647 
fxus64 kbmx 062002 
afdbmx 


Area forecast discussion 
National Weather Service Birmingham Alabama 
302 PM CDT Monday Oct 6 2008 


Discussion... 


Quite a messy picture over the next 2 days or so...with a bit of 
difference between the models to negotiate. Although the details 
are up for grabs to some extent...fairly confident most locations 
should see at least some of the much needed rain in this time 
period. For the last half of the week...weather pattern is a bit 
lackadaisical...before a highly amplified pattern develops with a 
deep trough in the west...and a ridge over the southeast. 


Tonight through Wednesday...models have been somewhat consistent 
trying to form/generate some precipitation associated with some low/middle 
level lift and moving the area into southwestern portions of 
central Alabama ahead of the slowly approaching upper low. I may 
be just a tad fast on precipitation onset...but believe most areas west 
of Interstate 65 should see at least some rain by the end of the 
day Tuesday. Certainly...one way or the other... moisture is on 
the increase no matter which model you look at. GFS has come more 
in line with NAM with regards to generating precipitation during the day 
tomorrow...and by tomorrow night is categorical. Believe we will 
see a tight east to west gradient in probability of precipitation tomorrow...with none 
east/categorical west. Tuesday night...mav is tough to beat when 
it GOES categorical within the first 3 forecast periods...so I 
will not try to do so. 


One significant question is with regards possibility for 
thunder...and any concerns for strong storms. At this point... 
convective/severe potential looks limited. Barotropic structure 
of the system should help to limit dynamic parameters. While dew 
points in the low 60s and significant cloud cover should prevent 
thermodynamic parameters from getting out of hand. That said...the 
storm prediction has all of central Alabama highlighted by a see 
text in their day 2 and day 3 outlooks. The biggest question 
regarding the potential for strong/severe storms Tuesday into 
Wednesday is the evolution of the subtropical jet. 


Strong ridge over the eastern United States Monday into Tuesday 
should be slow to break down so the rapid return of moisture into 
central Alabama looks unlikely. The better chance of strong/severe 
storms will reside farther south. Late Tuesday/early Wednesday...if 
drier air is able to push in quicker than most guidance suggests...a 
few elevated hail producing storms could become possible across 
western Alabama. The front should exit central Alabama Wednesday 
afternoon...with the 850 trough lagging only by a few hours marking 
the end of any significant rain chances. 


By Thursday...models begin to diverge with the exact track of the 
weakening remnant low...but both the GFS and Euro eventual build 
an anomalously strong ridge over the southeast. While the Euro is 
tending to let some probability of precipitation leak in under the ridge...GFS is not 
quite as amplified and keeps the ridge axis overhead...shunting 
any precipitation to the south. Latest GFS probability of precipitation are marginal...so at 
this point...inclined to keep probability of precipitation out of the forecast for the 
remainder of the period. Of note...12z mex guidance GOES crazy on 
maximum temperatures Saturday...more than 10 degrees above normal. Will 
temper those highs down a bit...but still expect above normal 
temperatures for the weekend at this time. 


Jd/81 
12/sirmon 




&& 


Aviation...18z taf discussion. 


Middle and some lower level clouds will increase through the period as 
a frontal system moves closer to central Alabama. Expect that 
increasing cloud cover will allow the dewpoint depressions to be 
slightly higher than previous mornings...so may not have visible 
restrictions overnight. However...some haze may return due to the 
moisture influx. Other than that...no major aviation concerns. 


17/klaws 


&& 


Preliminary point temps/pops... 
Gadsden 57 77 59 71 55 / 0 10 90 80 40 
Anniston 61 77 64 73 56 / 0 10 90 80 40 
Birmingham 63 77 64 73 57 / 10 60 90 70 30 
Tuscaloosa 62 77 64 76 59 / 10 90 90 50 20 
Calera 62 78 64 74 57 / 10 70 90 70 30 
Auburn 60 74 63 71 59 / 10 20 90 80 30 
Montgomery 65 78 65 76 59 / 20 80 90 60 20 
Troy 64 75 67 74 59 / 20 80 80 70 20 


&& 


Bmx watches/warnings/advisories...none. 
&& 


$$ 


81/81/17