Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 302334

Area Forecast Discussion
National Weather Service Birmingham AL
534 PM CST Mon Jan 30 2023

...New AVIATION...

(This afternoon through Tuesday)
Issued at 1223 PM CST MON JAN 30 2023

Most of the area is currently rain-free now that the weak front
has settled along the Gulf coast other than a few isolated showers
across our southeast counties. A Gulf ridge stretched across the
Bahamas has prevented any meaningful airmass change with deep
zonal flow present over Central Alabama. Will continue to see
humid and mild surface conditions this afternoon with highs
ranging from the lower 70s south to upper 60s north.

Saturated surface conditions will likely contribute to patchy fog
tonight, especially prominent across the south. At the same time,
scattered light showers may pass across our northern counties
after midnight as another weak low-level shortwave propagates
across the Tennessee Valley while a secondary cold front moves
into the region. Forcing appears very limited, so not expecting
any meaningful accumulation, but may help to limit fog
development. Will watch trends to see if a Dense Fog Advisory is
needed. Similar conditions are expected tomorrow as the front
stalls generally east to west across the Tennessee Valley creating
a large temperature gradient. Highs will range from the mid 40s
northwest to lower 70s southeast with cloudy skies and potential
for a few passing showers in the north.



(Tuesday night through next Sunday)
Issued at 125 PM CST MON JAN 30 2023

Rain will be a persistent event this week, especially across the
northern counties, where rain chances are elevated Tuesday night,
Wednesday night, and Thursday morning. The potential for heavier
rainfall across the entire area through the day Thursday still
exists, and flooding potential is still being monitored,
particularly in areas along the I-20 corridor that may receive
higher rainfall totals during the morning and afternoon Thursday.
Made slight tweaks to PoPs in line with latest guidance. After the
frontal passage Thursday night, highs Friday, Saturday, and Sunday
will be cooler, staying in the 50s by and large across the region.


Previous long-term discussion:
(Tuesday night through Sunday)
Issued at 357 AM CST MON JAN 30 2023

Post frontal isentropic lift will persist Tuesday night through
Wednesday night with west-southwest 850-500mb flow atop a shallow
cool airmass. The highest rain chances will remain in a consistent
corridor along and north of I-20 through Thursday morning with a
quasi-stationary meandering in southern Alabama. Rainfall rates
Tuesday night through Wednesday night should be relatively low as
embedded shortwaves remain weak.

The ejection of a more significant shortwave from the Texas will
lead to a more widespread and heavier rainfall event Thursday into
early Friday. The potential for isolated flooding will be watched,
but confidence is currently too low to mention a threat for
flooding in our products. Cooler and drier air will move into the
region for Friday night and Saturday. A weak system could bring a
slight increase in moisture for Sunday.



(00Z TAFS)
Issued at 521 PM CST MON JAN 30 2023

MVFR cigs cover all of Central Alabama late this afternoon. The
clouds were being produced by moist south winds just above 1000ft
agl overrunning weak north winds at the surface. The cigs will
lower overnight as the air mass cools with widespread IFR/LIFR
cigs by 08Z. Fog will also become an issue for areas south of I-20
with vsbys aob 1 mile at MGM/TOI between 06z and 15z. Light rain
will develop across north Alabama by 06z, but mostly stay north of
I-20, and no rain included at any TAF site. Conds will slowly
improve after 15z, but cigs will likely stay below 1000 ft agl
thru the end of the TAF period.




An extended wet period is expected this week, with high RH values
and light northerly winds through Thursday. Rain chances will be
greatest along and north of I-20 through Thursday morning, while
high rain chances on Thursday will encompass the entire area.
Northerly winds will be stronger Friday behind a frontal passage,
with RH values below 55 percent across the region.


Gadsden     49  57  43  51 /  30  30  50  30
Anniston    52  61  46  53 /  20  20  30  20
Birmingham  52  56  43  51 /  20  20  40  20
Tuscaloosa  51  57  44  53 /  20  20  40  20
Calera      53  61  45  55 /  20  20  30  20
Auburn      55  68  53  63 /  10  20  20  20
Montgomery  56  69  52  63 /  10  10  10  10
Troy        59  73  55  67 /  10  20  20  10




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