July Like Conditions Return On the First Day of Fall

Although anticrepuscular rays appear to converge onto a point opposite the sun, the convergence is actually an illusion. The rays are in fact (almost) parallel, and the apparent convergence is to the vanishing point at infinity.  Anticrepuscular rays are near-parallel, but appear to converge at the antisolar point because of linear perspective. Anticrepuscular rays are most frequently visible near sunrise or sunset. These were observed this morning, but were seen a few other mornings this week just before and during sunrise.

And at the same time as the above image, this storm was over the ocean. Looking toward Canaveral AFS, seaside.

TODAY: Today is the first full day of fall, as of 5:05AM. That might be true in regard to how the earth is aligned with, and rotating around, the sun; but the weather today looks much more like that characterized by a mid-July day. One with plentiful moisture and little to no synoptic scale boundaries. It won't be quite as hot as it is in July, but otherwise all things appear to be equal. And like in mid-summer, outlining any specifically higher potential areas for rainfall is difficult other than the blanket, all inclusive "all over the interior" stand-by.


As of 1pm , the sea breezes have begun per visible satellite imagery. Some showers were ignited earlier due to an outflow boundary off the NE coast in the Flagler County area which moved ashore in that region, but otherwise showers are few and far between. Moisture content today is high (2.00" +), and once moisture convergence begins as the sea breezes approach each other it will be even higher. Steering today is weak, but generally from the WSW-SW at 10mph or less, and apparently restricted to the north half of the state. Toward Lake Okeechobee and South into the Everglades currents are less than 5mph. Showers should start to begin well before the sea breezes meet, but most prolifically after 3:30-4pm. A few more lightning prone storms could form before and during that time, but have the greatest overall coverage and strength after 4pm -6pm.


Ocean showers were lacking this morning other than right over the coast of Central and North Brevard, since steering is no longer bringing them ashore north of Palm Beach County. A few formed within two hours of sunrise, and one was easily visible a full hour before sunrise as the first rays breached the horizon and lit the top of this tall shower under otherwise nearly full-dark conditions still in place while the moon and stars were quite visible even still...

Fairly uniform distribution of moisture and instability with weak steering, especially over the Southern 1/3 to 1/2 of the state. Further north toward Brevard, showers or storm debris could move offshore toward early evening, and perhaps a series of storms/outflows could back build to US1 after 5:30pm, and maybe move offshore north of the Beachline or just maybe as far south as Sebastian Inlet.

 Like most July days, the bulk of activity today will be over the interior, but visible from the coast albeit at a "not so far away' distance. It looks like there should be a good coverage of activity today, and like yesterday some storms could contain considerable amounts of dangerous lightning activity and very heavy rain. With slow storm motion, and with rains likely impacting some of the same areas impacted yesterday, localized street nuisance flooding/puddling is possible. Rains were quite heavy yesterday over the interior at some locations, and some areas received heavy rain more than once. 

Rain so heavy it looks 'bluish'. Note how lush the interior swamp lands are now after a full summer of storms.

Strong storms are not anticipated in regard to winds/hail, but if so would be most likely to occur toward the far north where slightly colder temperatures aloft might exist later today.. the strongest storms will likely occur due isolated/localized mesoscale boundary interactions.  


Storms/showers/remaining light rain pockets could continue in the chosen select areas until 10pm tonight, if not later. The rains today when all is said and done will favor more toward the east side of the state, but most anywhere 10-20 miles away from the immediate coasts could see rain today. The least likely area appears will be over the Western Panhandle, but there too, a strong storm or two could occur but of more isolated nature.

SATURDAY/SUNDAY: So far it appears nothing significant enough beyond what has been written for two days now has changed. Thus, more July like weather. Activity could start a bit earlier on Saturday...it is interesting to be watching this (below):

This area of disturbed weather  has no apparent surface lows, or any lows really although some guidance points to weak cyclonic circulations in the mid-upper levels here and there. Overall, this appears to be deep moisture being rotated around the western and southern periphery of high pressure that extends well out into the Atlantic.  The activity is propagating generally in the direction of the yellow arrows. Even though this is not a 'system', some of the moisture associated with this activity could come in to play over the weekend for at least the South half of the state.

 MONDAY/BEYOND: There is a nearly cutoff low pressure system, quite large, parked over Illinois. This area is quite expansive and Florida is just barely receiving some the mid level circulation around it (hence, the light WSW steering currents in the mid-levels). The surface front from it is almost completely wrapped around the low, but a weak lee side trough has popped up from time to time down the Appalachians, with a more well defined boundary tracking south then almost due west in the Southern Plains.


Most guidance has leaned toward filling the low and lifting it out toward the NE on Monday, while the frontal boundary gradually drops south and east with time into the far Deep South and into the Panhandle of Florida by Tuesday. At that point and beyond it becomes nearly indiscernible and dislocated from the parent low pressure area now very far away,  as nothing more than a gradual change in wind direction and atmospheric drying. 


Thus, by Monday rain chances might be restricted to the Southern Half of the state, but not entirely. There has consistently been a drying out period portrayed, but much will depend on where the boundary ends up over the state (assuming it washes out over the state). Wherever it ends up will end up being a focusing mechanism for moisture convergence so that despite lowered overall atmospheric moisture being infiltrated into the state due to the loss of the tropical connection, there could still be showers and thunder somewhere, apparently the whole way into next weekend. So far, Tuesday seems to be the most quiet day other than the far South and the Panhandle (where the front will reside at that time). The morning GFS of 2AM has the boundary washing out over Central Florida heading into mid-week next week as high pressure moves in to the north and easterly flow returns, but none of this looks particularly legit from a meteorlogically realistic aspect, so the future like all of them....heads toward:


"Live as if you were living already for the second time, and as if you acted the first time as wrong as you're about to act now"

Only Thing to "Fall' on Friday Will Be Raindrops

The Sun’s away

And the bird estranged;

The wind has dropped,

And the sky’s deranged;.....

This morning 9/22/2011 at sunrise

......Summer has stopped.

And some are very frustrated about seeing it go so fast. My sentiments exactly.

Grrrr...

Fall begins at 5:05 A.M. EDT, Friday morning. The autumnal equinox is defined as the point at which the Sun appears to cross the celestial equator from north to south. The word equinox means “equal night”: Night and day are about the same length of time. In addition to the near equal hours of daylight and darkness, the equinox is a time when the Sun’s apparent motion undergoes the most rapid change. Around the time of the equinox, variations in the position on the horizon where the Sun rises and sets can be noticed by alert observers from one day to the next. Eventually, it will be rising and setting along the southern horizons as we progress toward December 21-22 as the first day of the Winter Solstice approaches. 

TODAY: Deeper layer moisture is entering the picture as expected, although this still does not mean widespread rains due to lack of any boundaries and few triggers. Ample daytime heating though will give rise to  respectable upward motion (vertical velocities). The models are again a bit out of whack, with even the short term RUC rotating an  inverted mid-level trough from south to north during the day across South and Central Florida. This, in turn, would change steering currents from SSE to nearly SSW-SW by late today. Do not believe that will occur to such an extreme, but continued SSE-S Flow seems more likely, with winds closer to the ground remaining ESE-SE. This would progress the east coast sea breeze inland for the focusing mechanism for the peak storm period after 3-4pm west of I-95. If winds aloft do become more southerly, then outflow or even back building could work storms toward US1 north of Vero Beach by 5pm, to possibly the beaches from Daytona and north. Best hedged bet relies on storms remaining in the interior at this point though.

Up to this point this morning, it appears some showers with lightning from time to time generated from eddies off the western Bahamas,   worked into Palm Beach County. Since earlier this morning, they have been working up the east coast, with some renegade showers reaching the coast further north toward Flagler County. The showers seem to be increasing off shore now that the sun has risen. With that, perhaps the RUC has something there with the more SSE-S Flow to develop later in the day

 . 

But for now, it's probably best to rely on persistence, since there is nothing evident that would preclude a persistence forecast of past model trends. What is happening out in the Gulf is interesting though. It appears much of the activity there is being provoked by divergent Southern Branch jet stream winds...which will remain over the Gulf for at least 2 more days. These are shown further down in this post.

Showers along the East Coast should work north and possibly increase after 10AM. Some could contain lightning, more so after 11AM to noon. If so, outflow from these near the coast and just offshore combined with the prevalent ESE-SE flow at the surface will send boundaries inland for greater storm coverage. Storms could start to occur earlier today than in the past two days., possibly peaking between 3-5pm.

FRIDAY-SUNDAY: Not any change in line of thought for this time frame with an increased chance of thunderstorms   most anywhere. The pattern will eventually evolve as to end the morning rain showers near the coast or at least put a lid on the amount of them, with afternoon storms forming by early to mid-afternoon and ending near sunset. Storm motion will be slow, but they should work northward and  a bit toward the east, especially on Saturday and Sunday.

It was noted that a La Nina pattern was evolving or had evolved in August in a post over a week ago. What does that can mean as we work into winter? 

In regard to the tropics, tropical storms and hurricanes have hit Florida during La Nina events in October. So far, it looks unlikely to occur, at least through the first week of October. There has been, coincidentally since the La Nina Event was made public, a developing southern branch jet stream running across Southern California toward Florida...it is quite apparent still in model guidance..and is expected to remain in place to varying degrees over the Gulf and near Florida for quite some time to come.

 Here is the forecast for today's jet stream and the forecast of October 6  

 

A general  discussion concerning La Nina years follows.  Note that from these images above and then  provided below, that a La Nina like  pattern seems to already be established. It does not mean this will always be the pattern all the time, just the more prevalent one. 

.La Niña conditions returned in August 2011 due to the strengthening of negative sea surface temperature (SST) anomalies across the eastern half of the equatorial Pacific Ocean (Fig. 1). With the exception of the far westernmost Niño-4 region, all of the latest weekly Niño index values were –0.5oC or less . Also supporting the return of La Niña conditions was the strengthening of the below-average subsurface oceanic heat content anomaly in response to increased upwelling and further shoaling of the thermocline across the eastern Pacific Ocean

The better model performance, combined with the historical tendency for significant La Niña episodes (as in 2010-11) to be followed by relatively weaker La Niña episodes, leads to increased confidence that La Niña will persist into the winter. While it is not yet clear what the ultimate strength of this La Niña will be, La Niña conditions have returned and are expected to gradually strengthen and continue into the Northern Hemisphere winter 2011-12.

The Climate Prediction Center defines. . ."La Niña conditions" as existing when: A one-month negative sea surface temperature anomaly of -0.5C or less is observed in the Niño-3.4 region of the equatorial Pacific Ocean (5ºN-5ºS, 120ºW-170ºW) and an expectation that the 3-month Oceanic Niño Index (ONI) threshold will be met AND An atmospheric response typically associated with La Niña is observed over the equatorial Pacific Ocean Across the contiguous United States, temperature and precipitation impacts

associated with La Niña are expected to remain weak during the remainder of the Northern Hemisphere summer and early fall, and to generally strengthen during the late fall and winter. 

During September-November 2011, there is evidence that La Niña favors an increased chance of above-average temperatures across the mid-section of the country, and an increased chance of above-average precipitation across the Pacific Northwest

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.html

La Niña episodes are associated with three prominent changes in the

wintertime atmospheric flow across the eastern North Pacific and North

America. The first is an amplification of the climatological mean wave

pattern and increased meridional flow across the continent and the eastern

North Pacific. The second is increased blocking activity over the high

latitudes of the eastern North Pacific. The third is a highly variable

strength of the jet stream over the eastern North Pacific, with the mean jet

position entering North America in the northwestern United States/

southwestern Canada.

Accompanying these conditions, large portions of central North America

experience increased storminess, increased precipitation, and an increased

frequency of significant cold-air outbreaks, while the southern states

experiences less storminess and precipitation. Also, there tends to be

considerable month-to-month variations in temperature, rainfall and

storminess across central North America during the winter and spring

seasons, in response to the more variable atmospheric circulation throughout

the period

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensocycle/nawinter.shtml

 

Will a 'Caribbean Express' on the Tropical Connection Dampen Weekend Plans?

Sunrise Sea Storm On The Approach This Tuesday Morning, Looking South-southeast from Cape Canaveral 

TODAY: Very little change in thinking required today through Wednesday. Mainly SE winds, light but prevailing from the surface to 10,000 feet over South and Central Florida continue to draw in sporadic atmospheric moisture globs. As anticipated, the east coast (namely Brevard and eventually parts of Volusia and Flagler) got in on the rain act over night through late morning. The Brevard Activity has ended, but not before sending outflow to the west through north, which is generating more activity further from the coastal communities toward I-95 and west.  Expecting most thunder and lightning over the interior today, isolated and possibly becoming a bit more scattered toward late afternoon and dinner time over the interior..mainly from Osceola County and north in the same locations as late yesterday, although more could be found toward I-10 as well. Some stronger storms are possible later today to the far north near Gainesville and west of JAX, although some high clouds on the approach from the west might offset that possibility.

It is up for debate as to whether the west coast sea breeze will be able to from today, or at least in regard to how far that breeze will work east and away from the coast. The pressure gradient at the surface is light through the lower levels, so with daytime heating it should be able to work a good  10 -15 miles inland. The East Coast Sea breeze has started already, but should make less inland progress north of Volusia County. Stronger storms are possible over far North Florida and perhaps toward the SW Coast. 

TONIGHT/WEDNESDAY: Increasing moisture on continuing SE winds (light and variable at the surface overnight) should continue. The diurnal cooling of the land mass overnight in opposition with the now warmest waters most of the east coast sees at this time of year could give rise to more showers and maybe some thunder after midnight, mainly upstream of the North and Central Bahamas where wind current eddies provoke/stir the atmosphere over the warm waters to generate showers. This morning the 'chosen spot' was  eastern Brevard County. Guidance points toward that location again, but the reality is that there is no definitive way to know for sure if there or anywhere will fall victim. My location received over 1.8" of rain between 1AM -11AM this morning.

Downpour around 9:30AM, Accompanied by Thunder

 
THURSDAY/WEEKEND: Will put this entire frame in one category for the time being.
The frontal boundary alluded to yesterday near the Mississippi River, sure enough as guessed (despite what some guidance had shown), is now no longer forecast to progress beyond NW Florida toward NE Florida for quite some time to come. The parent upper level low is shown by the GFS to nearly cut-off from the main jet stream flow..although in doing so over Lake Superior, it is resupplied by impulses from the Northern Branch Jet Stream from the WNW (Canada)...these impulses or waves of energy evoke the low to Drop toward the SSE over Lake Michigan as the are pulled in and drop down the backside of the low. 


Despite the normal attempts to continue eastward it begins to confront the vast high pressure area that stretches from the far Eastern Atlantic to the United States.  If one is to believe the GFS, this trough is no match for such a might region of high pressure, so instead of moving further east it simply works south with time...with each disturbance feeding in from the back (west)...it drops yet further south through the Tennessee Valley. As such, the pressure gradient in the mid-upper levels tightens harboring more of a steady SSW flow aloft, while winds at the surface remain much lighter, enough to allow sea breezes each day.  


Meanwhile, as the trough/low drops further south, the "Caribbean Moisture Express" is enhanced further both from the far SW Gulf as well as the south and Central Caribbean.  If again, one is to believe the GFS, then this moisture will feed the whole way up the Eastern Seaboard over  Appalachians toward Maine through Monday next week as a series of impulses exits Florida (perhaps as a result of diurnal afternoon thunderstorm activity over the state) or off the coast of SE Georgia, all commencing sometime around Thursday but much more pronouncedly by Saturday.

Colors are depicting the amount of deep layer moisture. Purple is very high moisture content (necessary to produce rain) whereas the light blue toward the Rockies is very low. This is the forecast of the GFS for Sunday evening. But it continues through early next week. Moisture is being converged or squeezed between high pressure on the far right and low pressure to the west. In this image is also shown some higher moisture dropping into Louisiana/Eastern Texas. That is a reflection of another disturbance dropping south, to eventually join forces with the "Tropical Connection Train" by Tuesday.

 Again, the extended as always is to speak in only very general terms. The next model run will show a variation of this theme...and by the end of the weekend if not much sooner the picture could be quite different. In fact, there might be several variations or completely different conclusions on a continuing basis. The truth can only be revealed as it happens, or at least within a 24-48 time frame. 


 It would not surprise me if even a surface low forms over or near Florida during the course of the weekend. There is  a brief time frame where Florida is shown to be in northerly winds, as perhaps one indeed does form, but then gets scooted up the east coast as some sort of faux warm front.


Flooding might become a big concern for eastern parts of the Mid-Atlantic and west toward Eastern Tennessee and into Virginia before all is said and done if the scenario depicted this morning actually unfolds and comes to fruition.


TROPICS: The tropics are being watched, and there might be an "Ophelia" on the approach in the next couple of days. At this point, it appears any said such storm would have to be either diverted north or continue westward into the Caribbean...and over the Leeward/Windward Islands. If it is diverted north, that would mean a break in the pattern just described above...and anything beyond Monday is completely out-to-lunch on the GFS run of 8AM this morning. 

The rains finally broke this morning

Slow Transition to Moisture Laden Southeast Flow Emerging Through Wednesday

A slightly better chance of thunderstorms today toward Ocala and interior Volusia/Flagler and in the Gainesville area. Also along the SW Coast. Coast showers could re-appear within 1 hour of sunset (very isolated) along the Central to Southeast Coast...more numerous the NE Coast toward JAX and SE Georgia.

TODAY: Not much change in the line of thinking from yesterday's post. An inverted trough has appeared, temporarily as almost a very weak close surface low over Brevard County. This feature will move inland with the sea breeze and daytime heating as a weakly defined, inverted thermal trough to act as a focal point for more thunderstorms than the past few days over the interior (which isn't saying much). Lightning was observed near noon time in North Brevard as the showers, moving generally toward the NNW moved inland from Central Brevard.  There is a small chance of an isolated shower or two re-appearing within one hour of sunset along the beaches most anywhere while the activity over the interior should dwindle rapidly after sunset. Northeast Florida seems the most likely candidate for that early evening activity, although one or two is possible Central.


TUESDAY: Another slice and dice day of where/when the renegade showers will occur. Most likely before 11AM along the east coast, progressing into the interior by shortly after noontime and re-emerging as thunderstorms from early afternoon, and peaking in strength between 4:30-7pm. in other words, much like today.


WEDNESDAY and Beyond: The NAM has been consistent (for a change) at showing a region of higher moisture (PWAT) air over the SW Atlantic to progress WNW toward Florida during the course of the next 48 hours. For two consecutive runs one can actually trace the rain field areas it depicts approaching systematically toward the east coast of Florida for arrival by late Wednesday afternoon. The GFS is far less as obvious, but both do show a broader coverage of atmospheric moisture for a greater coverage of showers and some thunderstorms, but by no means will every one be seeing rain. All in all, it might seem more like a typical summer day albeit just a tad cooler by a few degrees. Favoring the west side late in the day for the heavier storm activity. Thursday looks similar.


Elsewhere, during the next few days a frontal boundary will be inching eastward toward the State. It is moving at such a snail's pace as it rams into the ridge running down the Appalachians as noted in the image above (with yet more in the Atlantic)..that it can barely reach Central Florida before being stretched thin (Saturday/Sunday time frame).  For comparison's sake, were this a 'normal' frontal boundary in mid-winter it would be through the state by Tuesday night from its current location, which is  down the Mississippi River Valley area.  It still appears the boundary will make it to Central Florida or thereabouts, and be able not to progress much further. That is at the surface. Just above the surface the upper level supporting trough lags well behind..as if to emphasize this is not a 'big temperature dropper', but rather a focal point for showers/thunder.


Beyond Saturday we are already into the time frame of greater unreliability and tremendous variations from run to run, although the GFS has been fairly consistent in having this boundary merge with a broad area of low pressure over the Caribbean.  In fact, the morning run now cuts the remaining frontal boundary off into a close surface to upper level low pressure area encompassing most all of Florida by the middle portions of next week. This is highly unlikely as well as any other extended outlook has and ever will be. But the implications, or rather, the tendency for this model to want to evolve into some sort of transformation of low pressure areas off and on again for over a week near or over Florida in the extended can't be completely ignored. There is a brief drying period during the transformation, but the gist has been that no big temperature dropping frontal systems appears yet to be fully in the making for a big cool off for anywhere beyond the Panhandle and Northern portions of the state into October. That too, could change. But not within the next week when fall begins on September 22nd at 5:05AM. Last year, our first fall like day arrived almost simultaneously with the passage of Tropical Storm Nicole (September 31st). From October 1st and beyond, summer or any semblance of summer ceased to exist.

Persistent Current Patter Remains In Place Through Tuesday

Sunday morning rain-shower near the Coast of North Brevard County. This shower seemed to form along the leading edge of wind surge, which never quite made it beyond the immediate coast...and after which retreated to offshore. This could be the chain of events that unfolds the next two or three mornings, which an enhanced area of more prolonged rainfall somewhere between Coastal North Brevard toward St. Augustine each day during that time frame.

General Area of Rain shower activity today (mostly isolated), except possibly along the coast from North Brevard, through Volusia, and into Flagler County where there is potential for some higher rainfall totals. Little change in the current pattern is expected through Tuesday.

TODAY-TUESDAY: Little change in the overall pattern appears to be in order for the next 48-72 hours. Weak low pressure that formed near the Carolina Coast slid NNE ward during the past 24 hours and has left a remnant mid-level boundary just off the SE U.S. coast. 


Yesterday, the end of that boundary reached into the JAX area, whereas this morning the boundary had pushed south toward Daytona as high pressure built down the Appalachians. It is that boundary which will be the prime instigator for potential more coastal rain events due to the fact that this thinly stretched out boundary cannot progress further east due to a vast high pressure area extending completely across the Atlantic to the coast of Africa and southern portions of Europe.  It is possible that heavy rain fall events could occur in the next 48 hours somewhere along coastal North Central to Northeast Florida from overnight to early morning and one or more of these days. Meanwhile, a frontal boundary will be inching in from the west (now across the Southern and Central Plains)...but the log jam will be hard to break. Thus, little change for a while until 'something gives'.


The weather today is a far cry from what occurred on this date in 1926 (85 years ago), the year of the Great Miami Hurricane. Even as little as 24 hours prior to that storm, hurricane warnings were not hoisted. 


I will add that there is also a secondary bubble of high pressure over the SE States center just NNW of Florida. This appears to have broken off from the fixture that was over Texas most of this year (since early mid-spring time) which generate the drought there. That high pressure is almost completely gone for now, but an even large high pressure dome could be in the making for much of the Western U.S. during the week ahead. It was the leading (and in sinking( side of that high pressure that was responsible for the string of dry days over Florida last week. That high pressure will gradually flatten out with time, with a portion eventually  ejecting eastward into the Atlantic with the other portion retrograding into the NW Gulf and back into Texas. This process will be a slow one though.

Did you hear about the big rainfall totals overnight Friday night into early Saturday near Jacksonville? Here is a Storm Total (of rainfall) obtained via weathertap.com compiled from the JAX radar yesterday morning, followed by a preliminary informational statement release by that office. This was Day 1 evidence of that boundary at play. 

"A FRONT STALLED OUT OVER THE AREA COUPLED
WITH A MID LEVEL DISTURBANCE HELPED PRODUCE STRONG STORMS WITH
HEAVY RAIN ACROSS A PORTION OF THE JAX METRO AREA. 3.35 INCHES OF
RAIN WAS REPORTED AT CRAIG FIELD OVERNITE. HOWEVER...THERE HAVE
BEEN DOPPLER ESTIMATES OF NEARLY 10 INCHES NEAR JAX AND PONTE VEDRA
BEACH. MAJOR FLOODING WITH UP TO 3 FEET OF STANDING WATER AT JAX BCH
AND 6 INCHES OF STANDING WATER IN A CLUB NEAR ARLINGTON.
DOPPLER RADAR CONTINUES TO INDICATE CONVERGENT BANDS OF SHOWERS...
SOME HEAVY...ALONG THE COAST" - JAX (Jacksonville NWS Office)

Meanwhile, this morning the same sort of event occurred in Volusia County, although not nearly to such a degree. It appears it might not be over quite yet, even though as of this time the rain there has ended, more lurks very close to the coast if not already back on shore as I type. I've noted an area of interest in lavender where more convergent rain-bands could set up today or tonight in the first image.


Elsewhere, despite model guidance and actual 'near current' data portraying dry conditions over South Florida, rain showers moved into Palm Beach County..much to everyone's surprise. These are low topped showers, but nonetheless persistent. These showers appeared yesterday morning and once again this morning despite lack of rock hard evidence that would call for them to be placed in a forecast due to lack of any sufficient surface features other than some moisture.  There appears to be a small cyclonic circulation approaching far SE Florida as of noon time, so more showers could move into Dade/Broward Counties, and after a break toward the Keys, they might be in for more later today and tonight as well.


Otherwise, when looking at parameters to support thunderstorms, the most unstable atmosphere has been along the east coast of Central Florida mainly from Central Volusia to Central Indian River Counties. Despite these parameters that are based on low level factors, the mid-levels are too dry to support anything other than low topped showers in the absence of a triggering mechanism other than convergence which happens rather sporadically and haphazardly. Only closer to the near 'phantom boundary' near Volusia/Flagler where moisture is deeper through a greater extent of the atmosphere does it appear more certain that rain chances should  be higher, as well as some thunder. Even an offshore waterspout should not be counted out. A YouTube friend of mine shared that he saw a waterspout offshore South Brevard Saturday morning, but this was not noted in official documentation released from MLB.


MONDAY/TUESDAY: As it appears now, little will change in the given on again/off again pattern until a deeper, stronger  trough can approach from the west   toward the state to nudge high pressure out of the way.  I will write that this was originally portrayed to occur (several days ago) in full by Saturday, then Sunday..but it keeps being pushed further out in time. Thus, although a BIG change is expected to transition through on Wednesday and be in full affect by Thursday..we'll just have to keep monitoring. It is the time of year for the first cold front to reach Central Florida, so this train of reasoning is not out of the question.


BEYOND: With the above already stated, one can make the assumption (and if 'reading' the models, it would be a fact)..that by Thursday the mean moisture advection will commence from the SouthWestern Atlantic and even the northern Caribbean. This would bring forth even deeper atmospheric moisture and a return to thunderstorms, especially by late Wednesday and more so on Thursday through Saturday. That is the course of thought as of this morning, but it will take two more model runs (or by tomorrow morning) for this to be more assured.  In the great beyond, a combination of the front (trough) from the continent is depicted to merge with moist/cyclonic (low pressure) circulation from the Caribbean over Florida, at which point the GFS looses credibility completely. The over all trend though, is increased rain chances on Wednesday as thunder storms become more likely (or in other terms, beyond occurring in only random/isolated fashion).

Sunday Morning, September 18, 2011 

A Few Isolated, Strong Storms Possible Mid- Afternoon Until 9pm

Sunrise Thunderstorms East of Florida This Morning

TODAY: A state divided with further complications. A tropical wave over South Florida with abundant moisture and a high energy vort max from the Continent at the base of a large upper level trough approaches, so far, unseen due to lack of moisture further north. But, it will run into ample moisture toward mid-late afternoon across South Central Florida.


SOUTH FLORIDA: A dampening out tropical wave containing abundant moisture is washing across South Florida south of Lake Okeechobee. Showers and some thunder began fairly early there as a result. Little is happening further north.  Storms might let up for a short time early afternoon, but pick up again as a disturbance approaches from the NW-WNW aloft most directly entering Central Florida.


CENTRAL FLORIDA: Isolated Storms, but they could be strong as a large disturbance begins to move in closer to the peninsula this afternoon. Moisture in the atmosphere is very low north of the Beach line, but there is just enough to maybe squeeze out a storm toward DAB or JAX if the timing is right, but it will be late.


Further South toward the Beach Line, what remains of the old boundary of the past 5 Days has pushed south and is aligning very close to the jet stream flow aloft to move in as the day progresses. Moisture is just enough to squeeze out some storms, and with the winds aloft forecast to be in the 40-60 kts range, combined with the upper level vort max (shown below) this might not be enough yet to trigger storms alone. It does look however, like a storm or two could get going on the NE side of Lake Okeechobee, which like yesterday, would send an outflow boundary northward to meet up with that old mid-level boundary referenced above. That boundary has been the cause of storms for several days now..and this might be its last shot.


Surface winds north of the lake are forecast to be quite light and variable in the lower levels of the atmosphere after good heating has set in and breaks down the light NW flow now in place as I type, so a light sea breeze should initiate by 2pm  ...coming off of warm and moist ocean water temperatures above them. There has been some drying in the atmosphere mostly north of Ft Pierce/Vero...so this area north of Vero will have to wait until late as the sea breeze is in place for a few hours to get things going -  timed with the upper level disturbance..as well as some colder air aloft in the mid-levels that comes with it.

 If things play out just right in the timing of the disturbance, late time of day after sea breezes have come in to play and the Lake Breeze, and any outflow from the south...any storm or three to go up toward the Beach line and south in Osceola County and north of the lake  could be strong and hold itself together to the coast. At one point storms might become almost scattered in nature right along the boundary after 6pm . Again, it could end up being later. Guidance portrays rains in those areas as soon as 4pm..but I'm hedging toward later, as has been the case the past 4 days...other than an earlier storm toward Ft. Pierce and maybe working toward Sebastian Inlet. 

This was my line of thinking early this morning. This satellite water vapor image shows the storms that were ignited during the predawn hours along the boundary that seems to have shifted south. There is an apparent low pressure circulation east of JAX as well today..that area is forecast to drop south a bit during the day and maybe even back in toward the coast toward 6pm, thus, a storm could occur near JAX and DAB closer to that boundary along which some atmospheric moisture which would have to converge along it.  


TUESDAY: There might be an isolated storm once again east central, but if so..early. Otherwise, it looks more like far SW Florida will have the rain chances later on Tuesday and Wednesday.


THURSDAY/FRIDAY: Maria is supposed to have moved well north and east of the state, and will leave a weal mid level trough behind along the East coast from just of JAX to off the mid-Atlantic. High pressure building in across the east tier of states is forecast to recirculate moisture along the trough into JAX and eventually further south heading toward Saturday. However, at this hour the storm is nearly stationary and is being sheared apart. Will it maintain? So far the models have been saying 'yes' in some form or another.


SATURDAY/BEYOND: Winds become more easterly to southeasterly, and advect more tropical moisture into the state heading into next week. At which point, rain chances could be in place each and every day toward the end of the month. The Tropics from the eastern Gulf, all of the Caribbean, and toward the Bahamas will need to be watched during this time frame for development, especially heading toward the end of next week.

Questions Abound Today Concerning Where, When, and If

Storm Approaching Merritt Island toward Port St John on Saturday viewed near the South Gate Entrance of the Kennedy Space Center near Port Canaveral. It is evident from this image that this storm was 'feeding' on the mid-level boundary across Central Florida by the long line of clouds on the right portion of the image . Although not frequent, this storm ejected powerful lightning bolts and dropped very heavy rain. Another storm was further north, and outflow from that storm fed into this storm, further magnifying its very small but dutiful strength.

Zoomed in a bit. Lightning was coming out well to the left and right of the rain core noticeable in the center

TODAY: Very difficult forecast for today. And no surprise. Recall the model forecasts for today were 'dumped', and it was stated we'd figure it out today?...It is still hard to figure out even at this hour.  After looking through overnight guidance, that which came out so far this morning, as well as monitoring actual information using 3 hour animations of the changes since sunrise...today's post is again in lieu of any model. They all agree to disagree concerning where and when it will rain today...if anywhere.  Thus, here's the line of thought and how it transpired.


Initially, it looked like good rain coverage over most of the state along and south of I-4 with the most south of Lake Okeechobee oozing into toward East Central and perhaps toward Jacksonville. But....

IN looking at water vapor loops, it appeared that a weak circulation off of SE Florida which contains drier air might prevent the tropical wave forecast to move in from the East to have the effect thought in regard to increased rain chances over South Florida (which was to be high end coverage). In fact, it is now noon and there is not hint of rain to occur anytime soon. In fact, after reviewing time sequenced loops of the past several hours, this area is becoming more stable. There is moisture, but it is at the wrong levels to generate storms.  The other area is the old boundary across North Central Florida. It seems to have moved little, and actually a storm went up along it off shore earlier this morning that showed rotation and quite a bit of lightning. This boundary remains in place today, but not nearly as clearly.

Rotating Thunderstorm Off Shore Along the Boundary Across Central Florida

See the colored text for important  finer details. With all factors considered and after some internal 'negotiating a reason for rain', the case for best rain chances was  created. Storms were thought to form west of the coast of SE Florida and move toward the West Coast as well as over the Keys. Across Central in the white lines is south of that boundary that has been in place for 4-5 days. Out in the Northern Gulf though appears to be a disturbance moving east to move over the state..or approach after 5pm. This could add lift but add nothing for an atmosphere too dry over NW Florida but toward JAX is a different story.  The SPC analysis page also shows a circulation over NE Florida and it now shows up on the satellite image last hour (below). I was also watching for an outflow boundary to move west from the Atlantic to maybe start off some showers around 1pm ..but that seems to be fizzling well off to the east...although one model managed to pick up on it, to generate rain by 1pm. Not going to happen though

The circulation near JAX is evident, and another along the East Central Coast which was on analysis is not evident but drawn in with a question mark. Note how at noon nothing is happening  anywhere. 

Finally, the last factor that just became evident is that unlike any model forecast has shown and which explains why nothing is happening, most of the state has become capped in the mid-levels with convective inhibition. Thus, it looks to be another late day to evening rain chance, if any. One model showed close to no rain most anywhere today which might have ended up being right on...


The other 'finally' is that the next trough approaching from the WNW-NW forecast to up the rain chances on Monday might be moving in faster than thought. This could mean less rainfall coverage tomorrow due to the bad timing of its arrival for late day storms (except toward the South Half of the State). Thus, the forecast for Monday is in limbo. 


And one more thing while on a roll, so too may be the forecast for Tuesday out to lunch (per TV). Much depends on how strong, big, and in which direction Maria takes in the next 48 hours.


 If it stays further to the east than thought, the state might not get into the sinking air surrounding the storm..so there could be some rain chances as shown by the very conservative and unreliable NAM model.  The next boundary moving in tomorrow could get hung up across South Central Florida on Monday (in that case) and be a rain player for 'somewhere' for Tuesday, of isolated fashion.  Beyond Tuesday, the rain chances dwindle either way with an up tick on the weekend coming up.

FINAL CONCLUSION: This might be way over generous on the rain fall today but watching these areas when push comes to shove. The red is most concentrated rainstorms, and the areas near those red L's need
to be monitored. South Central is where the most unstable air is evolving as of noon time with the greatest moisture in the mid levels right along that old boundary shown in purple. With stronger upper level winds pushing in from the WNW late today and increasing mid level winds late as well, storms appear to be late in coming (after 5pm) once again north of Okeechobee County/St Lucie County. If a storm forms along that boundary and rolls off to the southeast (or even northeast toward Volusia), it could become quite potent toward Seminole County and into NE Orange and North to North Central Brevard County or into Volusia as it meets the east coast sea breeze from the SE - SSE which will form later in the day to any degree of 'strength'.  If it can rain...unlike some models show nearly none, we'll find out later today. But , if so, it could linger over interior South Central toward the east coast of Brevard/Indian River/St. Lucie County until mid-evening.

Summer's Last Gasps Through Monday, Cape Verde Season Shut Down (?)

Launch of a Delta II Rocket this morning from Cape Canaveral as captured by this blogger

“The views expressed herein are those of the author and do not necessarily represent those of the National Weather Service or affiliate/related organizations. Please consult .gov sites for official information”

TODAY'S SYNOPSIS (ANALYSIS): Not sure if there is a lot to talk about today or if there is very little. In general, the surface boundary has moved very little since yesterday and has become much less defined. Today seems to be a sort of 'transition' day with the mid-level trough having shifted much further north. Although moisture is now much further north nicely aligned with the best wind fields, instability further north is very insufficient for surface based storms, but sufficient to carry a storm based in the mid-levels. Exactly how the transition will have evolved further prior to sunset is unknown. None of the models have seemed to once again captured reality. In review of radar/satellite animations and trends, it is apparent that a weak disturbance is again crossing the state, but of much weaker origin than that of yesterday. It also appears to be based in the mid-levels but does have lightning associated with it regardless. This area of interest is  to cross just north of  Dead Central along the Beach Line and south of I-4, but favoring more toward the North.


Further South, dry air in the mid-levels is attempting to impinge across Southwest Florida but might make little more progress. This could actually enhance thunderstorms along the Southern  portions toward the Everglades/Lake Okeechobee/ and near the coast from Ft. Lauderdale north to  Ft. Pierce, especially along the east coast sea breeze.


Further North toward Central. Very light east coast sea breeze circulation close to the decaying surface boundary should prevail. Skies are quite sunny and heating is strong, but there is a very persistent area of sinking air over Brevard County in the wake of yesterday's system. Another disturbance (weak) is approaching, but will take until nearly 3-4pm to reach beyond the Orlando area, during which time the far east might be able to fully 'recover' and uncap. Thus, Brevard in particular is highly uncertain.

In this image from the Storm Prediction Center's webpage it can be seen that precipitable water is lower over the SE Gulf and trying to move into SW Florida. This is attributed solely to lower moisture in the mid-levels and could eventually enhance storm strength across South Florida especially along the East Coast sea breeze and around Lake Okeechobee breezes as far north as Ft. Pierce. The area near Brevard is circled mainly because nothing could happen in this area today. BUT, on the other-hand, conditions could change quite rapidly between 5-6pm as the area of weak rain-showers with some lighting approaches from the West, especially along and east of the east coast sea breeze .  

 The area in red is noted as being a bit capped this afternoon which currently completely precludes the area from receiving rain today. However, if it suddenly becomes uncapped late today, it would be right as the weak disturbance approaches from the west. To add, spiraling low level currents associated with the east coast seabreeze could build up around Canaveral Bight toward Port St. John and south toward Sebastian/Vero.  Southern Brevard/Indian River/St. Lucie Counties might contend as well with outflows from storms around the Big Lake to add to the mix. Under the assumption of course that anything can get going. Might be a late rain or storm show far east coast again tonight with rains lingering toward 10pm...and storms could get feisty if they can manifest along coastal Brevard and Indian River Counties.


Final note that again models are useless today. For example, according to the GFS it should be raining over much of East Central as I type, yet the sky is blue. Perhaps it is just fast. If it is correct but wrong on the timing, then east central could get a prolonged rain (light) in places through 10pm tonight. Looking out there now though, nothing suggests it will even rain at all.

**NOTE Best bet is keep an eye to the sky for those in this purple area heading toward 5pm and beyond in Brevard.. The surface boundary is still around there regardless and you never know when someone will slide one under the table to the waiter.

SUNDAY: Another random day of either very low rain chances or good ones. Thus, we'll play it by ear . I can see what guidance states but I again do not trust it mainly because it looks like something might be waiting in the wings well out in the Gulf which could head toward the state. The only thing that does not change is that the areas for rain look best roughly as in the same spots it has already occurred during the past 3 days.


MONDAY: Perhaps the last gasp of summer in the rain department. Not that we won't have more rain chances coming down the pipe. Simply, it looks like the end of the diurnal cycle, which actually ended with the passage of Irene. After Monday rain chances go to near zero through Friday when a small chance will be introduced somewhere, probably over South Florida. There where be some small chances somewhere, but it would be fleeting and small.


TROPICS: The Climate Prediction Center formally announced that as of August we are in a La Nina pattern. Much more will be posted in that regard in a follow up post in a day or so concerning what impact that has on Florida weather later in the year and into the winter. In regard to the tropics, it often means a continued late Tropical Season. Already, and as noted the other day, the Caribbean 's Pot Has yet to really be stirred...and is prime and ready for activity. It is that time of year that the Cape Verdes Season ends..and  it is definitely looking like there is little more to come down the pipe from there from off of Africa. Thus, we shift toward the Caribbean/ Eastern Gulf and western Atlantic closer to Florida and the Bahamas.  


Indeed, the morning GFS has a very large cyclonic circulation developing over the entire Caribbean all of next week including the Bahamas, all of the Great Antilles..and portions of the Lesser Antilles after Maria has made its final goodbyes (more on that storm tomorrow).


In closing, it was during the La Nina of 1999 that two storms came out of the Caribbean..one of them being..ironically...IRENE, in October.

Harvey and Irene , September and October 1999, La Nina