Area Forecast Discussion
Issued by NWS Birmingham, AL
FXUS64 KBMX 312354
Area Forecast Discussion
National Weather Service Birmingham AL
654 PM CDT TUE MAY 31 2016
For 00Z Aviation.
TONIGHT THROUGH WEDNESDAY.
Afternoon radar shows several pop up thunderstorms along
I-20 stretching from St. Clair county to the MS border. some of
these are producing heavy rainfall, frequent lightning and small
hail. Another outflow boundary moved south along I-65 and produced
a few brief storms in the Montgomery area. Currently we are
looking at two outflow boundaries converging near Alexander city
that are expected to produce quickly developing storms. Storms are
currently moving very slow and are likely to remain in the same
area that they develop, producing moderate rainfall. With all the
outflow boundaries moving through the areas and the evening
approaching, storm activity will begin to expire around 6pm today
and calmer conditions are expected in to the evening hours.
Tomorrow morning is expected remain on the calm side as lifting
will be weak. But again with the afternoon heating and southerly
flow, showers and isolated thunderstorms are expected to return.
WEDNESDAY NIGHT THROUGH MONDAY NIGHT.
Not much to change in this time period. Superblend and latest
guidance was on par with the previous forecast with the next
widespread rain event coming Sunday as upper trough moves past.
Previous discussion follows:
Alabama will remain under the influence of an upper ridge through
Friday. Subtle features will enhance local convection but overall
rain chances will remain low during the period. The presence of
the ridge will also keep the recent string of above average
daytime going through Friday. On Wednesday, the low level flow
will become southerly as the trof over the East coast weakens and
the storm system over Texas increases in strength. This low level
flow pattern will enhance rain chances over the northern counties
Wednesday afternoon and will forecast slightly higher rain chances
in this region. Thursday and Friday will see a similar set-up with
the better rain chances north of I-20, which is more on the
periphery of the upper ridge. By Saturday and Sunday an upper
trough will dig southward into the Mississippi River Valley region
and break down the upper ridge over the Southeast states. This
will result in higher rain chances and cooler daytime temperatures
across central Alabama. Sunday looks like the day with the most
widespread coverage of showers and thunderstorms. By Monday the
upper trof axis will push far enough east to bring drier mid level
air into north Alabama, with the rain shifting to areas south of
00Z TAF Discussion.
Afternoon convection has started to dwindle, and all rain is
expected to be done by 03z-05z time frame. With the exception of
TOI, the little bit of rain left out there at 00z does not appear
to have any potential impacts on central Alabama TAFs. Computer
models suggest a calm and fog free night, with only some high
cloud cover. While there are bound to be some pop up thunderstorms
after about 17z Wednesday, they should be fewer in number than
Tuesday. Thus, have opted to leave rain out of the TAFs for now.
Rainfall coverage will remain spotty through Friday due to the
presence of an upper ridge over the southeast states. Above
normal temperatures will also continue thru Friday. Rain chances
will increase this weekend as an upper trough axis approaches
North Alabama. There are no fire weather concerns at this time.