Area Forecast Discussion
Issued by NWS Lake Charles, LA

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158
FXUS64 KLCH 290954
AFDLCH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
454 AM CDT FRI APR 29 2016

.SYNOPSIS...
UPPER LEVEL DISTURBANCE IS ROTATING OVER THE SOUTHWEST U.S. MOVING
TO THE EAST...WITH A DEVELOPING SURFACE LOW ASSOCIATED WITH THIS
STORM SYSTEM OVER EASTERN NEW MEXICO. WATER VAPOR IMAGERY ALSO
SHOWS SOUTHERN JET BECOMING MORE ACTIVE BRINGING AN INCREASE IN
TROPICAL EAST PACIFIC MOISTURE INTO THE REGION. THESE FEATURES
WILL COMBINE OVER THE NEXT 48 HOURS TO BRING THE POSSIBILITY OF
HEAVY RAINFALL AND SEVERE WEATHER TO THE FORECAST AREA.

&&

.DISCUSSION...
A QUIET...BUT RATHER HUMID START TO THE FORECAST. SOME PATCHY FOG
WILL OCCUR UNTIL SHORTLY AFTER SUNRISE. OTHERWISE...FORECAST AREA
TODAY WILL HAVE SOMEWHAT OF A CAP...WITH NO REAL TRIGGER...EXCEPT
FOR DAYTIME HEATING. SO WILL JUST GO WITH LOW END CHANCES FOR
SHOWERS MAINLY IN THE AFTERNOON...AND OVER WESTERN SECTIONS OF THE
FORECAST AREA. WITH DEVELOPING SURFACE LOW IN THE TEXAS
PANHANDLE...COULD BE A LITTLE BREEZY...BUT AT THIS POINT LOOKS
LIKE WINDS STAY BELOW ADVISORY CRITERIA.

THE DEVELOPING LOW PRESSURE AND STORM SYSTEM OVER THE TEXAS
PANHANDLE TODAY...WILL MOVE NORTHEAST INTO THE SOUTHERN PLAINS
TONIGHT INTO SATURDAY MORNING...THEN TO THE MID-MISSISSIPPI
VALLEY BY SUNDAY MORNING...THEN OFF TO THE MID-ATLANTIC STATES BY
MONDAY MORNING. A TRAILING COLD FRONT FROM THE LOW...WILL MOVE
SLOWLY ACROSS THE FORECAST AREA SATURDAY NIGHT INTO
SUNDAY...BEFORE THE FRONTAL BOUNDARY MOVES INTO THE COASTAL WATERS
BY MONDAY MORNING AND STALLS.

INCREASING MOISTURE...ALONG WITH INCREASING LIFT FROM THE FRONT
AND A SERIES OF UPPER LEVEL DISTURBANCES...WILL ALLOW FOR A
COMPLEX OF THUNDERSTORMS TO DEVELOP OVER CENTRAL TEXAS LATE TODAY
INTO TONIGHT...WITH THIS ACTIVITY MOVING EASTWARD INTO WESTERN
PORTIONS OF THE FORECAST AREA TONIGHT...THEN SLOWLY MOVING ACROSS
THE REMAINDER OF THE FORECAST AREA ON SATURDAY. WITH ACTIVITY
REDEVELOPING ON SATURDAY NIGHT OVER THE FORECAST AREA...AHEAD OF
SLOW MOVING COLD FRONT...THAT WILL KEEP ACTIVITY GOING THROUGH THE
FIRST HALF OF SUNDAY.

PRECIPITABLE WATER VALUES WILL INCREASE TO BETWEEN 1.5 AND 1.75
INCHES TONIGHT AND TO OVER 1.75 INCHES TO NEARLY 2 INCHES ON
SATURDAY...THESE VALUES ARE AT OR ABOVE TWICE THE STANDARD
DEVIATION OF NORMAL. MEAN RH VALUES WILL ALSO BE OVER 70 TO 80
PERCENT...SO CONVECTION SHOULD BE EFFICIENT PRECIPITATION
PRODUCERS. THEREFORE...HEAVY RAINFALL IS BECOMING MORE LIKELY.
STORM TOTAL FROM WPC QPF AND MODEL BLEND...FAVOR 2 TO 4 INCHES ON
AVERAGE NORTHWEST OF AN OPELOUSAS TO CAMERON LINE FROM LATE
TONIGHT THROUGH SATURDAY NIGHT...AND 2 TO 3 INCHES SOUTHEAST OF
THAT LINE FROM SATURDAY INTO SUNDAY MORNING...WITH ISOLATED HIGHER
AMOUNTS POSSIBLE. WILL LET THE DAY SHIFT TAKE ANOTHER LOOK AT THIS
LATER TODAY...AND IF THESE PRECIP NUMBERS CONTINUE...A FLASH FLOOD
WATCH WILL LIKELY HAVE TO BE ISSUED. IT SHOULD BE NOTED...THAT WPC
DOES HAVE THE UPPER SOUTHEAST TEXAS PORTION OF THE FORECAST AREA
HIGHLIGHTED FOR A MODERATE RISK OF EXCESSIVE RAINFALL FROM TONIGHT
INTO SATURDAY MORNING...AND A SLIGHT RISK OF EXCESSIVE RAINFALL
FOR A MAJORITY OF THE FORECAST AREA FOR THE DAY ON SATURDAY INTO
SATURDAY NIGHT.

ALSO...WITH SPEED MAX INCREASING BULK SHEAR VALUES...AND FAVORABLE
LAPSE RATES...THERE COULD BE SOME STRONG TO SEVERE STORMS ON
SATURDAY...WITH STRAIGHTLINE WINDS FROM WET MICRO-BURSTS THE MAIN
CONCERN. SPC ALSO HAS THE FORECAST AREA OUTLINED IN MARGINAL TO
SLIGHT RISK OF SEVERE STORMS ON THE DAY 2 OUTLOOK (SATURDAY.)

HEAVY RAINFALL AND SEVERE THREAT WILL GRADUALLY DIMINISH ON SUNDAY
AS THE FRONT SAGS INTO THE COASTAL WATERS...WITH RAIN CHANCES
BRIEFLY DECREASING.

RAIN CHANCES WILL INCREASE AGAIN ON MONDAY INTO TUESDAY...AS COLD
FRONT WILL STALL OVER THE COASTAL WATERS...AND ACTIVE SOUTHERN JET
WILL AGAIN BRING DISTURBANCES TO CAUSE OVER-RIDING TYPE
SHOWERS...AND WITH DECENT ELEVATED INSTABILITY...THUNDERSTORMS.
PWAT AND MEAN RH VALUES ARE AGAIN HIGH DURING THIS PERIOD...SO
WILL HAVE TO WATCH AGAIN FOR HEAVY RAINFALL...ESPECIALLY IF WE
RECEIVE A GOOD AMOUNT OF RAINFALL DURING THE WEEKEND.

NORTHERN AND SOUTHERN STREAM DISTURBANCES MERGE BY WEDNESDAY
ALLOWING FOR LARGE UPPER LEVEL TROUGH ALONG THE EAST COAST. THIS
WILL HELP BRING A DEEPER NORTHWEST FLOW ALOFT OVER THE FORECAST
AREA AND DRY CONDITIONS FOR THE END OF THE FORECAST PERIOD.

RUA

&&

.MARINE...
ELEVATED SOUTHERLY WINDS WILL OCCUR TODAY INTO SATURDAY...AS
GRADIENT TIGHTENS OVER THE NORTHWEST GULF...IN RESPONSE TO
DEVELOPING LOW PRESSURE OVER THE TEXAS PANHANDLE MOVING INTO THE
SOUTHERN PLAINS. WIND SPEEDS WILL BE A STEADY 15 TO 20 KNOTS WITH
SOME HIGHER GUSTS. WILL KEEP THE SMALL CRAFT EXERCISE CAUTION
HEADLINE THROUGH SATURDAY. AS THE LOW PRESSURE MOVES OFF TO THE
NORTHEAST AND A COLD FRONT APPROACHES THE COASTAL WATERS ON
SUNDAY...THE SOUTHERLY WINDS ARE EXPECTED TO DECREASE.

OFFSHORE WINDS ARE EXPECTED TO DEVELOP ON EARLY MONDAY...AS A WEAK
COLD FRONT MOVES INTO THE COASTAL WATERS AND STALLS.

RUA

&&

.PRELIMINARY POINT TEMPS/POPS...
AEX  88  71  81  69 /  20  60  70  70
LCH  85  73  80  71 /  20  40  60  70
LFT  86  74  82  72 /  10  20  50  70
BPT  85  72  81  70 /  20  50  70  70

&&

.LCH WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
TX...NONE.
GM...SMALL CRAFT EXERCISE CAUTION THROUGH SATURDAY MORNING FOR GMZ450-
     452-455-470-472-475.

&&

$$

PUBLIC...07



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