FXUS64 KLCH 051759
AFDLCH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
1159 AM CST SAT DEC 5 2009
.AVIATION...
CLR SKIES...UNLIMITED VSBY THRU THE EVE HRS. A BIT OF BR THRU THE
OVERNIGHT HOURS.
&&
.PREV DISCUSSION... /ISSUED 1053 AM CST SAT DEC 5 2009/
UPDATE...
IMPRESSIVE VISIBLE SATELLITE IMAGERY THIS MORNING SHOWING THE
AREAS OF SNOWFALL FROM YESTERDAY...WITH TWO NOTICEABLE SWATHS OF
HEAVIER SNOWFALL EVIDENT. ONE BAND OF SNOW ACCUMULATION STRETCHES
FROM SOUTHWEST OF HOUSTON NORTHEASTWARD ALONG A LINE FROM LIBERTY
TX TO AROUND LEESVILLE LA...WITH A SECOND BAND FROM HATHAWAY TO
VILLE PLATTE TO SIMMESPORT. THESE TWO BANDS OF SNOW CORRELATE
WELL WITH THE GROUND REPORTS OF 2-3 INCHES OF SNOW. BASED ON THE
SATELLITE IMAGERY...APPEARS THE HEAVIEST SNOWFALL FROM YESTERDAY
OCCURRED IN WESTERN HARDIN COUNTY...CENTRAL VERNON
PARISH...EASTERN EVANGELINE PARISH...AND WESTERN ST LANDRY
PARISH.
APPEARS THE ENTIRE CWA EXCEPT FOR A FEW AREAS OF EXTREME
SOUTHEASTERN ST. MARY PARISH AROUND MORGAN CITY AND AMELIA SAW
FREEZING TEMPERATURES THIS MORNING...WITH EVEN ALL COASTAL
STATIONS REACHING 32 DEGREES. DUE TO THE REMAINING SNOW COVER AND
MOISTURE ON THE GROUND ACROSS MANY AREAS...FREEZING FOG WAS EVEN
OBSERVED ACROSS MUCH OF CENTRAL AND SOUTHERN LOUISIANA THIS
MORNING...AN EXTREMELY UNUSUAL EVENT FOR THIS REGION OF THE
COUNTRY.
WITH ALL LOCATIONS NOW ABOVE FREEZING...ALL HAZARDS HAVE BEEN
ALLOWED TO EXPIRE. REMOVED MENTION OF FOG FROM GRIDS AND MADE
SOME MINOR ADJUSTMENTS TO HIGH TEMPS FOR TODAY. REST OF FORECAST
APPEARS TO BE ON TRACK.
SHAMBURGER
MARINE...
MSAS ANALYSIS INDICATES WINDS HAVE FALLEN BELOW SCA ACROSS ALL THE
COASTAL WATERS AND HAVE LET THE HAZARDS EXPIRE AS SCHEDULED.
SHAMBURGER
PREV DISCUSSION... /ISSUED 732 AM CST SAT DEC 5 2009/
DISCUSSION...
PATCHY FREEZING FOG BEING REPORTED ACROSS PARTS OF SOUTHWEST AND
CENTRAL LOUISIANA. UPDATED ZONES TO MENTION THIS UNUSUAL FOG.
FOG NOT EXPECTED TO LAST FOR MORE THAN TWO HOURS.
PREV DISCUSSION... /ISSUED 535 AM CST SAT DEC 5 2009/
AVIATION...
HIGH PRESSURE CURRENTLY CENTERED OVER E TX...RIDGING ACRS LA.
THIS HAS ALLOWED WINDS TO DECOUPLE THIS MORNING WITH WINDS OUT OF
THE NORTH LESS THAN 5 KNOTS OR CALM ACRS THE AREA. WITH CLEAR
SKIES AND MOIST GROUND...PATCHY RADIATIONAL FOG HAS DEVELOPED IN
SOME LOCATIONS...MOST NOTABLY AT KAEX WHERE THE VIS HAS DROPPED TO
AROUND 1/4SM IN FZFG WITH VV001. HAVE KEPT FOG OUT OF THE FORECAST
FOR THE SRN TERMINALS DUE TO ITS EXTREMELY PATCHY NATURE...BUT DID
ADD A BRIEF TEMPO GROUP OF IFR VSBY TO KLCH WHERE THE VSBY HAS
BEEN GRADUALLY LOWERING THE PAST COUPLE OF HOURS. OTHERWISE...VFR
CONDITIONS TO PREVAIL THROUGH THE NEXT 24 HOURS AS THE HIGH SHIFTS
EAST ACRS THE AREA. WINDS ARE EXPECTED TO REMAIN LIGHT...GRADUALLY
VEERING FROM A NORTHERLY DIRECTION TO AN EAST OR SOUTHEAST
DIRECTION BY SUNDAY MORNING.
PREV DISCUSSION... /ISSUED 441 AM CST SAT DEC 5 2009/
SYNOPSIS...
COOL HIGH PRESSURE...EXTENDING FROM SAN ANTONIO THROUGH MEMPHIS
WILL TRAVEL EASTWARD...REACHING A JACKSON-TO-NASHVILLE LINE BY
SATURDAY EVENING...BEFORE DOMING ACROSS WESTERN VIRGINIA ON SUNDAY.
FURTHER-UP...PACIFIC WESTERLIES CONTINUE IMPINGING UPON THE SIERRA
MADRE ORIENTAL RANGE...GENERATING SHORT-WAVE IMPULSES THAT TRAVEL
ACROSS THE WESTERN GULF COAST STATES.
PRESSURES BEGIN FALLING ON THE SOUTHWEST PERIPHERY OF THE VIRGINIA
ANTICYCLONE...INDUCED BY WESTERLY IMPULSES PASSING OVERHEAD. A
CONSEQUENT COASTAL TROUGH (OR BACKDOOR WARMFRONT) WILL SET-UP...
EXTENDING FROM BROWNSVILLE TO BEAUMONT.
DISCUSSION...
FOR TODAY...DRY AND COLD SINKING AIR WILL MAINTAIN CLEAR SKIES
ACROSS THE AREA. THE TEMPERATURES WILL BE ON THE CHILLY SIDE
DUE TO A COLD START. IN ADDITION...EVAPORATIONAL COOLING
(STANDING WATER FROM PREVIOUS SNOWFALL) WILL PARTIALLY OFFSET THE
RADIATIONAL WARM-UP. THE AFTERNOON TEMPERATURES WILL BE RUNNING
ABOUT 15 DEGREES BELOW NORMAL.
FOR TONIGHT...A SLOW WARM-UP BEGINS AS A WEAK GULF RETURN FLOW
SETS-UP.
FOR SUNDAY...THE RETURN FLOW STRENGTHENS INTO A WARM CONVEYOR BELT
AIRSTREAM. INCOMING CAMPECHE AIR WILL UPSLIDE COLD CONTINENTAL AIR
IN PLACE ACROSS THE FORECAST AREA. OVERRUNNING RAIN IS THE RESULT.
OUTLOOK...
COLD HIGH PRESSURE BUILDING OUT OF THE GREAT PLAINS WILL PUSH THE
BACKDOOR WARMFRONT INTO THE NORTHWEST GULF OF MEXICO ON MONDAY
THE INCLINED FRONTAL WEDGE NOW POINTING LIKE A COLD FRONT.
THE BERMUDA HIGH RE-BUILDING WESTWARD THROUGH THE GULF OF MEXICO
WILL PUSH THE PREVIOUS COLD FRONT WESTWARD...NOW AS A WARM FRONT.
FINALLY...ANOTHER GREAT PLAINS LOW...THIS TIME IN THE COLORADO
FRONT RANGE...WILL FORM ON TUESDAY...THEN TRAVEL EAST-NORTHEAST
SHOVING THE PREVIOUS WARM FRONT BACK INTO THE NORTHWEST GULF
OF MEXICO AS A COLD FRONT...WHICH SUBSEQUENTLY LEAVES THE AREA.
&&
.PRELIMINARY POINT TEMPS/POPS...
KLCH 37 58 56 68 57 / 0 50 60 0 60
KBPT 39 58 54 67 57 / 0 60 60 0 60
KAEX 31 57 49 63 49 / 0 40 60 0 60
KLFT 36 59 54 68 55 / 0 40 60 20 60
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
TX...NONE.
GM...NONE.
&&
$$
