Near Term [Through Today]...
The forecast for the next 12-18 hours will be complicated by a messy
mesoscale weather pattern due to the effects of a large MCS that
traversed the forecast area overnight.
One feature of interest will be an outflow boundary stretching
from AAF-CEW-MEI (roughly Apalachicola to Meridian MS) that is
reinforced by the warmer Gulf waters. The outflow boundary is likely
to be a focusing mechanism for convective development today.
Models are in good agreement that a mid-upper level PV anomaly
should push into the area around 15-18Z, and this could contribute
to some earlier thunderstorm activity along and near the outflow
Overall, the primary convective focus today seems to be the aforementioned outflow boundary - which should place the best
thunderstorm chances in our Florida zones.
Northern parts of our area, particularly southwest Georgia, should be more stable given the convective overturning by the previous MCS.
Some storms could be severe once again, as models are in good agreement on moderate to strong instability and about 35-40 knots of 0-6km wind shear.
The combination of instability and shear could lead to some organized
multicell structures with a threat for damaging winds and marginally
As the PV anomaly pushes through, a corresponding shortwave ridge should build in around 00-03Z, which should lead to a decrease in the intensity and coverage of thunderstorms around the end of the period.
Short Term [Tonight Through Monday]...
Scattered thunderstorms will gradually diminish during the evening,
though a few marginally severe storms will remain possible until
around 11 pm EDT.
The GFS and ECMWF have some subtle differences in their solutions in our region.
The GFS maintains a weak short wave trough (with enhanced deep layer moisture) at 500 mb across the FL Peninsula through Monday, while the ECMWF develops a 500 mb high over Apalachee Bay by Monday afternoon.
The GFS solution would imply higher rain chances for our area, especially over our eastern zones. The ECMWF would suggest a drying trend, especially by Monday.
Our solution is a blend of the two, with a southwest to northeast PoP gradient ranging from 20% along the FL Panhandle Coast to 40% north of Valdosta and Albany.
This PoP distribution remains the same for Monday, but is lower everywhere by 10%.
A few pulse severe storms are possible Sunday afternoon, but the synoptic pattern does not appear quite as favorable for severe storms as what may occur today.
Our temperature forecast represents the consensus of the guidance, with highs in the mid 90s and lows in the lower 70s.
If the ECMWF verifies better than the GFS, high temperatures may be a little warmer than this.
Long Term [Monday Night Through Saturday]...
The synoptic pattern will shift to a more normal summertime scenario with ridging over west, positively tilted trough over Cntrl and ridge over ern most states.
This trough will pivot Ewd and amplify with axis over local region
by sunrise Thurs leading to increasing Gulf inflow of deep layer
moisture and an upward trend in precip.
Expect possibly Wed and Thurs, afternoon diurnally driven
seabreezes will be the main generator of convection each day with
locally heavy rain wherever boundaries clash.
Some model difference in how much Gulf deep moisture inflow advects Newd ahead of trough and, what impact, if any, weak low Gulf low will have.
Low across Yucatan to start the period which by mid week is forecast to move into Ern gulf along a surface trough axis and all this lessens confidence of forecast beyond day 4 until models come into better agreement.
Daytime rain chances will vary from 30% Tues and 40-50% Wed thru
Fri. Highs will reach the lower to mid 90s on Mon, low 90s Tues
and around 90 Wed thru Fri.
VFR conditions may be interrupted by some MVFR CIGS or VIS in the 10-15Z timeframe at some of the terminals.
A return to VFR conditions is expected after that, with scattered
showers and thunderstorms again - particularly in the afternoon.
The best chances of thunderstorms will be at ECP, TLH, and VLD.
Some of the strongest storms could produce gusty winds upwards of 30 knots and briefly produce IFR VIS.
The surface pressure pattern will remain essentially unchanged
through early next week, as our marine area remains situated between a weak trough to the north and a ridge to our south, resulting in mainly light west to southwest winds and relatively low seas.
The exception will be during the afternoon & evening hours, when strong daytime heating will cause winds and chop to increase to moderate levels near the coast.
Relative humidity will remain well above critical thresholds, so red
flag conditions are not expected.
Most of the significant rain on Friday occurred in Southeast AL and
Basin averages ranged from 0.50 to 2 inches- with a few spot amounts of around 3 inches.
This will of course cause some sudden rises in river stages/flows this weekend in this region, but at this time we don`t expect any river flooding.
Just how much increase occurs will become clearer later this morning, when the river models first ingest the actual rainfall amounts.
Otherwise, nearly all of our local rivers were below action stage.
We expect rainfall totals from today through Monday to range from
0.30 to 0.75 inches, with the highest values from Tallahassee
Because this will occur in an area that didn`t get much rain on Friday, river flooding is unlikely in these areas.
Otherwise, locally heavy rain will be possible this afternoon and
evening, but the probability of flash flooding is low.
Preliminary Point Temps/PoPs...
Tallahassee 92 72 93 71 94 / 60 40 30 30 20
Panama City 85 75 87 74 87 / 50 20 20 20 10
Dothan 93 74 94 73 95 / 50 30 30 30 20
Albany 94 73 94 72 95 / 40 20 40 40 20
Valdosta 93 71 95 71 96 / 60 40 40 40 20
Cross City 89 71 92 69 92 / 50 30 30 30 20
Apalachicola 86 74 87 74 87 / 30 20 10 20 10