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Area forecast discussion...updated 
National Weather Service Mobile Alabama 
1022 am CST Monday Nov 23 2009 


Mesoscale update...tricky temperature and sky forecast for the rest 
of today given the current overcast low stratus deck. The 12z 
soundings from lix and bmx indicated moisture trapped below 850 mb 
under a strong subsidence inversion. With weak high pressure 
settling over the area today...there are no significant changes in 
the low to middle level flow to help to clear this stratus deck out. So 
we will have to rely on the November sun to help erode the cloud 
cover. The latest visible satellite imagery does shows the stratus 
beginning to erode from the south and west and expect this trend to 
continue...with clouds beginning to break up in the south and west 
zones this afternoon. With this in mind...have only nudged high 
temperatures down a degree or two in these areas. However...if The Breaks 
do not materialize by early afternoon...then highs will end up 
several degrees cooler. Much of interior southwest and south central 
Alabama look to stay in the clouds for most of the day...as the low 
November sun angle will spend much of the day trying to break up the 
4000-5000 feet thick stratus deck. Therefore...have trended down temperatures 
at least a category (upper 50s to around 60). 


Update to the gridded and zone forecasts will be sent shortly. 34/jfb 




/previous discussion issued 445 am CST Monday Nov 23 2009/ 


Short term...(today and tonight)...weak surface low pressure near The 
Big Bend area of Florida will drift east and slowly dissipate 
through tonight as a ridge of high pressure noses into the region 
from the northeast. Widespread low clouds...light fog and drizzle 
noted over most of the southeastern states this morning...and expect 
this to persist well into the morning hours but gradually dissipate 
by late afternoon. Will not mention any measurable rain chance for 
today... but would not be surprised if morning commuters have to 
swipe windshield wipers occasionally in areas of drizzle. Partly 
cloudy conditions by late afternoon and early this evening...giving 
way to another round of low clouds and fog tonight. A light north to 
northeasterly wind flow is expected today and tonight. Daytime maximum 
temperatures today at or just slightly above normal...overnight min temperatures 
tonight generally several degrees above normal. 12/ds 


&& 


Long term...by 12z Tuesday surface ridge over the southeast Continental U.S. Begins to 
shift n'ward in response to next long wave trough/closed low moving 
east northeast from the Central Plains to the middle MS River Valley. 
This pattern will continue to give way to near seasonable temperatures with 
partly sunny conditions on Tuesday due to increasing high cloudiness 
ahead of an approaching cold front associated with main upper system 
to the northwest. The cold front will move well to the east and south of 
the County warning forecast area by 18z Wednesday with chance probability of precipitation mostly in the form of showers 
well offshore away from the coast early Wednesday morning. As upper system 
moves more northward on Wednesday model guidance preferably the GFS and 
European model (ecmwf) show another short wave on the heals of the first digging 
mostly east of the MS River Valley giving way to much drier/cooler 
conditions for much of the deep south late in the week and the first 
part of the weekend. Min temperatures will range from the middle to upper 30s 
both Friday and Sat...with highs in the upper 50s well inland and the 
lower 60s closer to the coast on Friday. Slightly warmer conditions 
combined with mostly sunny skies are expected each afternoon over 
the weekend. Will continue to use the current 00z mex guidance for 
temperatures in the extended grids. /32 


&& 


Aviation...(12z issuance)...LIFR conditions over the region early 
this morning with low cloud deck producing ceilings around 400 feet. The 
low ceiling will persist through about 15z...gradually scattering out by 
the late afternoon hours. Will likely see a few hours of VFR 
conditions late this afternoon and early this evening...but possibly 
will return to MVFR or IFR conditions tonight as low clouds and fog 
again develops across portions of the region. 12/ds 


&& 


Marine...weakening surface low near The Big Bend area of Florida 
early this morning is expected to weaken further and dissipate by 
tonight. Winds are forecast to be light to moderate offshore today 
and Tuesday as weak high pressure moves across the marine area. 
Meanwhile...a weak frontal passage is expected Tuesday night or 
Wednesday morning. This will result in an increase in the offshore 
winds...along with building seas...during the middle and late part 
of the week. 12/ds 


&& 


Fire weather...afternoon relative humidities look to be much lower 
Friday through Sunday...in the wake of the cold front which moves 
across the region by middle week. At this time humidities levels look 
to be above critical thresholds later in the week but will be 
monitored closely as we near the end of the work week. /32 


&& 


Preliminary point temps/pops... 
Mobile 68 48 72 48 / 10 05 10 05 
Pensacola 67 51 69 51 / 10 05 10 10 
Destin 67 54 67 54 / 10 05 10 10 
Evergreen 64 44 70 42 / 10 05 10 10 
Waynesboro 65 42 72 43 / 05 05 05 05 
Camden 62 44 71 45 / 10 10 10 05 
Crestview 69 46 71 44 / 10 05 10 10 


&& 


Mob watches/warnings/advisories... 
Alabama...none. 
Florida...none. 
MS...none. 
GM...none. 
&& 


$$