Severe Thunderstorm Warning 182, NWS New Orleans, LA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
349 PM CDT TUE AUG 12 2008

.DISCUSSION...
THE SURFACE LOW OVER NORTHWESTERN LOUISIANA AND UPPER SHORTWAVE
TROUGH OVER NORTHEASTERN TEXAS HAVE BEEN GENERATING QUITE A BIT OF
SHOWER AND THUNDERSTORM ACTIVITY THIS AFTERNOON. THE STRONGEST
ACTIVITY FOR OUR AREA THUS FAR HAS BEEN IN THE NORTHERN PORTION OF
THE FORECAST AREA WHERE SEVERAL BOW ECHOES HAVE KNOCKED DOWN TREES
AND POWER LINES. THE THREAT CONTINUES THROUGH THE REST OF THE
AFTERNOON AND EVENING WITH THE ENTIRE FORECAST AREA UNDER TORNADO
WATCH 823. THE SPECIAL 18Z KLIX UPPER AIR SOUNDING SHOWED AN
IMPRESSIVE LOW LEVEL WIND FIELD WITH 40 KNOTS RECORDED AT 850MB.
THERE WAS NOT MUCH IN TERMS OF DIRECTIONAL SHEAR BUT THE SPEED
SHEAR SHOULD BE ENOUGH TO SUPPORT A DAMAGING WIND AND ISOLATED
TORNADO THREAT...A VERY UNUSUAL SCENARIO FOR AUGUST ALONG THE GULF
COAST. WILL KEEP A CLOSE EYE ON THE SOUTHSHORE...NORTHSHORE...AND
IN COASTAL MISSISSIPPI WHERE THERE HAS BEEN ENOUGH SUN TO WARM
INTO THE UPPER 80S AND LOWER 90S.

WITH REGARDS TO HEAVY RAINFALL...THE NORTHERN SECTIONS OF THE
FORECAST AREA HAVE RECEIVED ABOUT 1 TO 1.5 INCHES SINCE MIDNIGHT.
ANOTHER INCH WOULD BE POSSIBLE IN THE STRONGEST STORMS. LUCKILY
THE STORMS ARE MOVING PRETTY QUICKLY AND HAVE NOT BEEN TRAINING SO
ANY FLOOD THREATS COULD BE EASILY HANDLED WITH LOCALIZED PRODUCTS.
HOWEVER...WILL CONTINUE TO MENTION HEAVY RAIN WORDING IN THE
HAZARDOUS WEATHER OUTLOOK AND ZONES.

THE LOW PRESSURE AREA SHOULD CONTINUE TO MOVE EASTWARD TONIGHT
AND TOMORROW MORNING WITH MUCH DRIER AIR FILTERING IN BEHIND THE
FRONTAL BOUNDARY. MOST OF THE RAIN SHOULD BE OUT OF OUR AREA BY
NOON WITH THE BOUNDARY LINGERING IN THE NORTHERN GULF.

THURSDAY AND FRIDAY SHOULD BE FAIRLY DRY WITH TEMPERATURES BACK IN
THE LOW 90S BEFORE RETURN FLOW KICKS BACK IN LATE FRIDAY
AFTERNOON. SCATTERED POPS RETURN IN TIME FOR THE WEEKEND AND EARLY
NEXT WEEK AS AN UPPER LOW DROPS INTO THE SOUTHERN PLAINS.

&&

.AVIATION...
NUMEROUS SHOWERS AND THUNDERSTORMS HAVE AFFECTED MCB AND BTR AND
THIS TREND WILL SHIFT TO MSY AND GPT THIS EVENING. RAIN AND MIST
WILL BE THE PREVAILING WEATHER FROM 06Z THROUGH 15Z WEDNESDAY WITH
CONVECTION AT TIMES. EXPECTING SW WINDS TO REMAIN UP UNTIL 02Z FOR MCB
AND BTR. OCCASIONAL MVFR CEILINGS ARE EXPECTED THIS AFTERNOON AND
EVENING WITH IFR TO LIFR CEILINGS AT KMCB AND KBTR WEDNESDAY
MORNING.

&&

.MARINE...
A SMALL CRAFT ADVISORY WILL REMAIN IN EFFECT FOR THE GULF COASTAL
WATERS AND TIDAL LAKES AS AFTERNOON SOUNDING SHOWED 25 KNOTS AT 2500
FEET AT SLIDELL. SOME DEEPENING OF THE LOW IS EXPECTED THIS EVENING
AND WINDS ARE EXPECTED TO REMAIN NEAR OR ABOVE SMALL CRAFT ADVISORY
CRITERIA THROUGH TONIGHT. SEAS WILL BUILD TO 5 TO 7 FEET THROUGH
TONIGHT. WINDS WILL BEGIN TO DIMINISH WEDNESDAY AFTERNOON. HIGH
PRESSURE WILL PREVAIL ACROSS THE COASTAL WATERS FOR THE END OF THE
WEEK.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  72  89  68  92 /  60  30  10  10
BTR  75  90  71  93 /  60  40  10  10
MSY  75  90  74  92 /  60  50  20  20
GPT  75  88  71  92 /  70  50  20  20

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
MS...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 7 AM CDT WEDNESDAY FOR GMZ530.

     SMALL CRAFT ADVISORY UNTIL 12 PM CDT WEDNESDAY FOR GMZ550-555-
     570-575.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1126 AM CDT TUE AUG 12 2008

GMZ530-550-555-570-575-LAZ034>040-046>050-056>070-MSZ068>071-077-
080>082-131630-
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-
1126 AM CDT TUE AUG 12 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF THE COASTAL
WATERS OF SOUTHEAST LOUISIANA AND SOUTH MISSISSIPPI...SOUTHEAST
LOUISIANA AND SOUTHERN MISSISSIPPI.

.DAY ONE...THIS AFTERNOON AND TONIGHT
A POTENT UPPER LEVEL DISTURBANCE WILL MOVE BETWEEN INTERSTATES 10 AND
20 TODAY. STRONG LOW LEVEL WINDS WILL PROVIDE ENOUGH SHEAR TO
POTENTIALLY PRODUCE SEVERE THUNDERSTORMS DURING THE AFTERNOON AND
EARLY EVENING HOURS. THUS...THE STORM PREDICTION CENTER HAS PLACED
THE ENTIRE FORECAST AREA UNDER A SLIGHT RISK FOR SEVERE WEATHER. THE
MAIN THREATS WITH ANY SEVERE ACTIVITY WOULD BE DAMAGING WINDS IN
EXCESS OF 60 MPH AND ISOLATED TORNADOES.

IN ADDITION...THESE THUNDERSTORMS WILL HAVE THE POTENTIAL TO
PRODUCE LOCALIZED HEAVY RAINFALL...WHICH COULD CAUSE MINOR
FLOODING ON ROADWAYS AND IN LOW LYING AREAS. A GENERAL 1.5 TO 2
INCHES CAN BE EXPECTED AREAWIDE...WITH ISOLATED AREAS OF 3 TO 4 INCHES.

A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR LAKES PONTCHARTRAIN
AND MAUREPAS AND ALL GULF COASTAL WATERS THROUGH TONIGHT...WITH WINDS OF
20 KNOTS AND 5 TO 7 FOOT SEAS EXPECTED.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY
THE SMALL CRAFT ADVISORY WILL CONTINUE THROUGH WEDNESDAY MORNING ACROSS
THE COASTAL WATERS OF SOUTHEAST LOUISIANA AND SOUTHERN MISSISSIPPI.

ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE...ESPECIALLY
DURING THE AFTERNOON AND EVENING HOURS EACH DAY. ORGANIZED
HAZARDOUS WEATHER IS NOT ANTICIPATED.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS POSSIBLE THIS AFTERNOON AND EVENING.

LAZ034>036-048-121815-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1230 PM CDT TUE AUG 12 2008

...THUNDERSTORM WITH STRONG GUSTY WINDS MOVING TOWARD THE
FELICIANAS...

AT 1228 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
THUNDERSTORM WITH STRONG GUSTY WINDS 7 MILES SOUTHWEST OF NEW
ROADS...OR ABOUT 5 MILES NORTH OF LIVONIA...MOVING NORTHEAST AT 41
MPH.

THE STRONG THUNDERSTORM WILL BE NEAR...
  NEW ROADS BY 1240 PM
  ST. FRANCISVILLE BY 1250 PM
  WAKEFIELD BY 1255 PM
  ZACHARY BY 100 PM
  JACKSON BY 105 PM

WIND GUSTS TO 50 MPH ARE POSSIBLE WITH THIS STORM.

IF YOU ARE CAUGHT OUTSIDE...SEEK SHELTER FROM THE WEATHER IN A STRONG
BUILDING. GUSTY WINDS AND VERY HEAVY RAIN ARE ALL POSSIBLE WITH THIS
THUNDERSTORM. STAY INSIDE AWAY FROM WINDOWS UNTIL THE STORM HAS
PASSED.

BE PREPARED TO TAKE QUICK ACTION IF A WARNING IS ISSUED. STAY TUNED
TO NOAA WEATHER RADIO OR YOUR FAVORITE LOCAL MEDIA OUTLETS FOR
FURTHER DETAILS OR UPDATES FROM THE NATIONAL WEATHER SERVICE.

32

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
144 PM CDT TUE AUG 12 2008

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

0112 PM     TSTM WND DMG     JACKSON                 30.83N 91.21W
08/12/2008                   EAST FELICIANA     LA   LAW ENFORCEMENT

            POWER LINES REPORTED DOWN IN JACKSON.

&&

PGRIGSBY

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE NEW ORLEANS LA
227 PM CDT TUE AUG 12 2008

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

0112 PM     TSTM WND DMG     JACKSON                 30.83N 91.21W
08/12/2008                   EAST FELICIANA     LA   LAW ENFORCEMENT

            POWER LINES REPORTED DOWN IN JACKSON.

0200 PM     TSTM WND DMG     CLINTON                 30.86N 91.01W
08/12/2008                   EAST FELICIANA     LA   LAW ENFORCEMENT

            MULTIPLE REPORTS OF TREES AND POWER LINES DOWN ACROSS THE
            PARISH.

0205 PM     TSTM WND DMG     OSYKA                   31.01N 90.47W
08/12/2008                   PIKE               MS   LAW ENFORCEMENT

            TREES REPORTED DOWN IN SOUTHERN PIKE COUNTY IN THE OSYKA
            AND MAGNOLIA AREA.

&&

PGRIGSBY

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE NEW ORLEANS LA
256 PM CDT TUE AUG 12 2008

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

0112 PM     TSTM WND DMG     JACKSON                 30.83N 91.21W
08/12/2008                   EAST FELICIANA     LA   LAW ENFORCEMENT

            POWER LINES REPORTED DOWN IN JACKSON.

0200 PM     TSTM WND DMG     CLINTON                 30.86N 91.01W
08/12/2008                   EAST FELICIANA     LA   LAW ENFORCEMENT

            MULTIPLE REPORTS OF TREES AND POWER LINES DOWN ACROSS THE
            PARISH.

0205 PM     TSTM WND DMG     OSYKA                   31.01N 90.47W
08/12/2008                   PIKE               MS   LAW ENFORCEMENT

            TREES REPORTED DOWN IN SOUTHERN PIKE COUNTY IN THE OSYKA
            AND MAGNOLIA AREA.

0240 PM     TSTM WND DMG     MCCOMB                  31.25N 90.47W
08/12/2008                   PIKE               MS   LAW ENFORCEMENT

            MULTIPLE REPORTS OF TREES DOWN IN PIKE COUNTY. TREES WERE
            REPORTED DOWN IN THE CITY OF MCCOMB AND AT THE
            INTERSECTION OF FERNWOOD RD AND PLEASANT GROVE ROAD TO
            THE EAST OF MCCOMB. REPORTS CAME IN FROM 220-240 PM.

&&

PGRIGSBY