Issued by NWS Lake Charles, LA
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000 FXUS64 KLCH 100524 AFDLCH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 1124 PM CST TUE FEB 9 2010 .DISCUSSION... FOR THE 10/06Z TAF ISSUANCE. && .AVIATION... NO REAL CHANGES TO THE AVIATION FORECAST TONIGHT WITH VFR CONDITIONS EXPECTED TO PREVAIL FOR THE NEXT 24 HOURS. FAIRLY QUIET WEATHER CURRENTLY WITH HIGH PRESSURE AT THE SURFACE CONTINUING TO BUILD IN AND PRODUCE DRY CONDITIONS IN THE LOW LEVELS. MEANWHILE...UPPER LEVEL MOISTURE IS BEGINNING TO MOVE INTO THE REGION FROM THE EAST PACIFIC RIDING IN ON A FAST SOUTHERN JET STREAM. MOISTURE WILL CONTINUE TO STREAM IN FROM THE WEST WITH THE SOUTHERN JET WITH CLOUDS IN THE UPPER LEVELS BEGINNING TO THICKEN BY MORNING AND LOWERING INTO THE MID LEVELS BY LATE AFTERNOON AND ON WEDNESDAY EVENING. RUA && .PREV DISCUSSION... /ISSUED 805 PM CST TUE FEB 9 2010/ UPDATE...LOOKS LIKE THE COMBINATION OF UPPER LEVEL PACIFIC MOISTURE MOVING IN FROM THE WEST AND A SUSTAINED GRADIENT AT THE SURFACE MAINTAINING LIGHT WINDS TNITE WILL BE SUFFICIENT TO PRECLUDE A HARD FREEZE. JUST A LIGHT FREEZE AREAWIDE OVERNIGHT. MARINE...WINDS ARE DIMINISHING ON SCHEDULE AS HIGH PRESSURE GRADUALLY BUILDS IN FROM THE NORTHWEST. THIS WILL ALLOW THE INNER WATERS SMALL CRAFT ADVISORY TO EXPIRE AT 9 PM. SWEENEY PREV DISCUSSION... /ISSUED 512 PM CST TUE FEB 9 2010/ DISCUSSION... CLOUDS CLEARED OUT NICELY TODAY GIVING WAY TO SUNNY ALBEIT COOL AND BREEZY DAY. DEWPOINTS HAVE DROPPED INTO THE TEENS AND 20S AS COLD CANADIAN AIR CONTINUES TO SPILL INTO THE REGION IN THE WAKE OF THE FRONT THAT MOVED THROUGH THE AREA LAST NIGHT. WITH HIGH PRESSURE STARTING TO SETTLE INTO THE AREA TONIGHT...WINDS ARE EXPECTED TO DECREASE THOUGH NOT GO COMPLETELY CALM. STILL...UNDER A CLEAR SKY...TEMPERATURES DROP QUICKLY AFTER SUNSET AMID THIS DRY CONTINENTAL AIRMASS...AND HAVE GONE WITH LOWS BELOW FREEZING OVER ALL AREAS EXCEPT THE IMMEDIATE COAST. THE DURATION OF TEMPERATURES IN THE UPPER 20S OVER THE EAST TEXAS LAKES AND CENTRAL LOUISIANA IS EXPECTED TO BE BRIEF...THUS DID NOT ISSUE A HARD FREEZE WARNING. MID/UPPER LEVEL MOISTURE WILL BEGIN STREAMING INTO THE AREA FROM THE WEST TOMORROW AHEAD OF AN INCOMING STORM SYSTEM CURRENTLY JUST OFF THE CA COAST. COLD HIGH PRESSURE WILL CONTINUE TO PREVAIL AT THE SURFACE...AND WITH THE DECREASED INSOLATION COURTESY OF THE INCREASING CLOUD COVER...HIGHS TOMORROW ARE EXPECTED TO STRUGGLE TO REACH THE UPPER 40S TO NEAR 50. AS THE AFOREMENTIONED MID/UPPER LEVEL LOW SLIDES INTO NORTHERN MEXICO TOMORROW EVENING...ISENTROPIC LIFT IS FORECAST TO COMMENCE OVER CENTRAL TEXAS...AND SPREAD EAST THROUGH THE OVERNIGHT HOURS. FORECAST SOUNDINGS SHOW A CONSIDERABLE AMOUNT OF DRY AIR UNDERNEATH THE MID/UPPER LEVEL MOISTURE THAT IS GOING TO TAKE SOME TIME TO SATURATE...SO I DO NOT ANTICIPATE MUCH PRECIPITATION REACHING THE GROUND OVERNIGHT WEDNESDAY. ONE DILEMMA IS THAT BY EARLY THURSDAY...THE DRY LAYER SHOWN BY SOME MODELS IS QUITE SHALLOW...AND COULD SATURATE VIA DIABATIC PROCESSES SOONER THAN MODELS ARE INDICATING. SHOULD THAT OCCUR...A SATURATED TEMPERATURE PROFILE THAT IS MOSTLY SUB FREEZING WOULD RESULT. CONSEQUENTLY...HAVE STARTED THE POSSIBILITY OF WINTRY PRECIP AFTER MIDNIGHT WEDNESDAY. THE FORECAST DILEMMA THROUGH THURSDAY INTO FRIDAY MORNING BECOMES ONE OF THE TEMPERATURE PROFILE...WITH SOME FAIRLY SIGNIFICANT DIFFERENCES IN THE FORECAST MODELS TO CONTEND WITH. UTILIZED SEVERAL PRECIPITATION TYPE TECHNIQUES ON MULTIPLE MODELS...AND THE WORST SCENARIO I ARRIVED AT WAS A STRIPE OF 2-4 INCHES GENERALLY ALONG AND NORTH OF A LINE FROM WOODVILLE TEXAS TO OPELOUSAS LOUISIANA...WITH THE RAIN/SNOW LINE COMING AS FAR SOUTH AS THE I-10 CORRIDOR. THE BEST CASE SCENARIO IS AREAWIDE COLD RAIN. AS YOU CAN SEE...THE SPECTRUM OF POSSIBILITIES IS QUITE LARGE...AND AT THIS TIME...A FORECAST OF DEFINITIVE WINTER PRECIPITATION TYPE OR ANY ACCUMULATION THEREOF IS QUITE DIFFICULT. GIVEN THIS LOW DEGREE OF CONFIDENCE...OPTED TO CARRY A RAIN/SLEET/SNOW MIX RATHER THAN HANG MY HAT ON ONE TYPE OR THE OTHER...AND NO ACCUMULATIONS. FORECAST BEYOND DAY 4 UNCHANGED. MARINE... GUSTY NORTH WINDS AND ROUGH SEAS WILL CONTINUE THIS EVENING IN THE WAKE OF A COLD FRONT THAT MOVED THROUGH THE COASTAL WATERS LAST NIGHT. WINDS WILL START TO DIMINISH TONIGHT INTO WEDNESDAY MORNING. A GULF LOW IS FORECAST TO DEVELOP ON THURSDAY...BRINGING PROLONGED WIDESPREAD PRECIPITATION WITH MODERATE EAST TO NORTHEAST WINDS AS IT TRACKS EAST ACROSS THE NORTHERN GULF THURSDAY AND THURSDAY NIGHT. 13 && .PRELIMINARY POINT TEMPS/POPS... KLCH 30 50 32 44 34 / 0 10 30 80 100 KBPT 30 50 33 43 35 / 0 10 40 90 100 KAEX 30 48 29 43 31 / 0 10 20 50 100 KLFT 31 49 32 44 33 / 0 10 20 70 100 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL 9 AM CST WEDNESDAY FOR THE FOLLOWING ZONES: WATERS FROM CAMERON, LA TO HIGH ISLAND, TX 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. && $$
