Flash Flood in Louisiana, July 20, 2003

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS/BATON ROUGE LA
200 AM CDT SUN JUL 20 2003

TODAY SHOULD BE ANOTHER ONE SIMILAR TO YESTERDAY WITH THE RIDGE OVER
THE SOUTHWEST CONTINUING TO ALLOW EMBEDDED DISTURBANCES ALOFT TO
ROTATE SOUTHWARD OVER THE AREA. PREFER THE ETA/MESOETA SOLUTION AT
THIS TIME AS THE GFS STILL LOOKS A BIT TO WET PROBABLY DUE TO
CONVECTIVE FEEDBACK ISSUES. FORECAST SOUNDINGS FROM THE MESOETA
STILL INDICATE ABUNDANT PWS WITH VALES AOA 2 INCHES WHICH SUGGEST
HEAVY RAIN A GOOD POSSIBILITY AGAIN TODAY. WOULD NOT THOUGH RULE OUT
AN ISOLATED PULSE STORM POSSIBLY REACHING SEVERE THRESHOLDS FOR WIND
ALTHOUGH THE CURVATURE PROFILE WOULD NOT SUGGEST THIS TO BE OVERLY
WIDESPREAD. FORECAST TIME HEIGHTS THEN INDICATE SOME SIGNIFICANTLY
DRIER AIR ALOFT COMING IN TO PLAY MONDAY WHICH BRINGS IN THE NEXT
CHALLENGE. OVERNIGHT LOWS ESPECIALLY ACROSS THE NEW ORLEANS METRO
AREA ARE ONLY PROGGED TO DROP INTO THE UPPER 70S TO NEAR 80 RANGE.
WITH AFTERNOON TEMPERATURES IN THE LOWER TO MID 90S POSSIBLE MONDAY
AND TUESDAY...AFTERNOON HEAT INDEX READINGS COULD EASILY CLIMB INTO
THE 105 TO 110 RANGE WHICH MAY POSE A DANGER FROM EXCESSIVE HEAT. AT
THIS TIME...WILL ISSUE A HEAT WATCH FOR MONDAY STRICTLY FOR THE
AFOREMENTIONED AREA AT THIS TIME AND THEN ALLOW THE DAY SHIFT TO
DETERMINE IF AN ADVISORY IS WARRANTED AND SHOULD THE WATCH AREA BE
CHANGED. WEDNESDAY SHOULD OFFER SOME RELIEF FROM THE HEAT AS THE GFS
REMAINS CONSISTENT WITH A BROAD UPPER TROUGH DROPPING INTO THE LOWER
SOUTHEAST STATES PUSHING AN ASSOCIATED FRONT INTO THE NORTHERN GULF.

PRELIM NUMBERS...

MCB 89/72/93/74 5221  BTR 90/73/93/75 5221
MSY 90/75/93/77 5221  GPT 88/73/91/76 5231

.NEW...NONE
LA...EXCESSIVE HEAT WATCH LAZ060>064.
MS...NONE.

09

LAZ034>040-046>050-056>070-MSZ068>071-077-080>082-211100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1020 AM CDT SUN JUL 20 2003

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

.DAY ONE...TODAY AND TONIGHT

AN AREA OF NUMEROUS SHOWERS AND THUNDERSTORMS WITH HEAVY RAIN WILL
PERSIST THIS MORNING ACROSS WESTERN AND NORTHERN ST. TAMMANY PARISH.
TOTAL RAINFALL AMOUNTS OF 3 TO 5 INCHES ARE EXPECTED THROUGH NOON
WHICH WILL CAUSE FLOODING OF STREETS...CREEKS...AND LOW LYING
AREAS.

ELSEWHERE...SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL
DEVELOP THROUGH THE DAY ACROSS EAST CENTRAL AND SOUTHEAST LOUISIANA
AND SOUTH MISSISSIPPI. LOCALLY HEAVY RAINFALL AMOUNTS OF 1 TO 3
INCHES ARE EXPECTED. IN ADDITION...THE STRONGER THUNDERSTORMS WILL
PRODUCE FREQUENT LIGHTNING AND WIND GUSTS TO 40 MPH. AN UPPER LEVEL
DISTURBANCE COMBINED WITH A VERY MOIST AND UNSTABLE ATMOSPHERE
WILL AID IN THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS TODAY.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

...AN EXCESSIVE HEAT WATCH IS IN EFFECT FOR MONDAY PRIMARILY FOR THE
NEW ORLEANS METROPOLITAN AREA...

AFTERNOON TEMPERATURES MONDAY ARE EXPECTED TO CLIMB INTO THE LOWER
TO MID 90S WITH ASSOCIATED HEAT INDEX READINGS AROUND 105. OVERNIGHT
LOWS ACROSS THE WATCH AREA MONDAY NIGHT ARE ONLY EXPECTED TO DROP
INTO THE UPPER 70S WITH AFTERNOON TEMPERATURES ON TUESDAY AGAIN
CLIMBING INTO THE LOWER TO MID 90S. ONLY ISOLATED SHOWERS AND
THUNDERSTORMS ARE EXPECTED ON MONDAY AND TUESDAY.

A WEAK COLD FRONT IS EXPECTED TO MOVE THROUGH SOUTHEAST LOUISIANA
AND SOUTH MISSISSIPPI ON WEDNESDAY BEFORE STALLING IN THE NORTHERN
GULF ON THURSDAY. SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE
ALONG AND AHEAD OF THIS BOUNDARY WEDNESDAY AND THURSDAY. A FEW
STORMS MAY BRIEFLY APPROACH SEVERE THRESHOLDS.

A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS IS THEN POSSIBLE FRIDAY
AND SATURDAY.

.SPOTTER INFORMATION STATEMENT...

THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS AND EMERGENCY
MANAGEMENT PERSONNEL...IN SUPPORT OF SEVERE WEATHER OPERATIONS...IS
NOT REQUESTED AT THIS TIME.