Severe Thunderstorm Warning 469, NWS Jackson, MS

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
1225 PM CDT THU JUL 30 2009

.UPDATE...
EXPANDED FFA TO INCLUDE TENSAS AND CATAHOULA PARISHES. LATEST TRENDS
IN RADAR DATA SHOWING LEAD OUTFLOW BOUNDARY GRADUALLY BECOMING NE/SW
ORIENTED AND SLOWING. THIS COMBINED WITH LATEST OUTPUT FROM 12Z NAM
AND ASSOCIATED LOCAL WRF ENSEMBLE OUTPUT...SUGGESTS THAT AN AXIS OF
HEAVIER RAIN NEXT 12-18 HOURS COULD SET UP FROM S OF KTVR TO NEAR
KGTR. AT LEAST NORTHERN PORTIONS OF CATAHOULA AND TENSAS PARISHES
HAVE RECEIVED VERY HEAVY RAINFALL LAST FEW WEEKS AND ARE PRONE TO
FLASH FLOODING FROM ANY EXCESSIVE RAINFALL NEXT 24 HOURS.  LATEST
GUIDANCE DOES SUGGEST THAT ORGANIZED CONVECTION WILL EVENTUALLY
SHIFT INTO SOUTHERN ZONES LATER THIS EVENING OR FRIDAY MORNING...BUT
WILL NEED TO REEVALUATE THIS MORE WITH AFTERNOON PACKAGE. NO CHANGES
TO FORECAST OTHER THAN THE FFA EXPANSION.                       /08/

REST OF PREVIOUS DISCUSSION...

SHORT TERM UPDATE...LATEST SATELLITE IMAGERY SHOWS SOME IMPRESSIVE
FLOW AROUND A MIDLEVEL SHORT WAVE THIS MORNING OVER THE ARKLATEX
REGION. SHV SOUNDING SHOWED SOME LOW LEVEL WINDS OF 30 TO 40 KNOTS.
THIS TROUGH WAS UNDER THE ENTRANCE REGION OF AN INTENSIFYING UPPER
JET STREAM OVER THE PLAINS. LOCAL WRF MEMBERS 8 OUT OF 10 SHOW AN
IMPRESSIVE LINE OF HEAVY STORMS MOVING INTO THE DELTA REGION LATE
THIS AFTERNOON THROUGH THIS EVENING...WHICH WILL BREAK OUT SOME
SEVERE STORMS. EXPECT SHOWERS AND THUNDERSTORMS TO DEVELOP BY EARLY
THIS AFTERNOON. STRONG STORMS WILL BE POSSIBLE IN THE NORTHWEST
DELTA REGION BY EARLY AFTERNOON. SO WILL KEEP HIGH END POPS FOR THE
NORTHWEST HALF. HEAVY RAINS WILL AGGRAVATE MOIST SOIL CONDITIONS
OVER MOST OF THE REGION. SO WILL KEEP FLASH FLOOD WATCH OVER THE
SAME AREA...WHICH HAS HAD PREVIOUS DAYS OF HEAVY RAINFALL. WITH THIS
IN MIND WILL KEEP CURRENT FORECAST ON TRACK.          /17/

HAZARD WEATHER UPDATE...
UPDATE...WITH REGARD TO HAZARDOUS WEATHER NEXT 24 HOURS...BECOMING
INCREASINGLY CONCERNED ABOUT SIGNIFICANT FLASH FLOOD POTENTIAL...
PARTICULARLY FOR THE ARKLAMISS DELTA THIS AFTERNOON...AND EVENTUALLY
EXPANDING ENE INTO THE GOLDEN TRIANGLE REGION THIS EVENING AND INTO
THE OVERNIGHT. VERY ANOMALOUS SETUP FOR JULY ACROSS REGION THIS
MORNING...WITH 30-40 KT 850 MB LLJ SHOWN BY PROFILERS/VWP ACROSS
AR/LA/E TX. THIS IS FEEDING 16-17C 850 MB DEWPOINTS AND A SWATH OF 2
INCH PW VALUES INTO THE REGION. COMBINATION OF STG LLJ AND EXTREME
MOISTURE LEADS TO MOISTURE TRANSPORT VALUES IN EXCESS OF 300 G/KG
FOCUSED INTO THE ARKLAMISS BY LATER TODAY...AND ACROSS MUCH OF NRN
MS TONIGHT. SFC ANALYSIS SHOWS A SUBTLE BOUNDARY LYING FROM THE
ARKLATEX ENE INTO NRN AL. EXPECT THIS TO BE THE FOCUS FOR HEAVY
CONVECTIVE RAINS THIS AFTERNOON INTO TONIGHT AS UPPER WAVE CURRENTLY
DRIVING MCS OVER ARKLATEX APPROACHES. WIDESPREAD RAINFALL AMOUNTS OF
1-3 INCHES LOOK LIKELY ACROSS THIS REGION BY 12Z FRI...BUT LOCALIZED
TOTALS OF 5 TO 10 INCHES LOOK POSSIBLE WHERE TRAINING OCCURS GIVEN
EFFICIENT RAINFALL AND POTENTIAL FOR BACK BUILDING GIVEN VERY WEAK
CORFIDI VECTORS WITH SOME ORIENTATION ALONG THE FLOW PARTICULARLY
TONIGHT. 06Z RUN OF LOCAL WRF ENSEMBLE SHOWS PROBABILITIES GREATER
THAN 50 PCT OF SOME 5 INCH RAINFALL TOTALS OVER THE DELTA...WITH
10-20 PCT PROBS OF SPOTS GREATER THAN 10 INCHES.

FFG VALUES ARE EXTREMELY LOW ACROSS ALL OF THE REGION N OF
I-20...AND SOME SPOTS COULD SEE SIGNIFICANT FLASH FLOODING. FARTHER
S...ORGANIZED HEAVY RAINFALL SEEMS LESS LIKELY...AND FFG VALUES ARE
MUCH HIGHER GIVEN RECENT DRY WEATHER. HOWEVER...SOME LOCALIZED
PONDING ISSUES COULD BE A CONCERN WHERE CONVECTION DEVELOPS.

WHILE FLASH FLOODING IS THE BIGGEST CONCERN...SEVERE WEATHER IS ALSO
AN ISSUE...PARTICULARLY FOR THIS AFTERNOON AND EVENING. WELL
ORGANIZED MCV MOVING THROUGH E TX AS THE PRESENT TIME AS SHOWN BY 50
KT REAR INFLOW JET AT 850 MB AS SHOWN A PALATINE TX PROFILER. AREA
SOUNDINGS SHOW SBCAPE VALUES OF 3500 TO 4500 J/KG BY AFTERNOON GIVEN
TEMPS NEAR 90F AND DEWPOINTS IN MID 70S. COMBINED WITH ENVIRONMENTAL
500 MB FLOW OF 20-35 KT..EXPECT SOME ORGANIZATION TO CONVECTION
WITH LINES AND POSSIBLY A FEW HP SUPERCELLS AS DISCUSSED BY SPC.
THIS SHOULD LEAD TO SOME WET MICROBURSTS...AND WITH SUPERCELLS A LOW
RISK FOR MARGINALLY SEVERE HAIL AND POSSIBLY A TORNADO GIVEN
MODERATE VALUES OF LOW LEVEL HELICITY AND VERY LOW LCL HEIGHTS.

HWO COVERS SETUP QUITE WELL...BUT DID TWEAK THE HAZARD GRIDS TO
INCREASE THE FLASH FLOOD AND SEVERE POTENTIAL VALUES JUST A BIT
GIVEN LATEST OBSERVATIONAL AND MODEL TRENDS.             /08/

&&

.AVIATION...
MAIN FOCUS WILL BE CONVECTIVE POTENTIAL. EXPECT GREATEST RISK FOR
PERSISTENT MVFR/IFR CONDITIONS IN PRECIP TO BE AT KGWO/KGTR THROUGH
THE NEXT 24 HOURS...WITH KGLH...KJAN AND KMEI ALSO LIKELY TO
EXPERIENCE SUCH CONDITIONS AT TIMES. KHBG LOOKS TO HAVE MORE OF A
DIURNAL CONVECTIVE RISK THIS AFTERNOON...AND WILL INDICATE
ACCORDINGLY IN TAFS. LATEST GUIDANCE DOES SUGGEST THAT ORGANIZED
CONVECTION WILL EVENTUALLY SPREAD INTO KHBG...AND HAVE SHOWN
PREDOMINANT TSRA THERE TOWARD MORNING. BEHIND THIS CONVECTIVE
SETUP...WINDS WILL SHIFT MORE TO NW AND BECOME LIGHT LATE TONIGHT AT
NORTHERN/CENTRAL ZONES...LIKELY ALONG WITH IFR/LIFR CONDITIONS GIVEN
DRY AIR ALOFT OVERSPREADING EXTREMELY MOIST LOWER LEVELS GIVEN
RECENT AND ADDITIONAL RAINFALL.

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...FLASH FLOOD WATCH THROUGH FRIDAY MORNING FOR MSZ018-019-025>050.

LA...FLASH FLOOD WATCH THROUGH FRIDAY MORNING FOR LAZ007>009-015-016-
     023>025.

AR...FLASH FLOOD WATCH THROUGH FRIDAY MORNING FOR ARZ074-075.

&&

08/17

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
206 PM CDT THU JUL 30 2009

ARZ074-075-LAZ007>009-015-016-023>025-MSZ018-019-025>050-311915-
ASHLEY-CHICOT-MOREHOUSE-WEST CARROLL-EAST CARROLL-RICHLAND-
MADISON LA-FRANKLIN LA-CATAHOULA-TENSAS-BOLIVAR-SUNFLOWER-LEFLORE-
GRENADA-CARROLL-MONTGOMERY-WEBSTER-CLAY-LOWNDES-CHOCTAW-OKTIBBEHA-
WASHINGTON-HUMPHREYS-HOLMES-ATTALA-WINSTON-NOXUBEE-ISSAQUENA-
SHARKEY-YAZOO-MADISON MS-LEAKE-NESHOBA-KEMPER-WARREN-HINDS-RANKIN-
SCOTT-
206 PM CDT THU JUL 30 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHERN AND CENTRAL
MISSISSIPPI...SOUTHEAST ARKANSAS AND MOST OF NORTHEAST LOUISIANA.

.DAY ONE...TONIGHT AND FRIDAY...
PERIODS OF THUNDERSTORMS WITH VERY HEAVY RAINFALL MAY PRODUCE FLASH
FLOODING ACROSS THE AREA THROUGH EARLY FRIDAY MORNING. WHILE THE
ENTIRE AREA HAS A RISK OF FLASH FLOODING...THE GREATEST RISK LOOKS TO
BE FROM THE LOWER DELTA REGION INTO NORTH CENTRAL AND CENTRAL
MISSISSIPPI...INCLUDING THE JACKSON METRO AREA...VICKSBURG...YAZOO
CITY...KOSCIUSKO... TALLULAH...AND WINNSBORO. LOCALIZED RAINFALL
AMOUNTS IN EXCESS OF 5 INCHES ARE LIKELY...WHICH WOULD POTENTIALLY
CAUSE SIGNIFICANT FLASH FLOODING OF LOW LYING AREAS. A FLASH FLOOD
WATCH IS IN EFFECT FOR THIS AREA INTO FRIDAY MORNING.

THERE WILL ALSO BE A RISK OF STRONG TO SEVERE THUNDERSTORMS THROUGH
THE NIGHT...BUT ESPECIALLY DURING THE EVENING HOURS. WINDS TO 60
MPH...HAIL TO THE SIZE OF PENNIES...FREQUENT LIGHTNING...AND
TORRENTIAL RAINFALL WILL OCCUR WITH THE MOST INTENSE STORMS.

THE RISK OF THUNDERSTORM ACTIVITY WILL DIMINISH FROM THE NORTHWEST
LATE TONIGHT INTO FRIDAY MORNING.

.DAYS TWO THROUGH SEVEN...FRIDAY NIGHT THROUGH WEDNESDAY...
THE PROBABILITY OF WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER CALL TO ACTION STATEMENT...
THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND
EMERGENCY MANAGEMENT PERSONNEL IN SUPPORT OF SEVERE WEATHER
OPERATIONS...MAY BE NEEDED TONIGHT.

LAZ026-MSZ051>066-072>074-311915-
CONCORDIA-NEWTON-LAUDERDALE-CLAIBORNE-COPIAH-SIMPSON-SMITH-JASPER-
CLARKE-JEFFERSON-ADAMS-FRANKLIN MS-LINCOLN-LAWRENCE-
JEFFERSON DAVIS-COVINGTON-JONES-MARION-LAMAR-FORREST-
206 PM CDT THU JUL 30 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHERN MISSISSIPPI AND
EXTREME EAST CENTRAL LOUISIANA.

.DAY ONE...TONIGHT AND FRIDAY...
THUNDERSTORMS CAPABLE OF PRODUCING LOCALIZED SEVERE WEATHER INCLUDING
DAMAGING WINDS TO 60 MPH...HAIL TO THE SIZE OF NICKELS...FREQUENT
LIGHTNING AND TORRENTIAL RAINFALL...WILL BE POSSIBLE THROUGH THE
EVENING HOURS. SIMILAR ACTIVITY COULD THEN REDEVELOP LATE TONIGHT
INTO FRIDAY.

SCATTERED TO NUMEROUS THUNDERSTORMS WILL CONTINUE TO MOVE ACROSS THE
AREA THROUGH THE EVENING. THIS ACTIVITY WILL THEN DIMINISH AFTER
SUNSET...BUT AS A COMPLEX OF THUNDERSTORMS APPROACHES FROM THE
NORTHWEST...THUNDERSTORM ACTIVITY WILL LIKELY INCREASE AGAIN LATE
TONIGHT INTO FRIDAY.

.DAYS TWO THROUGH SEVEN...FRIDAY NIGHT THROUGH WEDNESDAY...
THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER CALL TO ACTION STATEMENT...
THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND
EMERGENCY MANAGEMENT PERSONNEL IN SUPPORT OF SEVERE WEATHER
OPERATIONS...MAY BE NEEDED TONIGHT INTO FRIDAY.

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT
WWW.SRH.NOAA.GOV/JAN. THIS INCLUDES THE GRAPHICAL HAZARDOUS WEATHER
OUTLOOK.

08

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JACKSON MS
208 PM CDT THU JUL 30 2009

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

0147 PM     TSTM WND DMG     COLUMBIA                31.26N 89.83W
07/30/2009                   MARION             MS   TRAINED SPOTTER

            A FEW SIGNS WERE BLOWN OVER AT THE COLUMBIA WALMART.

0152 PM     TSTM WND DMG     2 NE COLUMBIA           31.28N 89.80W
07/30/2009                   MARION             MS   EMERGENCY MNGR

            EMERGENCY MANAGER REPORTED A LARGE TREE WAS BLOWN DOWN
            ONTO HIGHWAY 44.

&&

HAMRICK

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JACKSON MS
232 PM CDT THU JUL 30 2009

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

0210 PM     TSTM WND DMG     3 SE SUMRALL            31.39N 89.51W
07/30/2009                   LAMAR              MS   LAW ENFORCEMENT

            MULTIPLE TREES DOWN ON THE SOUTHEAST SIDE OF SUMRALL.

&&

HAMRICK

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE JACKSON MS
240 PM CDT THU JUL 30 2009

LAZ016-MSZ040-042-043-047>049-053>055-302050-
CLAIBORNE MS-HINDS MS-RANKIN MS-WARREN MS-MADISON MS-SIMPSON MS-
COPIAH MS-ISSAQUENA MS-YAZOO MS-MADISON LA-
240 PM CDT THU JUL 30 2009

...STRONG THUNDERSTORMS TO AFFECT CENTRAL MISSISSIPPI THROUGH
AFTERNOON RUSH HOUR...

SCATTERED TO NUMEROUS THUNDERSTORMS WILL MOVE ACROSS CENTRAL
MISSISSIPPI THIS AFTERNOON. SOME OF THESE STORMS WILL PRODUCE WIND
GUSTS OF 40 TO 50 MPH...TORRENTIAL DOWNPOURS OF RAIN...SMALL HAIL
AND CONTINUOUS CLOUD TO GROUND LIGHTNING STRIKES. THUNDERSTORMS WILL
BE MOVING INTO THE VICKSBURG AREA AROUND 3 PM...AND THE JACKSON
METRO AREA BETWEEN 4 AND 5 PM.

GIVEN THE VERY WET SOILS FROM RAINFALL THE LAST SEVERAL DAYS...FLASH
FLOODING AS WELL AS DOWNED TREES MAY OCCUR FROM THESE STORMS. PEOPLE
SHOULD MONITOR WEATHER CONDITIONS CLOSELY...AND LISTEN FOR LATER
STATEMENTS AND POSSIBLE WARNINGS.

PEOPLE IN SOUTHERN YAZOO...SOUTHEASTERN ISSAQUENA...NORTHERN
COPIAH...NORTHWESTERN SIMPSON...MADISON...WARREN...RANKIN...HINDS AND
NORTHERN CLAIBORNE COUNTIES SHOULD MONITOR THESE STORMS CLOSELY.

AEG