Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 202352
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
652 PM CDT Sun May 20 2018

.UPDATE...
Aviation Discussion.

&&

.SHORT TERM...

With little cloud cover across central Alabama, temperatures are
warming quickly with readings in the lower 80s in many locations.
Surface based CAPE values are already near 2500 J/kg due to slightly
cooler mid level lapse rates and surface dewpoints in the lower
70s. Expect CAPE values will climb to around 3500 J/kg this
afternoon with Downdraft CAPE values near 1000 J/kg. An easterly
wave over south Georgia and the Florida peninsula will track
northwest and push a boundary into southeast Alabama this
afternoon. It will encounter a very unstable air mass and
thunderstorms will develop quickly between 2 pm and 4 pm, with
some storms producing locally strong wind gusts. The storms will
propagate and develop towards the I-20 corridor during the late
afternoon and evening hours. If storms become organized in a line,
rain chances will need to be raised above the current 40-50
percent values south of I-20.

58/rose


.LONG TERM...
Monday through Saturday.

A disturbance embedded within southeasterly surface to 850mb flow
is expected to move toward the forecast area on Monday from the
northeastern Gulf of Mexico. Cooler temperatures and enhanced rain
chances should accompany this feature, especially over our eastern
and southeastern counties. A similar setup is expected for Tuesday
as this system meanders and becomes less defined. By Wednesday and
Thursday the disturbance may be undetectable, but high PWAT values
and daytime heating may lead to scattered showers and storms.

As we head into Friday and Saturday, there is a general consensus
for an anomalous pattern developing over the Gulf of Mexico and
Southeast CONUS. The recent tendency of a troughy pattern over the
region may evolve into a much larger trough with subtropical
characteristics and perhaps an area of surface low pressure in the
Gulf. For now persistent 40 POPs will continue for this period,
but these values could increase once models get a better handle on
this situation.

87/Grantham

&&

.AVIATION...
00Z TAF Discussion.

Scattered showers and storms continue this evening, and per hi-res
model guidance, activity is expected to linger for several more
hours. Have included VCTS and tempo groups for most terminals to
cover this activity.

Low clouds and light fog are possible tonight, and have included
MVFR cigs at all terminals. Winds remain out of the southeast
overnight at 3-6kts. Expect this to limit widespread fog
development. Model guidance is in good agreement with low clouds
hanging around through much of Monday morning.

14

&&

.FIRE WEATHER...

A moist summertime pattern is expected over the next seven days
and should result in daily rain chances. Patchy fog/low clouds
will be possible each morning particularly where rainfall occurs
during the prior afternoon and evening. Otherwise, there are no
fire weather concerns at this time.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     87  65  82  64  83 /  40  40  50  40  50
Anniston    87  65  81  65  82 /  40  40  50  40  60
Birmingham  90  68  83  67  84 /  40  40  40  40  50
Tuscaloosa  90  69  85  67  86 /  40  40  40  30  40
Calera      88  67  82  66  83 /  40  40  40  40  50
Auburn      84  65  79  66  79 /  50  40  60  50  70
Montgomery  90  66  83  67  84 /  40  40  60  40  60
Troy        87  66  81  66  83 /  50  40  70  50  60

&&

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

&&

$$



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