Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Birmingham Alabama
540 am CST Tuesday Dec 1 2015
for 12z aviation.
Currently this morning we have a cold front knocking on our door
step across west central Tennessee into northeast Mississippi and
south central Louisiana. This front is expected to slowly push
into central Alabama today as the main surface low pushes to the
northeast from Iowa toward the Great Lakes. We should see a tad
cooler temperatures work into the northwest counties of central
Alabama today as the front progresses. The I-85 and southward
corridor should remain mild for one more day. As the front works
its way further into the area tonight...the main rain axis should
shift accordingly into the central part of the area from northeast
to southwest (roughly centered on the I-59/20 corridor).
Instability remains low with this system with only showers
mentioned. With the low rain amounts of recent days...overall rain
should be manageable and no widespread flooding is anticipated.
Storm total amounts from now through Wednesday are expected to be
anywhere from 1/3 inch in the far southeast to 1/2 to 1 inch in
the northwest and 1-2 inches across the central portions.
By Wednesday...as the surface low moves across the Great Lakes
into eastern Canada and toward New England...this front will
finally get the tug it needs to pull our rain to the east/
southeast and out of the area by late Wednesday afternoon. Drier
air behind the system looks better and will go with a rain free
forecast for Wednesday night on through the weekend as a large
ridge builds across the eastern United States which will help
cooler temperatures work back into the area for the latter part of
the week Post front. We will be back to more normal readings for
this time of year...maybe even a degree or two cooler for central
In the far extended...by next Monday/Tuesday guidance attempts to
break down the eastern Continental U.S. Ridge and develop another surface
system. Models continue to struggle with the timing on this and
i'm trending to the slower scenario. For now...i'll keep low probability of precipitation
in for Monday/Tuesday time frame with a moderating air mass as we
move into the beginning of next week.
12z taf discussion.
Slow moving frontal system will finally help spread rain...with
associated low ceilings and visibilities...across a larger portion
of central Alabama today. IFR conditions have already arrived to
bhm and eet...with sub-1000 feet ceilings not far away from tcl.
Those conditions are expected to spread east and south through
the day...perhaps getting as far south as mgm before 00z. While
ceiling levels will not necessarily be steady state...average
ceiling heights (once they go down) should stay below 1000 feet but
above Landing minimums in most areas. The front that causing the
adverse weather is moving quite slowly...so conditions are
unlikely to improve until (at the earliest) just beyond this 24
hour forecast cycle.
A slow moving cold front will bring widespread rain to north
central Alabama today...with coverage shifting southeastward
tonight into Wednesday. Drier and slightly cooler conditions will
spread into the area Wednesday into Thursday. No fire weather
concerns at this time through the week.