Flood in Texas, August 15, 2002

SOUTHWEST LOUISIANA AND SOUTHEAST TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
250 AM CDT THU AUG 15 2002

UPDATED FOR COASTAL WATERS

LATEST WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS SHOWS MID AND
UPPER LEVEL TROF CONTINUING ALONG TEXAS COAST WITH CYCLONIC
CIRCULATION IN THE MID LEVELS NOTED OVER EAST CENTRAL TEXAS
MOVING TO THE EAST. UPPER AIR ANALYSIS ALSO SHOWS DIFLUENT PATTERN
ALOFT OVER THE WESTERN GULF AND INTO THE FORECAST AREA.

MOISTURE ANALYSIS FROM 15/00Z AGAIN SHOWS VERY MOIST AIRMASS IN PLACE
WITH KLCH REPORTING A PWAT OF JUST OVER 2 INCHES AND MEAN RH AT 79
PERCENT. WITH LATEST VAD WIND PROFILE FROM KLCH SHOWS MEAN WIND
THROUGH 10K FT FROM 200 AT 29 KNOTS. LOOKING TO THE SOUTH-SOUTHWEST
AND ALONG THE TEXAS COAST...KCRP HAD PWAT OVER 2.3 INCHES AND MEAN
RH AT 85 PERCENT.

LOCAL NWS RADARS THIS MORNING SHOWING GOOD CONCENTRATION OF SHOWERS
AND THUNDERSTORMS OVER THE COASTAL COUNTIES OF SOUTHEAST TEXAS AND
THE NORTHWEST GULF EXTENDING TO THE NORTH AND NORTHEAST AND JUST
ENTERING THE LAKES AREA OF SE TEXAS AND WEST CENTRAL LOUISIANA. THIS
IS IN AREA WHERE LAPS IS SHOWING BEST LOW LEVEL MOISTURE AND
THETA E CONVERGENCE. SURFACE OBS ALSO NICELY SHOW THIS LOW LEVEL
SPEED CONVERGENCE CAUSING THE LIFT WITH WINDS AT 07Z AT SRST2 AND
CAMERON FROM THE SOUTHEAST AT 17 KNOTS COMPARED TO INLAND LOCATIONS
OF KBPT WEST AT 6 KNOTS AND KLCH SOUTHEAST AT 5 KNOTS. REPORTS FROM
ALERT GAUGES IN JEFFERSON COUNTY AND KBPT ASOS INDICATE BETWEEN 1/2
AND 1 INCH OF RAIN HAS FALLEN IN THE LAST 3 HOURS.

FOR TODAY...WITH VERY MOIST AIRMASS IN PLACE AND MORE DEEP TROPICAL
MOISTURE TO ADVECT IN...AS WELL AS UPPER LEVEL TROF OVERHEAD...
THE LIKELIHOOD OF SHOWERS AND THUNDERSTORMS WILL CONTINUE. QUESTION
IS HOW MUCH AND WHERE THE HEAVIEST RAIN WILL FALL. MID LEVEL
CIRCULATION OVER EAST TEXAS WILL MOVE SLOWLY OFF TO THE EAST. THIS
WILL PUSH VORT MAX NORTHEAST AND UP THE TEXAS COAST AND ACROSS THE
WESTERN HALF OF THE FORECAST AREA TODAY. GUIDANCE IS SHOWING LIFT AND
DIFLUENCE ASSOCIATED WITH THIS VORT MAX TO BE QUITE ROBUST WITH AVN
THE MOST IMPRESSIVE. HOWEVER...AS HPC STATED IN THEIR MODEL
DISCUSSION...THE AVN IS HAVING GRID SCALE FEEDBACK PROBLEMS WITH THIS
SYSTEM. THEREFORE...WILL LEAN TOWARD THE ETA AND HPC QPF NUMBERS
WHICH SHOW 1 TO 1.5 INCHES AREAWIDE AND A REGION OF LOCALLY UP TO 3
INCHES FROM EXTREME SE TX INTO SOUTHWEST AND WEST CENTRAL LOCATION.
THIS IS THE AREA WHERE THE BEST FOCUS FOR LOW LEVEL CONVERGENCE IS
LIKELY TO OCCUR. STILL...IF THESE NUMBERS VERIFY THEY ARE STILL
BELOW FLASH FLOOD GUIDANCE VALUES FOR LOWER SOUTHEAST TEXAS AND
SOUTHWEST LOUISIANA...WHICH ARE BETWEEN 3 TO 4.5 INCHES FOR 3 TO 6
HOURS. ALSO...BEST LIFT ASSOCIATED WITH THE VORT MAX IS EXPECTED
TO OCCUR BETWEEN 15Z AND 18Z...WITH IT WEAKENING AS IT PULLS OFF TO
THE NORTHEAST DURING THE AFTERNOON HOURS.

MOISTURE DECREASES SOMEWHAT ON FRIDAY...ALONG WITH LESS IMPRESSIVE
LIFT AS VORT MAX MOVE OFF TO THE NORTHEAST...BUT STILL HIGH ENOUGH
(JUST UNDER 2 INCHES) AND WEAKNESS STILL SEEN IN UPPER LEVELS TO
PRODUCE ABOVE NORMAL COVERAGE FOR SHOWERS AND THUNDERSTORMS.

DRIER AIR SEEN ON SATURDAY WITH PWAT CLOSER TO 1.6 INCHES AND MEAN
RH IN THE 50 PERCENT RANGE AS UPPER LEVEL SUB-TROPICAL RIDGE BEGINS
TO BUILD IN FROM THE EAST. WITH CLOSER TO NORMAL MOISTURE VALUES...
SHOULD SEE POPS AND TEMPS AROUND SEASONAL NORMS FOR THE WEEKEND
INTO EARLY NEXT WEEK.

MARINE FORECASTER WILL HAVE SMALL CRAFT ADVISORY FOR COASTAL WATERS
OUT 60NM.

.PRELIM NUMBERS...
    TH    FR    SA SU  T F S S
BPT 85 76/88 76/90 76  935242
LCH 85 75/88 75/90 75  935242
LFT 87 74/88 74/90 75  735242
AEX 85 72/89 73/94 73  735242

.LCH...SMALL CRAFT ADVISORY HIGH ISLAND TO ATCHAFALAYA RIVER OUT 60NM

7-RUA

LAZ027>033-041>045-051>055-TXZ180>182-201-215-216-152100-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE LAKE CHARLES LA
435 AM CDT THU AUG 15 2002

...LOCALLY HEAVY RAINFALL POSSIBLE TODAY...

AN UPPER LEVEL DISTURBANCE MOVING UP THE TEXAS COAST AND A VERY
MOIST TROPICAL AIRMASS WILL COMBINE TO PRODUCE NUMEROUS SHOWERS AND
THUNDERSTORMS TODAY. RAINFALL AMOUNTS WILL LIKELY AVERAGE 1 INCH
AREAWIDE. THE LOCATION WITH THE GREATEST POTENTIAL FOR THE HEAVIEST
RAINFALL WILL BE EXTREME SOUTHEAST TEXAS INTO EXTREME SOUTHWEST AND
WEST CENTRAL LOUISIANA. LOCALLY 2 TO 4 INCHES OF RAIN WILL BE
POSSIBLE IN THIS AREA.

THE RAPID MOVEMENT OF INDIVIDUAL STORMS WILL LIMIT THE DANGER
OF WIDESPREAD FLOODING. HOWEVER...PONDING OF WATER ON STREETS AND
LOW LYING AREAS WITH POOR DRAINAGE WILL BE POSSIBLE.

ALL INTEREST IN SOUTHEAST TEXAS AND SOUTHWEST LOUISIANA SHOULD KEEP
IN TOUCH WITH THE LATEST FORECASTS AND STATEMENTS FROM THE NATIONAL
WEATHER SERVICE ON THIS SITUATION.

RUA