5/29/10 Gulfcoast Severe Weather threat increasing

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Mesoscale Discussion 740

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MESOSCALE DISCUSSION 0740 NWS STORM PREDICTION CENTER NORMAN OK 1025 AM CDT SAT MAY 29 2010 AREAS AFFECTED...SRN-SERN LA/SERN MS/SRN AL/FL PANHANDLE/SRN GA CONCERNING...OUTLOOK UPGRADE VALID 291525Z - 291630Z A SLIGHT RISK AREA WILL BE ADDED TO THE CONVECTIVE OUTLOOK AT 1630Z FROM SRN/SERN LA EWD ACROSS SERN MS...SRN AL AND PARTS OF THE FL PANHANDLE AND SRN GA. 12Z UPPER AIR ANALYSIS SHOWED A CLOSED LOW CENTERED OVER CENTRAL/SRN MS WITH 50 METER HEIGHT FALLS AND -14.5 C AT 500 MB PER JAN SOUNDING. 25-30 KT MIDLEVEL FLOW WILL TRANSLATE THROUGH THE BASE OF THIS LOW ACROSS SERN LA AND FAR SERN MS TODAY WHILE THE CLOSED LOW/COLDER MIDLEVEL TEMPERATURES SHIFT SLOWLY SEWD. IN ADDITION TO SEA/LAKE BREEZE BOUNDARIES...STREAMLINE ANALYSES THIS MORNING INDICATED A LOW LEVEL CONVERGENCE ZONE EXTENDING FROM THE NERN GULF /150 SW AAF/ THROUGH WRN FL PANHANDLE INTO CENTRAL/NERN AL ALONG SRN EXTENT OF ONGOING CONVECTIVE CLUSTER 40 SW ANB. A SECOND BOUNDARY EXTENDED EWD FROM THIS CLUSTER THROUGH CENTRAL GA TO SERN SC AND MARKED THE NRN EXTENT OF HIGHER SURFACE DEWPOINTS /UPPER 60S-LOWER 70S/. FORECAST DETAILS WILL BE FORTHCOMING IN THE 1630Z OUTLOOK. ..PETERS.. 05/29/2010

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GULF COAST STATES

CYCLONIC FLOW AROUND UPPER LOW CENTRAL MS WITH RELATIVELY COOL MID
LEVEL AIR MASS AND LAPSE RATES FROM 6.5-7C/KM ENCOMPASSES MUCH OF
GULF STATES FROM LA EWD. WHILE THE OVERALL MARGINAL SHEAR WILL
FAVOR PRIMARILY MULTICELLULAR CONVECTION...THE PRESENCE OF A MOIST
AIR MASS WITH PW/S OF 1.5 INCHES OR GREATER...POTENTIALLY MLCAPES OF
2000 J/KG OR GREATER...PARTICULARLY IN AREAS RECEIVING STRONG
MORNING HEATING WILL SUPPORT THUNDERSTORM DEVELOPMENT BY EARLY
AFTERNOON MUCH OF GULF STATES AREA.

LARGE HAIL AND DOWNBURSTS WIND DAMAGE WILL BE COMMON IN THE MOST
VIGOROUS THUNDERSTORMS. REGION FROM SERN LA EWD TO S OF UPPER LOW
CIRCULATION INTO SRN AL/SWRN GA APPEARS TO HAVE GREATEST SEVERE
POTENTIAL BASED ON ABOVE DISCUSSED CONDITIONS AND HAVE BEEN UPGRADED
TO A SLIGHT RISK.

OTHER MORE WIDELY SCATTERED PULSE SEVERE THREAT WILL EXTEND EWD FROM
TN VALLEY TO MID ATLANTIC STATES WHERE LAPSE RATES AND SHEAR ARE
WEAKER.

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Severe Tstorm watch issued

Severe Thunderstorm Watch 232

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Public (Test) | Counties | Probabilities | Aviation | Warnings | Initial RADAR

Hazard Tornadoes EF2+ Tornadoes Likelihood Very Low Very Low Severe Wind 65 kt+ Wind Moderate Low Severe Hail 2"+ Hail Moderate Low [SIZE=8pt]Note: The expiration time in the watch graphic is amended if the watch is replaced, cancelled or extended.[/SIZE] Note: Click for Watch Status Reports. SEL2 URGENT - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WATCH NUMBER 232 NWS STORM PREDICTION CENTER NORMAN OK 1200 PM CDT SAT MAY 29 2010 THE NWS STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR PORTIONS OF MUCH OF SOUTHERN AND CENTRAL ALABAMA MUCH OF FLORIDA PANHANDLE PARTS OF SOUTHWEST GEORGIA EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM NOON UNTIL 700 PM CDT. HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 115 STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES SOUTH SOUTHEAST OF CRESTVIEW FLORIDA TO 60 MILES NORTH OF MONTGOMERY ALABAMA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2). REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES. DISCUSSION...WITH A MOIST AND MDTLY UNSTABLE AIR MASS IN PLACE COUPLED WITH 25-30KT OF CYCLONIC SHEAR ON E SIDE OF UPPER LOW NEAR KJAN...THUNDERSTORMS WILL INCREASE IN NUMBER AND INTENSITY ACROSS THE WATCH AREA THRU THE AFTERNOON. MULTICELLULAR/PULSE MODE OF STORMS WILL SUPPORT LARGE HAIL AND DAMAGING DOWNBURSTS WINDS AS STORMS MOVE SLOWLY N AND NW TO E OF UPPER LOW CENTER. AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM MOTION VECTOR 19010. ...HALES Hazard Tornadoes EF2+ Tornadoes Likelihood Very Low Very Low Severe Wind 65 kt+ Wind Moderate Low Severe Hail 2"+ Hail Moderate Low [SIZE=8pt]Note: See the experimental Public Watch (SEL) product with explicit hazard information section below. The expiration time in the watch graphic is amended if the watch is replaced, cancelled or extended.[/SIZE] Note: Click for Watch Status Reports. SEL2 URGENT - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WATCH NUMBER 232 NWS STORM PREDICTION CENTER NORMAN OK 1200 PM CDT SAT MAY 29 2010 THE NWS STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR PORTIONS OF MUCH OF SOUTHERN AND CENTRAL ALABAMA MUCH OF FLORIDA PANHANDLE PARTS OF SOUTHWEST GEORGIA EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM NOON UNTIL 700 PM CDT. SCATTERED LARGE HAIL TO 2.0 INCHES IN DIAMETER WIDELY SCATTERED DAMAGING WINDS TO 70 MPH THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 115 STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES SOUTH SOUTHEAST OF CRESTVIEW FLORIDA TO 60 MILES NORTH OF MONTGOMERY ALABAMA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2). REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES. DISCUSSION...WITH A MOIST AND MDTLY UNSTABLE AIR MASS IN PLACE COUPLED WITH 25-30KT OF CYCLONIC SHEAR ON E SIDE OF UPPER LOW NEAR KJAN...THUNDERSTORMS WILL INCREASE IN NUMBER AND INTENSITY ACROSS THE WATCH AREA THRU THE AFTERNOON. MULTICELLULAR/PULSE MODE OF STORMS WILL SUPPORT LARGE HAIL AND DAMAGING DOWNBURSTS WINDS AS STORMS MOVE SLOWLY N AND NW TO E OF UPPER LOW CENTER. AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM MOTION VECTOR 19010. ...HALES

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Severe Thunderstorm Watch 233

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Public (Test) | Counties | Probabilities | Aviation | Warnings | Initial RADAR

Hazard Tornadoes EF2+ Tornadoes Likelihood Very Low Very Low Severe Wind 65 kt+ Wind Moderate Moderate Severe Hail 2"+ Hail Moderate Low [SIZE=8pt]Note: The expiration time in the watch graphic is amended if the watch is replaced, cancelled or extended.[/SIZE] Note: Click for Watch Status Reports. SEL3 URGENT - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WATCH NUMBER 233 NWS STORM PREDICTION CENTER NORMAN OK 1235 PM CDT SAT MAY 29 2010 THE NWS STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR PORTIONS OF LARGE PART OF SOUTHEASTERN LOUISIANA MUCH OF SOUTHERN MISSISSIPPI COASTAL WATERS EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 1235 PM UNTIL 800 PM CDT. HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 105 STATUTE MILES EAST AND WEST OF A LINE FROM 50 MILES NORTH NORTHEAST OF MC COMB MISSISSIPPI TO 40 MILES SOUTHEAST OF HOUMA LOUISIANA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3). REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES. OTHER WATCH INFORMATION...CONTINUE...WW 232... DISCUSSION...AIR MASS TO W AND S OF UPPER LOW NEAR KJAN HAS BECOME MDTLY UNSTABLE WITH MLCAPES AOA 2500 J/KG. WITH A CYCLONIC FLOW OF RELATIVELY COOL/STEEP MID LEVEL LAPSE RATES ASSOCIATED WITH UPPER LOW...STORMS WILL INCREASE RAPIDLY IN NUMBER AND INTENSITY AS THEY MOVE/PROPAGATE SEWD ACROSS THE WATCH. MULTICELLULAR/PULSE MODE IN RELATIVELY WEAK SHEAR REGIME SHOULD SUPPORT BOTH LARGE HAIL AND DAMAGING DOWNBURSTS WINDS WITH STRONGEST STORMS. AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM MOTION VECTOR 31015. ...HALES Hazard Tornadoes EF2+ Tornadoes Likelihood Very Low Very Low Severe Wind 65 kt+ Wind Moderate Moderate Severe Hail 2"+ Hail Moderate Low [SIZE=8pt]Note: See the experimental Public Watch (SEL) product with explicit hazard information section below. The expiration time in the watch graphic is amended if the watch is replaced, cancelled or extended.[/SIZE] Note: Click for Watch Status Reports. SEL3 URGENT - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WATCH NUMBER 233 NWS STORM PREDICTION CENTER NORMAN OK 1235 PM CDT SAT MAY 29 2010 THE NWS STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR PORTIONS OF LARGE PART OF SOUTHEASTERN LOUISIANA MUCH OF SOUTHERN MISSISSIPPI COASTAL WATERS EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 1235 PM UNTIL 800 PM CDT. WIDELY SCATTERED DAMAGING WINDS ISOLATED WIND GUSTS TO 70 MPH POSSIBLE WIDELY SCATTERED LARGE HAIL TO 2.0 INCHES IN DIAMETER THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 105 STATUTE MILES EAST AND WEST OF A LINE FROM 50 MILES NORTH NORTHEAST OF MC COMB MISSISSIPPI TO 40 MILES SOUTHEAST OF HOUMA LOUISIANA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3). REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES. OTHER WATCH INFORMATION...CONTINUE...WW 232... DISCUSSION...AIR MASS TO W AND S OF UPPER LOW NEAR KJAN HAS BECOME MDTLY UNSTABLE WITH MLCAPES AOA 2500 J/KG. WITH A CYCLONIC FLOW OF RELATIVELY COOL/STEEP MID LEVEL LAPSE RATES ASSOCIATED WITH UPPER LOW...STORMS WILL INCREASE RAPIDLY IN NUMBER AND INTENSITY AS THEY MOVE/PROPAGATE SEWD ACROSS THE WATCH. MULTICELLULAR/PULSE MODE IN RELATIVELY WEAK SHEAR REGIME SHOULD SUPPORT BOTH LARGE HAIL AND DAMAGING DOWNBURSTS WINDS WITH STRONGEST STORMS. AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM MOTION VECTOR 31015. ...HALES

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525
FZUS74 KLIX 311405
MWSLIX

MARINE WEATHER STATEMENT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
905 AM CDT MON MAY 31 2010

GMZ555-311530-
905 AM CDT MON MAY 31 2010

...STRONG THUNDERSTORMS MOVING INTO THE LOUISIANA SOUNDS...

AT 859 AM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS INDICATED
THUNDERSTORMS...PRODUCING STRONG WINDS TO 33 KNOTS AND LIGHTNING
FROM 8 NM NORTHWEST OF BRETON SOUND TO 17 NM EAST OF BARATARIA
BAY...MOVING EAST AT 5 KNOTS.

INTENSE LIGHTNING IS OCCURRING WITH THESE STORMS. IF CAUGHT ON THE
OPEN WATER STAY BELOW DECK IF POSSIBLE...KEEP AWAY FROM UNGROUNDED
METAL OBJECTS. OIL CLEAN UP PERSONNEL SHOULD SEEK COVER FROM THESE
STORMS.

LAT...LON 3001 8890 2936 8927 2936 8940 2938 8940
2940 8943 2939 8950 2941 8957 2942 8958
2947 8955 2949 8962 2952 8966 2978 8947
2979 8945 2980 8946 3000 8932

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