Area Forecast Discussion
Issued by NWS Lake Charles, LA

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000
FXUS64 KLCH 240259
AFDLCH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
959 PM CDT SAT MAY 23 2015

.UPDATE...
STORMS ENDING OVER THE REGION THIS EVENING AS GULF MOISTURE
PROFILE CONDS TO DEEPEN. LOOKING FOR STORM REDEVELOPMENT TMRW
MORNING AFTER SUNRISE. OTHERWISE A QUIET NIGHT AS STORMS IN CNTRL
TX MOV EASTWARD OVERNIGHT.

&&

.PREV DISCUSSION... /ISSUED 342 PM CDT SAT MAY 23 2015/

..SCENARIO FOR HEAVY RAINFALL WHICH MAY LEAD TO FLOODING STILL EXISTS
FROM SUNDAY INTO MONDAY...

DISCUSSION...
SURFACE BOUNDARY HAS PUSHED THROUGH THE FORECAST AREA ALLOWING
SOUTHEAST WINDS AND A WARM AND HUMID AIR MASS TO RETURN TO THE
FORECAST AREA. WITH THE RETURN OF THE MOISTURE...SO HAS SCATTERED
SHOWERS AND THUNDERSTORMS. THIS ACTIVITY WILL CONTINUE UNTIL
SUNSET. SOME BRIEF DOWNPOURS AND FREQUENT CLOUD TO GROUND
LIGHTNING WILL BE THE MAIN CONCERNS.

CONDITIONS STILL SEEM TO BE COMING TOGETHER FOR WHAT NORMALLY
WOULD BE A HEAVY RAINFALL EVENT FOR THE FORECAST AREA. UPPER
LEVEL LOW OVER THE EASTERN ROCKIES AND TROUGH EXTENDING DOWN
THROUGH THE SOUTHWEST U.S. WILL MOVE SLOWLY EASTWARD AS IT BUMPS
UP AGAINST AN UPPER LEVEL RIDGE ANCHORED OVER THE SOUTHEAST U.S.
THIS WILL ALLOW FOR AN INCREASING DEEP MOIST FEED WITH DIVERGENT
PATTERN ALOFT TO DEVELOP OVER THE REGION FROM SUNDAY INTO EARLY
NEXT WEEK.

AS THE TROUGH APPROACHES TONIGHT...LOW LEVEL JET WILL INCREASE
OFF THE GULF. THEREFORE...SCATTERED NOCTURNAL SHOWERS WILL FORM
OVER THE GULF AND MOVE INLAND DURING THE LATE NIGHT PERIOD.

MEANWHILE...BAND OF SHOWERS AND THUNDERSTORMS WITH HEAVY DOWN
POURS IS EXPECTED TO FORM OVER CENTRAL TEXAS WITH A SHORT WAVE
MOVING AWAY FROM THE MAIN TROUGH. THIS BAND IS EXPECTED TO REACH
SOUTHEAST TEXAS BY LATE MORNING THEN ACROSS THE FORECAST AREA
DURING THE AFTERNOON HOURS. VERY MOIST ENVIRONMENT FOR THIS BAND
TO WORK WITH...AS PRECIPITABLE WATER VALUES WILL BE OVER 2
INCHES...TWICE THE STANDARD DEVIATION...AND MEAN RH OVER 80
PERCENT. SO VERY PRECIPITATION EFFICIENT STORMS THAT COULD PRODUCE
HEAVY RAINFALL RATES.

MAY SEE A BRIEF BREAK IN THE ACTIVITY SUNDAY EVENING AS ACTIVITY
RAINS ITSELF OUT. HOWEVER...AS WHAT NORMALLY HAPPENS WITH UPPER
LEVEL SYSTEMS AND A TROPICAL LIKE AIR MASS...NOCTURNAL
REDEVELOPMENT WILL LIKELY TAKE PLACE BY OVERNIGHT SUNDAY ACROSS
SOUTHEAST TEXAS...PUSHING INTO SOUTHWEST LOUISIANA BY MONDAY
MORNING. WITH THE CURRENT ANTECEDENT CONDITIONS (WET
GROUNDS...HIGH HYDROLOGIC FLOWS)...A FLASH FLOOD WATCH WAS ISSUED
BY THE PREVIOUS SHIFT FOR WESTERN LOUISIANA AND SOUTHEAST
TEXAS...BEGINNING TOMORROW AND CONTINUING INTO MONDAY. CURRENT QPF
PROJECTIONS SHOW AVERAGE RAINFALL AMOUNTS DURING THIS PERIOD
(SUNDAY INTO MONDAY) IN THE WATCH AREA FROM 2 TO 4 INCHES...WITH
LOCALLY HIGHER AMOUNTS WHERE SOME OF THE STRONGER CONVECTIVE
BURSTS DEVELOP. AT THIS TIME...DID NOT EXPAND THE WATCH FURTHER TO
THE EAST. HOWEVER...THE WATCH MAY HAVE TO BE EXPANDED AND EXTENDED
AS THE PATTERN WILL ONLY SLIGHTLY SWITCH TO THE EAST BY TUESDAY.

ALTHOUGH THE UPPER LEVEL SYSTEM WILL WEAKEN AND PULL OFF TO THE
NORTHEAST ON WEDNESDAY...AND TAKING WITH IT THE VERY HIGH MOISTURE
ENVIRONMENT...ENOUGH GULF MOISTURE HANGING AROUND ALONG WITH
ENOUGH OF A WEAKNESS ALOFT TO CALL FOR DAILY CHANCES OF DIURNALLY
DRIVEN SHOWERS AND STORMS FOR THE REMAINDER OF THE FORECAST
PERIOD.

RUA

MARINE...
SOUTHEAST TO SOUTH WINDS WILL PERSIST OVER THE COASTAL WATERS
THROUGH THE WEEKEND INTO EARLY NEXT WEEK...AS HIGH PRESSURE OFF
THE SOUTHEAST U.S. COAST RIDGES INTO THE NORTHERN GULF. THE
SOUTHEAST WINDS WILL BECOME MODERATE TO STRONG LATER TONIGHT
THROUGH MONDAY AS THE PRESSURE GRADIENT INCREASES ACROSS THE
NORTHWEST GULF AS LOW PRESSURE DEVELOPS EAST OF THE ROCKIES AND
MOVE INTO THE PLAINS. SUSTAINED WINDS TONIGHT MAY NEAR 20 KNOTS
AT TIMES...ALTHOUGH WILL LIKELY BE IN THE 15 TO 20 KNOT RANGE FOR
A MAJORITY OF THE TIME...SO WILL KEEP JUST SMALL CRAFT EXERCISE
CAUTION GOING.

AN UPPER LEVEL DISTURBANCE WILL HELP BRING WIDESPREAD SHOWERS AND
THUNDERSTORMS OVER THE COASTAL WATERS BY SUNDAY AFTERNOON...WITH
WIDESPREAD ACTIVITY CONTINUING INTO MONDAY. THESE STORMS WILL HAVE
THE POTENTIAL FOR HEAVY RAINFALL REDUCING VISIBILITIES BELOW 1
NM...FREQUENT CLOUD TO WATER LIGHTNING...AND LOCALLY HIGHER WINDS
AND SEAS.

RUA

&&

.PRELIMINARY POINT TEMPS/POPS...
AEX  71  83  69  81 /  30  70  70  70
LCH  74  83  72  83 /  30  70  80  70
LFT  73  85  72  84 /  30  60  60  70
BPT  76  82  73  84 /  30  80  80  70

&&

.LCH WATCHES/WARNINGS/ADVISORIES...
LA...FLASH FLOOD WATCH FROM 7 AM CDT SUNDAY THROUGH MONDAY EVENING
     FOR LAZ027-030-041-073-074.

TX...FLASH FLOOD WATCH FROM 7 AM CDT SUNDAY THROUGH MONDAY EVENING
     FOR TXZ180-201-215-216-259>262.

GM...SMALL CRAFT EXERCISE CAUTION THROUGH SUNDAY AFTERNOON FOR GMZ450-
     452-455-470-472-475.

&&

$$

PUBLIC...19


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