Severe Thunderstorm Warning 108, NWS New Orleans, LA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
340 AM CDT WED MAY 14 2008

.SHORT TERM...
THE THING WE WILL BE LOOKING FOR TODAY WILL BE THE TRIGGER TO GET
SOMETHING GOING. CONVECTION NORTH AND NW OF THE AREA TODAY IS
BEING HELPED AND SUPPORTED BY MODERATE MID AND UPPER DYNAMICS AS
SMALL DISTURBANCES ARE KICKED OUT OF THE SW BY A STRONG UPPER
TROUGH AND ASSOCIATED UPP LOW NOW BEGINNING TO MOVE EAST OVER NEW
MEXICO. THE STRONG LATE SEASON COLD FRONT HAS STALLED THIS MORNING
FROM ST. LOUIS TO DALLAS TO DEL RIO. THE FRONT WILL SLOWLY SINK
SE OVER THE NEXT FEW DAYS AS THESE DISTURBANCES CONTINUE TO MOVE
ALONG ITS AXIS TO THE ENE. HEATING OVER OUR AREA SHOULD BE THE
MAIN TRIGGER AS WELL AS CONVERGENCE SETTING UP IN THE BL FROM MSY
TO NEAR BTR AND OUTFLOWS MOVING AWAY FROM THE LARGE CONVECTIVE
COMPLEXES UP NORTH.

THE NEXT QUESTION WILL BE WHAT DAY WILL BE BEST FOR SEVERITY?
ATTM...THE BEST ANSWER WOULD BE TODAY. THIS IS B/C WE SHOULD SEE
ENOUGH HEATING TO BRING US TO OUR CONVECTIVE TEMP FOR MOST
LOCATIONS ESPECIALLY OVER SE LA. WITH NO SUPPORTING DYNAMIC
STRUCTURE ALOFT...TS WILL NOT HAVE AN EXTRA ADVANTAGE TO BECOME
STRONGLY ENHANCED AND SO ANY TS THAT DO BECOME SEVERE SHOULD
REMAIN ON THE LOW SIDE OF SEVERE CRITERIA. THE BEST AREA FOR THIS
LOOKS TO BE FROM MSY TO MCB WESTWARD. THE FOCUS FOR SEVERITY WILL
SHIFT A LITTLE ON THU TO BE LOCATED MAINLY OVER THE EASTERN THIRD
OF THE AREA. TIMING WILL HAVE A LOT TO DO WITH THIS AND FOR
BREVITY...WE WILL KEEP EVERYONE IN A SLIGHT RISK TODAY AND
TOMORROW.

THE MAIN CONCERN WILL BE HEAVY RAINFALL WHERE THESE LARGE
CONVECTIVE COMPLEXES DEVELOP. LOOKING AT THE MOVEMENT AND
DEVELOPMENT VECTORS THROUGH THU...THERE DOES NOT SEEM TO BE A LOT
OF DIFFERENCE IN WHAT IS OCCURRING UP NORTH. SISTER CELLS AND
MOISTURE WILL FEED INTO THE LARGER COMPLEX FROM SOUTH TO NORTH AT
ROUGHLY 20KT. THE ENTIRE COMPLEX WILL MOVE ENE AT 15KT. A SLOW
PROCESS OF BACKBUILDING WILL START THU AND WE COULD SEE SOME
ISOLATED LOCATIONS WITH HIGH TALLIES OF RAINFALL.

.LONG TERM...
THE FRONT MOVES THROUGH BY FRIDAY BRINGING SOME COOL DRY AIR FOR
THE REMAINDER OF THE WEEKEND INTO NEXT WEEK.

&&

.AVIATION...
OCCASIONAL MVFR CEILINGS WILL PLAGUE EACH OF THE TAF SITES TODAY AND
TONIGHT. THE CHANCES FOR CONVECTION WILL BE ON THE INCREASE BY THIS
AFTERNOON...ESPECIALLY AT KMCB...KBTR...AND KMSY. SCATTERED
CONVECTION IS EXPECTED TO CONTINUE INTO THE OVERNIGHT HOURS.

.MARINE...
MODERATE ONSHORE FLOW WILL CONTINUE THROUGH THURSDAY IN ADVANCE OF A
COLD FRONT THAT WILL MOVE ACROSS THE COASTAL WATERS FRIDAY. MODERATE
OFFSHORE FLOW WILL BRIEFLY DEVELOP IN THE WAKE OF THE FRONT.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  83  68  83  65 /  50  40  60  40
BTR  84  71  84  67 /  50  40  60  40
MSY  84  72  84  69 /  50  30  60  40
GPT  83  73  83  69 /  40  40  60  40

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...NONE.
MS...NONE.
GM...NONE.
&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
602 AM CDT WED MAY 14 2008

GMZ530-550-555-570-575-LAZ034>040-046>050-056>070-MSZ068>071-077-
080>082-141700-
LAKE PONTCHARTRAIN AND LAKE MAUREPAS-
COASTAL WATERS FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER
TO LOWER ATCHAFALAYA RIVER LA OUT 20 NM-
COASTAL WATERS FROM PASCAGOULA MS TO THE SOUTHWEST PASS OF THE
MISSISSIPPI RIVER OUT 20 NM-
COASTAL WATERS FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER
TO LOWER ATCHAFALAYA RIVER LA FROM 20 TO 60 NM-
COASTAL WATERS FROM PASCAGOULA MS TO THE SOUTHWEST PASS OF THE
MISSISSIPPI RIVER FROM 20 TO 60 NM-POINTE COUPEE-WEST FELICIANA-
EAST FELICIANA-ST. HELENA-TANGIPAHOA-WASHINGTON-ST. TAMMANY-
IBERVILLE-WEST BATON ROUGE-EAST BATON ROUGE-ASCENSION-LIVINGSTON-
ASSUMPTION-ST. JAMES-ST. JOHN THE BAPTIST-UPPER LAFOURCHE-
ST. CHARLES-UPPER JEFFERSON-ORLEANS-UPPER PLAQUEMINES-
UPPER ST. BERNARD-UPPER TERREBONNE-LOWER TERREBONNE-
LOWER LAFOURCHE-LOWER JEFFERSON-LOWER PLAQUEMINES-
LOWER ST. BERNARD-WILKINSON-AMITE-PIKE-WALTHALL-PEARL RIVER-
HANCOCK-HARRISON-JACKSON-
602 AM CDT WED MAY 14 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF GULF OF
MEXICO...SOUTHEAST LOUISIANA AND SOUTHERN MISSISSIPPI.

.DAY ONE...TODAY AND TONIGHT
A SLIGHT RISK OF SEVERE THUNDERSTORMS WILL REMAIN THROUGH TONIGHT.
THE HAZARDS POSSIBLY ASSOCIATED WITH SEVERE THUNDERSTORMS WILL BE
STRONG DAMAGING WINDS...LARGE HAIL...FREQUENT LIGHTNING...VERY
HEAVY RAINFALL AND AN ISOLATED TORNADO.

HIGH FLOWS AND FLOODING WILL CONTINUE ALONG THE MISSISSIPPI AND
ATCHAFALAYA RIVERS. PLEASE REFER TO THE LATEST RIVER FLOOD
STATEMENTS FOR UPDATED INFORMATION.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY
A SLIGHT RISK OF SEVERE THUNDERSTORMS WILL REMAIN THROUGH THURSDAY NIGHT.
THE MAIN HAZARD EXPECTED WITH ANY SEVERE THUNDERSTORMS WILL BE
STRONG DAMAGING WINDS...LARGE HAIL...FREQUENT LIGHTNING AND VERY
HEAVY RAINFALL.

HEAVY PROLONGED RAINFALL WILL BECOME AN INCREASING THREAT LATE
TONIGHT THROUGH THURSDAY NIGHT AS CONDITIONS BEGIN TO EVOLVE FROM
A SEVERE WEATHER THREAT TO MORE OF A HEAVY RAINFALL POSSIBILITY.

.SPOTTER INFORMATION STATEMENT...
PERSONNEL WITH PUBLIC SAFETY RESPONSIBILITIES SHOULD MONITOR
FORECASTS THROUGH THURSDAY NIGHT.

17

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
300 PM CDT WED MAY 14 2008

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0215 PM     HAIL             15 W BATON ROUGE        30.45N 91.38W
05/14/2008  E0.25 INCH       WEST BATON ROUGE   LA   TRAINED SPOTTER

            NEAR US190 AND 81

0245 PM     HAIL             LIVONIA                 30.56N 91.55W
05/14/2008  E1.75 INCH       POINTE COUPEE      LA   LAW ENFORCEMENT

            GOLFBALL-SIZED HAIL REPORTED NEAR LIVONIA

0250 PM     HAIL             ERWINVILLE              30.53N 91.41W
05/14/2008  E1.75 INCH       WEST BATON ROUGE   LA   BROADCAST MEDIA

            SEVERAL REPORTS OF GOLFBALL-SIZED HAIL REPORTED VIA MEDIA

&&

25

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
302 PM CDT WED MAY 14 2008

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0250 PM     HAIL             ERWINVILLE              30.53N 91.41W
05/14/2008  E2.75 INCH       WEST BATON ROUGE   LA   PUBLIC

            PUBLIC REPORTED BASEBALL-SIZED HAIL NEAR ERWINVILLE

&&

25

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
309 PM CDT WED MAY 14 2008

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0248 PM     TSTM WND DMG     5 SSE LIVONIA           30.50N 91.52W
05/14/2008                   POINTE COUPEE      LA   LAW ENFORCEMENT

            TREES AND POWER LINES DOWN NEAR PARISH LINE SOUTH OF
            LIVONIA. GOLFBALL-SIZED HAIL ALSO REPORTED.

&&

25