854 
FXUS64 KBMX 250832
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
332 AM CDT Sat Jul 25 2020

.SHORT TERM...
/Updated at 0329 AM CDT Sat Jul 25 2020/

Today through Sunday.

Central Alabama will be under the influence of a large scale upper 
ridge that extends from the Plains states eastward to the mid-
Atlantic states. Deeper moisture over the Gulf of Mexico will not 
make much headway northward due to the presence of the ridge, and 
rain chances will be near normal values for late July, with mainly 
diurnally driven storms. Enhanced sea-breeze activity due to Hanna 
will likely push northward into the far southern counties of central 
Alabama this afternoon. Models indicate a patch of higher mid level 
moisture over northeast Alabama that gets wedged between the bottom 
side of the aforementioned ridge and southeast flow on the eastern 
side of tropical cyclone Hanna. Forecast will show slightly higher 
rain chances in the northeast counties today and Sunday. Models also 
indicate higher 1000-850mb thickness values over the weekend, with 
widespread low 90s expected. 

58/rose


.LONG TERM...
/Updated at 0329 AM CDT Sat Jul 25 2020/

Sunday night through Friday.

Afternoon thunderstorms expected for much of the upcoming week.

The tropical air mass left in the wake of Hanna will slowly lift 
northward into the Gulf Coast States Sunday night into Monday. PWATs 
are forecast to increase from 1.8" Sunday night to 2.2-2.3" by 
Wednesday, so it's safe to say that any afternoon thunderstorms that 
develop will be very efficient rainfall producers. In regards to the 
coverage of thunderstorms, I've carried a general upward trend in 
PoPs with 50-60% chances across the north on Monday with 70% percent 
in the south as the tropical air mass lifts into Central AL. Then, 
as the PWATs continue to increase through mid-week, I've gone 70% 
chance of afternoon thunderstorms area-wide. Another factor to 
consider for Tuesday into Wednesday is a cold front that is expected 
to slide southward through the Ohio Valley. The frontal boundary 
itself will most likely not make it into our area, but it could 
increase the moisture convergence for the Deep South, aiding in the 
convective initiation both Tuesday and Wednesday afternoons. The 
biggest question and uncertainty in the forecast is just how much 
the convection tapers off through the evening and overnight hours. 
For now, I've kept roughly 20% chance of thunderstorms overnight 
Monday into Tuesday, increasing to 30-40% for Tuesday night and 
Wednesday night given the potential for increase moisture 
convergence. 

We finally see a pattern transition Thursday into Friday as models 
begin to hint at the tropical air mass shifting eastward as high 
pressure builds in across the Gulf of Mexico. This will cut-off the 
deep tropical moisture flow in our area, slowly decreasing PWATs 
Thursday and Friday. Therefore, I've trended PoPs downward (40-50%) 
as we get closer to the weekend. 

25/Owen

&&

.AVIATION...
06Z TAF Discussion.

The evening convective activity has now dissipated and no
additional activity is expected thru 15z. Mainly cirrus clouds
thru the overnight hours. Sct cumulus will develop by 13z with 
lcl cigs arnd 2800 ft agl 13-15z. A few showers will develop by 
15z with sct TSRA between 18z and 01z. Handled TSRA with PROB30 
groups as rain chances remain below 50 percent.

58/rose


&&

.FIRE WEATHER...

Afternoon minimum RH values should remain near or above 45 
percent through Monday. Showers and thunderstorms will remain in 
the forecast through the period with best chances during the 
afternoon and into the early evening hours. Some localized areas 
of patchy fog may develop overnight in areas that receive heavy 
rain earlier that day. Surface and transport winds are expected to
remain fairly light but generally out of the southeast through 
this weekend. Tropical moisture increases next week, leading to
higher rain chances each afternoon. 

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     90  72  89  70  92 /  40  20  40  10  50 
Anniston    90  72  91  71  92 /  40  20  50  10  50 
Birmingham  91  74  92  73  92 /  40  20  40  10  60 
Tuscaloosa  92  74  93  73  91 /  30  20  30  10  60 
Calera      91  73  92  72  91 /  40  20  40  10  60 
Auburn      90  73  90  72  90 /  40  20  40  10  60 
Montgomery  92  74  93  73  91 /  40  20  30  20  70 
Troy        91  73  92  72  90 /  40  20  30  20  70 

&&

.BMX WATCHES/WARNINGS/ADVISORIES/...
None. 

&&

$$