Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 191900

Area Forecast Discussion
National Weather Service Birmingham AL
200 PM CDT Thu May 19 2022

Long Term Update.


/Updated at 0120 PM CDT Thu May 19 2022/

It`s another summer-like day across Central Alabama, and we`re on
our way to afternoon highs that will be at least 10 degrees above
normal for this time of the year. We`ll stay high and dry once
again, as an upper level shortwave passes off to our north over
Central Tennessee. The 12z KBMX sounding pretty much offers little
to no chance of convective activity with lots of dry air aloft
and PWATs only around 1 inch. A little more moisture exists down
across southeastern counties, where some fair weather cumulus has
developed this afternoon. Elsewhere, only thin high cirrus remains
under full sunshine.

There`s always a forecast challenge, even if you don`t have any
rain in the forecast. Tonight will be one of those nights as
isentropic lift in southerly low level flow will help to develop
widespread low stratus clouds. Overcast skies are likely across
much of the area which will keep low temperatures overnight closer
to raw model guidance. Birmingham only dropped to 75 last night,
with observations just a tad lower than that at Montgomery and
Troy. We`ll certainly be warm and muggy by sunrise Friday
morning. Patchy fog will also be possible along and south of the
I-85 corridor. Clouds are expected to mix out shortly after
sunrise with another very warm day expected. 1000-850mb
thicknesses still support lower 90s for highs areawide. As
southerly flow continues to increase moisture across Central
Alabama, we`ll likely start to see isolated showers and storms
popping up across far southern Alabama and the Florida Panhandle
Friday afternoon. Confidence in the chance of any isolated
showers or storms entering into our far southeast counties remains
low at this time, and have kept mention of PoPs out of the
forecast for now.


/Updated at 0158 PM CDT Thu May 19 2022/

A pattern change is on the way beginning this weekend as the ridge
axis shifts further east while an upper-level shortwave passes
across the region. Deeper moisture will be in the process of
proliferating northward on Saturday, but targeting a specific area
for convective initiation is still difficult with forecast soundings
indicating an abundance of dry air aloft may still linger over
Central Alabama. This could limit the amount of development we can
realize, so kept highest PoPs across our southern counties where
higher dewpoints will reside in addition to deeper moisture
presence. Some models indicate a large amount of instability may
develop across southern AL/MS, but other guidance is less unstable
given the dry air aloft mixes to the surface and causes dewpoints to
fall. Mid-level flow also appears to be quite weak. Nonetheless,
will need to monitor thermodynamic trends for the possibility of a
few strong storms. It still appears that PoPs will be highest on
Sunday as a cold front moves into northwest AL then begins to stall
as it encounters ridging to our southeast, and no major forecast
changes were needed. Another focus for rain may develop by midweek
as another trough ejects across the Midwest.


Previous long-term discussion:
/Updated at 0322 AM CDT Thu May 19 2022/
Saturday through Thursday.

After a very dry first few weeks of May, we will experience a
significant shift in the weather pattern beginning on Saturday as an
extended period of wetter weather takes shape. Southerly surface to
700 mb flow is expected as an upper-level trough encompasses most of
the CONUS, while embedded southern stream disturbances approach our
area from the west. The increase in moisture will become apparent on
Saturday as rain chances may increase from the south in response to
a broad and weak shortwave in the southern jet stream.

A cold front will approach the forecast on Sunday, further enhancing
lift and moisture for showers and thunderstorms over a broad area.
Monday continues to trend wetter as the slow-moving shortwave
continues to hang around in the presence of a stalled front.

Rain chances should decrease some on Tuesday as the shortwave begins
to shear out and depart in response to another trough axis moving
into the Southern Plains. This system may bring yet another cold
front with showers and thunderstorms to the region on Wednesday.



18Z TAF Discussion.

VFR conditions will continue through the short term with
southwesterly surface winds between 5 and 10 knots. High
confidence exists of low stratus development after 06z quickly
spreading from south to north across the terminal locations. IFR
stratus is expected at MGM and TOI for possibly several hours,
while TEMPO IFR was added in northern terminals with prevailing
MVFR. Clouds will mix out between 13 and 15z Friday morning.




A couple hot and dry days end the work week, before moisture and
rain chances return over the weekend. 20ft winds from the southwest
at 6-12 mph today become southerly Friday, at 6-10 mph. With
increasing moisture and cloud cover, ceilings below 1500ft are
possible Friday morning. Minimum relative humidity values stay in
the 30s and 40s through Friday afternoon.


Gadsden     68  92  67  91  66 /   0   0   0  20  20
Anniston    69  92  68  89  67 /   0   0   0  30  20
Birmingham  74  93  70  92  69 /   0   0   0  30  20
Tuscaloosa  72  92  70  92  69 /   0   0   0  30  20
Calera      72  92  70  90  70 /   0   0   0  40  20
Auburn      70  90  69  87  67 /   0  10  10  50  20
Montgomery  73  93  69  91  69 /   0  10  10  50  20
Troy        73  92  70  90  67 /   0  10  10  60  20




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