036 
fxus64 klch 211731 
afdlch 


Area forecast discussion 
National Weather Service Lake Charles la 
1131 am CST Sat Nov 21 2009 


Aviation... 
for the 21/18z taf issuance... 
upper level low located over east central Texas this late morning 
with associated surface low located in the northwest Gulf about 
100 miles south-southeast of Lake Charles. Both systems will move 
slowly off to the east-northeast today and tonight. Steady light to moderate 
rain with MVFR ceilings and visibilities will continue into the 
afternoon hours. Rain is expected to end at kbpt taf site by late 
afternoon...and remainder of taf sites during the evening hours. 


After the rain ends...low end MVFR ceilings will prevail through 
the night as wrap around moisture from the upper low continues. 


Some drier air will gradually filter in during the morning hours 
on Sunday with a gradual scattering out of the cloud cover from 
west to east. 


Rua 


&& 


Previous discussion... /issued 1019 am CST Sat Nov 21 2009/ 


Update...new discussion available. 


Discussion...analysis suggesting surface low over the coastal waters 
centered about 100 miles south southwest of Cameron. Feature to 
continue a northeast track with current scattered rains tapering 
off as the day progresses. Clouds...rains and a northerly flow 
developing over the entire area will limit any significant warmup 
from our current temperatures so a rather dismal day continuing. Grids/zones 
look on track and see no need for any changes. 


Marcotte 


Previous discussion... /issued 558 am CST Sat Nov 21 2009/ 


Discussion... 
latest upper air analysis/water vapor satellite imagery showed 
split flow across noam...with the subtropical jet running from the 
Pacific across northern Mexico and through the central Gulf...and 
the active polar jet streaming across the western and northern 
Continental U.S.. vigorous middle/upper low was noted over central/eastern 
Texas. 


At the surface...low pressure system currently over the northwest Gulf 
about 150 miles south of Sabine Pass...with high pressure 
centered over the Ohio River valley. Regional radars show a large 
swath of light to moderate mainly stratiform rain over the coastal 
waters and into East Texas and Louisiana...with a few convective 
cells starting about 60 nm south of Grand Chenier and extending 
south into the Gulf. 


Middle/upper low is forecast to continue heading east across the 
region today...lifting northeast into central MS tonight. The surface 
low is expected to track east northeast across the northwest 
Gulf...Crossing southeast Louisiana tonight. Widespread and 
primarily isentropic lift driven rains will continue on the north 
side of the surface low. Isolated elevated thunder is possible over 
the Gulf waters...but little to no lightning is expected inland. The 
rainfall will gradually come to an end from west to east this 
afternoon and tonight as the low shifts east of the area. Total 
rainfall amounts should generally remain under one inch. 


Very light wrap-around rain or drizzle is possible over east 
central Louisiana Earl Sunday before the middle/upper system pulls 
away...but at this time opted to leave the forecast dry. A 
generally zonal pattern behind this departing system along with 
the dry air it will have brought in will keep rain out of the 
forecast on Monday. 


A brief period of return flow will occur Monday afternoon into 
early Tuesday ahead of the next frontal system slated to move 
through the area Tuesday afternoon and night. Nevertheless...this 
front looks to be quite starved of moisture and the middle/upper 
level support will pass well north of the area. Thus...only slight 
chance of rain is warranted at this time. Temperatures will creep 
above normal ahead of this system...but fall back to at or below 
normal Tuesday night and remain there the rest of the work week. 


Thanksgiving day looks dry and mild...with early morning temperatures in 
the lower to middle 40s and daytime highs in the lower to middle 60s. 


Forecast for the weekend and beyond becomes more uncertain...as 
the global models become quite divergent in their solutions. 
Should the European model (ecmwf) pan out...yet another vigorous storm system would 
affect the area early next week. 


Marine... 
low pressure moving east across the northwest Gulf will bring 
strong winds and rough seas today. Widespread rain with isolated 
thunderstorms will accompany the system. Winds and rains will 
diminish tonight into Saturday as the system exits to the east. 
Gale Warning may be becoming a bit more marginal based on latest 
observation...but at the time of extension there were still some gusts in 
excess of gale force being reported. Will continue to monitor for 
possible cancellation before the scheduled 16z expiration time. 


Aviation... 
areas of rain continue to overspread southeast Texas and southern 
Louisiana as a surface low continues to move east northeast across the 
northwest Gulf. Winds have not strengthened as much as initially 
anticipated...but still expect NE winds around 8-12 knots this morning 
as the low treks toward southeast Louisiana...gradually shifting 
north during the afternoon and decreasing as it moves away from the area 
late this afternoon and evening. Patchy light rain will linger this 
morning at all taf sites...with occasionally moderate rainfall 
possible especially at klft and kara. In addition...MVFR ceilings 
are expected today...lowering to IFR by late afternoon and evening 


&& 


Preliminary point temps/pops... 
klch 59 48 64 46 71 / 70 10 10 10 10 
kbpt 59 47 67 48 72 / 50 10 10 10 10 
kaex 56 48 63 43 70 / 70 20 10 10 10 
klft 59 50 62 47 69 / 80 20 10 10 10 


&& 


Lch watches/warnings/advisories... 
la...none. 
Texas...none. 
GM...Small Craft Advisory until 6 PM CST this evening for the 
following zones: Calcasieu Lake...coastal waters from 
Cameron, la to High Island, Texas out 20 nm...coastal waters 
from Intracoastal City to Cameron, la out 20 nm...coastal 
waters from lower Atchafalaya River to Intracoastal City, 
la out 20 nm...Sabine Lake...Vermilion Bay...waters from 
Cameron, la to High Island, Texas extending from 20 nm to 60 
nm...waters from Intracoastal City, la to Cameron, la 
extending from 20 nm to 60 nm...waters from lower 
Atchafalaya River to Intracoastal City, la extending from 
20 nm to 60 nm. 


&& 


$$ 

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