National Weather Service Raw Text Product

066 
FXUS64 KMOB 181816
AFDMOB

Area Forecast Discussion
National Weather Service Mobile AL
116 PM CDT Wed Aug 18 2021

.NEAR TERM /Now Through Thursday/...Currently, an upper ridge 
stretched southwest over eastern portions of the Southeast. A 
surface ridge stretched west just south of the northern Gulf coast. 
The airmass over the forecast area showed a southwest to northeast 
moisture gradient on the morning soundings, ranging from around 2.0" 
over southwestern portions of the forecast area to 1.8" over 
northeastern areas. Scattered showers and thunderstorms have formed 
along and south of the I-10 corridor, but so far have been 
struggling to move further inland.

Through the afternoon, am expecting a slow inland progression of 
convection as moister air along the coast moves inland. Have placed 
better PoPs closer to the coast, though, as a result for this 
afternoon. Highest instability also is expected to be closer to the 
coast, in the moister airmass. Areas along the I-10 corridor will 
see MLCapes this afternoon topping out in the 2000-2500J/kg range 
with a downward tapering to 1000-1500J/kg range as one moves inland 
to the Highway 84 corridor. The latest SPC analysis shows DCapes 
around 1000J/kg over the majority of the forecast area. Am expecting 
the best chance, albeit small chance, of strong to severe storms 
being over the southern half of the forecast area, with the better 
combination of ingredients present. Temperatures topping out in the 
low to mid 90s are expected this afternoon.

Tonight through Thursday, the upper ridge shifts southwest over the 
northern Gulf coast, with the surface ridge shifting north to over 
the northern Gulf coast. Guidance is advertising an upper level 
shortwave trough passing north of the forecast area Thursday. 
Moisture levels increase, with highest levels being along and 
northwest of the I-65 corridor (2.1"-2.3" northwest, 1.9-2.1" 
southeast). Am still expecting overnight convection to form south of 
the coast after midnight tonight, then begin to move onshore during 
the morning hours. With areas northwest of I-65 seeing the increase 
in upper subsidence last due to the passing shortwave trough along 
with better moisture levels, have painted highest PoPs northwest of 
I-65 for Thursday. A few may be strong to marginally severe. Best 
chance of any rowdy storms will be along and north of the Highway 84 
corridor. 

Have put fog into the forecast for tonight, mainly over areas well 
north of I-10. Guidance is advising low level winds becoming light, 
but not quite calm. With boundary layer moisture levels remaining 
high, patchy fog development is likely, enough to mention in the 
forecast.

With moisture levels increasing along with upper subsidence, am 
expecting overnight temperatures to fall into the low to upper 70s, 
a bit above seasonal norms. Thursday, with highest PoPs and cloud 
cover being over northwestern portions of the forecast area, a 
northwest to southeast temperature gradient is expected. High 
temperatures around 90 are expected well north of the I-65 corridor 
and along the coast to mid 90s southeast. Heat Indices topping out 
in the 100-105 degree range are expected Thursday.
/16
&&

.AVIATION...
18Z issuance...At 17z, general VFR conditions were noted across the 
forecast area and nearby, with local drops to MVFR levels in 
isolated to scattered northward moving showers and thunderstorms 
along the I-10 corridor. Reported winds were southerly between 5 to 
10 knots. 

Am expecting the showers and thunderstorms to continue to form along 
the I-10 corridor early this afternoon and move north through the 
afternoon hours. Coverage is expected to be greatest over the 
southern half of the forecast area, in a more moist airmass. Local 
low to mid MVFR conditions are expected in the stronger convection. 
This convection is expected to last into the early evening hours, 
mainly along and north of the Highway 84 corridor. Overnight, as 
winds lighten to 5 knots or less, fog development is expected after 
05z, with the greatest VISBY drops being possible well north of the 
I-10 corridor, with local drops to low end MVFR/IFR possible. This 
fog should quickly mix out after sunrise Thursday, with general VFR 
conditions inland. Showers and thunderstorms forming offshore 
overnight tonight are expected to move inland during the morning 
hours, bringing local drops to mid to upper end MVFr levels 
Thursday morning. Southerly winds will increase to 5 to 10 knots.
/16

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...None.
FL...None.
MS...None.
GM...None.
&&

$$

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