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fxus64 kmob 120523 aab 
afdmob 


Area forecast discussion...update to aviation 
National Weather Service Mobile Alabama 
1130 PM CST Thursday Mar 11 2010 


Aviation...(06z issuance)abundant moisture from last night's rain 
will help fog development tonight. A weak upper system will work 
with a stalled surface boundary over the area to create showers... 
maybe a few thunderstorms...late tonight into Friday morning. Result 
will be VFR conditions deteriorating to IFR or worse at times 
overnight until the rain works its way over the forecast area. 


This rain is expected to move east of the forecast area by 18z Friday...with 
clearing under drying northwesterly flow for the latter half of the 
package. 


/16 


&& 


Short term (tonight through Sunday night)...another difficult 
forecast on tap for tonight into Friday morning. A strong shortwave 
currently rotating through the base of the strong system over the 
Central Plains takes on a negative tilt while moving an associated 
surface low from the Sabine River area northeastward across central 
Mississippi into northern Alabama through 12z Friday. The strong 
170+ knot upper jet meanwhile tracks northward out of the northern 
Gulf tonight while the strong shortwave advances quickly across the 
southern states and into the region. Expect a broken line of 
convection to to move across much of the forecast area overnight 
then exit over the eastern portion Friday morning. There is a 
consensus among the models for two favored areas for more convection 
along the line which is over the marine area and most of the coastal 
counties with the left exit region of the upper jet...and also the 
extreme northwestern portion of the forecast area associated with 
the strong shortwave. Have gone with likely probability of precipitation over much of the 
coastal counties and extreme northwestern portion of the area as a 
result...with good chance probability of precipitation elsewhere for tonight. The strong 
shortwave sweeps across the forecast area Friday morning and have 
gone with likely probability of precipitation over the eastern third of the area with probability of precipitation 
tapering off to the west...then low probability of precipitation for Friday afternoon. 
Model soundings show fairly dry conditions over the area currently 
but this will change through tonight as 850mb flow increases to 
around 30 knots after midnight resulting in moisture return below 
800 mb while dry air remains in place aloft. Model soundings do not 
show very favorable lapse rates and the sref shows a good chance for 
convective available potential energy slightly above 500 j/kg. There are several sources of 
uncertainties with the evolution of this system such as the amount 
of dry air present aloft and also for the potential for convection 
over the marine area to limit moisture further north and limit the 
potential for convective development over the forecast area. At 
this time...expect wet bulb zero values to be around 8 kft and 
considering the uncertainties and marginal cape and after discussing 
with Storm Prediction Center...have gone with isolated embedded strong storms in grids 
for the area after midnight and over the easternmost sections Friday 
morning. Will have small probability of precipitation over the northernmost counties for 
Friday night through Saturday for wrap around precipitation otherwise dry 
conditions follow through Sunday night. Seasonable temperatures on 
Friday and followed by cooler conditions through Sunday night. /29 


&& 


Long term (monday through thursday)...dry conditions continue for 
Monday as ridging moves across the area. A series of shortwaves 
move across the region Tuesday through Wednesday night supporting 
small probability of precipitation for the forecast area. Dry conditions follow for 
Thursday as shortwave ridging builds into the area. Somewhat cool 
temperatures continue through the period. /29 


&& 


Marine...onshore flow will increase tonight ahead of an approaching 
low pressure system and associated cold front that will move across 
the marine area late tonight. Strong west to northwest winds will 
follow in the wake of the front through Saturday as the low moves 
east off the middle Atlantic coast and high pressure builds across the 
northern Gulf. /13 


&& 


Fire weather...a low pressure system will develop over the Southern 
Plains and advance eastward into the eastern states through Friday 
and bring scattered to numerous showers and thunderstorms to the 
area. Drier conditions follow for Saturday and Sunday. Afternoon 
relative humidities will remain above critical levels Friday. 
Relative humidities will drop briefly below critical levels over the 
interior portion of the northwest Florida Panhandle on Saturday and 
Sunday afternoon but will not satisfy duration criteria. /29 


&& 


Preliminary point temps/pops... 
Mobile 56 71 45 66 / 50 30 05 10 
Pensacola 59 72 48 66 / 60 50 10 10 
Destin 59 70 51 65 / 60 60 10 10 
Evergreen 53 71 43 66 / 50 60 10 10 
Waynesboro 49 68 42 62 / 50 40 10 20 
Camden 53 69 42 62 / 50 50 10 20 
Crestview 55 73 44 69 / 60 60 10 10 


&& 


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


$$