Area Forecast Discussion
Issued by NWS Lake Charles, LA

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000
FXUS64 KLCH 280433
AFDLCH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
1133 PM CDT MON APR 27 2015

.AVIATION...IFR CIGS WITH INSTABILITY SHOWERS AND THUNDERSTORMS AS
A TRIPLE POINT LOW ON A FRONTAL WAVE OCCLUSION DRAGS ALONG JUST
OFF THE LOUISIANA COAST OVER THE REMAINDER OF TNITE. THE UPPER LOW
RESPONSIBLE FOR DISTURBANCES CAUSING THE PERIODIC SHOWERS AND
THUNDERSTORMS WILL MOVE INTO THE ARKLATEX EASRLY TUESDAY AFTERNOON
AND 24 HOURS FROM NOW WILL BE LIFTING ACROSS THE MISSISSIPPI
RIVER, WITH IMPROVING CONDITIONS BEYOND.

SWEENEY

&&

.PREV DISCUSSION... /ISSUED 1037 PM CDT MON APR 27 2015/

DISCUSSION...
LOCAL 88DS SHOW THE VAST MAJORITY OF THE FORECAST AREA IS DRY ATTM
WITH MAYBE SOME PATCHY DRIZZLE HERE AND THERE. HOWEVER REGIONAL
88DS SHOW THE NEXT LINE OF THUNDERSTORMS...ALBEIT A RATHER NARROW
LINE...DEVELOPING ALONG AN OLD OUTFLOW CROSSING NERN/E-CNTL TX.
QUITE A BIT OF SPREAD IN TERMS OF MODEL SOLUTIONS ON THE EVENTUAL
OUTCOME OF THIS CONVECTION THROUGH THE OVERNIGHT HOURS...BUT
CONSIDERING THAT THESE STORMS ARE MOVING INTO WHAT REMAINS A MOIST
AND SOMEWHAT UNSTABLE AIRMASS (ALTHOUGH THIS ISN`T TOTALLY KNOWN
GIVEN THE UNFORTUNATE LACK OF A 00Z KLCH SOUNDING) HAVE ADJUSTED
THE POST-MIDNIGHT POPS TO INCLUDE THIS ACTIVITY PUSHING EWD ACROSS
THE NRN 2/3 OF THE FORECAST AREA. HELD ONTO SEVERE WORDING AS WELL
JUST TO BE SAFE...AS WELL AS NOT MAKING ANY ADJUSTMENTS TO THE
INHERITED FLASH FLOOD WATCH.

UPDATE ALREADY ISSUED.
25

PREV DISCUSSION... /ISSUED 654 PM CDT MON APR 27 2015/

AVIATION...THE PESKY UPPER LEVEL LOW OVER NORTHWEST TEXAS IS
PROGGED TO SLIDE EAST INTO THE ARKLATEX BY TUESDAY AFTERNOON. ALONG
THE RED RIVER VALLEY TONIGHT. THE ASSOCIATED TRIPLE POINT LOW
SOUTH OF SABINE PASS WILL SWING INTO SW LA TNITE AND HEAD ACROSS
THE ATCHAFALAYA TUESDAY MORNING.

PERIODS OF TSTMS WITH STRONG WINDS AND HEAVY RAINS WILL PRODUCE
IFR AT TIMES, ENDING AROUND MIDNIGHT AT BPT AND LCH AND LATE TNITE
AT LFT AND ARA. UPPER LEVEL DISTURBANCES AROUND THE UPPER LOW ARE
EXPECTED TO SET OFF INSTABILITY SHOWERS AND THUNDERSTORMS AROUND
AEX. DUE TO THE COLD TEMPS ALOFT PRODUCING HIGH CAPES, HAIL WILL
BE A PROBLEM ALONG WITH GUSTS.

THE UPPER LOW PASSAGE TUESDAY EVENING WILL SPELL AN END TO THIS
UNSTABLE AND INCLEMENT PATTERN.

SWEENEY

PREV DISCUSSION... /ISSUED 240 PM CDT MON APR 27 2015/

DISCUSSION...
QUITE THE ACTIVE WX PATTERN CONTINUES...WITH THIS MORNING`S
MASSIVE MCS & ASSOCIATED SQUALL LINE LONG GONE...WITH NEW TSRA
DEVELOPING ACROSS THE REGION THIS AFTERNOON. SO FAR...MOST HAVE STAYED
BELOW SEVERE LIMITS...BUT NOW JUST BEGINNING TO GET A FEW SVR HAIL
REPORTS WITH CELLS ACROSS INLAND SE TX/W LA. ADDITIONAL SVR TSTM
COULD OCCUR AT ANY GIVEN MOMENT AS THE ATMOSPHERE WILL CONTINUE
TO BECOME MORE UNSTABLE LATER THIS AFTERNOON AND EVENING.

WITH THE ONGOING ACTIVITY AND EXPECTED ADDITIONAL DEVELOPMENT THIS
EVENING AND OVERNIGHT...EXTENDED THE FLOOD WATCH THROUGH 7 AM TUE
MORNING. WHAT TO EXPECTED LATER THIS EVENING...NAM12 & HRRR
GUIDANCE SHOWS ANOTHER POSSIBLE MCS DEVELOPING ACROSS TX AHEAD OF
THE SFC LOW TO MOVE ESE TOWARDS...YOU GUESSED IT...SE TX BY 10
PM-MID...AND SPREADING E ACROSS C AND SC BETWEEN MID AND 4 AM TUE
MORNINGS. TIMING SUBJECT TO CHANGE IF SYSTEM SPEEDS UP...BECOMES
SVR EARLIER...ETC.

A CHANCE OF SHRA/TSRA WILL REMAIN THROUGH TUE AFTERNOON...AS THE
UPPER LEVEL COLD LOW MOVES OVER THE REGION WITH CONTINUED INSTABILITY
ALOFT. BY TUE AFTERNOON...COOLER AND DRIER AIR WILL EVENTUALLY PUT
AN END TO THE SVR WX AND PRECIP...AND EXPECTED TO REMAIN PRECIP
FREE THROUGH NEXT WEEKEND. FOR WED & THU...EXPECTED LOWS IN THE
LOWER 50S...AND HIGHS IN THE 70S. BY FRI INTO THE WEEKEND...A
SLOW WARMING TREND WILL CONTINUE.

DML

MARINE...
MODERATE TO STRONG EASTERLY FLOW IS EXPECTED TO PERSIST THIS
AFTERNOON AS THE PRESSURE GRADIENT REMAINS ELEVATED AHEAD OF A
DEVELOPING SURFACE LOW. FOR THIS...SCA ISSUED FOR THE REMAINDER OF
THE DAY INTO TUE. THUNDERSTORM CHANCES WILL CONTINUE AS A SERIES
OF UPPER LEVEL DISTURBANCES MOVES ACROSS THE REGION. SOME OF THESE
STORMS WILL BE CAPABLE OF BECOMING SEVERE...WITH STRONG
WINDS...WATERSPOUTS...HAIL...AND DANGEROUS CLOUD TO WATER
LIGHTNING. A SURFACE LOW WILL DEVELOP OVER TEXAS AND MOVE ACROSS
THE REGION TONIGHT...DRAGGING A COLD FRONT THROUGH THE COASTAL
WATERS. THIS WILL BRING AN END TO RAIN CHANCES...AND RESULT IN A
MODERATE TO STRONG NORTHERLY FLOW TUESDAY AND WEDNESDAY. WITH THE
STRONG OFFSHORE FLOW EXPECTED AFTER THE FRONT...SCA WILL CONTINUE
INTO WED.

DML

&&

.PRELIMINARY POINT TEMPS/POPS...
AEX  60  66  50  70 /  80  30  10  10
LCH  65  74  52  73 /  80  20  10  10
LFT  67  75  53  70 /  70  30  10  10
BPT  64  73  51  74 /  70  20  10  10

&&

.LCH WATCHES/WARNINGS/ADVISORIES...
LA...FLASH FLOOD WATCH UNTIL 7 AM CDT TUESDAY FOR LAZ027>033-041>045-
     052>055-073-074.

TX...FLASH FLOOD WATCH UNTIL 7 AM CDT TUESDAY FOR TXZ180-201-215-216-
     259>262.

GM...SMALL CRAFT ADVISORY UNTIL 7 PM CDT WEDNESDAY FOR GMZ450-452-455-
     470-472-475.

     SMALL CRAFT EXERCISE CAUTION UNTIL 7 AM CDT TUESDAY FOR GMZ430-
     432-435.

&&

$$


AVIATION...11



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