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As you are probably already aware. A s/w kicking out of the four corners region tonight and tomorrow will lift NE through the plains and into the great lakes region eventually phasing w/ the AJ over South central Canada and developing a large, cold PV near Hudson bay FRI and SAT.
But first several weaker waves of Low pressure will ride along a cold front--- anchored by a primary low located near Lake Superior late tonight and Thursday. As it progresses eastward there is going to be a pretty significant severe wx outbreak across the SRN plains/ Lower MS valley as the potent s/w (I just talked about above) kicks eastward across TX and approaches the area creating an environment favorable for large scale lift.
The 12z ETA is developing a very intense LLJ from the SRN plains to the GL region between 0z and 06z THU w/ speeds reaching 70-75 KT from MO into IN. this should help to transport moisture and instability northward ahead of the front, keeping the severe threat going well into the overnight hours and maximizing helicity values where the LLJ intersects the area w/ the greatest speed and directional shear. As a result SOME thunderstorms which develop ahead of any linear convective feature could easily rotate. Instability may be lacking somewhat, however the combination of favorable jet dynamics, increasing Low level frontogenesis / convergence, and PVA ahead of the s/w will maximize UVV ahead of the front and result in severe weather anyway.
It appears as if there WILL NOT be a significant SVR wx episode across FL given the fact that the best dynamics which will lead to the severe wx tonight and THU will push northeastward into the GL and New England. The wild card here is the ETA jumping on a piece of STJ energy which gets separated from the main s/w as it lifts out. IF this proves to be stronger, a more pronounced SFC wave could develop along the front and enhance the potential for stronger – dynamically enhanced lift ahead of the front and thusly a BETTER shot a severe wx FRI morning and early afternoon across the FL peninsula.
The GFS is weaker w/ this feature which does not help w/ ironing out the uncertainties here. So for now I feel that the SVR thereat is low but if a stronger trend WRT that s/w develops in later runs, things may become dicier.
That said w/ some convergence and lift ahead of the front as it sags southward across FL into an area w/ increasing theta-e and more favorable instability parameters (CAPE 250-1000 J/kg, TTs 40-50, K values > 30, LI 0 to -2, weakening CIN) the potential exists for thunderstorms w/ heavy rain given high PWs and SFC dewpoints ahead of the front increasing to 65-70 F (hmmm I THOUGHT this was JAN…lol). Instability will be mitigated significantly by pre existing cloud cover inhibiting surface heating.
The front will push into SFL/keys while becoming quasi stationary SUN and as a result low-mid level moisture should preclude the chance for a good weekend south of a TPA – MCO – DAB line. Some weak s/w energy coming across the gulf as the STJ comes to life may try to spin up additional waves of low pressure along the boundary enhancing precip potential. North of there the drier air should bleed in as high pressure slowly builds southeastward from the plains.
At this point I don’t think the crux of the cold air is going to reach SFL, but further north the low level arctic air may be able to make it down underneath the upper level flow in a weak CAD situation as a the 1040 high reaches New England funneling cold air down east of the mountains into SE GA / NE FL. This however would not reach the region until MON night and TUE.
Morale of the story for FL is colder, yes, brutal? No. but first we have to get through the SAT-MON period w/ the front getting hung up over the state.
In the longer range, the east may remain below average through the next 10 days, but the plains could warm significantly as the long wave trough slides eastward and PV moves out of Canada toward Greenland rebuilding strong +NAO.
