Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Birmingham Alabama
1015 am CDT Monday Sep 1 2014
Central Alabama is under the influence of an upper high centered
near the Georgia coast. Precipitable water values this morning are
near the 75th percentile...so there plenty of moisture available
for afternoon convection. Mesoscale-scale models do not show any
organized development today...just the pop-up variety resulting
from diurnal heating. A thick layer of middle level clouds blanketed
the I-20 corridor from Tuscaloosa to Birmingham this morning...and
there might be just enough differential heating to initiate
convection...but not enough confidence to show any specific areas
with higher rain chances. The bottom edge of a short wave trough was
approaching western Tennessee...and this feature will likely kick
off some convection across northern Mississippi this afternoon.
Some of this activity could reach northwest Alabama...and added slight
chance of storms to the northwest counties. For now blanketed the area
with 20 percent probability of precipitation...but may need to update later based on radar
12z taf discussion.
Kept the forecast VFR for Alabama locations through the period. Patchy
MVFR fog has developed...but was isolated and not affecting any
terminals at release. The overall lack of mean moisture and lift
will keep showers and storms more limited than the past few days.
Therefore...no mention of any precipitation in the forecast although
isolated activity is expected east. Surface high pressure remains
near The Spine of the Appalachians which will keep south to
southwest winds across central Alabama. These winds will be around
6 kts daytime and light and variable overnight.
/issued 648 am CDT Monday Sep 1 2014/
Looking at the big picture...upper level ridging continues across
the southeast Continental U.S. With a strong shortwave pushing eastward
across the Central Plains and Midwest. Closer to home...the
remnants of the vorticity/trough exiting to the northeast is
producing some high cloud cover across the state as well as a few
light showers across NE Alabama. At the surface...some patches of fog is
being observed in areas where there is less cloud cover. Abundant
moisture combined with lift will allow for some isolated
showers/storms across east central Alabama primarily during the
afternoon hours today.
The upper ridge will build slightly westward into middle week but
small weaknesses within the ridge will allow for diurnal
convection each day. Models depict a weak surface boundary pushing
southward into Tennessee/Kentucky by Tuesday night before stalling. This
feature shouldn't have much if any impact across our area.
Therefore have maintained climatology probability of precipitation of 20-30 percent each
afternoon and evening through much of the work week. Temperatures
will be slightly above normal with highs generally in the low/middle
Convective coverage looks to be a bit better over the weekend as
another frontal boundary is prognosticated to slide southward into the
region. Unsure of just how far south the boundary will push but it
should be close enough to help aid in increasing shower/storm
coverage Saturday into Sunday. Surface flow looks to become northerly
during this time which will help bring temperatures back down near normal.
Preliminary point temps/pops...
Gadsden 92 70 93 68 92 / 20 10 20 20 30
Anniston 91 71 92 70 94 / 20 10 20 20 30
Birmingham 93 75 93 74 94 / 20 10 20 20 30
Tuscaloosa 94 73 94 72 95 / 20 10 20 20 30
Calera 94 73 93 72 94 / 20 10 20 20 30
Auburn 92 72 93 72 93 / 20 10 20 20 30
Montgomery 95 73 95 73 96 / 20 10 20 20 30
Troy 94 71 93 71 94 / 20 10 20 20 30