558 
fxus64 klch 201102 
afdlch 


Area forecast discussion 
National Weather Service Lake Charles la 
602 am CDT Sat Mar 20 2010 


Discussion... 
for 12z taf issuance. 


&& 


Aviation... 
latest satellite imagery and surface observations show mainly high 
clouds streaming over the forecast area with some middle 
cloudiness overhead as well. Klch/kaex showing some slight 
restrictions to visibility ongoing where temperature/dewpoint spreads and 
surface winds are lowest. These should continue at least temporarily past 
sunrise. MVFR conditions could also develop at klft/kara just 
after sunrise when spreads are lowest. Observation show lower ceilings... 
although still VFR...just off to our west over interior southeastern Texas. 
This cloud cover expected to spread across the area later this 
morning into the afternoon. Latest model suite still depicts 
widespread shower and thunderstorm activity developing by late 
afternoon ahead of approaching frontal boundary. With this 
issuance carrying prevailing thunder just prior to frontal passage..with 
prevailing IFR...light rain and strong nearly winds in the hours 
just after frontal passage. Strong nearly winds and MVFR will then continue 
through the end of the period. 


25 


&& 


Previous discussion... /issued 525 am CDT Sat Mar 20 2010/ 


Synopsis...a strong cold front moving through north central Texas 
will be punching into southeast Texas this afternoon then speeding 
quickly through the remainder of the area this evening. Strong 
winds and sharply colder temperatures can be expected...along with 
thunderstorms later this afternoon and this evening. Temperatures 
could dip to the freezing mark over interior portions of southeast 
Texas as Arctic air from the Canadian prairies and southern rockies 
moves out over North Texas associated with a closed upper low 
moving through the Red River valley and into Louisiana on Sunday. 


Short term...due to cloud cover, Arctic air producing 20dm height 
falls, strong cold advection after the front, went lower than 
guidance on temperatures through Sunday. Due to the speed of the 
oncoming system, trimmed back on probability of precipitation from guidance. Total area 
affected will be large but duration of precipitation will be limited. A 
lake Wind Advisory will likely be needed for tonight. 


Long term...temperatures should rebound nicely on Monday with 
ridging sliding in behind the departing low. Blended Euro with GFS 
temperatures late next week due to model differences. Chance of precipitation 
still looks reasonable Thursday and Thursday night as a much 
weaker short wave trough takes the southern track and moves through. 


Marine...gales look reasonable considering the very tight 
gradient associated with this system with the GFS still impressive going 
for widespread 30 knot winds with cold advection over the 61 
degree Gulf waters. Gradient finally loosens Sunday night. 


&& 


Preliminary point temps/pops... 
klch 66 35 50 37 65 / 60 40 10 10 0 
kbpt 66 33 53 37 66 / 60 20 10 10 0 
kaex 69 34 46 38 63 / 50 60 40 20 0 
klft 68 38 50 42 64 / 20 60 10 20 0 


&& 


Lch watches/warnings/advisories... 
la...none. 
Texas...none. 
GM...Small Craft Advisory from 7 PM Sunday to 10 am CDT Monday for 
the following zones: waters from lower Atchafalaya River to 
Intracoastal City, la extending from 20 nm to 60 nm. 


Gale Warning from 7 PM this evening to 7 PM CDT Sunday for the 
following zones: 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. 


Small Craft Advisory from 7 PM Sunday to 4 am CDT Monday for the 
following zones: 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. 


Small Craft Advisory from 7 PM this evening to 7 PM CDT Sunday 
for the following zones: Calcasieu Lake...Sabine Lake... 
Vermilion Bay. 


Small Craft Advisory from 7 PM this evening to 10 am CDT Monday 
for the following zones: coastal waters from lower 
Atchafalaya River to Intracoastal City, la out 20 nm. 


Small Craft Advisory from 7 PM this evening to 4 am CDT Monday 
for the following zones: coastal waters from Cameron, la to 
High Island, Texas out 20 nm...coastal waters from 
Intracoastal City to Cameron, la out 20 nm. 


&& 


$$