FXUS64 KLCH 062350
AFDLCH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
550 PM CST SUN DEC 6 2009
.AVIATION...
VFR CONDITIONS REGIONWIDE WILL BE REDUCED TO MVFR THIS
EVENING FOR LOWERING CEILINGS...AND EVENTUALLY AFTER MIDNIGHT BE
REDUCED TO LIFR/IFR AS RAIN CHANCES INCREASE AND CEILINGS AND
VISIBILITIES ARE LOWERED. CONDITIONS WILL BE SLOW TO IMPROVE
DURING DAYLIGHT HOURS ON MONDAY.
&&
.PREV DISCUSSION... /ISSUED 403 PM CST SUN DEC 6 2009/
DISCUSSION...
LATEST RADAR IMAGERY SHOWS A RAPID INCREASE IN SHOWER ACTIVITY
ACROSS SOUTHEAST TEXAS NEAR THE HOUSTON AREA WHERE DEWPOINTS ARE
NOW IN THE 50S AND 60S. THIS PRECIPITATION IS EXPECTED TO
CONTINUE TO INCREASE AND EXPAND ACROSS OUR CWA DURING THE EVENING
AND OVERNIGHT HOURS AS A WARM FRONT MOVES NORTHWARD AND REACHES
THE COAST AROUND MIDNIGHT. TEMPERATURES ARE EXPECTED TO SLOWLY
RISE THROUGH THE NIGHT...WITH SFC DEWPOINTS OVER SOUTHERN ZONES
INCREASING INTO THE 50S AND 60S AS WELL. INCREASING WAA ALONG THE
FRONTAL BOUNDARY SHOULD ALLOW FOR A FEW THUNDERSTORMS TO DEVELOP
OVER THE COASTAL WATERS...AND LATEST 4.0 KM WRF MODEL SUGGESTS
SOME OF THESE MAY AFFECT THE COASTAL COUNTIES AND PARISHES
OVERNIGHT AS WELL. HAVE KEPT LIKELY POPS FOR ALL AREAS TONIGHT.
AS SYSTEM EXITS THE AREA TO THE EAST MONDAY MORNING...THE FRONT
WILL OOZE SOUTHWARD INTO THE COASTAL WATERS AND STALL AS A
POWERFUL 500MB 100KT+ SPEED MAX DIVES DOWN THE WEST COAST OF THE
CONUS AND LEE TROUGHING DEVELOPS EAST OF THE ROCKIES. AS THIS JET
STREAK PLOWS RAPIDLY EASTWARD TOWARDS THE LOWER MISSISSIPPI
VALLEY MONDAY NIGHT...THE FRONT WILL LIFT BACK NORTHWARD AND REACH
THE COAST AROUND SUNRISE TUESDAY MORNING. THE INCREASING LIFT
ALONG THE BOUNDARY WITH IMPRESSIVE LATE FALL GULF MOISTURE TO ITS
SOUTH WILL RESULT IN WIDESPREAD SHOWERS AND THUNDERSTORMS
DEVELOPING ALONG AND NORTH OF THE WARM FRONT...WHICH WILL SPREAD
NORTHWARD ACROSS THE CWA FROM MONDAY EVENING THROUGH THE DAY ON
TUESDAY. THUS LIKELY POPS APPEAR WARRANTED DURING THIS TIMEFRAME.
SOMEWHAT HARD TO BELIEVE BUT MOST AREAS WILL SEE HIGH TEMPS IN
THE 70S ON TUESDAY WITH DEWPOINTS ALSO POTENTIALLY REACHING THE 70
DEGREE MARK IN THE SOUTHERN ZONES.
GFS AND NAM FORECAST SOUNDINGS LATE MONDAY NIGHT AND TUESDAY SHOW
PWATS RISING TO NEAR 2 INCHES ALONG THE WARM FRONT...WITH CAPE
VALUES RISING TO AROUND 1000 J/KG...STRONG LOW LEVEL SHEAR...AND
NO CAPPING INVERSION PRESENT. THIS ALL SUGGESTS STRONG
THUNDERSTORMS MAY FORM ALONG THE WARM FRONT LATE MONDAY NIGHT AND
SPREAD NORTHWARD ACROSS THE AREA ON TUESDAY MORNING...WITH
ADDITIONAL THUNDERSTORMS POSSIBLE IN THE OPEN WARM SECTOR ON
TUESDAY AFTERNOON. SPC HAS THE ENTIRE AREA IN A SLIGHT RISK FOR
SEVERE THUNDERSTORMS ON TUESDAY WHICH SEEMS ENTIRELY REASONABLE.
MUCH OF THE PRECIPITATION SHOULD MOVE QUICKLY EAST OF THE AREA
TUESDAY EVENING AS THE MAIN UPPER LEVEL IMPULSE LIFTS INTO THE
OHIO VALLEY. NORTHWESTERLY FLOW BEHIND THE UPPER SYSTEM WILL FORCE
A STRONG COLD FRONT SOUTHWARD INTO THE GULF OF MEXICO AND GIVE OUR
AREA A COUPLE OF DAYS OF COOL AND DRY WEATHER. UNCERTAINTIES BEGIN
ON FRIDAY AS FRONT MAY COME BACK NORTHWARD ONCE AGAIN...BUT MODELS
DIFFER ON HOW FAR INLAND WARM SECTOR CAN RETURN. WITH KEEP
FORECAST NEAR MEX GUIDANCE AT THIS TIME.
MARINE...
MSAS ANALYSIS SHOWS WINDS NEAR SCA IN THE OUTER COASTAL WATERS AND
JUST UNDER CRITERIA IN THE NEARSHORE WATERS. EXPECTING WINDS AND
SEAS TO CONTINUE INCREASING THIS EVENING AS THE WARM FRONT
MOVES NORTHWARD TO NEAR THE COAST TONIGHT. WINDS AND SEAS WILL
DECREASE FROM WEST TO EAST AFTER MIDNIGHT AS THE SYSTEM MOVES
EASTWARD AND THE FRONT OOZES BACK TO THE SOUTH AND STALLS. A MUCH
STRONGER SYSTEM WILL APPROACH THE LOWER MISSISSIPPI VALLEY MONDAY
AND ACROSS THE AREA ON TUESDAY...WITH STRONG SOUTHERLY
WINDS...ROUGH SEAS...AND NUMEROUS SHOWERS AND THUNDERSTORMS
EXPECTED. AS THE SYSTEM LIFTS NORTHEASTWARD WILL SEE THE FRONT
MOVE BACK TO THE SOUTH WITH GUSTY OFFSHORE WINDS RETURNING FOR
WEDNESDAY AND THURSDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
KLCH 58 53 65 56 73 / 20 60 40 70 60
KBPT 59 53 63 56 71 / 30 60 40 70 60
KAEX 55 47 61 51 69 / 20 60 20 70 60
KLFT 59 52 67 57 75 / 20 60 40 70 60
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
TX...LAKE WIND ADVISORY UNTIL 6 PM CST THIS EVENING FOR THE FOLLOWING
ZONES: JEFFERSON...ORANGE.
GM...SMALL CRAFT ADVISORY UNTIL 6 AM CST MONDAY FOR THE FOLLOWING
ZONES: 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 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.
SMALL CRAFT ADVISORY UNTIL 3 AM CST MONDAY FOR THE FOLLOWING
ZONES: COASTAL WATERS FROM CAMERON, LA TO HIGH ISLAND, TX
OUT 20 NM...WATERS FROM CAMERON, LA TO HIGH ISLAND, TX
EXTENDING FROM 20 NM TO 60 NM.
&&
$$
