FXUS64 KLCH 120336
AFDLCH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
936 PM CST FRI DEC 11 2009
.UPDATE...LOWERED TEMPS A FEW DEGREES DUE TO WET BULBING AS RAIN
FALLS THROUGH A DRY LAYER BELOW 1700 FEET. OTHERWISE PREVIOUS FCST
IS ON TRACK WITH WIDESPREAD RAIN AND EVEN A FEW EMBEDDED
THUNDERSTORMS TONIGHT AND INTO SATURDAY. RADAR ESTIMATES SHOW OVER
AN INCH OF RAIN HAS ALREADY FALLEN SOUTH OF FRANKLIN. WELL WITHIN
FLOOD GUIDANCE VALUES OF NEARLY 4 INCHES IN 3 HOURS.
&&
.MARINE...WINDS AT THE DATA BUOY SOUTH OF HIGH ISLAND SHOWING
GUSTS TO 33 KNOTS. WILL CONTINUE TO MONITOR FOR ANY GALES BUT
INDICATIONS ARE THAT A LACK OF COLD ADVECTION OVER THE WATERS
SHOULD KEEP GUSTS FROM REACHING GALE FORCE TNITE. SUSTAINED WINDS
ARE RANGING FROM 23 TO 27 KNOTS. SEAS ARE BUILDING PAST 8 FEET.
A SMALL CRAFT ADVISORY REMAINS IN EFFECT.
SWEENEY
&&
.PREV DISCUSSION... /ISSUED 345 PM CST FRI DEC 11 2009/
SYNOPSIS...
ONGOING LEESIDE FORCING...CAUSED BY TRAVELLING PACIFIC SHORTWAVES
IMPINGING UPON THE SIERRA MADRE ORIENTAL RANGE AND GENERATING
STRETCHING VORTICITY DOWNSTREAM...IS SPINNING-UP A FRONTAL-WAVE
CYCLONE SITUATED JUST OFFSHORE BROWNSVILLE.
THE WAVE CYCLONE WILL MOVE NORTHWARD...FOLLOWING THE OUTLINE OF THE
TEXAS COAST...BEFORE REACHING BEAUMONT AROUND NOON SATURDAY.
FURTHER-UP...THE SUBTROPICAL JET CORES THROUGH GUADALAJARA THROUGH
BEAUMONT MERGING WITH THE POLAR-FRONT JET. THE JET CORE WILL DRIFT
EASTWARD...EXITING INTO SOUTHEAST LOUISIANA ON SUNDAY.
DISCUSSION...
A ROBUST SOUTHERLY CONVEYOR BELT IS CARRYING BAY-OF-CAMPECHE AIR
THROUGH THE FORECAST AREA...WHILE FURTHER-UP...THE PINEAPPLE EXPRESS IS
CARRYING PACIFIC MOISTURE AND CLOUDS THROUGH THE AREA.
INTERMITTENT STABLE RAIN IS EXPECTED THIS EVENING...BECOMING MORE
CONTINUOUS DURING THE OVERNIGHT HOURS. RAINFALL AMOUNTS MAY BE
LARGER THAN PREVIOUSLY THOUGHT...DUE TO THE WESTWARD CORRECTION IN
THE TRACK OF WAVE CYCLONE.
OVERRUNNING RAIN WILL TRANSITION OVER TO MORE CONVECTIVE RAIN ON
SATURDAY. PROBLEM AREA MAY BE SOUTH CENTRAL LOUISIANA...WHERE THE
INSTABILITY IS THE GREATEST. RAIN MAY BE HEAVY AT TIMES. A FLASH
FLOOD WATCH IS NOW IN EFFECT FOR SOUTH CENTRAL LOUISIANA AND AREAS
MAINLY EAST OF I-49.
SHORT-RANGE OUTLOOK...
THE WAVE CYCLONE CONTINUES ITS JOURNEY NORTHEAST...TRAVELING ACROSS
JACKSON AROUND MIDNIGHT SUNDAY. ITS ASSOCIATED CIRCULATION WILL
BRING A WEAK COLD FRONT THROUGH WESTERN UPPER GULF COAST STATES.
THE BERMUDA HIGH PRESSURE RIDGE QUICKLY RECOVERS...HALTING THE COLD
FRONT ACROSS THE NORTHWEST GULF OF MEXICO ON SUNDAY.
THE STALLED COLD FRONT WILL RETURN NORTHWARD AS A WARM FRONT BY
SUNDAY EVENING...REACHING THE LOUISIANA COAST AROUND MIDNIGHT
MONDAY...BEFORE EXITING CENTRAL LOUISIANA BY MIDMORNING MONDAY.
MARINE...
A STRONG EASTERLY STRESS UPON THE COASTAL WATERS WILL GENERATE
EASTERLY SWELLS WHICH WILL REMAIN INTACT THROUGH THIS EVENING. THE
PERSISTENT EASTERLY STRESS WILL INITIATE AN EKMAN TRANSPORT OF WATER
TO THE LOUISIANA AND UPPER TEXAS COASTS...THE RISING TIDE LEVELING
OFF AROUND MIDNIGHT SATURDAY...BEFORE RECEDING BY SATURDAY AFTERNOON.
THE ACTUAL TIDES WILL BE RUNNING ABOUT A FOOT ABOVE THE NORMAL LUNAR
TIDES...FROM FRIDAY EVENING THROUGH MIDNIGHT SATURDAY. MINOR
NUISANCE FLOODING IS POSSIBLE.
TRARES
&&
.PRELIMINARY POINT TEMPS/POPS...
KLCH 46 60 55 73 60 / 80 70 20 10 10
KBPT 46 59 51 72 59 / 80 70 20 10 10
KAEX 39 55 52 70 53 / 80 80 20 10 10
KLFT 44 60 58 72 61 / 80 80 20 10 10
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...FLASH FLOOD WATCH FROM 6 AM CST SATURDAY THROUGH SATURDAY
AFTERNOON FOR THE FOLLOWING ZONES: ACADIA...AVOYELLES...
IBERIA...LAFAYETTE...LOWER ST. MARTIN...ST. LANDRY...ST.
MARY...UPPER ST. MARTIN...VERMILION.
TX...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 6 AM CST SATURDAY FOR THE FOLLOWING
ZONES: COASTAL WATERS FROM CAMERON, LA TO HIGH ISLAND, TX
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...
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.
&&
$$
