NEAR TERM [Through Tonight]...
Zonal flow dominates U.S. from Ern Pacific to Ern most states.
Shortwave ridge from Appalachians into Gulf of Mex beginning to
break down while trough across extreme Wrn Atlc digs Swd.
At surface, high pressure over Srn Appalachians nosing Swd to reach N GA by sunrise and this will help to retard further progress of upstream front with Srn tail over Wrn LA/Ern TX.
Deep low in Wrn Atlc continues to lift NEWD overnight. All this places local area between high to our north and exiting low to our NE. With the shifts in above upper/lower systems, this will back upper flow from N TO NW and, with weak shortwave approaching from west in nearly flat upper ridge, higher level clouds will spread Ewd across our area before sunrise.
At the surface, this will veer light lower level flow from NE to a little more Ely. This translates to a small moderation of recent temps and a small increase in deep layer moisture as reflected in area model soundings i.e. RAP13 with TAE PWATs increasing from 1.21 to 1.31 inches and DHN from 1.05 TO 1.37 inches from 00z Mon to 12z Mon.
Will go with zero-10% over land and 20-30% over water POP gradient.
Lows from the low 60s north to the upper 60s near the coast.
SHORT TERM [Monday Through Tuesday Night]...
A weak disturbance will move through the region starting Monday with
gradually increasing moisture levels. This will result in low end rain chances throughout the short term period.
Drier continental air will try and build in from the northeast by Tuesday resulting in a tight pop gradient with better chances from Tuesday into Wednesday across the Florida zones and adjacent coastal waters.
Temperatures will moderate through the period with highs returning to the mid and upper 80s, with lows generally in the mid to upper 60s.
LONG TERM [Wednesday through Sunday]...
Complex forecast throughout the long term period. A variety of factors are at play here during the period and the lack of consistent model agreement doesn`t help things very much.
At the start of the period a tropical disturbance will be nearing the
Yucatan Channel / western Cuba moving around the southwestern edge of a ridge of high pressure off the Eastern CONUS. As moisture from this disturbance streams northward, the large scale western CONUS trough will continue to amplify as a potent upper low drops out of the Gulf of Alaska and into the Pacific Northwest.
As the pattern evolves throughout the long term period, the Western CONUS trough is expected to amplify and progress eastward into the Plains in the Fri-Sun timeframe.
Surface cyclogenesis is anticipated ahead of this highly amplified and progressive trough by Friday in the Central Plains. The aforementioned tropical disturbance and associated moisture will gradually lift northward starting Thursday night and continue into the weekend. The speed and movement of this upper trough will have a significant impact on how much tropical moisture gets into the region.
There has been some marginal consistency today with the last three
runs of the GFS, though there are the usual timing differences
with a Day 6-8 forecast. The 29/12z GFS has slowed slightly from
it`s 06z predecessor, but still is ahead of the Euro with this
system. The Canadian remains slow and given its difficulties
handling the tropical side of this system, it`s solution has been
discounted. It did increase forecast confidence slightly that the
29/12z GFS was reasonably close to the 29/00z GFS Ensemble mean, indicating that we might be moving toward some sort of model
agreement with this system. Nevertheless, overall confidence in
the longer range portion of the forecast continues to be much
lower than normal.
With this forecast package, used a model blend weighted closer to
the 29/06z GFS solution with a smaller contribution from the 29/00z
Euro to account for potential slower progression of the system.
This results in a period of increased rain chances starting Friday
night through Sunday morning with the bulk of any precip probably
arriving on Saturday. Gradual clearing is anticipated on Sunday
afternoon, though if slower model solutions verify, then rain chances could extend through the weekend.
Temperatures for the period should largely be above climatology until the tail end of the period where some cooler temperatures would work in behind the frontal system.
AVIATION [Through 18z Monday]...
VFR conditions are anticipated to prevail through the TAF cycle.
The only potential restrictions look to be at VLD 09Z-12Z with a
combination of MVFR ceilings and visibility and possibly brief
IFR CIGS toward sunrise.
Winds will predominantly be easterly through much of this week and
remain below headline criteria.
Nightly surges in the easterly flow to 15 knots looks possible Wednesday and Thursday before an approaching frontal system shifts winds to southerly during the weekend.
Relative humidity values will will remain above critical levels with a moistening trend to begin the work week.
The Choctawhatchee River at Bruce is likely to crest on Monday
afternoon below flood stage.
All other rivers remain below action stage and should do so into the middle part of this coming week.
While there is still a lot of uncertainty in the long term period of the forecast, the threat for significant rainfall by the weekend is low.
PRELIMINARY POINT TEMPS/POPS...
Tallahassee 65 83 65 86 67 / 10 40 30 40 20
Panama City 69 83 70 85 72 / 20 40 30 40 20
Dothan 62 82 64 86 65 / 10 20 20 20 20
Albany 62 82 64 87 64 / 10 20 20 10 20
Valdosta 63 83 64 86 64 / 10 30 30 20 20
Cross City 64 85 68 86 65 / 10 40 30 40 20
Apalachicola 70 82 72 83 73 / 20 40 30 40 20