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fxus64 klix 212122 
afdlix 


Area forecast discussion 
National Weather Service New Orleans la 
322 PM CST Sat Nov 21 2009 


Short term... 
surface low pressure system estimated 1006mb about 40 miles south 
of Marsh Island and moving northeast around 15 knots towards 
pointe au fer island. It should move ashore around 7 PM and place 
the lower parishes briefly in warm sector for a short duration 
opportunity of surface based convection. Tornadic supercell 
indicated in the coastal waters abgout 15 miles south of MS river 
Delta is moving right of mean flow and trajectory should keep cell 
well away from land areas...but prompted marine warnings for 
likely tornadic waterspout. Other weaker rotating cell moved 
ashore near Caminada Pass and weakened. Dry slot has worked around 
occluded low circulation and appears to be destabilizing the 
airmass near the coast. Will continue to be vigilant for deeper 
convective development...but many factors inhibiting conditions to 
be any more than an isolated risk at best through the evening. 


Models seem to have better handle on situation than past runs and 
will be going close to GFS with regards to system passage and wind 
fields...thereby dictating rest of forecast elements. Wrap-around 
clouds may remain in the area Sunday until deformation zone and 
upper trough finally moves east of region and some light sprinkles 
or patches of drizzle may take place at times Sunday 
morning...will not anticipate any measurable amounts after sunrise 
Sunday. 


Long term... 
lower extension of cold front swings through the region Tuesday 
but models continue to indicate low level moisture diverging upon 
arrival. No changes made to the long term as dry days are expected 
through the week. Temperatures should be near to slightly below 
normal each day. 


&& 


Aviation... 
scattered showers continue to move across the area. Dry air has be 
protruding in from the south...with rain to in all directions around 
terminals but south. A large band of light to moderate rain to the 
west of the area will track eastward across the area this evening. 
Ceilings and visible will lower to IFR with this rainfall. Activity should 
diminish through the overnight hours. IFR ceilings will move in from the 
west tonight as low pressure system just off the la coast moves east-northeast 
across the coastal parishes. Visible should be MVFR or lower through the 
night due to saturated soil. Conditions will be slow to improve 
tomorrow. Meffer 


&& 


Marine... 
will maintain Small Craft Advisory through 6 PM as winds appear to 
be increasing into criteria with the approach of the low. Winds 
should diminish rather quickly after low moves ashore early this 
evening. Gustiness may continue through Sunday as drier air and 
modest cold air advection moves into the north Gulf. 


&& 


Preliminary point temps/pops... 
mcb 49 60 48 69 / 80 10 10 0 
btr 51 62 48 69 / 40 10 10 0 
msy 54 63 51 69 / 70 10 10 0 
gpt 55 65 50 69 / 80 20 10 0 


&& 


Lix watches/warnings/advisories... 
la...none. 
GM...Small Craft Advisory until 6 PM Saturday for the following 
zones: coastal waters from the Southwest Pass of the 
Mississippi River to lower Atchafalaya River la from 20 to 
60 nm...and coastal waters from the Southwest Pass of the 
Mississippi River to lower Atchafalaya River la out 20 nm. 


MS...none. 
GM...Small Craft Advisory until 6 PM Saturday for the following 
zones: coastal waters from the Southwest Pass of the 
Mississippi River to lower Atchafalaya River la from 20 to 
60 nm...and coastal waters from the Southwest Pass of the 
Mississippi River to lower Atchafalaya River la out 20 nm. 


&& 


$$ 


24/rr 
meffer