the blog post 'three day series' on November 22, 2010 which was also taken from the book. It was mentioned in this post that the photograph was one of my all time favorite photos as a child of 11 years old. 

Remember, 'many' years ago, color photographs or almost any for that matter of tornadoes were very hard to come by in print to the general public. Here's is the post in which the photograph was used.

http://highspeeddirt-steve.blogspot.com/2010/11/final-portion-of-tornado-story.html

 And here is the book  which contained the text of the account and the tornado photograph (not one in the same). Also, within this book was the image shown above, but with no information other than what you see in the provided caption.

AMAZINGLY, the photographer recently discovered the post in a Google Search and we've been in contact the past two days. He has given permission to use the photograph again. Here is THE lowdown about the photo. Note that the photo was sold to the AP, which likely means the rights were also sold; this post is risky, legally speaking. But seriously:

"When the tornado was spotted, everybody ran to the basement of the dorm.  Then the funnel went back up in the cloud and I ran upstairs to my room and got the camera.  Went back down to the basement and crawled out of a window to take the picture with the intention  of jumping back in if the storm came our way.   It was about a half mile away .  They guys in the parking lot were running to get in their cars to to to the children's colony to see if they could help.  It's a place for kids with disabilities. I hitched a ride to Little Rock (about 45 miles) and took the film to the newspaper.  When the guy came out of the dark room he said, " Front Page!". So it was on the front page the next day......

 

I am fine with you putting the photo on your site, it's flattering that you enjoy it.  I have not seen the book, "Weather made Clear".  Professor Xzin McNeil or McNeall made a book " Storm Resistant Construction Techniques", at the University of Arkansas maybe in 1965 or 66.  Might have been tornado resistant ...... I also have a copy of that IF I can dig it up. It appeared in the AR State Newspaper the next day , the Tulsa Tribune, and the Winnepeg Free Press .  I sold it to Associated Press and UPI and so it was in an encyclopedia and probably elsewhere.

Off to chop the weeds. . .

I'll be back in contact with you,

Bill 

FLORIDA FORECAST:

SUNDAY THROUGH TUESDAY: The state will be under  the influence of clockwise high pressure circulations, and relatively dry air in the levels that matter most for generation of rain. Skies will be mostly clear overnight with scattered low topped clouds during the afternoons mainly inland and on the west side of the state. Could be a chance of a rain shower extreme South Florida and far NW Florida going into Tuesday.

WEDNESDAY: Models diverge at this point. The NAM indicates the potential for strong to marginally severe thunderstorms over Central and strong thunderstorms over South Florida, but extremely isolated. On the other hand, the GFS is continuing the dry trend with the uneventful passage of a dry cold front. The difference lies wherein the NAM washes out the frontal boundary over Central Florida whereas the GFS takes it clearly through or almost nearly so, just like the front of Monday morning. However, unlike that previous front that left moisture and boundaries over South Florida..the GFS is not so generous with this  next system. 

Recall, the last front was also interacting with moisture associated with the synoptic scale pattern which evolved into Invest 91L and the moisture fields involved with it. Therefore, the previous front was much more active.  For what it is worth, The Weather Channel in my location is showing isolated thunderstorms Wednesday through Friday. I believe this will be the case if the boundary/front acts per the NAM's dreams. Too soon to say..but for now, I'm riding with the GFS due to its continuity. The NAM seems to pick up on upcoming pattern changes almost hyperactively at at times. I think a change is in the works for Florida, but it could still take quite some time.

But you know, it's kind of 'funny'. Earlier last week on the evening of April 25th, I made a post to Facebook after looking at the 18Z NAM from that day...commenting "Wow! The NAM is on Steroids for the Deep South by Wednesday!". A few folks responded... "LOL".  Little did we know that not even steroids, 'coke', 'speed', and  coffee  combined would result 24-48 hours later. No, not even LSD would do the trick, but I wish it was all a hallucination today. But the reality and the model foreast was to be, as justified by the issuance by The Storm Prediction Center of a 'Hatched High Tornado Risk".

Otherwise, temperatures will be much warmer and bit more humid during the overnight hours through late morning as prevailing easterlies continue, gusty at times mostly inland and right on the beaches.  

These easterlies are not long fetch, across the Atlantic Ocean type, but rather coming around circulations originating off the mid-Atlantic which are pulling dry air around them and then across the Atlantic with little time for deep layer moisture enhancing modification.

Rip current threats are elevated along the entire east coast of Florida; something to keep in mind now that ocean temperatures are becoming increasingly more comfortable further north up the coast toward Cape Canaveral. The water temperatures from Daytona to Jacksonville have yet to warm to a point I'd consider going in to.

April 27, 2011: And 7 Hours 24 Minutes, 380 Miles That Redefined Tornado History

Radar Composite of the one, single  MegaTornadic Supercell Thunderstorm that originated in Mississippi at 3:40pm EDT and lasted until 10:40pm  (at least) on April 27, 2011. Note that it had a 'hook' shape (indicative of a tornado or the high potential to contain one) almost from birth.  Nearly every thunderstorm that erupted this day was rotating.

Swath of Rotating Storms this Day, nearly all of which produced a tornado, some extremely long tracking. If you live in Florida, can you imagine a tornado producing thunderstorm to be in  South Carolina while enjoying your morning coffee, only to have it cross Orlando near bed time the same day, same storm? Not unlike anticipating the approach of a very small but very violent Hurricane Charley, only smaller, but much stronger.

THE EPIC TORNADO EVENT OF APRIL 27th 2011 HAS OR WILL GO DOWN IN METEOROLOGICAL HISTORY, ALONG WITH THE TRI-STATE TORNADO, THE SUPER OUTBREAK, AND A NUMBER OF SMALLER OUTBREAKS BUT OF NO LESS INTENSITY (some of them were actually STRONGER if that's possible).   No point to go into the details of this event, the information is aplenty...beyond what we may even want or need to hear or know.


It should also be pointed out that BEFORE the day in the Deep South, there was two to three previous days while this system was still evolving that produced tornadoes and large hail back torward Abilene, Texas and east and north into Oklahoma, Arkansas, Missouri, and Illinois.


The point is, we have lived during a period in history now with not only this event, but just recently those of the Tsunami/Earthquake in Japan and Haiti, Hurricanes Andrew and Katrina, the dubbed Moore, Oklahoma EF5 Tornado with the strongest recorded tornado wind yet measured (305 mph). Further information, videos, and stories will be coming across the air waves for many more days to come. 


Many lives have been lost, and the number continues to rise with reportedly those still unaccounted for (which may or may not equate to fatalities).  I watched the entire event unfold on the internet 'as it happened', beginning back in Mississippi...by the time this one storm only had passed Birmingham, AL there was no doubt how fully epically extraordinary the day had become. Realize, that during the time of the 'big one' making news, there were many other tornadoes occurring as well, of no less significance. The  Smithville, Mississippi tornado, for instance, has already been confirmed as being of  EF-5 intensity. That is strong enough to wipe a two story structure to the foundation, pull pavement from the ground, and as I heard recently, it pulled a fire hydrant out of the ground! 


I suspect that at some point the Tuscaloosa to Birmingham storm will be found to have exhibited EF5 strength at some point during its grind across the state, most certainly EF-4.

BEFORE AERIAL VIEW: What appears to be a common Strip Mall and surrounding community

AFTER: Same Location. Note the Strip Mall area. Almost looks like the pavement was scoured. In fact, there is not even debris laying around. It is simply GONE! Imagine those huge projectiles flying through the air for the next area down the line and the impacts those would have on the human skin....that's one way of 'imaging' it to be, uh, conservatively. (I do not believe this was from Tuscaloosa)

BEFORE/AFTER within the same track, same tornado. Your common, everyday neighborhood
If you were to stand in the middle of this, it would almost cover an area as far as the eye can see, 360 degrees of it.

THIS IS A RADAR IMAGE OF THE TORNADIC STORM RIGHT AFTER PASSING
OVER TUSCALOOSA. NOTE THE PURPLE RADAR RETURN IN THE LOWER LEFT/CENTRAL PORTION OF THE IMAGE. THIS IS DEBRIS BEING PICKED UP BY RADAR (the term being thrown around lately as if common knowledge is "Debris Ball". IT WAS NOT AS EVIDENT BEFORE PASSING OVER THE CITY.


I had never heard the term, "Debris Ball" until this year. I don't know if it is something new, or if these events are just so rare that the term was not used widely enough to be easily heard (by myself).  


Below is an image captured during live coverage on the internet. We can see the tornado on a building mounted video cam, and  radar at the same time.

The following day Florida experienced some severe, non tornado producing weather as well. However, had the conditions that evolved during the early evening over East Central Florida been only a bit different, a weak tornado or strong waterspout could have occurred near Port Canaveral. This would have been if the surface winds had been just a bit more from the SE rather than the SSE and the storm had made a harder turn toward the right than it did into  Titusville/Port St. John instead where it produced pea to golf ball sized hail. This storm was mean, inhaling 35mph easily strong SSE winds from the coast and across both intracoastal waterways. The moisture at low levels was so  dense, and the atmosphere so unstable away from the coast that the beaches appeared to be in a dark fog bank under subsidence (settling) behind the East Coast Sea-breeze when seen from Merritt Island. The view into this storm was quite different.

Near the top we see the normal shelf cloud that precedes a strong storm; meanwhile, the storm acquired an attendant inflow band close to the ground near Frontenac. You can see how moisture was feeding into the storm from left to right just above the ground. Hail was falling toward the right side of this photo. That's water vapor in action. Lighting was quite frequent in this storm, even where it originated back in Osceola County.

FORECAST:
TODAY: Chance of showers far SE Florida and possibly thunder western portions of Dade/Broward Counties, evolving more into an isolated strong storm or two into Collier, Hendry, or Lee Counties. Very late toward dark a storm could evolve as far north as Sarasota. Otherwise, further north into Central and North Florida it will be quite pleasant with hardly a cloud in the sky. ENE-E winds at 10-15mph with a high near 80F at the coast and mid-80Fs inland.


TONIGHT/SUNDAY: Chance of a coastal shower or two beginning near daybreak Sunday over Indian River to St. Lucie Counties...perhaps crossing into far South Brevard before 11AM. If these materialize they will be low topped showers. Any activity will progress a bit inland and diminish by mid- afternoon. Perhaps some rejuvenation toward the west side of the state in the early evening.


During Sunday North Brevard near the Beachline will be on a 'gradient' of greater atmospheric moisture with more moist air to the south and much drier air toward the north, those areas from there to the south will see more clouds and maybe the showers...whereas the area just to the north into Georgia will be under full subsidence and much less moisture and may see another clear day altogether.


TUESDAY-FRIDAY: I'm leaving this open ended at this point, other than it will be getting much warmer once again as a frontal boundary approaches late Tuesday through Thursday. The latest European Model was almost a full 18 hours faster than the GFS, but in either case I'm not expecting any stormy weather impacts from this front as it approaches. Rain chances appear will mainly exist during the first few hours after the front moves by in a more stable environment. This boundary will wash out to be replaced by possibly another within 48-72 hours. Again, the details are even more sketchy as model discrepancies are now compounded.  


THUNDERSTORM SEASON WILL SOON BE HERE:
One thing does seem to be in the process though, as I write...if fact, as of yesterday.
Florida is in a transitional phase. Fronts can barely clear the state, and when forecast to do so, could start to actually hang up over South Florida instead..oops. This trend will continue into the first week of June, with the fronts stalling further and further north toward Central and then North Florida. Where ever the fronts stall, chances of thunderstorm activity (some strong) will be possible going into the first two weeks of June, during which time the bona-fide Thunderstorm season will also be evolving. First over the Southern Portion of the state, possibly as soon as within the next 10-20 days..and spreading north with time. Some years, the evolution occurs almost everywhere all at once or nearly so...other years the trend is more 'classic'.

Slight Chance of Strong to Marginally Severe Storms Today - With Caveats

This is the official thunderstorm outlook issued by the Storm Prediction Center (SPC) this morning.
Severe Storms are Possible Roughly north of I-4. Additional images are included further down in this post with a slight variation to this outlook of the authors own  only.

WEB PAGE UPDATES: If you haven't visited the web page recently, you will now find the current, running  conditions for Cocoa Beach just south of SR 520 reflected on the page. This information is not available via mail distribution. The page has been reformatted to hold larger images and the Post History (archives) is now only available view a pull down menu so that the day's post (only) will load faster. 

RECAP: If you are not already aware, an EPIC TORNADO OUTBREAK has occurred over the past 24 hours in the Deep South from Mississippi, Alabama, North Georgia, parts of North Carolina, Tennessee, South Carolina and Virginia just to name a few. The fatality count when I woke was 174 and is now over 217. The huge piles of twisted debris (including vehicles) is still being dug through, so it seems probable that more fatalities will be accounted for before the day is through.  The shear number of tornadoes and the path length of a few of them, one (or many) of which were generated from one single storm that tracked over 300 miles from Mississippi to nearly Virginia, is astoundingly record breaking or nearly so.  Yesterday is going down in weather history to match that of the infamous Tri-State Tornado of March 18, 1925 and the Super Outbreak of April 1974.  Interestingly, another infamous outbreak occurred in Kansas on nearly the same date  (April 26, 1991).  In fact, one of the tornadoes yesterday, the worst so far known of which hit a part of Tuscaloosa, Alabama closely resembled the Andover Tornado from certain angles with the appropriate lighting.


 This day is already going down in Meteorological History as an Epic Event of unmatched or nearly so proportions due to the number and intensity of tornadoes. In fact, there was more tornadoes reports or nearly so that of hail.  Aerial and ground assessments are being made today to determine the strength, width, and length of tornado paths. I have not seen any indications of EF5 intensity yet, but certainly EF3/EF4 strength tornadoes will be determined (on a scale of 0-5).  I am not going to go into the finer details, images, and video links that are widely available on the Internet concerning this event in assumption that anyone who desires to hunt this information out can easily do so at will with minimal effort via a Google or YouTube Search. There is a LOT of video out there that is quite astounding and shocking, but this is one is a astounding for starters. Once you reach this link, you will see others as well. This tornado resembles the Andover, KS Tornado of April 26, 1991:


http://www.youtube.com/watch?v=9M_mcOL99qA


RECAP LOCALLY: A few storms finally materialized after dark yesterday which impacted mainly Okeechobee and Osceola Counties. The storms made it as far east as the Brevard County line. Lightning was beautifully visible from the beaches of Brevard and surrounding areas as the activity peaked, but as it reached Brevard it ran into a stout, strong sea breeze 'wall' and collapsed.


TODAY: The Storm Prediction Center has issued a severe thunderstorm watch box this morning for most of the area in the outlined Slight Risk area shown above. 


Refer to http://www.spc.noaa.gov for details.


Otherwise, they have  'generously' placed the entire peninsula in a chance of thunderstorms today; however, most of this area will not receive rain today. Therefore, I introduce the self annotated images  below:

The first image shows the current location of an approaching cold front with my own slight risk area overlayed on the current (high) dewpoints. Note  that really the only difference in my self assessed slight risk for severe  is that it is a bit further south than that of the official outlook.


To the right is the SPC outlook for General Thunderstorms which shows all of the state in a chance of thunder after 4pm with a higher chance of coverage within the bounds of the blue line. I have added two items here. First, the extension south of a chance of severe level thunderstorms (green line)  and second, the chance of strong thunderstorms within the orange/brown area.


Note that these areas do NOT mean that everyone within either of these regions will even receive rain today. Storms will be isolated, with a greater coverage or chance (more appropriately) of coverage within the two areas. No guarantees. Odds are there will be less coverage rather than more than current thinking. 


TODAY: Cold front will move only slowly South and East today through sunset. The strongest activity will be located closer to the front where the more favorable wind fields exist to support severe level type storms combined with colder air aloft  for  stronger surface thunderstorm winds and possibly hail, although it  does not seem severe sized category hail is possible south of a St. Augustine to Cedar Key line.


FURTHER SOUTH: First off, be aware that the activity over most of North Central Florida to South Florida will be in no way related to the Epic Event that occurred yesterday over parts of the Deep South into the Mid-Atlantic and Mississippi River Valley Basin area. Today will be more like a summer day over Central and South Central Florida that would favor stronger storms due to 1) a dry mid layer, and 2) somewhat cold air aloft, but not impressively so.
This activity will be most enhanced near Lake Okeechobee Boundaries and/or both west and east coast sea breeze convergence boundaries just inland from either coast or a combination thereof.


Yesterday, the sea breeze boundary started up not only earlier than thought  by several hours, but was also stronger. Even as I type the same trend seems to be getting underway. Winds at Melbourne are SSW though still,  whereas at the beach in Cocoa Beach the winds are SE-SSE so perhaps the sea breeze is holding off just a bit more today.


The first image above is an overlay with dew point temperatures. We see very high dew point air at the surface embedded within the prevailing SSW Flow off of the Gulf. However, not shown is a pronounced tongue of warm, dry air in the mid levels.  


Therefore, the atmosphere south of the Slight risk area (especially on the east side) will remain capped and non-conducive for even a shower well into the early afternoon.  A weak surface, thermal type low pressure circulation could develop over the interior through early afternoon which might enhance the east coast sea breeze south of Daytona Beach, but I do not think that low level moisture will be completely scoured. 


What happened yesterday to prevent daytime storms, as I see it, was that the winds at the lower levels over came the winds in the mid-levels and essentially 'cut-off' any otherwise potential convection. This very will could be the case once again today; however, given that nearly every single model is breaking out precipitation this morning I will not differ far from this solution. However, I think it will be only isolated in nature rather than the great coverage that is shown by model guidance. Assuming it can manifest at all.


The capping environment is forecast to break down from west to east beginning around 1-2pm..with activity spreading west and south from North and Northwest Florida...and possibly up from the SW near Lake Okeechobee after 2:30pm. 


Showers/storms appear will enter Central Florida proper (such as Orlando/Daytona/Lake County between the hours of 3pm- 6pm with the strongest storms just west of how far inland the East Coast Sea-breeze penetrates. Expecting it to penetrate inland more the further south one goes, thus the slanted nature of my "Possible Strong" area.


It is possible that no thunder will be revealed east of I-95 south of Titusville/Mims area...but this is not set in stone.


**For Official short term graphic casts and hazardous weather potentials please consult the NWS web page/blog at. This page is normally updated by them as conditions warrant for either the good or bad. (Central Florida Interests).


http://www.srh.noaa.gov/mlb/blog.php


OTHERWISE: Activity will dwindle after dark, although some nocturnal activity once again cannot be fully discounted anywhere over South Central Florida toward the east side.


OVERNIGHT: The cold front itself will move south into Central Florida with the best chance of rain showers just ahead to just behind the boundary along the east side of the state from Daytona Beach to Ft Pierce. The front will be located approximately near South Brevard shortly after day break.


FRIDAY: The front will progress in a much weakened state with virtually no upper level support remaining as it continues south toward Southern Palm Beach county by peak heating hours. South Florida can expect another day of diurnally driven thunder and showers until it progresses to the Keys or Florida Straits after dark.


WEEKEND: Onshore winds of 10-18 mph over the weekend. Much drier to start the weekend with only a gradual moistening of the atmosphere through Monday morning...with a bigger rebound into Tuesday afternoon. Another front will approach the state on Tuesday into Wednesday, but just exactly where it will get hung up to the north, if it does, is TBD. It might not reach the state at all. 

Strong/Marginally Severe Storm or Two Possible East Central/South Florida Late Today

IMAGE: The Outlook area for General Thunderstorm Activity today issued by the Storm Prediction Center  (SPC) for late this afternoon through early evening.  Please consult the SPC website at spc.noaa.gov for all official information. Note: you can also click on the title of this post to go to the NWS MLB latest forecast update and graphic:  http://www.srh.noaa.gov/images/fxc/mlb/Latest.gif

RECAP: A strong storm materialized late afternoon through early evening along a moisture/wind convergence boundary that had materialized along the Lake Okeechobee "Shadow"/East Coast Sea Breeze boundary.  Hail to nickel size and a funnel cloud were photographed and submitted to a local news channel out of West Palm Beach of the funnel near Ft. Pierce in St. Lucie County. Details are sketchy as to whether it actually reached the surface, but either way, the storm was well structured / organized and visible even as far north as North Brevard County with a bit of a back-sheared anvil look and solid updraft. Other photographs were taken by others closer to the activity  of the hail/funnel/storm structure...but you know the drill, "All Rights Reserved".

These images show the storm as it appeared
from Cape Canaveral which was well
to the South over St. Lucie County, Fl. The
backshearing of the anvil (against the upper level winds) is seen behind the telephone pole in this first photograph captured from my camcorder. Rain showers and some thunder had also occurred from Mims/Titusville/ KSC/Cape Canaveral earlier in the afternoon.











TODAY: The first image shows the area most likely to get a thunderstorm (s) outlined by the Storm Prediction Center based in  Norman, Oklahoma. This area is not annotated (yet) with a "See Text" refrain for strong storms, likely because any strong activity will be very isolated, if it can manifest at all. I've generated an image from the OFFICIAL latest post from the NWS in Melbourne, which will likely be updated later in the day after this post is complete. I'll check it before posting today. Otherwise, expecting a strong/marginally severe storm is POSSIBLE in one of three areas as annotated and numbered below. Each area is squared off, then circled for a better location/chance per only the morning model guidance (which will change with every hour!), with annotations. They are also numbered, but the number does not necessarily reflect a greater likelihood of a strong storm, or even rain at all for that matter in any of these locations. The purple text of my own doing highlights the main reason for the green circled areas (based on morning guidance).

EXPLANATION OF EACH AREA FOLLOWS: Firstly, strong day time heating will occur today as noted by the NWS.  There is a big glitch here though, and that is upper level, thin high cirrus clouds. This could put a big damper on late day activity anywhere over the North half of the state.


Highs appear will reach the low 90Fs inland otherwise, with perhaps a few near mid-90Fs. Breezy all locations, especially over the causeways where the wind will run right up the intracoastal. A bit cooler beach-sides.  Some showers could occur in the absence of the sea breeze from North of Daytona and down the coast to Broward County, with the first activity south and working north with time, but currently the cirrus clouds are putting the big snuff on this possiblity. Some lightning could occur with this activity almost in any location...but I'm favoring far SE Florida primarily for the early afternoon activity. Showers further north will be generated purely through horizontally stretched moisture convergence rather than vertically...so not expecting much thunder further north. Further south the geography alone combined with the gradient flow will add in better but not great convergence there. Later today: 


(1) East Central Florida - Local geography could play a role this late afternoon/early evening as was the case yesterday. Expecting a late afternoon sea breeze close to the coast. The past hour or so winds have been between South and SSE. This is forecast to change to a solid SE-ESE after 4:30pm (but just noticed that MLB is now ESE) as is a local station from Weather Underground in Cocoa Beach. Meanwhile, winds just above the surface will remain from the SSW at 15-20mph.  The 200-300mb jet stream will be nosing into North Central Florida late afternoon about the same time the sea breeze 'could' set up (appears it already has begun). Moisture convergence would be the main initiating factor late in the day aided by stronger winds aloft late, and a possible cool mid-level "pool" within a dry mid layer. Thus, stronger wind gusts and small hail are possible. Any sustained updraft near devoid of rain or nearby rain-cooled air could generate a funnel cloud as was the case yesterday over St. Lucie County. 


This occurs most likely when the sea breeze/gradient flow converges with the moisture/thermal gradient all in delicate unison over the Intracoastal or near shore Atlantic waters as the storm is about to peak or just peaks in height. Again, this is assuming there even IS a storm here. I have annoted this as #1 based on the notion that the NAM and GFS have targeted this area with higher precipitation between 5-9pm. Interestingly, the NAM even shows a light precipitation 'backwards hook' field going across the Mims/Titusville area with a pin prick precip core to the SW near Cocoa. This could be a flanking updraft field, but such a notion is purely conjecture/day dreaming on my part. This model, nor any really, can pick up on such storm development. Big con for this area is early afternoon cirrus clouds which will be in place through mid-afternoon, at least. Model guidance is also showing a lowering of the lifted condensation level east Central over Eastern Central Brevard after 6-7pm time frame in the absence of a precipitation field. This would aid in storms becoming fully surface based.  This is sketchy/questionable. Should this be where the model should be showing the rain in reality as opposed to further to the W-NW over the Mims area south to Cocoa? Will anything form here at all due to the current presence of cirrus clouds? They seem to be on the verge of thinning out.


(2) Further north from near Daytona/Ormond Beach to St. Augustine. This area is being watched for stronger synoptic scale winds and the tip of better moisture convergence from the South. This area does not seem as likely to generate a strong storm due to lack of convergence or a trigger, but it gets more iffy the further south one goes in that area going toward Daytona/New Smyrna. Con for this area is also cirrus clouds. The West Coast Sea Breeze does not play in today and the cirrus here also appears to be thinning as of 1:30pm.


(3) South Brevard/St. Lucie/Martin/North 1/2 of Palm Beach County: Very sketchy. Only one model shows a precip bullseye down there. One which later took that chance out. But I'm looking to differ. The best onshore/sea breeze flow should be down in SE /South Central Florida (coastal) beginning after 4:30pm and maximized after 6:30pm (as is the case in the other locations). Dew-points inland will be allowed to rise after peak heating has subsided, thus moisture convergence will increase in all areas. This area could get an additional boost from the Lake Okeechobee "Shadow Affect"  from South Brevard to Martin County. Oddly, one model showed that something to generate down there would latch on to upper level jet stream winds and take a deviant right turn down the sea breeze boundary toward SE Palm Beach County before exiting off shore and dying. VERY odd ball, but 'odd events' have occurred in the past in all 3 of these locations, even on a normal summer day. They are normally lmited though to when the gradient flow winds are much weaker than they are today. Less cirrus clouds in this area...at least for now, favors this area.


All activity, assuming it can be generated, will be on the East Side of the state, with initiation contingent upon how far inland the Sea Breeze can penetrate...but it's hard to imagine that despite that fact I'm sitting here typing with an ESE wind to my back. that not far away to the west toward I-95 there is likely no sea breeze. So far, it seems to be not much further than I-95...additionally, the Big Lake Shadow is showing up with a vector toward North East Brevard along I-95 near Titusville along its Eastern Flank. Far South Florida seems to getting scoured out by the combined gradient flow with the Sea breeze so the Miami Metro area/ Dade and most of Broward can likely be tagged' out' for storms today.


*As of 12:45pm the Hazard outlook from the MLB NWS has not changed. See this link for the latest update or click on the title of this post to be steered there:


http://www.srh.noaa.gov/images/fxc/mlb/Latest.gif


THURSDAY: Different type of day and much to cumbersome to go into detail with. Best chance of strong/severe storms is over North and far North Central Florida with a secondary area over Eastern Portions of North Central to Dead Central (near the Beach line to Eau Gallie Cswy corridor) late afternoon as noted yesterday.  All activity will occur along a pre-frontal boundary over North Central to Central rather than on the front proper. South Florida may also see another round of thunder/showers in the afternoon due to different circumstances altogether, favoring SE Florida.


FRIDAY: South Florida and portions of South Central will be favored during the noon time to Early Evening as the front moves further south and goes stationary over the Keys area by late Friday through Sunday. Over the weekend the Keys and extreme South Florida might have a chance of showers and thunder, especially far SW Florida over the weekend.


MONDAY-TUESDAY: Moisture inches back northward into Central and then all of the peninsula, by late Tuesday in response/ advance of another approaching frontal boundary. This boundary might not penetrate as far south and could get hooked up across North Central or North Florida beyond next Tuesday...so later next week week is still up for grabs over the peninsula as to whether rain chances COULD remain for much of the second half of next week. It appears that if this does occur that showers would be caused by a long fetched/duration onshore moisture/flow component, with thunder favoring SW to West Central Florida. Way too soon to say.