556 
fxus64 kbmx 162032 
afdbmx 


Area forecast discussion 
National Weather Service Birmingham Alabama 
332 PM CDT Tuesday Mar 16 2010 


Discussion... 


I wish I had better news as far as sun for central Alabama...but I 
just don't. There are some lucky ones out there though...as folks 
from Clanton to Phenix City southward are seeing plenty of sun this 
afternoon. But this will soon go away as our next weather maker is 
already cranking up the clouds just to our west. 


Wednesday and thursdays weather will come in the form of two 
shortwave troughs that will rotate around the base of the long wave 
upper level pattern. Both of these shortwaves will swing south of 
the Gulf Coast states...keeping any surface low that develops well 
to the south. Without any real forcing...the most we'll be seeing 
around the state on Wednesday/Thursday will be some annoying light 
showers...and only enough to keep 20-30 pop in the forecast. 


Once the second of these two trough rotates out of the region... 
decent ridging works into the southeast. This will warm things up 
considerably for Friday and Saturday...and keep a fairly progressive 
pattern going for US...at least compared to last week. The 
upper level ridge slides off to the east...our next system will 
begin marching across the plains and the Midwest. 


Per usual...we still have some uncertainty with this day 5-6 system 
..but the evolution is becoming clearer...Thats for sure. This 
next system will come in late Saturday night...likely after 
midnight...in the form of a cold frontal passage. Most of the model 
inconsistency is in regards to the strength of the surface low as it 
rotates out of the middle Mississippi Valley and into the Ohio Valley. 
This is causing models to continue depicting weak southerly flow 
ahead of the front....which means not much in the way of dew 
points. This would limit surface based instabilities...but middle level 
lapse rates of 6-6.5 degrees celsius would be enough to get some 
good convection initiated. These low dew points are very common in 
long range models...and with some type of GFS error in AWIPS... 
ended up running with the 12z Euro /and some tweaking/ dew points. 
This gets low to middle 50s into central Alabama for now. This 
should get enough instability into the area to warrant at least 
strong thunderstorms late Saturday night and Sunday morning as the 
front moves through the County Warning Area. As we did last night...with more model 
continuity comes higher certainty in these thunderstorms...so if 
trends look to persist tonight and tomorrow for this weekend...will 
likely run with a much more aggressive forecast. 


High pressure settle into the eastern half of the U.S. After this 
weekends system...so look for a drying pattern to begin by Monday. 


27 


&& 


Aviation...18z taf discussion. 


Low clouds and MVFR conditions will continue to be prevalent 
throughout the forecast period throughout the northern taf 
sites...and are expected to slowly rise to low end VFR conditions 
through the afternoon hours. Forecasts for mgm and toi are a bit 
tricky...as clouds have not built as far south as previously 
planned. Decided to leave broken clouds for mgm and scattered to 
broken clouds for toi through the overnight period. The only 
uncertainty in the forecast exists for toi into tomorrow 
afternoon...as a low pressure area passes off to the southeast. 
Decided to place MVFR conditions there with vcsh through the end of 
the taf period. 


56/Goggins 


&& 


Preliminary point temps/pops... 
Gadsden 45 58 41 63 37 / 10 20 30 30 10 
Anniston 44 58 43 63 40 / 10 20 30 30 10 
Birmingham 45 59 44 63 42 / 10 20 30 20 10 
Tuscaloosa 45 61 44 64 37 / 10 20 10 20 10 
Calera 46 59 45 63 42 / 10 20 30 20 10 
Auburn 44 58 43 63 43 / 10 30 30 30 10 
Montgomery 46 58 46 64 41 / 10 30 30 30 10 
Troy 41 58 43 63 39 / 20 30 20 30 10 


&& 


Bmx watches/warnings/advisories...none. 


&& 


$$ 


27/56