Severe Thunderstorm Warning 231, NWS New Orleans, LA

AREA FORECAST DISCUSSION...CORRECTION TO 2ND PERIOD POP AT GPT
NATIONAL WEATHER SERVICE NEW ORLEANS/BATON ROUGE LA
345 PM CDT THU AUG 31 2000

NUMEROUS STRONG TO SEVERE THUNDERSTORMS HAVE ERUPTED NEAR AND JUST
SE OF THE SURFACE TROUGH ACROSS S MS/E CENTRAL LA. CELLS ARE
DEVELOPING ABOUT AS FAST AS POSSIBLE WITH NOTHING ON THE RADAR SCOPE
TURNING TO SEVERE WITH VILS OVER 70 J/KG 15 MINUTES LATER. DRIER
AIR...WHICH WAS IN PLACE ACROSS THE NORTHERN ZONES EARLY TODAY HAS
MOISTENED UP RAPIDLY DUE TO THE EXTREME INSTABILITY AND SURFACE
CONVERGENCE. MODELS...PARTICULARLY THE ETA ARE UNDER-FORECASTING QPF
AND POPS. THE ETA MASS GUIDANCE FIELDS LOOK GOOD HOWEVER...SO WILL
USE THIS MODEL WITH MAJOR ADJUSTMENTS TO QPF.

THE ONLY SIGNIFICANT CHANGE NOTED IS THE ADVECTION OF HIGHER MEAN
RELATIVE HUMIDITIES INTO THE SE LA ZONES ON FRIDAY AS THE UPPER LOW
OVER GA RETROGRADES SLOWLY W TO THE AL/GA BORDER. THIS WILL KNOCK
DOWN TEMPERATURES...INSTABILITY AND SEVERE POTENTIAL IN SE
MS...OTHERWISE EXPECT CONTINUED HIGH HEAT AND GOOD CHANCE OF
AFTERNOON AND EARLY EVENING THUNDERSTORMS...A FEW SEVERE ELSEWHERE.
EVEN WITH THE HIGHER POPS...TEMPERATURES SHOULD BE SEVERAL DEGREES
ABOVE THE HIGHEST GUIDANCE NUMBERS WITH THE EXCEPTION OF A FEW RAIN
COOLED LOCATIONS AT NIGHT.

GIVEN THE DROUGHT CONDITIONS WE HAVE ENDURED...IT WOULD BE ODD TO
MAINTAIN NEAR NORMAL POPS FOR MORE THAN A FEW DAYS...SO WILL GO
ALONG WITH DRIER PATTERN EVOLVING IN THE EXTENDED FORECAST...SUNDAY
...LABOR DAY AND TUESDAY WITH HEAT CONTINUING.

MCB 73/99/72/98 1523    BTR 76/99/75/98 2523
MSY 78/98/77/97 3434    GPT 76/94/75/94 3534

.NEW...NONE
LA...HEAT ADVISZORY THROUGH FRIDAY SE LA ZONES - LAZ058>070.
MS...NONE.

22

LAZ034>040-046>050-056>070-MSZ068>071-077-080>082-311900-

THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1046 AM CDT THU AUG 31 2000

...THERE IS A CHANCE OF SEVERE THUNDERSTORMS THIS AFTERNOON...

AN AREA OF LOW PRESSURE OVER THE LOWER MISSISSIPPI VALLEY IN
COMBINATION WITH INCREASING SOUTHEASTERLY FLOW WILL PRODUCE
SCATTERED THUNDERSTORMS DURING THE AFTERNOON.  SEA BREEZE AND LAKE
BREEZE BOUNDARIES WILL LIKELY FOCUS THE THUNDERSTORMS OVER THE
INLAND AREAS WITH SOME OF THE STORMS REACHING SEVERE LEVELS.

THE MAIN CONCERN WILL BE DAMAGING WIND GUSTS OF 45 TO 60 MPH...
MARBLE TO DIME SIZED HAIL...FREQUENT LIGHTNING AND BRIEF HEAVY
RAINFALL. THE PERIOD OF HIGHEST THREAT SHOULD ONSET AROUND 2 PM AND
CONTINUE THROUGH 830 PM. THE AREA OF CONCERN WILL BE ALL OF
SOUTHEAST LOUISIANA EAST OF THE ATCHAFALAYA RIVER AND SOUTHERN
MISSISSIPPI. MOVEMENT OF THE STORMS WILL VARY DEPENDING ON SEA
BREEZE INTERACTIONS1 BUT THE PREVAILING MOVEMENT SHOULD BE FROM THE
NORTH AT 10 TO 15 MPH.

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

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1155 AM CDT THU AUG 31 2000

LAZ056>070-312300-
ASSUMPTION-LOWER JEFFERSON-LOWER LAFOURCHE-LOWER PLAQUEMINES-
LOWER ST BERNARD-LOWER TERREBONNE-ORLEANS-ST CHARLES-ST JAMES-
ST JOHN THE BAPTIST-UPPER JEFFERSON-UPPER LAFOURCHE-
UPPER PLAQUEMINES-UPPER ST BERNARD-UPPER TERREBONNE-
INCLUDING THE CITIES OF...GRAND ISLE...HOUMA...METAIRIE...NEW ORLEANS
1155 AM CDT THU AUG 31 2000

...A HEAT ADVISORY IS IN EFFECT THIS AFTERNOON...
...AFTERNOON HEAT INDICES 105 TO 115 DEGREES...

HIGH TEMPERATURES ARE EXPECTED TO BE IN THE 95 TO 100 DEGREE
RANGE AND HEAT INDICES ARE EXPECTED TO BE AT DANGEROUS LEVELS OF 105
TO 115 DEGREES. LOW TEMPERATURES TONIGHT WILL BE 80 DEGREES OR
HIGHER.

THE HEAT INDEX IS A MEASURE OF HOW HOT IT FEELS WHEN THE EFFECTS OF
HUMIDITY ARE COMBINED WITH THE TEMPERATURE. A HEAT INDEX OF 105
DEGREES IS THE LEVEL WHERE MANY PEOPLE BEGIN TO EXPERIENCE EXTREME
DISCOMFORT OR PHYSICAL STRESS. THE HEAT INDEX IS MEASURED UNDER
SHADY CONDITIONS...AND DIRECT EXPOSURE TO SUNLIGHT CAN INCREASE THE
HEAT INDEX AS MUCH AS 15 DEGREES.

EFFECTS CAN BE MINIMIZED BY REDUCING OUTDOOR ACTIVITIES...DRINKING
PLENTY OF WATER OR NON-ALCOHOLIC BEVERAGES...AND WEARING LIGHT-
COLORED CLOTHING. IF POSSIBLE...SPEND TIME IN AIR CONDITIONED
FACILITIES.

PETS CAN ALSO SUCCUMB TO THE EFFECTS OF EXCESSIVE HEAT. ENSURE PETS
HAVE ADEQUATE DRINKING WATER AND A SHADY PLACE TO REST. DO NOT KEEP
PETS IN CARS WITH WINDOWS ROLLED UP...EVEN PARTIALLY.

DO NOT LEAVE CHILDREN AND SMALL PETS IN CLOSED AUTOMOBILES.
TEMPERATURES INSIDE A CAR WITH THE WINDOWS UP CAN REACH OVER 150
DEGREES QUyICKLY...RESULTING IN HEAT STROKE AND DEATH FOR SMALL
CHILDREN AND PETS.

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