Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Birmingham Alabama
727 am CDT sun may 24 2015
for 12z aviation.
Short term...today and Monday.
The air mass is still relatively dry across central Alabama with
precipitable water values near 1.1 inches. However...middle level
moisture will increase today ahead of a slow moving short wave
trough over Texas. Higher resolution models show scattered convection
developing across southwest Alabama around noon and spreading
rapidly northward during the early afternoon hours...and reaching
the I-65 corridor by middle afternoon. Forecast soundings indicate a
good amount of drier air aloft...so some of the storms could
produce some wind gusts of 30-40 miles per hour. 0-6km bulk shear values are
fairly weather...so storms will be mainly pulse type and not able to
sustain much longevity. The convection will quickly subside this
evening across Alabama due to loss of daytime heating.
However...lift associated with the Texas short wave trough will keep
storms rather active over Mississippi. The lift associated with
this trough axis will push into West Alabama on Monday...and kept
fairly high rain chances for Monday and Monday evening. Cloud
cover and meager bulk shear values should keep convection below
Long term...Tuesday through Saturday.
Deeper moisture will overspread over the area during this period
with precipitable water values ranging from 1.50 to to 1.80
inches. A short wave trough will rotate northeast through the
Midwest states on Tuesday and produce some higher bulk shear
values over Mississippi Tuesday afternoon. A band of higher bulk
shear could reach West Alabama Tuesday evening...but forecast
values are still below 40 knots. The Storm Prediction Center has
areas along and north of I-20 in a slight risk for storms on
Tuesday and Tuesday night. Forecast soundings across West Alabama
for Tuesday afternoon and evening do not seem to favor severe
storms due to high precipitable water values...marginal bulk shear
and weak middle level lapse rates. North Alabama will remain on the
bottom side of a weak upper trough on Wednesday and will continue
likely rain chances. Upper height rises for the period Thursday
through Saturday will likely lead to slightly less activity each
day...with afternoon temperatures climbing back into the middle to
12z taf discussion.
MVFR ceilings have expanded westward into eastern portions of central
Alabama...and are currently impacting ktoi and kanb. Kmgm may also
be affected over the next few hours. Otherwise...VFR conditions
are expected through much of the forecast period with prevailing
surface winds around 10 to 15 knots during the afternoon hours.
Scattered showers and thunderstorms are possible across western
portions of central Alabama this afternoon...but confidence of
enough coverage to include in the taf is low at the current time.
Low level moisture will continue to increase overnight tonight and
MVFR to IFR ceilings are expected to impact all terminals after 06z.
Preliminary point temps/pops...
Gadsden 84 68 82 68 81 / 20 20 60 50 70
Anniston 83 70 83 69 82 / 10 20 50 50 60
Birmingham 84 70 83 70 82 / 30 30 60 50 70
Tuscaloosa 87 70 83 70 83 / 40 30 60 50 80
Calera 85 70 83 69 83 / 30 30 60 50 60
Auburn 84 67 83 68 82 / 10 10 50 30 60
Montgomery 88 71 86 71 85 / 30 20 60 30 60
Troy 87 69 85 69 84 / 30 20 50 30 60