FXUS64 KLCH 270318
AFDLCH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
918 PM CST THU NOV 26 2009
.UPDATE...
MAIN FORECAST CHALLENGE CONTINUES TO BE THE POSSIBILITY
OF FREEZING TEMPERATURES IN THE NORTHERN ZONES FOR
TONIGHT...ESPECIALLY IN CENTRAL LOUISIANA. TEMPERATURES HAVE
PLUMMETED THIS EVENING WITH MANY LOCATIONS ALREADY IN THE MID TO
UPPER 30S ACROSS NORTHERN ZONES. MOS GUIDANCE CONTINUES TO
INDICATE PORTIONS OF CENTRAL LOUISIANA MAY REACH OR FALL BELOW THE
FREEZING MARK BY MORNING...MAINLY ACROSS RAPIDES AND AVOYELLES
PARISHES. HOWEVER...DEWPOINTS REMAIN IN THE MID TO UPPER 30S AND
THIS HAS LEVELED OFF THE EARLIER QUICK TEMPERATURE DROP. IN
ADDITION...WIDESPREAD CIRRUS CLOUDS CONTINUE TO SPREAD INTO THE
CWA FROM THE WEST...ALTHOUGH PROGRESS EASTWARD HAS BEEN SLOW SO
FAR. MODEL TIME HEIGHT TRENDS SHOW A RATHER THICK BLANKET OF
CIRRUS OVER MUCH OF THE AREA AFTER MIDNIGHT TONIGHT...WHICH WOULD
LIKELY KEEP TEMPERATURES ABOVE THE MOS FORECASTS.
THUS...DEFINITELY A DIFFICULT SITUATION BUT DUE TO THE MARGINAL
TEMPERATURES AND OTHER NEGATING FACTORS WILL NOT ISSUE A FREEZE
WARNING AT THIS TIME. HOWEVER...SOME RURAL AREAS OF
VERNON...RAPIDES...AVOYELLES...ALLEN...AND EVANGELINE PARISHES MAY
REACH FREEZING FOR A BRIEF PERIOD OVERNIGHT. HAVE LOWERED LOW
TEMPERATURES ACROSS NORTHERN ZONES...AND WILL MENTION AREAS OF
FROST FOR ALL NORTHERN AREAS. SHOULD TEMPERATURES DROP MORE
QUICKLY THAN EXPECTED THE REST OF THE EVENING...A FREEZE WARNING
COULD BE ISSUED LATER ON.
.MARINE...
MSAS ANALYSIS INDICATES WINDS HAVE FALLEN BELOW SCA ACROSS THE
OUTER ZONES...AND HAVE LET THE SCA EXPIRE AS SCHEDULED. WINDS WILL
CONTINUE TO SUBSIDE TONIGHT AS HIGH PRESSURE SETTLES OVER THE CWA.
SHAMBURGER
.PREV DISCUSSION... /ISSUED 524 PM CST THU NOV 26 2009/
DISCUSSION...
COOL HIGH PRESSURE WILL DRIFT THROUGH SOUTHEAST TEXAS THIS
EVENING...BEFORE ENTERING THE LOUISIANA COASTAL WATERS BY FRIDAY
EVENING. VFR FLIGHT CONDITIONS ARE EXPECTED.
PREV DISCUSSION... /ISSUED 248 PM CST THU NOV 26 2009/
DISCUSSION...
SURFACE HIGH PRESSURE THIS AFTERNOON LOCATED OVER CENTRAL TEXAS
GRADUALLY MOVING OFF TO THE EAST. NORTH FLOW AROUND THE HIGH
BRINGING IN A COOL AND DRY AIR MASS WITH DEWPOINTS IN THE UPPER
20S TO LOWER 30S. WATER VAPOR IMAGERY SHOWS UPPER LEVEL TROF AXIS
FROM THE EASTERN GREAT LAKES TO THE NORTH CENTRAL GULF COAST
MOVING QUICKLY TO THE EAST. AS THE TROF MOVES OFF TO THE
EAST...UPPER LEVEL EAST PACIFIC MOISTURE IS MOVING ACROSS OLD
MEXICO AND TEXAS TOWARD THE FORECAST AREA.
CHALLENGE IN THE SHORT TERM IS THE FORECAST FOR THE OVERNIGHT
LOWS. WITH THE EXPECTED LIGHT AND VARIABLE TO...AT TIMES...CALM
WINDS...AND DRY AIR MASS WITH LOW DEWPOINTS...TEMPERATURES SHOULD
BE ABLE TO DROP FAIRLY QUICKLY AFTER SUNSET WITH SOME OF THE
COLDEST TEMPERATURES SO FAR THIS SEASON LIKELY. IT LOOKS LIKE CIRRUS
CLOUDS ASSOCIATED WITH THE EAST PACIFIC MOISTURE WILL BE MOVING
ACROSS WITH THE SUBTROPICAL JET. THEREFORE...THIS MAY INDEED HELP
KEEP TEMPERATURES FROM "BOTTOMING OUT"...AND WILL NOT ISSUE A NPW
FOR A FREEZE WARNING. SOME ISOLATED SPOTS IN THE USUALLY COLD
LOCATIONS IN THE EXTREME NORTHERN ZONES MAY BRIEFLY NEAR FREEZING
FOR AN HOUR OR TWO. AT ANY RATE WITH THE CALM WINDS AND
TEMPERATURES IN THE LOW TO MID 30S...SHOULD SEE SOME
FROST...ESPECIALLY AROUND HIGHWAY 190 AND NORTHWARD. WILL ISSUE A
SPECIAL WEATHER STATEMENT TO COVER THIS.
THE HIGH PRESSURE SYSTEM WILL BE EAST OF THE AREA BY FRIDAY NIGHT
WITH LIGHT RETURN FLOW BEGINNING AND A MODERATION IN TEMPERATURES
FOR THE WEEKEND.
NEXT COLD FRONT LOOKS TO COME ACROSS THE FORECAST AREA ON MONDAY.
SHOULD BE SIGNIFICANT MOISTURE RETURN AHEAD OF THIS FRONT TO CALL
FOR A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS BEGINNING ON SUNDAY
NIGHT INTO MONDAY.
EVEN THOUGH THE FRONT MOVES OFFSHORE MONDAY NIGHT...ACTIVE
SOUTHWEST AND MOIST FLOW ALOFT WILL CONTINUE TO OVERRIDE THIS
FRONT WITH COOL...CLOUDY AND RAINY CONDITIONS POSSIBLE INTO
WEDNESDAY.
RUA
MARINE...
A COUPLE OF SHIP REPORTS RECENTLY 60 NM OFFSHORE SHOW NORTHERLY
WINDS AROUND 20 KNOTS. WILL KEEP THE SMALL CRAFT ADVISORY GOING
FOR THE OUTER COASTAL WATERS FOR ONE MORE FORECAST CYCLE UNTIL
WINDS BEGIN TO DECREASE.
WINDS SHOULD CONTINUE TO DECREASE OVERNIGHT AS THE CENTER OF A
SURFACE HIGH MOVES NEAR THE COASTAL WATERS. THIS HIGH WILL BE
MOVING OFF TO THE EAST ON FRIDAY NIGHT INTO SATURDAY ALLOWING FOR
LIGHT RETURN FLOW OFF THE GULF TO START.
THE SOUTHERLY WINDS WILL INCREASE ON SATURDAY NIGHT INTO SUNDAY AS
A COLD FRONT BEGINS TO APPROACH THE AREA...WITH SCATTERED SHOWERS
ALSO BEGINNING TO DEVELOP.
THIS COLD FRONT IS EXPECTED TO MOVE INTO THE COASTAL WATERS ON
MONDAY WITH STRONG NORTHERLY WINDS DEVELOPING BEHIND IT WITH SMALL
CRAFT ADVISORY CONDITIONS AGAIN LIKELY.
RUA
&&
.PRELIMINARY POINT TEMPS/POPS...
KLCH 36 64 48 70 56 / 0 0 0 10 10
KBPT 38 66 49 71 59 / 0 0 0 10 20
KAEX 33 64 41 69 51 / 0 0 0 10 10
KLFT 35 64 43 70 55 / 0 0 0 10 10
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
TX...NONE.
GM...NONE.
&&
$$
