NATIONAL WEATHER SERVICE TALLAHASSEE FL
256 PM EDT Sun Apr 6 2014
Near Term [Through Tonight]...
The stalled front will slowly lift north overnight with the boundary
expected to be north of our CWA by daybreak.
This is in response to a developing area of low pressure along the western Gulf coast that will lift northeast into the Lower Mississippi Valley.
As a result, the widespread rains, some heavy, that we`ve seen today over our SE AL and northern tier GA zones will shift further to the north.
However, we do show a tight PoP gradient that will now be tapered NW to SE from categorical to nil.
An isolated strong to severe storm may reach our far westernmost zones by 12z Mon (7am cdt).
Otherwise, the severe weather threat will commence after daybreak.
See short term discussion below for details.
Min temps will be in the lower to mid 60s.
Short Term [Monday Through Tuesday Night]...
The latest GFS, ECMWF, NAM, and SREF continue to forecast a synoptic environment that appears favorable for severe thunderstorms ahead of a slow-moving cold front on Monday.
As mentioned in our previous forecast discussion, the environment may be even a little more favorable than what was thought 24 hours ago due to better buoyancy (i.e. increase CAPE owing to steeper boundary layer lapse rates and higher dewpoints).
Now the main question (in terms of severe storm potential) becomes how favorable will the mesoscale and storm scale environments be.
To that end, this morning`s run of our local ensemble of Convection Allowing Models (ECAM) shows several tracks of Updraft Helicity (UH) of 100 m-2/s-2 or more, especially west of the Apalachicola / Chattahoochee River.
There is also a high coverage of 10m wind speeds of 40 kt or more.
The simulated reflectivity fields show bands of deep moist convection
oriented northeast to southwest, as well as a few discrete cells ahead of these rain bands.
All of this seems to confirm what the large scale environment forecasts have been suggesting for several days- that some of the thunderstorms on Monday will produce damaging winds, and that the amount of wind damage reports we get may be more than we`ve seen in over a year.
Additionally, isolated tornadoes are possible.
The threat of large hail appears low (but not quite zero) because of the poor lapse rates aloft; but of course a strong, rotating updraft could overcome this limitation and produce large hail as well.
Both the large scale and high-res NWP models forecast a gradual weakening trend as the QLCS translates eastward into North FL and South Central GA Monday night, but the threat of isolated severe storms will continue through at least 06 UTC.
The heavier rain will finally exit east of our forecast area Tuesday morning, but slight PoPs will continue into Tuesday evening as a potent vorticity max rounds the base of the developing eastern CONUS long wave trough.
Clearing skies will return to the region for Wednesday.
After another warm day Monday, temperatures will cool to slightly below-average values.
Highs on Tuesday & Wednesday will be in the upper 60s (northwest) to mid 70s (southeast).
Lows will be in the 50s and 60s Tuesday, then upper 40s to lower 50s Wednesday.
Long Term [Wednesday Through Sunday]...
Weak troughing at 500mb over the Southeast on Wednesday night will become fairly zonal by week`s end.
We expect generally fair weather through the period.
After a chilly morning Thursday (with lows in the lower 40s), temperatures will gradually return to near-average levels by Friday, then slightly above average next weekend.
As the warm front lifts north, higher dew points along with warmer than normal min temps would normally aide in increasing widespread dense fog potential.
However, the offsetting factors will be increasing mid to upper level
cloudiness ahead of the developing upstream low pressure system
and well as sustained winds overnight around 10 kts.
With that said, we do expect widespread IFR/LIFR cigs with periods of
Additionally, periods of mostly light rain will impact the DHN, ECP and ABY terminals through sunrise with showers and TSTMS spreading from west to east during the morning and afternoon.
Some of the storms in the late morning and afternoon may be severe.
Winds and seas will increase from west to east later today and
tonight, and may reach advisory levels by Monday as the cold front
Conditions will improve briefly Monday night, then approach advisory levels once again on Tuesday as a low pressure system develops over the Carolinas.
No Fire Weather concerns are expected through the upcoming week.
Widespread 2-4 inches of rain fell across portions of South AL &
GA this morning, resulting in a sharp rise in the Pea River at
This river is now projected to go to flood stage on Monday.
Additional rises are expected in some of our AL & GA rivers from today`s heavy rains.
Another round of rain is expected on Monday, with 2 to 4 inches likely.
Isolated amounts up to 6 inches are possible, which could lead to flash flooding in portions of the FL Panhandle, Southeast AL, and South GA.
Preliminary Point Temps/PoPs...
Tallahassee 62 79 62 73 48 / 10 60 80 40 20
Panama City 67 75 59 70 51 / 30 80 70 20 20
Dothan 64 77 53 68 47 / 80 100 60 20 30
Albany 63 78 56 71 48 / 60 80 80 20 30
Valdosta 63 81 62 71 48 / 10 50 80 40 30
Cross City 63 81 65 75 47 / 10 30 80 50 20
Apalachicola 68 75 60 70 52 / 10 60 80 40 20
FL...Flash Flood Watch through Monday evening for Calhoun-Central
Walton-Coastal Bay-Coastal Gulf-Holmes-Inland Bay-Inland Gulf -Inland Walton-Jackson-South Walton-Washington.
High Rip Current Risk until 11 PM CDT this evening for Coastal Bay.
GA...Flash Flood Watch through Monday evening for Baker-Ben Hill-
AL...Flash Flood Watch through Monday evening for Coffee-Dale -Geneva-Henry-Houston.
GM...Small Craft Advisory from 2 AM to 8 PM EDT Monday for Apalachee Bay-Coastal waters From Ochlockonee River to Apalachicola FL out to 20 NM-Coastal waters from Suwannee River to
Keaton Beach FL out 20 NM-Coastal waters from Apalachicola to Destin FL out 20 NM-Waters from Suwannee River to Apalachicola FL from 20 to 60 NM-Waters from Apalachicola to Destin FL from 20 to 60 NM.