Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Birmingham Alabama
706 am CDT Wednesday may 27 2015
for 12z aviation.
12z taf discussion.
Variety of IFR/MVFR conditions across taf sites due to low ceilings
predominantly...although visible at eet was briefly impacted fairly
significantly. Fog is harder to come by...at least at taf sites
this morning. Once again...will transition from IFR/MVFR morning
conditions to another round of convection late morning through
early evening from west to east...and tried to time tafs according
to hrrr/rap guidance for most likely period of shower/thunderstorm
After convection ends this evening...uncertainty as to whether
ceilings/visible issues will crop back up. Surface ridge to the east weakens...as
does upper level flow...so do not see a strong advection/stratus
situation per southeast. With areas of locally heavy rainfall possible
and general low level moisture profiles...believe the concern will
be mainly light fog (br) overnight. Will leave out for now and
focus on daytime...and defer to following issuances.
/issued 352 am CDT Wednesday may 27 2015/
No rain in the immediate vicinity of central Alabama early this
morning. A cluster of showers and thunderstorms has been nearly
stationary across west central Mississippi the past 6 hours. This
area seems to be associated with the tail end of a vorticity maximum over
Iowa. A more organized area of convection has been slowly pushing
eastward over East Texas. The hrrr model has been performing well
the past few days and will lean heavily towards this model for
the rain forecast for today. The hrrr model expands the
Mississippi convection eastward later this morning and brings a
band of convection into West Alabama around noon today. Like
previous days..the convective band spreads eastward across central
Alabama during the afternoon hours and upticks in intensity as it
encounters a more unstable air mass. The convection will mostly be
east of Alabama by sunset and do not expect much coverage after 9
PM this evening. By Thursday the upper level zonal flow becomes
less pronounced and the convection should be more diurnal and less
On Friday and Saturday an upper ridge builds over the southeast
states...and drier middle level air works into southeast Alabama.
Higher rain chances for Friday and Saturday will be across the
northern counties. A short wave trough moving through the Ohio
Valley region on Saturday will push a trough axis into Tennessee.
This trough axis will likely stall out just north of Alabama as it
encounters the Southeast Ridge. A short wave trough over Texas will
help pull Gulf moisture northward Monday and Tuesday and help erode
the drier air associated with Southeast Ridge. Expect scattered
convection across all of central Alabama Monday and Tuesday.
Preliminary point temps/pops...
Gadsden 81 66 84 66 84 / 70 30 40 20 30
Anniston 83 67 84 67 85 / 60 30 40 20 30
Birmingham 82 68 84 68 85 / 70 30 40 20 30
Tuscaloosa 83 67 86 68 87 / 70 30 40 20 30
Calera 82 68 84 67 85 / 60 30 40 20 30
Auburn 85 65 83 66 84 / 60 30 50 20 20
Montgomery 85 68 87 68 88 / 60 40 50 20 30
Troy 85 67 86 67 87 / 60 30 50 20 20