134 
fxus64 kbmx 212107 
afdbmx 


Area forecast discussion 
National Weather Service Birmingham Alabama 
307 PM CST Sat Nov 21 2009 


Discussion... 


High pressure and a very dry airmass are keeping most of the rain away 
from central Alabama. Slowly but surely though...the atmosphere will 
begin to saturate and rain will eventually begin to reach the 
ground. Given the conditions...total rain amounts for this weekend 
should remain below 1 inch. 


Continue to base the forecast on the sref solution. It has 
performed much better than the GFS for this event as it had a 
better handle on the high pressure and the amount of dry air in 
the area. With the delay of this system...had no choice but to 
increase rain chances for Sunday. Rain will be light...but it will 
be enough to measure. 


Low pressure will exit the area on Monday...but clouds will be 
slow to retreat. The next cold front will move through the area 
late Tuesday into Wednesday. Moisture will be limited...so kept 
rain chances out of the forecast. 


A second cold front is set to move though late next week. Airmass 
behind this front is expected to be much colder which will help 
bring temperatures back down to normal. 


10/arm 


&& 


Aviation...18z taf discussion. 


Clouds and rain have been slow to arrive and have backed off arrival 
times at all taf sites. VFR conds will prevail through 23z with only 
scattered-broken middle level clouds. Rain will move into southwest Alabama by 
00z and reach sites mgm-toi-tcl. MVFR conds will spread into all 
sites by 03z mainly due to visibilities associated with rain...as lower 
ceilings will be slower to arrive due to dry air mass in place. Once 
rain begins...it will likely persist through 18z with visibilities 3-5 in 
rain/fog...with local visibilities below 3 miles in heavier showers. IFR ceilings 
will likely develop at kmgm and ktoi by 09z...and there is chance 
IFR ceilings could spread northward into all taf sites after 12z...but 
drier easterly low level flow may keep ceilings above 1000 feet above ground level. 


Overall trend will be for deteriorating conds during the overnight 
hours. 


58/rose 


&& 


Preliminary point temps/pops... 
Gadsden 45 50 46 58 43 / 70 90 90 10 10 
Anniston 48 55 48 62 46 / 70 90 90 10 10 
Birmingham 50 55 51 62 49 / 70 90 70 10 10 
Tuscaloosa 52 55 51 63 46 / 80 90 70 10 10 
Calera 52 56 50 63 46 / 80 90 70 10 10 
Auburn 50 52 49 62 48 / 90 90 80 10 10 
Montgomery 53 59 50 68 46 / 100 90 70 10 10 
Troy 52 60 50 66 45 / 100 90 70 10 10 


&& 


Bmx watches/warnings/advisories...none. 


&& 


$$