Flash Flooding in Louisiana, February 21, 2003

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS/BATON ROUGE LA
1130 AM CST FRI FEB 21 2003

LATEST MSAS SHOWS A DISTINCT EQUIVALENT POTENTIAL TEMPERATURE
GRADIENT WITH THE RELATIVELY STABLE AIR OVER SOUTH MISSISSIPPI AND
UNSTABLE AIR OVER SOUTHEAST....SOUTH CENTRAL AND SOUTHWEST
LOUISIANA. THE BOUNDARY WAS LOCATED FROM MOBILE BAY TO THE NEW
ORLEANS METRO AREA LAFAYETTE. IR SATELLITE IMAGERY CONTINUED TO SHOW
THE COLDER CLOUD TOPS JUST NORTH OF THE BOUNDARY AND RADAR SHOWS THE
SHOWERS AND THUNDERSTORMS DRIFTING NORTH. HAVE ISSUED A FLOOD WATCH
DUE TO THE EXPECTED RAINFALL OVER NEARLY SATURATED AREAS. IN
ADDITION...HAVE LOWERED TEMPERATURES ACROSS ZONES TO MATCH CURRENT
TRENDS.

.NEW...SMALL CRAFT ADVZY...COASTAL WATERS KPQL TO INTRACOASTAL CITY
       INCLUDING LAKES PONTCHARTRAIN AND MAUREPAS.
LA...FLOOD WATCH LAZ034>040-046>050-056>070
MS...FLOOD WATCH MSZ068>071-077-080>082

LAZ034>040-046>050-056>070-MSZ068>071-077-080>082-221300-

HAZARDOUS WEATHER OUTLOOK...RETRANSMISSION...
NATIONAL WEATHER SERVICE NEW ORLEANS LA
100 PM CST FRI FEB 21 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST LOUISIANA AND
EXTREME SOUTHWEST AND COASTAL MISSISSIPPI.

.DAY ONE...TODAY AND TONIGHT
A STRONG UPPER LEVEL DISTURBANCE ALONG WITH AN ASSOCIATED COLD FRONT
AT THE SURFACE IS EXPECTED TO MOVE THROUGH THE CENTRAL GULF COAST
REGION LATE THIS AFTERNOON AND CONTINUING THROUGH TONIGHT. NUMEROUS
SHOWERS AND THUNDERSTORMS WILL CONTINUE AHEAD OF THE APPROACHING
FRONT. AS THE SURFACE LOW PUSHES EAST...AN ASSOCIATED PRE-FRONTAL
TROUGH WILL SWEEP ACROSS THE AREA TONIGHT. A LINE OF STRONG
THUNDERSTORMS WITH VERY HEAVY RAINFALL IS EXPECTED ALONG THE
PRE-FRONTAL TROUGH TONIGHT.

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON
AND TONIGHT. SOME STORMS MAY REACH SEVERE THRESHOLDS LATER THIS
AFTERNOON AND TONIGHT. A SIGNIFICANT DAMAGING WIND EVENT WITH A FEW
STRONG TORNADOES ARE POSSIBLE. THE GREATEST SEVERE WEATHER THREAT
WILL OCCUR BETWEEN 5 PM LATE THIS AFTERNOON AND 3 AM SATURDAY
MORNING.

A FLOOD WATCH REMAINS IN EFFECT FOR SOUTHEAST LOUISIANA AND SOUTH
MISSISSIPPI THROUGH TONIGHT. SOME AREAS NORTH OF BATON ROUGE AND
EXTREME SOUTHWEST MISSISSIPPI HAVE ALREADY RECEIVED 3 TO 4 INCHES OF
RAIN. IN ADDITION...A SWATH OF 2 TO 3 INCHES OF RAINFALL OCCURRED
FROM SAINT CHARLES TO SAINT BERNARD PARISHES AND OVER PORTIONS OF
SAINT TAMMANY PARISH. A LINE OF THUNDERSTORMS WITH VERY HEAVY
RAINFALL IS EXPECTED ALONG THE PRE-FRONTAL TROUGH TONIGHT.
ADDITIONAL RAINFALL OF 3 TO 4 WILL CAUSE EXCESSIVE RUN-OFF WITH THE
POTENTIAL FOR FLASH FLOODING OVER RAIN SOAKED AREAS. ISOLATED STORM
TOTALS THROUGH SATURDAY MORNING COULD REACH 6 TO 8 INCHES.

MANY RIVERS ACROSS SOUTHEAST LOUISIANA AND SOUTH MISSISSIPPI ARE
ABOVE FLOOD STAGE OR ARE EXPECTED TO RISE ABOVE FLOOD STAGE. PLEASE
REFER TO RIVER FLOOD WARNINGS FOR EACH RIVER BASIN FOR ADDITIONAL
INFORMATION.

SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED TO DEVELOP ACROSS THE
TIDAL LAKES AND COASTAL WATERS IN ADVANCE OF THE FRONT TONIGHT AND
CONTINUE BEHIND THE FRONTAL BOUNDARY SATURDAY. WINDS AND SEAS ARE
EXPECTED TO DIMINISH ON SUNDAY.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY
SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED TO CONTINUE BEHIND THE
FRONTAL BOUNDARY SATURDAY. WINDS AND SEAS ARE EXPECTED TO DIMINISH
ON SUNDAY. OTHERWISE...NO SEVERE WEATHER IS EXPECTED SATURDAY
THROUGH THURSDAY.

.SPOTTER INFORMATION STATEMENT...

THE ACTIVATION OF STORM SPOTTERS AND HAM RADIO OPERATORS...IN
SUPPORT OF SEVERE WEATHER OPERATIONS...IS REQUESTED FOR THIS
AFTERNOON AND TONIGHT. LOCAL COUNTY AND PARISH EMERGENCY MANAGEMENT
SHOULD BE PREPARED AND STAFFED FOR SEVERE WEATHER POTENTIAL LATE
THIS AFTERNOON AND TONIGHT.