Severe Thunderstorm Warning 177, NWS New Orleans, LA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS/BATON ROUGE LA
355 PM CDT MON JUL 12 2004

.DISCUSSION...
HEAT AND STRONG AFTERNOON AND EVENING THUNDERSTORMS ARE THE MAIN
FORECAST CONCERNS. COVERAGE/RAIN CHANCES OF SHOWERS AND
THUNDERSTORMS HAS BEEN HIGHER THAN EXPECTED SEVERAL DAYS THE LAST
WEEK. THE RAIN HAS BROKEN THE OTHERWISE TYPICALLY OPPRESSIVE HEAT OF
SUMMER. WATER VAPOR LOOPS SHOW A WELL DEFINED UPPER LEVEL VORT MAX
MOVING SOUTH INTO SOUTHEAST MS. THIS UPPER LEVEL FEATURE COMBINED
WITH 1.75 TO 2 INCH PRECIPITABLE WATER/PW/ HAS ALLOWED FOR SCATTERED
CONVECTION OVER MUCH OF THE CENTRAL AND SOUTHERN ZONES DESPITE THE
LACK OF THE TYPICAL SEA BREEZES.

THE 500 MB PATTERN WILL FEATURE AN UPPER HIGH OVER THE ROCKIES WITH
A RIDGE AXIS EXTENDING SOUTHEAST INTO THE CENTRAL GULF COAST REGION
OR THE NORTHWEST GULF THROUGH SATURDAY. THE GFS/ETA INDICATES
ANOTHER VORT MAX WILL MOVE SOUTH AROUND THE PERIPHERY OF THE RIDGE
ACROSS NORTHERN MS/NORTHERN LA ON TUESDAY. PW/S ARE ONCE AGAIN
EXPECTED TO BE ABOVE NORMAL...BUT THE SEA BREEZE SHOULD BE
NON-EXISTENT AGAIN WITH WEST TO NORTHWEST SURFACE WINDS. THESE
FACTORS SHOULD OFFSET EACH OTHER TO BRING NEAR NORMAL POPS...40
PERCENT. WEDNESDAY IS A TRICKY FORECAST. THE ETA INDICATES THE
REMAINS OF AN INVERTED 500 MB TROUGH SITTING OFF THE COAST WHILE THE
UPPER RIDGE REBUILDS JUST NORTH OF THE FORECAST AREA. PW/S ARE
FORECAST TO REMAIN ABOVE NORMAL. A FRONTAL BOUNDARY MAY STALL OUT
JUST NORTH OF THE FORECAST AREA. WILL
CONTINUE WITH HIGH END SCATTERED POPS NEAR THE COAST...BUT LOWER
SOUTHWEST MS TO SLIGHT CHANCE DUE TO DRIER AIR BUILDING IN.
TEMPERATURES MAY REACH NEAR THE HIGHEST OF THE SEASON OVER THE
INLAND ZONES...SO THIS MAY NEED TO BE ADDRESSED IN A LATER
STATEMENT. FOR NOW...HEAT INDICES ARE HIGHLIGHTED IN THE HAZARDOUS
WEATHER OUTLOOK.

THE UPPER RIDGE SHOULD WEAKEN FRIDAY THROUGH SUNDAY WITH CONTINUED
DISTURBANCES MOVING THROUGH THE NORTHWEST FLOW AND POSSIBLY BRUSHING
OUR AREA. WILL MAINTAIN DAILY CHANCES OF SHOWERS AND STORMS THROUGH
THE PERIOD WITH TEMPERATURES RETURNING CLOSER TO NORMAL.

&&

PRELIMINARY POINT NUMBERS...
MCB  73 93 73 95 / 10 40 20 20
BTR  74 93 74 94 / 10 40 20 30
MSY  76 92 77 92 / 10 40 30 50
GPT  75 93 75 92 / 20 40 30 50
&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
MS...NONE.
SE LA AND MS COASTAL WATERS...NONE.
&&

22

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
430 PM CDT MON JUL 12 2004

LAZ034>040-046>050-056>070-MSZ068>071-077-080>082-131100-
AMITE-ASCENSION-ASSUMPTION-EAST BATON ROUGE-EAST FELICIANA-HANCOCK-
HARRISON-IBERVILLE-JACKSON-LIVINGSTON-LOWER JEFFERSON-
LOWER LAFOURCHE-LOWER PLAQUEMINES-LOWER ST. BERNARD-LOWER TERREBONNE-
ORLEANS-PEARL RIVER-PIKE-POINTE COUPEE-ST. CHARLES-ST. HELENA-
ST. JAMES-ST. JOHN THE BAPTIST-ST. TAMMANY-TANGIPAHOA-
UPPER JEFFERSON-UPPER LAFOURCHE-UPPER PLAQUEMINES-UPPER ST. BERNARD-
UPPER TERREBONNE-WALTHALL-WASHINGTON-WEST BATON ROUGE-WEST FELICIANA-
WILKINSON-
430 PM CDT MON JUL 12 2004

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

.DAY ONE...TODAY AND TONIGHT

AFTERNOON HEAT INDICES OF 99 TO 104 ARE EXPECTED OUTSIDE OF RAIN
AREAS THE REMAINDER OF THIS AFTERNOON. OTHERWISE...ISOLATED TO
SCATTERED THUNDERSTORMS WILL CONTINUE INTO THE EARLY EVENING HOURS.
A FEW OF THE STORMS MAY BRIEFLY BECOME SEVERE AND PRODUCE WIND GUSTS
TO 60 MPH ALONG WITH HAIL UP TO NICKEL SIZE...DANGEROUS LIGHTNING
AND TORRENTIAL RAINFALL.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

AFTERNOON HEAT INDICES FROM 100 TO 105 DEGREES ARE EXPECTED ON
TUESDAY AND HEAT INDICES 105 TO 110 DEGREES ARE POSSIBLE EACH
WEDNESDAY AND THURSDAY. A HEAT INDEX OF 105 DEGREES IS CONSIDERED
THE LEVEL WHERE MANY PEOPLE BEGIN TO EXPERIENCE EXTREME DISCOMFORT
OR PHYSICAL STRESS. OTHERWISE...ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS ARE EXPECTED EACH DAY. ISOLATED STRONG TO SEVERE
THUNDERSTORMS ARE POSSIBLE MAINLY ON TUESDAY AND AGAIN ON 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.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
415 PM CDT MON JUL 12 2004

LAZ061-063-122145-
UPPER JEFFERSON-UPPER PLAQUEMINES-
415 PM CDT MON JUL 12 2004

...STRONG THUNDERSTORMS OVER MARRERO...

AT 410 PM...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
CLUSTER OF STRONG THUNDERSTORMS OVER THE MARRERO AREA. THESE STORMS
ARE NEARLY STATIONARY IN MOVEMENT ALTHOUGH A SLIGHT DRIFT TOWARD THE
SOUTH IS POSSIBLE THROUGH 445 PM.

THE PRIMARY THREATS FROM THESE STORMS ARE DANGEROUS CLOUD TO GROUND
LIGHTNING...TORRENTIAL RAINFALL...SMALL HAIL AND WIND GUSTS TO 40
MPH...WHICH MAY DOWN SMALL TREE LIMBS OR BRANCHES AND BLOW AROUND
UNSECURED SMALL OBJECTS. SEEK SHELTER IN A SAFE HOME OR BUILDING
UNTIL THESE STORMS HAVE PASSED.

STAY TUNED TO NOAA WEATHER RADIO...LOCAL MEDIA...AND CABLE TELEVISION
PROVIDERS FOR LATER STATEMENTS AND POSSIBLE WARNINGS ON THIS CLUSTER
OF THUNDERSTORMS.