Weather

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afdlix 


Area forecast discussion 
National Weather Service New Orleans la 
421 am CDT Monday Oct 6 2008 


Discussion... 
short range models are having a time initializing the 
precipitable water value field across the Gulf. GOES sounder precipitable water 
display showed relatively dry air over the northwest Gulf and mass 
clouds and moisture over central and East Gulf. Surface high has 
retreated over the northeast Continental U.S. And upper level high over the 
East Gulf should speed up moisture return from the East Gulf today. 
The relatively dry air over northwest Gulf will advect north too 
across the forecast area today. With no uniformity to the moisture 
fields...we expect an increase in rain chances today and tonight 
but not as high NAM numbers...will go close to GFS probability of precipitation for today 
and tonight. GFS continue to show a vorticity maximum and quantitative precipitation forecast bullseye over 
the area Tuesday. Will carry likely probability of precipitation for frontal passage not 
the low developing. Upper level analysis at 500 mb a negatively tilted 
trough axis from western Montana to West Texas. An early 
negatively tilted trough usually equates to a quick shot of precipitation 
in a squall line along the Gulf and strong storms to the north. 
However...a vorticity maximum on the backside of the trough will likely 
prevent the trough from lifting north and keep the trough sharp 
and moving to the Mississippi Valley by Tuesday afternoon. 
Isotachs analysis at 250mb at 120 to 130 jet maximum nosing southeast 
across Washington to the Great Basin. However...this jet maximum 
become more west to east through Tuesday...according GFS...NGM and 
NAM. Ergo...upper level dynamics and energy should remain north. 
Strong storms are expected ahead the trough axis Tuesday afternoon 
and Tuesday night. A progressive flow will keep the westerly 
intact over the area through the weekend. Southwest flow is 
expected to bring these embedded disturbances across the area over 
the weekend. Will carry a chance of rain Friday night into 
Saturday. GFS has pegged the timing of the first system ... so 
will go along the GFS thinking with next stronger system moving 
through the forecast next Monday. 


&& 


Aviation... 
mostly VFR conditions should prevail at msy...btr...gpt...mcb 
today. The best chance for showers will be at btr this afternoon. 
Areas of fog/stratus are possible around msy and btr Monday 
night/Tuesday morning as more moisture pushes across the area. 25 


&& 


Marine... 
moderate flow due to the pressure gradient will ease today. This 
will allow winds and seas to fall below Small Craft Advisory 
criteria. Generally southeasterly flow will turn northwesterly on 
Wednesday as a cold front pushes through the area. 25 


&& 


Preliminary point temps/pops... 
mcb 85 68 84 68 / 20 30 60 60 
btr 85 69 84 69 / 30 30 60 50 
msy 84 73 85 71 / 20 30 60 60 
gpt 83 71 82 69 / 10 20 60 60 


&& 


Lix watches/warnings/advisories... 
la...none. 
GM...Small Craft Advisory until 10 am CDT this morning for gmz550-555- 
570-575. 


MS...none. 
GM...Small Craft Advisory until 10 am CDT this morning for gmz555-570- 
575. 


&& 


$$ 


18/25