Severe Thunderstorm Warning 69, NWS New Orleans, LA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS/BATON ROUGE LA
230 AM CDT SUN JUL 21 2002

A GOOD BIT OF CHANGE PROBABLE FOR THIS MORNING/S FORECAST PACKAGE.
FIRST CONCERN CONTINUES TO HOVER AROUND THE HEAT ADVISORY. WILL
CONTINUE THE HEAT ADVISORY FOR NOW ALTHOUGH PRESENT THINKING NOW IS
THAT THIS MAY BE THE LAST ONE REGARDING THIS HEAT EPISODE GIVEN THE
FACT THE FORECAST IS GOING TO CHANGE SOME.

THE OTHER FORECAST CONCERN NOW CENTERS AROUND SOME HIGHER RAIN
CHANCES FOR THE FORECAST AREA OVER THE NEXT FEW DAYS WHICH MAY HELP
SUPPRESS SOME OF THE EXTREME HEAT THE AREA HAS BEEN SUBJECTED TOO.
THE NWP MODELS THIS MORNING STILL HOLD THE EASTERN TROF IN PLACE
COUPLED WITH THE UPPER HIGH OVER THE CENTRAL STATES. LOOKING AT
CURRENT RADAR AND IR SAT TRENDS THOUGH SUGGEST THAT MID LEVEL
POCKETS OF ENERGY ROTATING AROUND THE EXTREME EASTERN HALF OF THE
UPPER RIDGE ARE NOW MAKING IT CLOSE TO THE FORECAST AREA. A STRONG
SLOW MOVING CLUSTER OF THUNDERSTORMS BUILDING WEST ACROSS THE
MISSISSIPPI SOUND SUPPORTS THIS THEORY. CURRENT THINKING NOW BASED
ON NEW GUIDANCE FROM THE AVN AND OTHER MODELS IS THAT EMBEDDED MID
LEVEL POCKETS OF ENERGY WILL CONTINUE MOVING SOUTHWARD AROUND THE
BASE OF THE UPPER TROF CLOSE TO THE FORECAST AREA. BEST CHANCE FOR
RAIN WOULD THEN BE ALONG AND EAST OF A LINE FROM MCB TO ASD TO GPT.
THE AVN DOES NOT MOVE THE UPPER HIGH AND EASTERN TROF VERY MUCH OVER
THE NEXT FEW DAYS SO FAIRLY DECENT RAIN CHANCES IN THE SCT CAT
SHOULD CONTINUE. FORECAST TIME HEIGHTS FURTHER SUPPORT THIS AS WELL
WITH A RAPID INCREASE IN MOISTURE DEPTH BEGINNING LATER TODAY.

THE LATTER HALF OF THE AVN IS STILL TRYING TO MOVE A WEAK FRONTAL
BOUNDARY AIDED BY THE EASTERN TROF THROUGH THE FORECAST AREA AROUND
MID WEEK. THIS REMAINS SUBJECT THOUGH GIVEN THE TIME OF YEAR IT IS
ALTHOUGH WILL GIVE SOME CREDENCE TO THE AVN AND KEEP THE LATTER HALF
OF THE FORECAST PACKAGE WITH SCT RAIN CHANCES. HOWEVER...IF THE
FRONT IS ABLE TO APPROACH THE NORTHERN GULF NEXT WEEK...DRIER AIR
ALOFT ASSOCIATED WITH THE FRONTAL/S PASSAGE WOULD SUGGEST SOME
DRYING AS NEXT WEEKEND APPROACHES.

PRELIM NUMBERS...

MCB 94/74/94/73 4342  BTR 94/75/94/74 3231
MSY 94/77/93/76 3231  GPT 93/75/92/74 4342

.NEW...NONE
LA...HEAT ADVISORY LAZ058>070.
MS...NONE.

09

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE NEW ORLEANS, LA
810 AM CDT SUN JUL 21 2002

CORRECTION FOR TIME FOR REPORT 25 SE BILOXI SHOULD BE 0300 AM CDT

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0300 AM    25 SE BILOXI              MS   MARINE THUNDERSTORM WIND
07/21/02   HARRISON                       BUOY 42007 REPORTED 52 KT
                                          WIND GUST

0625 AM    RIGOLETS                  LA   MARINE THUNDERSTORM WIND
07/21/02   ORLEANS                        EAST LAKE PONTCHARTRAIN
                                          REPORTED 38 KT WIND GUST

LAZ034>040-046>050-056>070-MSZ068>071-077-080>082-221200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1100 AM CDT SUN JUL 21 2002

...HEAT ADVISORY IS IN EFFECT FOR LOWER SOUTHEAST LOUISIANA...
...HEAT INDEX VALUES RANGING FROM 102 TO 110 THIS AFTERNOON...

.SYNOPSIS...STRONG HIGH PRESSURE AFFECTING THE CENTRAL GULF COAST
REGION WILL AGAIN LEAD TO DANGEROUS HEAT STRESS CONDITIONS ACROSS
THE FORECAST AREA THIS AFTERNOON. A SERIES OF WEAK UPPER LEVEL
DISTURBANCES WILL ALSO MOVE SOUTHWARD ACROSS THE LOWER MISSISSIPPI
VALLEY THIS AFTERNOON AND TONIGHT. WITH AN UNSTABLE AIRMASS ALREADY
IN PLACE...SCATTERED SHOWERS AND THUNDERSTORMS WILL ALSO BE POSSIBLE
ACROSS SOUTHEAST LOUISIANA AND SOUTH MISSISSIPPI THROUGH TONIGHT.

.THUNDERSTORMS...
SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP AS THESE UPPER LEVEL
DISTURBANCES INTERACT WITH OLD OUTFLOW BOUNDARIES AND DEVELOPING
LAKE AND SEA BREEZE BOUNDARIES. THUNDERSTORM WIND GUSTS TO 50
MPH...FREQUENT LIGHTNING AND LOCALLY HEAVY RAINFALL ARE LIKELY WITH
THE STRONGER STORMS. IN ADDITION...A FEW STORMS COULD APPROACH
SEVERE THRESHOLDS WITH THE POTENTIAL FOR DAMAGING WINDS.

.EXCESSIVE HEAT...
TEMPERATURES THIS AFTERNOON WILL BE IN THE MID 90S WITH HEAT INDEX
VALUES AROUND 105 TO 110 DEGREES IN THE ADVISORY AREA SOUTH OF LAKE
PONTCHARTRAIN...AND 102 TO 105 DEGREES ELSEWHERE.

.ACTIONS...HEAT PRECAUTIONS SHOULD BE TAKEN THIS AFTERNOON.

FOR MORE INFORMATION...VISIT OUR WEB SITE AT WWW.SRH.NOAA.GOV/LIX
(ALL LOWER CASE).