Area Forecast Discussion
Issued by NWS Birmingham, AL
FXUS64 KBMX 210536
Area Forecast Discussion
National Weather Service Birmingham AL
1136 PM CST Mon Feb 20 2017
For 06Z Aviation.
Today we start off with a decaying elongated surface ridge over
Eastern Conus along with east to southeast surface winds around
its base across Central Alabama. With only thin high clouds today,
we had no problem warming up once again today with return flow to
well above normal temperatures again. At the same time, in the
upper levels, a longwave trough extending from the Dakotas to
Texas will continue eastward through tonight. The southern portion
of energy from the trough is expected to become a closed low as
it moves into Louisiana and Arkansas. In response, the convection
we see this afternoon across Arkansas, Louisiana and into East
Texas will continue to the east tonight toward Alabama and should
arrive here in the wee hours of the night toward sunrise in the
west part of the state. With a decrease in intensity expected from
this afternoon, activity upon arrival in Central Alabama is
expected to be only light to moderate showers. No thunderstorms
are anticipated overnight.
Tuesday through Sunday.
Rain will be knocking on our western doorstep at 12Z Tuesday as a
closed 500mb trough moves ESE from the Ark-La-Tex. The GFS
continues to play catch up to the ECMWF which has been
consistently showing stronger lift and higher rainfall amounts.
The latest run of the ECMWF is even more aggressive, and POPs have
been raised as high as 90 percent for much of the area for
Tuesday. High POPs have also been included for Tuesday night with
deep southerly flow continuing as the upper low slips to our south
across the Gulf of Mexico. Rain chances will diminish as the
trough moves away on Wednesday with dry conditions for Thursday
and much of Friday.
The upper-low lingering near the Bahamas on Thursday into Friday
will serve to rob moisture from the next trough moving from the
Plains into the Ohio Valley. Unusually warm temperatures are
expected with many locations topping the 80 degree mark on
Friday. Enough moisture could meet with an approaching cold front
for showers to develop Friday night into early Saturday, but
potential rainfall amounts appear rather light at this time. A
cool morning is expected on Sunday behind the front as high
pressure moves into the region.
06Z TAF Discussion.
A slow moving closed upper low currently over Texas will bring a
large swath of showers into west Alabama by 12z. VFR conds expected
thru 12z with only mid to high level clouds and no pcpn. The
leading edge of the showers will arrive in west Alabama around 12z
and spread to the I-65 corridor by 17z. Cigs will gradually lower
from west to east during the day as the rain overspreads the
area. MVFR cigs should reach KTCL first with the remainder of the
airports lowering to MVFR between 16z and 20z. After 20z, IFR
cigs will become more likely, especially from I-65 westward. Sct shwrs
will remain in the area through the end of the forecast period due
to the presence of the upper low.
Dry weather is expected through early Tuesday morning. Widespread
rain is looking more likely for the daylight hours on Tuesday and
on through Wednesday morning. There are no fire weather concerns.
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 53 67 57 70 53 / 10 80 70 20 10
Anniston 56 68 57 71 54 / 10 80 70 30 10
Birmingham 58 66 58 73 55 / 20 80 70 20 10
Tuscaloosa 61 66 58 75 56 / 50 90 60 20 10
Calera 59 67 58 73 55 / 20 80 70 20 10
Auburn 57 70 59 72 56 / 10 70 70 30 10
Montgomery 61 70 59 75 57 / 20 80 70 30 10
Troy 59 71 59 74 56 / 20 80 70 30 10