Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 222355
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
655 PM CDT Mon May 22 2017

.UPDATE...
For 00Z Aviation.

&&

.SHORT TERM...
Tonight into Tuesday.

A surface frontal system across the southeast portions of Central
Alabama is expected to drift some back to the northwest closer to
the I-20/59 corridor tonight and likely stall until Tuesday when
another frontal system approaches the state. In the upper levels,
the main low is currently digging southward from Central Canada
into Minnesota tonight and into Iowa on Tuesday. Across Central
Alabama, we have southwest flow in the upper levels around the
main low with numerous short wave perturbations moving through
this tight flow from now into tonight and Tuesday. With dew
points remaining lower to the north of the surface front but
elevated overall, we will continue with a moist atmosphere to
feed the upper level waves as well as a focus with the meandering
front. This will aide in continued rain showers along with some
thunder at times to transverse across the area. Rain will be off
and on through the period with some heavy rain at times. The
highest total amounts continue to be expected across the southeast
1/3 of the area to the south of the surface front, and thus we
continue to have the flash flood watch in effect for tonight into
Tuesday.

Temperatures will be rain cooled for tonight and a little lower
across the northwest behind the front. However, the southwest
upper flow is not allowing any real cold air advection into the
area. During the day on Tuesday, look for cooler highs due to the
widespread precipitation expected.

08

.LONG TERM...
Tuesday night through Sunday.

Wave #3 will be the main upper-level trough axis, anomalously deep
for late May, and will be accompanied by a seasonably strong cold
front. Shear, forcing, and cooling aloft will all be impressive
with this system. However, moisture quality/instability is very
much in doubt as it will be coming in very quickly behind the
previous system (and trending quicker), with some models
especially the ECMWF indicating westerly/northwesterly low-level
flow ahead of it and only low 60s dew points. Expect the dynamics
to be enough for a fast- moving line of showers and storms
Tuesday night and Wednesday, some strong with gusty winds and
hail. However, not confident enough that convection will be strong
enough to produce severe winds/hail to mention anything in the
HWO. Rainfall amounts should also be lighter with this system as
well. Light rain/drizzle will linger Wednesday afternoon/evening
behind the front due to the cold core aloft, and refreshingly
cooler air will move in. The cool down won`t last very long, with
warmer temperatures and some shower/storm chances returning by the
weekend in west-southwest flow ahead of a trough moving through
the northern tier.

32/Davis


&&

.AVIATION...
00Z TAF Discussion.

Vis/Ceiling restrictions will remain in the forecast for all the
terminals. These restrictions appear like they will last much of
the forecast period. Showers and thunderstorms will also be around
many hours this forecast period. Therefore, rain mentioned
overnight with ceilings gradually dropping to IFR. Some
improvement on Tuesday in the ceilings but more thunderstorms are
anticipated.

Several upper level waves ride overhead this forecast period and
beyond. A quasi-stationary front also meanders around the state.
This will keep things somewhat chaotic the next 24 hours and
beyond. Moisture content is relatively high and some of the rain
may be heavy at times. Really tried to give some wind direction
but this is a situation where variable is best. At least the winds
will generally be 6kts or less.

75

&&

.FIRE WEATHER...

Several rounds of heavy rain and storms are expected now and
continuing through mid week. Another 2 to 3 inches of rainfall are
possible across the southern portions of Central Alabama by
Wednesday. Therefore, critical fire weather conditions will not
occur.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     62  76  61  72  53 /  90  70  70  60  30
Anniston    64  77  62  74  54 / 100  80  60  60  20
Birmingham  64  77  63  72  55 / 100  70  60  60  20
Tuscaloosa  62  79  62  73  54 / 100  70  60  50  20
Calera      64  78  62  73  55 / 100  80  60  60  20
Auburn      65  77  64  74  56 / 100  80  60  60  20
Montgomery  67  80  66  77  56 / 100  80  60  60  20
Troy        66  78  65  76  56 /  90  80  70  60  20

&&

.BMX WATCHES/WARNINGS/ADVISORIES/...
Flash Flood Watch through Tuesday evening for the following
counties: Autauga...Barbour...Bibb...Bullock...Chambers...
Chilton...Clay...Coosa...Dallas...Elmore...Greene...Hale...Lee...
Lowndes...Macon...Marengo...Montgomery...Perry...Pike...
Randolph...Russell...Sumter...Tallapoosa.

&&

$$



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