Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 051207

Area Forecast Discussion
National Weather Service Birmingham AL
707 AM CDT Wed Aug 5 2020

For 12Z Aviation.


/Updated at 345 AM CDT Wed Aug 05 2020/
Today through Thursday.

We have a quiet radar at this hour across Central Alabama. On
satellite, there is some mid level cloudiness still moving from S to
N across the area as broad upper level troughing continues across
the east half of Conus. A surface front and associated low are
slowly nudging south/southeast across the state. For today, the
front should nudge only a little further south. A couple of
shortwaves will move through the base of the trough and allow for
more scattered convection today. The upper trough is expected to
weaken across the Deep South as the main low over Ontario rotates
eastward tonight into Thursday. This will create a weaker flow
across Alabama. As a result, the surface front should stall and
meander back a tad to the north on Thursday. Isolated to scattered
pops will remain in for Thursday with the boundary in the vicinity
and the help of afternoon heating. Temperatures, although maybe a
degree warmer for Thursday, should not show any large changes.


/Updated at 345 AM CDT Wed Aug 05 2020/
Friday through Tuesday.

Dry and warm weather is forecast to persist across much of the Deep
South through this weekend as a pocket of relatively drier air
remains situated at the base of a residual, abating upper-level
trough. This should generally extend from Central AL to Lake Huron
Friday morning. With time, however, tropospheric moisture content
will gradually increase as low-level ridging becomes better
established to our southeast, and southerly/southwesterly flow
overspreads the Gulf Coast by late Saturday. Until then, highs in
the low to upper 90s are expected with mostly isolated afternoon
convection amidst a column of weak mean flow and PWs 1.4-1.6". With
these values and potential dry air in the mid-levels, any showers or
thunderstorms could produce gusty downdrafts. Any robust convection
and the potential for microbursts will be assessed each
respective day.

By early next week, zonal flow overcomes much of the CONUS with low
amplitude sub-tropical ridging stretched across the Southern Plains
to the Southeast, with perhaps a few weaknesses aloft that may
impact the forecast during this time as well. Nevertheless, moisture
increases by Sun/Mon and is generally focused across our southern
counties (dewpoints are forecast to steadily rise into the mid 70s
by then). I show an increasing trends in PoPs as a result and a
slight decreasing trend in afternoon temperatures. Against my better
judgment I`ve carried likely PoPs across the south and southeastern
counties on Mon/Tue, though medium range guidance is in good
agreement of further increasing PWs in the 1.9-2.1" range,
particularly in these areas, which seems reasonable. This typically
yields a generous coverage of afternoon/evening convection. In all,
I don`t foresee any impactful weather through the long-term as we`ll
remain on a diurnally-driven weather pattern and any issues will be
day-to-day mesoscale considerations.



12Z TAF Discussion.

Except for some isolated MVFR patchy fog, we have a VFR forecast
for the next 24 hours. A surface boundary is pushing southward
across C AL this morning. Winds will be becoming more west to
northwest behind it today. However, the system is not strong and
does not have tight pressure gradients. So, gusty winds are not
expected today. A few showers are possible with an upper shortwave
and daytime heating. Also, some isolated thunder cannot be ruled
out, but only showers are mentioned at terminals due to low
thunder probability.




Expect afternoon minimum RH values to be generally above 35
percent through Sunday with the lower values across the south and
southeast counties. Low-level moisture will increase late this
weekend and into early the next week, resulting in minimum RH
values only falling into the mid 40 percent range on Monday. This
will also lead to increasing rain chances which could linger into
mid next week.

Expect isolated to scattered showers and thunderstorms today with
light winds generally out of the north-northwest north of I-20,
and out of the south to southwest south of I-20. Winds become
light and variable later this evening.


Gadsden     89  68  90  69  93 /  30  20  20  10  20
Anniston    89  69  91  70  94 /  30  20  30  10  20
Birmingham  89  70  91  71  94 /  30  20  20  10  10
Tuscaloosa  90  70  92  71  95 /  20  20  20  10  10
Calera      89  69  90  71  93 /  30  20  20  10  10
Auburn      91  70  91  71  93 /  30  10  30  10  20
Montgomery  93  72  93  72  96 /  30  20  20  10  20
Troy        94  71  93  72  95 /  20  10  30  10  20





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