"But seeing they could not See; hearing they could not Hear"
“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”

"From its chamber comes the whirlwind, and cold from the scattering winds." - Job 37:9.

"The wind blows to the south and turns to the north; round and round it goes, ever returning on its course".

Saturday, April 9, 2011

Nearly Hot (Inland) Sunday - 'Capping' Warm Layer Aloft To Break Down By Mid-Week


TODAY: High pressure prevails over Florida, much like yesterday, although the surface ridge axis may have sunk south a bit today. In turn, chances of a shower far SW Florida look very fact..that is the case state wide. Land breeze over night along the coasts  will be over come by diurnal afternoon sea-breezes with a collision near the spine of the state near sunset with no affect. Temperatures aloft remain to warm and sufficient moisture is lacking as well. 

Meanwhile, a very significant severe weather situation is setting up for the Central Plains states later today where severe weather/tornadoes/large, damaging hail is a given.  Even as I write I'm seeing the values of various atmospheric parameters needed for the "Severe Weather Cake Batter Recipe" being revealed on an hourly basis. Additionally, severe weather has been ongoing in part of the Ohio River Valley as I write such as in Kentucky and West Virgina.


SEVERE STORMS/TORNADOES/SQUALL Beginning late this afternoon through Early Tuesday to impact a large portion of the country. Believe this storm system will be more significant that the one of last week in regards to tornado potential (and some could be quite strong) as well as a large hail threat; as opposed to mostly a marginal wind threat that impacted the eastern U.S. last week. NOTE: The bigger area of concern it not the area shown above. It will be over portions of Nebraska, Iowa, and South into Oklahoma to NE Texas..spreading east and expanding east , north and south through Sunday.

SUNDAY: Close to nearly HOT inland. Near classic inverted trough up the spine of the state form South to North  as temperatures reach the lower 90Fs over a broad expanse. All coasts are clear though with highs in the mid-80Fs , peaking early in the day.  But note the saving grace; dewpoint temperatures aren't going to be as high as would be the case in the summer, so tomorrow ill be like a 'taste' of summer without the salt. Coasts are 'clear' that is, except from 'Beach Flockers". Yes, "Meet the Flockers" is more than a movie.   This will be like the polar opposite to the "spine of the state" cold spells Florida experiences in the winter when a ridge extends from north to south.

Expect to see the hordes pouring out of the urban inland areas like ants fleeing the mound for sugar neatly posing as a line of sand along the coast. The severe weather will continue tomorrow far from home base as well, as the responsible upper level system moves East toward the Western Great Lakes region and an appendant cold frontal extension of this systems slices south through the Southern Plains into Texas.  All forms of severe weather are possible within these regions tomorrow.

MONDAY: Similar to Sunday, although perhaps not quite as HOT inland due to less than perfect conditions for a maxed out heating event. However, the East Coast will bear more of the brunt because the high pressure ridge axis that will have been stretched East to West across the state  at the mid-levels will start to drop south in response to the large storm system pushing across the Mississippi and Ohio Valleys, with the front pushing through the Deep South as well. 

In turn, not sure we'll get a sea breeze on Monday  north of West Palm Beach which will be closer to the ridge axis with less synoptic scale gradient WSW - SW supporting flow further south.  A late seabreeze is always possible though, just later than normal. Otherwise, dry.

TUESDAY: The dog tail end of the major storm system will pass through Georgia and cross the I-1O of North Florida Tuesday morning, and sink only slowly south toward St. Augustine trough noon time...with possibly additionally inching further south through late afternoon.  The last of the upper level winds with this system will pull out and away by early afternoon. There will be a chance of strong/marginally severe storms north of St. Augustine between 11am -3pm as is being made known by the NWS there and The Weather Channel, although I don't really see it to be a very big deal.

*** INSERT: There is the possibility that, although not reflected in any forecast and only ONE model, that as the system over North  Florida starts to collapse an Outflow boundary will push south into South Central Florida and meet a  region of greater instability further south over South Central Florida.  This would actually be the leading edge of cooler air aloft (and hence, a portion of the Subject Line of this post necessitating explanation). That being, erosion of the mid-level cap of warm air. This will be a very subtle event,, yet will be just the beginning of a new weather regime for the state.

 The GFS Model has shown for three consecutive runs that this sort of boundary which aloft will be simply a fall in heights of the standard 700mb level (and cooler air)...will be enough to establish a zone for thunderstorms or rain showers to form somewhere over South Central Florida after 5pm.  This activity would drift slowly toward the NE but weaken before reaching the coast. Again, this is merely a possibility. But the more significant thing to come out of Tuesday as 'boldly put' above will be the loss of the strong thermal 850mb lid over Central and parts of South Florida that has been in place.

WEDNESDAY: With virtually all upper level support far removed after sunset and the ridge axis now even further looks like the front will slide through the remainder of Central Florida overnight and into far South Florida by daybreak where it will remain.  Temperatures will be back to normal but the atmosphere will be a bit like a lady in waiting at this point with nothing to do  other than to generate some showers and perhaps thunder over South Florida ..favoring the SW side with a prevailing ENE-E wind most of the day.

THURSDAY: It appears the boundary will lift back north on Thursday as the displaced ridge attempts to reassert itself by building back toward the N from the SW...but will get hung up along a  line nearly paralleling the Turnpike up and down the state. This boundary may act to instigate some thunderstorms, some locally strong if this even materializes at all, due to cold air now aloft. Mainly west of I-95 for portions of South Florida and all of Central. There would be a convergence zone set up with the boundary where it meets  the east coast sea breeze. Would be very interesting to have this materialize...could make for quite a show west of I-95 from Volusia South to Okeechobee County, becoming less defined over South Florida where warmer air aloft remains.

FRIDAY: Have already bitten off more than I should chew, but I'm hungry for some thunder.  Next big storm system will already have been approaching the state on Thursday..and in response the boundary lifts north and east to Central Florida before washing out.  Could be another day of thunder favoring the East side of all of Central and South Florida, although The Weather Channel is showing "Sunny" on TV right now. Okay, so maybe that won't be the case.  But here's hoping for some drought relief.

CONCLUDING COMMENTS: Please note the image included in this post and the valid time. I believe they are seeing what I am (most of which I have not written about and is too lengthy an explanation to go into dissertation mode). But it does look like a  good chance of strong/severe storms going into Late Friday or Saturday (n that time frame, more likely Saturday) and a following short-lived respite, the extended out look is showing many days of possible thunderstorms off and on. 

NOTE: The above average precipitation depicted, it must be understood, is because this is normally considered our dry season before the summer thunderstorm season commences. So ABOVE AVERAGE  needs to be interpreted with that in mind. It does not mean insane heavy rains all the time or all day soaks. But who knows, maybe we'll have one or two of those somewhere along the line.

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TODAY- COWS in Iowa!!

Past big events
in Oklahoma

A Quick Comparison Of the NAM Forecast DSM 21z Hodograph With Past Big Tornado Events in Oklahoma
Consider other hodographs today as well because although it might appear at first glance that tornadic storms would be most likely only when the
hodograph shows vertical shear that veers strongly with height, such storms are also possible when
Fsct 12z DSM Hodograph
the hodograph is relatively straight. Considerable streamwise voracity may be present with a
straight hodograph if storm motions lie significantly to the right of the hodograph. Such deviant
right motion is commonly observed with severe storms, especially isolated supercells. In straight
hodograph environments, the effect of vertical shear is to shift the storm's precipitation core onto
the downshear side of the storm, where it then tends to suppress and eventually split the updraft
(B E. W. McCaul. Jr.. Steve Lazarus. Fred Carr)

See the Crazy COWS grazing (Cross Over Winds) from 850mb –700 mb  level winds over Western Iowa, NE Nebraska, and SE South Dakota at 21Z? And the extreme high Energy Helicity Index values along the upstream backed winds axis running over and to the east of DSM (Des Moines).

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The North Atlantic Oscillation

NAO: "The North Atlantic Oscillation Impact on Temperatures, Precipitation, Snowfall, and Snow Depth"

Latest guidance from the ECMWF Model, commonly referred to as "The Euro", indicates for several days/runs that we will be entering a period of a moderate to strong positive phase of the NAO. What 'could' that mean? Here's some information. Lsimple click on the Title of this post.

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