FXUS64 KLCH 101157
AFDLCH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
557 AM CST THU DEC 10 2009
.AVIATION...
12Z TAF DISCUSSION...VFR CONDITIONS EXPECTED THROUGH THE PERIOD.
SATELLITE IMAGERY SHOWS SUBTROPICAL JET STREAM EXTENDS FROM
NORTHERN MEXICO ACROSS OUR AREA INTO THE SOUTHEAST CONUS.
CONSIDERABLE MOISTURE ALOFT WILL CONTINUE TO SPREAD ACROSS THE
GULF COAST STATES...BRINGING WIDESPREAD CIRRUS CLOUDS TO AREA
AIRPORTS TODAY. AS LOW LEVEL MOISTURE BEGINS TO INCREASE AFTER 06Z
TONIGHT...CLOUD LAYER AROUND 6-7K FT WILL BEGIN TO AFFECT SOUTHERN
TERMINALS BY 12Z. CEILINGS LOOK TO LOWER MORE SUBSTANTIALLY AFTER
THE END OF THIS TAF PERIOD...WITH RAIN EXPECTED TO BEGIN IMPACTING
AREA AIRPORTS AFTER 12Z FRIDAY MORNING. NORTHEAST WINDS WILL
REMAIN RATHER BRISK TODAY...WITH WINDS VEERING TO A MORE EASTERLY
DIRECTION TONIGHT INTO FRIDAY AS AN AREA OF LOW PRESSURE DEVELOPS
IN THE WESTERN GULF OF MEXICO.
SHAMBURGER
&&
.PREV DISCUSSION... /ISSUED 406 AM CST THU DEC 10 2009/
DISCUSSION...
CHILLY START TO THE MORNING AS HIGH PRESSURE OVER NORTHEAST
OKLAHOMA CONTINUES TO BUILD INTO THE FORECAST AREA. HOWEVER...HIGH
LEVEL CLOUDS MOVING ACROSS IN THE JET STREAM HELPING KEEP AIR
TEMPERATURES UP SOME WITH ONLY ISOLATED SPOTS IN THE NORTHERN
ZONES SO FAR REACHING THE FREEZING MARK.
WILL CONTINUE TO BE A CHILLY DAY AS THE CENTER OF THE HIGH
PRESSURE SYSTEM SLOWLY MOVES NORTH OF THE FORECAST AREA...KEEPING
A NORTHERLY WIND FLOW AND COLD AIR ADVECTION. MEANWHILE...HIGH
LEVEL MOISTURE WILL CONTINUE TO BE PUSH OVER THE REGION IN THE JET
STREAM. THIS IN RETURN WILL KEEP SOLAR HEATING DOWN.
THEREFORE...HIGH TEMPERATURES TODAY SHOULD ONLY BE IN THE LOW TO
MID 50S.
THE SURFACE HIGH BY FRIDAY WILL BE OVER THE APPALACHIANS KEEPING
SURFACE FLOW NORTHEAST TO EAST AND COOLER CONTINENTAL CONDITIONS
NEAR THE SURFACE. IN THE MEANTIME...ACTIVE SOUTHERN JET WILL CARRY
A SERIES OF SHORT WAVES OVER THE REGION...WHICH IN TIME WILL
INDUCE LOW PRESSURE TO FORM OFF THE LOWER TEXAS COAST...WITH
COASTAL TROF FORMING JUST OFF THE IMMEDIATE COAST OF THE FORECAST AREA.
MOISTURE IN THE SOUTHERLY FLOW ABOVE THE SURFACE WILL BEGIN TO
OVER-RIDE THE COOLER SURFACE. ON FRIDAY 300K ISENTROPIC FIELD
SHOWS CONDENSATION PRESSURE DEFICITS BECOMING INCREASINGLY
SATURATED DURING THE DAY...WITH LIFT INCREASING BY AFTERNOON AHEAD
OF SHORT WAVE. THEREFORE...RAIN...STARTING OUT LIGHT...WILL FORM
AND SPREAD ACROSS THE AREA.
ON FRIDAY NIGHT...RAINS SHOULD CONTINUE TO BECOME MORE WIDESPREAD
AND INCREASE IN INTENSITY. SOUTHERLY FLOW WILL INCREASE JUST
ABOVE THE SURFACE AS SHORT WAVE MOVES ACROSS AND SURFACE LOW NEARS
THE COASTAL WATERS. THE SOUTHERLY FLOW WILL INCREASE MOISTURE
VALUES WITH PWAT PROGGED TO RANGE FROM 1.25 TO 1.5 INCHES WHICH IS
HIGH FOR DECEMBER AND OVER 150 PERCENT OF NORMAL. LOW LEVEL
CONVERGENCE ALSO LOOKS DECENT...ESPECIALLY AT 85H...ALONG WITH
FAVORABLE RIGHT ENTRANCE REGION OF JET STREAK DURING THE OVERNIGHT
HOURS. SO THERE SHOULD ALSO BE A CHANCE OF SOME ELEVATED THUNDERSTORMS.
QPF VALUES SHOW FORECAST AREA COULD SEE A DECENT SOAKING BY THE
TIME RAINS TAPER OFF SATURDAY AFTERNOON...WITH AVERAGE RAINFALL
AMOUNTS BETWEEN 1 AND 1.25 INCHES...WITH SOME LOCALLY HIGHER
AMOUNTS IF ELEVATED STORMS CAN GET GOING. ONCE AGAIN HEAVIEST
RAINFALL LOOKS TO OCCUR BETWEEN MIDNIGHT AND 6 AM.
WARMER CONDITIONS LOOK TO OCCUR ON SUNDAY AS SOUTHERLY SURFACE
WINDS BEGIN TO DEVELOP AHEAD OF THE NEXT COLD FRONT.
THIS COLD FRONT IS PROGGED TO MOVE ACROSS THE FORECAST AREA LATE
MONDAY NIGHT. SHOWERS ARE EXPECTED TO DEVELOP AHEAD OF THIS FRONT
ON MONDAY...ENDING EARLY TUESDAY...AS FRONT MOVES OFF TO THE
EAST...AND COOLER AND DRIER AIR AGAIN MOVES INTO THE REGION.
RUA
MARINE...
MSAS ANALYSIS CURRENTLY SHOWS MODERATE TO STRONG OFFSHORE FLOW
OVER THE COASTAL WATERS...WITH SMALL CRAFT ADVISORY WINDS
OCCURRING...ESPECIALLY BEYOND 20 NM.
THE SMALL CRAFT ADVISORY WILL CONTINUE THROUGH TODAY AS HIGH
PRESSURE TO THE NORTH CONTINUES TO PROVIDE COLD AIR ADVECTION
ACROSS THE REGION.
THE SMALL CRAFT ADVISORY WILL CONTINUE FURTHER INTO FRIDAY AND
FRIDAY NIGHT AS GRADIENT TIGHTENS BETWEEN HIGH PRESSURE NEAR THE
MID ATLANTIC STATES AND LOW PRESSURE OFF THE LOWER TEXAS COAST.
WINDS WILL ALSO BECOME MORE EASTERLY. THIS SHOULD HELP PROVIDE
SOME WATER PILING NEAR THE COAST WITH EKMAN EFFECT TO THE RIGHT OF
THE MAIN FLOW. THEREFORE...TIDES WILL BE RUNNING ABOVE PREDICTED
LEVELS. LATEST TIDE GUIDANCE SHOWS TIDES NEAR 1 FOOT ABOVE NORMAL
ON FRIDAY NIGHT.
WINDS WILL DECREASE ON SATURDAY AS THE PRESSURE GRADIENT RELAXES
ACROSS THE COASTAL WATERS.
RUA
&&
.PRELIMINARY POINT TEMPS/POPS...
KLCH 52 39 51 46 60 / 0 10 50 70 50
KBPT 52 40 53 48 58 / 0 10 50 70 40
KAEX 50 35 48 42 53 / 0 10 50 70 50
KLFT 53 38 51 47 61 / 0 10 50 70 50
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
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.
&&
$$
