Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 201749
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
1149 AM CST Sat Jan 20 2018

.UPDATE...
Morning Update.

&&

.SYNOPSIS...

Water vapor imagery depicts an upper level disturbance located
over southwest Mississippi while a shortwave ridge extended
northwest from the Florida peninsula through southwest Georgia
and into eastern Alabama. Surface high pressure was analyzed
across far southwest Georgia with low-level winds from the south
across our southwest counties and a southwest flow across the
remainder of our CWA. Satellite imagery indicated low level clouds
that are gradually mixing out with time.

20/12z BMX sounding indicates the lower levels below 830mb have
moistened with low-level moisture trapped underneath a stout
subsidence inversion at this level. Further aloft, a relatively
dry vertical profile still exists with generally westerly winds
from 20 to 35 kts through 350mb.

05

&&

.SHORT TERM...
Today and tonight.

An upper level disturbance located over southwest Mississippi will
continue to slowly drift east along the northern Gulf Coast over
the next 24 hours. At the surface, surface high pressure will
continue to move further southeast of the area, supporting a
further increase in low-level southerly flow that will support
warm air and moisture advection in the lower levels through the
period.

As a result, expect partly to mostly cloudy skies today with
warmer temperatures due to warm advection and decent solar
insolation. Lows tonight will be subject to the continuing
moderating trend with readings warmer to the west due to more
cloud cover while the cooler temperatures are expected to be found
across our eastern and northeast counties due to fewer clouds and
weaker low-level advection.

05

.LONG TERM...
Sunday through Saturday.

A progressive pattern will take hold for the extended part of the
forecast. Our area will be between shortwave troughs on Sunday
with a deep-layer ridge overhead. This favors warmer temperatures,
and some locations across our South could touch 70F on Sunday
afternoon. Mid to upper 60s should be common elsewhere.

Height falls are expected on Monday as a strong Plains trough
moves eastward. Moisture return should be sufficient for
widespread showers and possibly a bit of thunderstorm activity
along a cold front. Instability appears rather limited due to
dewpoints only reaching the upper 50s to around 60F, but lapse
rates are not too shabby. We will monitor for any upward trends in
dewpoints, which could lead to a marginal or low-end threat for
severe storms. This system should move through rather quickly with
dry and relatively mild weather returning for Tuesday through
Thursday. The next chance of rain could come with another system
late Friday into Saturday.

87/Grantham

&&

.AVIATION...
18Z TAF Discussion.

VFR and rain-free conditions expected for the next 24 hours and
beyond. A weak upper-level low is present west of the area, while
low-level moisture is beginning to return around the back side of
a low-level ridge. Satellite and surface obs indicate variable
patches of VFR cloudiness with an overall decreasing trend the
past couple hours. Skies should range mainly from FEW to SCT with
bases mainly 5-6k ft and above. Winds are southwesterly around 5-8
kts, becoming light to calm overnight.

32/Davis


&&

.FIRE WEATHER...

RH values will slowly increase through the weekend with values
remaining above critical levels. Light southerly winds are
forecast through the short term period and critical fire weather
conditions are not expected.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     57  36  64  44  63 /   0   0  10  10  80
Anniston    59  38  66  45  64 /   0   0  10  10  80
Birmingham  59  41  66  48  64 /   0   0  10  10  90
Tuscaloosa  61  41  67  50  65 /   0   0  10  10  80
Calera      59  40  66  49  64 /   0   0  10  10  80
Auburn      59  40  67  46  66 /   0   0  10  10  60
Montgomery  61  37  68  47  69 /   0   0  10  10  70
Troy        62  38  68  47  70 /   0   0  10  10  50

&&

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

&&

$$


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