897 
fxus64 kbmx 201954 
afdbmx 


Area forecast discussion 
National Weather Service Birmingham Alabama 
254 PM CDT Sat Mar 20 2010 


Short term...tonight through Monday. 


A great first day of Spring today with temperatures right where 
they should be for middle March. Southerly winds are increasing due 
to deepening surface low over Arkansas. A band of showers along 
the Texas and Louisiana state is ahead of a strong cold front 
marching through East Texas. Showers should stay confined to pre- 
frontal line...with line moving into West Alabama between around 2 
am CDT...so no rain this evening. Despite strong forcing and 
shear... instability is lacking as cold front pushes through area. 
Given the strong warm advection aloft...could see lightning 
anywhere along the line..even though middle level lapse rates are not 
that impressive. Strong thunderstorm wording will be maintained 
for the southwest counties after midnight due to wind gusts. 


The cold front will push through West Alabama Sunday morning and 
east Alabama in the afternoon. The front will pretty much mark the 
end of the heavier rainfall. Given the fast movement of the 
showers and thunderstorms...do not anticipate training of cells 
over a single area to cause any flash flooding concerns. Temperatures 
will drop of noticeably behind cold front on Sunday. There may 
be a break in the clouds Sunday afternoon across areas south of 
I-20 as middle level dry slot pushes into area ahead of main upper low. 
There will also likely be a break in the shower activity due to 
dry slot. 


Regarding the upper low...this one is deep and cold. It is 
forecast to pass right over north Alabama. Models are showing a 
500mb pocket of -28 celsius and 850mb temperatures near -8 
celsius. I believe this may be one the the coldest upper lows to 
track this far south this winter season. The extremely cold air 
associated with upper low will likely produce a mixture of 
rain/snow across much of north Alabama late Sunday night and into 
Monday morning. There may even be some periods of all snow...but 
ground temperatures are warm...so no accumulation expected. The 
higher elevations in northeast Alabama may see a dusting. The 
cloudy and cold conditions will continue all day Monday and into 
Monday night. Biggest change to forecast was to lower temperatures 
on Monday as readings will not likely get out of the middle 40s north 
of I-20. Low clouds will begin to decrease from west to east 
Monday night as low pressure moves out of area. 


Long term...Tuesday through Saturday. 


Sunshine and warmer temperatures will return on Tuesday as upper 
ridge builds into the lower Mississippi Valley. A weaker short 
wave trough will work eastward across the southern states Thursday 
and Friday. Best chances of rain with this system appears to be on 
Friday...with drier conditions returning in time for the weekend. 


58/rose 


&& 


Aviation...18z taf discussion. 


Added a little more detail for planning purposes on when the rain is 
expected to arrive. In addition to the rain...MVFR ceilings should 
begin to move in from west to east as early as 10z and continue 
through the rest of the forecast period. 


In the short term...no problems expected for the next 6 to 12 hours 
other than intermittent wind gusts. 


10/arm 


&& 


Preliminary point temps/pops... 
Gadsden 51 55 35 43 37 / 50 80 40 40 20 
Anniston 53 56 37 44 37 / 50 80 40 40 20 
Birmingham 53 55 34 45 40 / 70 80 40 40 20 
Tuscaloosa 52 54 37 47 40 / 90 80 40 40 10 
Calera 53 54 37 44 39 / 80 80 40 40 10 
Auburn 51 59 36 46 39 / 40 80 30 30 10 
Montgomery 55 57 39 49 40 / 70 80 30 30 0 
Troy 52 59 35 50 38 / 50 80 30 30 0 


&& 


Bmx watches/warnings/advisories... 
none. 


&& 


$$