HAMweather.com Area Forecast Discussion for County Warning Area LCH

Thu, 16 Feb 2012 12:50:20 GMT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
542 AM CST THU FEB 16 2012

.DISCUSSION...
LATEST UPPER AIR ANALYSIS/WATER VAPOR SATELLITE IMAGERY DEPICTED A
RIDGE OVER THE YUCATAN CHANNEL...WITH A MEAN TROF AXIS OVER THE
WRN CONUS. BETWEEN THESE TWO FEATURES...THE JET STREAM ARCED FROM
NORTHERN MEXICO TO THE MID ATLANTIC. WITHIN THE BASE OF THE MEAN
TROF...AN UPPER LOW WAS NOTED OVER SRN CA...WITH AN APPARENT LEAD
IMPULSE BEGINNING TO EJECT OUT ACROSS THE BAJA.

AT THE SFC...CDFNT WAS ANALYZED NEAR A LINE FROM MIDWAY BETWEEN
NATCHEZ AND MCCOMB MS...EXTENDING SW TO NEAR PECAN ISLAND AND ON
OUT INTO THE NORTHWEST GULF. 

WHILE WEAK LOW LEVEL CAA HAS ENSUED IN THE WAKE OF THE FRONT AND
PRE-FRONTAL TROF...THE REAL DRY AIR REMAINS BOTTLED UP WELL TO THE
WEST ACROSS CENTRAL AND NORTH CENTRAL TEXAS. WHAT THE COOLING HAS
ALLOWED IS FOR THE VERY MOIST LOW LEVEL AIRMASS IN PLACE TO REACH
SATURATION...RESULTING IN WIDESPREAD DENSE FOG FORMATION ACROSS
EAST TEXAS...WESTERN LOUISIANA...AND THE ADJACENT GULF WATERS.
EXPANDED THE EARLIER ISSUED MARINE DENSE FOG ADVISORY TO INCLUDE
THE 20-60NM ZONES WEST OF INTRACOASTAL CITY...WITH OFFSHORE
OBSERVATIONS NOW INDICATING FOG IN THESE ZONES AS WELL. IT IS
QUITE POSSIBLE THAT ADDITIONAL AREAL EXPANSIONS AND/OR EXTENSIONS
IN TIME WILL BE REQUIRED BEFORE ALL IS SAID AND DONE...AS BOTH
PROBABILISTIC AND DETERMINISTIC GUIDANCE INDICATE THE SEA FOG MAY
EXPAND FARTHER EAST AND LINGER LONGER THAN CURRENTLY FORECAST.
WILL CONTINUE TO MONITOR OBS FOR THE NEXT FEW HOURS. INLAND FOG
MAY ALSO EXPAND EASTWARD BEYOND THE CURRENT ADVISORY...BUT SHOULD
ERODE BY MID MORNING. 

CDFNT IS EXPECTED TO CONTINUE MOVING SLUGGISHLY TO THE SOUTHEAST
TODAY...WITH ISOLATED SHOWERS REMAINING A POSSIBILITY PRIMARILY
OVER THE GULF WATERS. OTHERWISE EXPECT A MOSTLY CLOUDY BUT DRY DAY
ACROSS THE REGION. ENJOY THE BREAK IN THE RAIN...BECAUSE MORE IS
ON THE WAY.

THERE ARE TWO DISTINCT PERIODS WHEN I BELIEVE RAIN CHANCES WILL BE
THE HIGHEST...AND THE FIRST OF THESE WILL OCCUR LATE TONIGHT INTO
EARLY FRIDAY AS THE LEAD IMPULSE IS PROGGED TO EJECT OUT ACROSS
THE REGION...TUGGING THE FRONTAL BOUNDARY BACK NORTHWARD AND
INDUCING DEEP ISENTROPIC LIFT. THIS INITIAL BURST OF RAINFALL
SHOULD EASE FIR DAY AFTERNOON FROM WEST TO EAST AS THE DISTURBANCE
PULLS AWAY...THOUGH HEALTHY CHANCE POPS WILL REMAIN INTO FRIDAY
EVENING AS LIFT WILL PERSIST.

THE SECOND...AND MORE POTENT...PERIOD OF ENHANCED RAIN CHANCES WILL
ARRIVE LATE FRIDAY NIGHT INTO SATURDAY...AS THE UPPER LOW OPENS UP
AND EJECTS OUT...INDUCING CYCLOGENESIS ALONG THE WRN FLANK OF THE
FRONTAL BOUNDARY. THE BOUNDARY...AND THE ASSOCIATED DEEP MOISTURE
POOL...ARE PROGGED TO SURGE NORTHWARD AS LOW LEVEL WIND FIELDS
RAPIDLY STRENGTHEN TO 40-50KT AT H85. THIS MOISTURE
INFLUX...COUPLED WITH STRONG SYNOPTIC SCALE LIFT...WILL RESULT IN
WIDESPREAD SHOWERS AND THUNDERSTORMS OVER THE 12 HOUR PERIOD FROM
ROUGHLY MIDNIGHT FRIDAY TO NOON SATURDAY. MEAN AREAL RAINFALL
AMOUNTS OF 1 TO 3 INCHES ARE EXPECTED FROM NORTHWEST TO SOUTHEAST...WITH
LOCALLY HIGHER AMOUNTS POSSIBLE. GLOBAL MODEL GUIDANCE...ESPECIALLY
THE ECMWF AND GFS...ARE IN MUCH BETTER AGREEMENT WITH THIS SYSTEM
THIS MORNING...AND HAVE GENERALLY TRENDED A BIT FARTHER NORTH WITH
THE TRACK OF THE SFC LOW. SHOULD THIS...OR A MORE INLAND SCENARIO
MATERIALIZE...THEN THE SEVERE WEATHER POTENTIAL WOULD INCREASE. AS
IT STANDS NOW...SPC HAS SOUTH CENTRAL LOUISIANA IN A SLIGHT RISK
ON THE LATEST DAY 3 OUTLOOK.

RAINFALL WILL COME TO AN END SATURDAY AFTERNOON AS THE SFC LOW
TRACKS OFF TO THE EAST...WITH DRIER AND COOLER WEATHER EXPECTED ON
SUNDAY. HOW LONG THIS DRY SPELL LASTS REMAINS TO BE SEEN...THOUGH
GLOBAL MODELS POINT TO RAIN CHANCES RETURNING BY EARLY TO MID
WEEK.

13

.MARINE...
AREAS OF DENSE SEA FOG WILL AFFECT THE GULF WATERS WEST OF
INTRACOASTAL CITY ALONG WITH SABINE AND CALCASIEU LAKES. A WEAK
FRONT MOVING THROUGH THE GULF WATERS THIS MORNING IS EXPECTED TO
STALL JUST SOUTH OF THE COASTAL WATERS LATER TODAY. AN AREA OF LOW
PRESSURE WILL FORM ACROSS THE NORTHWESTERN GULF LATE FRIDAY...AND
TRAVEL NORTHEASTWARD SATURDAY...BRINGING ANOTHER ROUND OF SHOWERS
AND THUNDERSTORMS DURING THIS PERIOD.

13

.AVIATION...
AREAS OF FOG WILL CONTINUE TO IMPACT AREA TERMINALS THROUGH MID
MORNING, HOWEVER THE FOG WILL MIX OUT DURING THE MORNING AND
CONDITIONS ARE EXPECTED TO BECOME MOSTLY VFR EVERYWHERE BEFORE
NOON. THIS EVENING...SHOWERS CREATING LOWER VIS MAY DEVELOP AND
SPREAD ACROSS THE AREA ALONG WITH LOWER CEILINGS. WINDS ARE
EXPECTED TO BE AROUND 10 KTS OR LESS THROUGH THE PERIOD. WINDS
WILL BE N TO NW THIS MORNING AND BECOME AND REMAIN NE DURING THE
MORNING.

TINGLER

.PRELIMINARY POINT TEMPS/POPS...
KLCH  73  55  65  56 /  10  40  60  80 
KBPT  73  55  65  56 /  10  50  60  80 
KAEX  71  50  64  53 /  10  20  50  70 
KLFT  74  56  65  57 /  10  30  60  80 

.LCH WATCHES/WARNINGS/ADVISORIES...
LA...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR ALLEN-
     BEAUREGARD-CALCASIEU-EAST CAMERON-JEFFERSON DAVIS-VERNON-
     WEST CAMERON.

TX...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR HARDIN-
     JEFFERSON-NORTHERN JASPER-NORTHERN NEWTON-ORANGE-SOUTHERN 
     JASPER-SOUTHERN NEWTON-TYLER.

GM...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR CALCASIEU 
     LAKE-COASTAL WATERS FROM CAMERON LA TO HIGH ISLAND TX OUT 
     20 NM-COASTAL WATERS FROM INTRACOASTAL CITY TO CAMERON LA 
     OUT 20 NM-SABINE LAKE-WATERS FROM INTRACOASTAL CITY TO 
     CAMERON LA FROM 20 TO 60 NM-WATERS FROM CAMERON LA TO HIGH 
     ISLAND TX FROM 20 TO 60 NM.