Severe Thunderstorm Warning 760, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
330 PM CDT THU AUG 7 2008

.DISCUSSION...LATEST SATELLITE IMAGERY SHOWS AN UPPER DISTURBANCE
APPROACHING THE REGION IN NORTHWEST FLOW. IT HAS TRIGGERED SOME
STRONG TO SEVERE CONVECTION THAT WAS PUSHING THROUGH OUR NORTHWEST
COUNTIES. ALSO HAD A FEW STRONG TO SEVERE STORMS THIS AFTERNOON
ACROSS THE EAST/NORTHEAST. AREA SOUNDINGS SHOWS PRECIPITABLE WATER
AROUND 2 INCHES...WHICH SPELLS THE CHANCE OF LOCALLY HEAVY RAINS FOR
THIS AFTERNOON INTO THIS EVENING. ALSO A FRONTAL BOUNDARY WAS MAKING
ITS WAY TOWARD THE REGION FROM THE NORTHWEST. SPC HAS A SLIGHT RISK
OF SEVERE ACROSS THE REGION WITH THE COMBINATION OF DAYTIME
HEATING...ML CAPES AROUND 3000 AND NORTHWEST FLOW OF 30-40
KNOTS...WHICH WILL HELP WITH OUR CHANCES OF ISOLATED SEVERE STORM
CLUSTERS. THE SHORT RANGE MODELS PUSH THE FRONT INTO THE REGION FOR
LATE THIS AFTERNOON INTO TONIGHT WITH THE AID OF NORTHWEST FLOW
ALOFT. THIS WILL PROVIDE ENOUGH LIFT FOR SOME GOOD CONVECTIVE
COVERAGE FOR TONIGHT. THE MODELS CONTINUE TO SHOW ONLY ONE BOUNDARY
WITH PLENTY OF PCP WATER AROUND 2 INCHES.  WITH THE GRADUAL MOVEMENT
OF THE BOUNDARY AND PLENTY OF LOW LEVEL MOISTURE...WILL PROBABLY SEE
TRAINING STORMS AND COULD HAVE SOME PROBLEMS WITH LOCALIZED
FLOODING. EXPECT TO SEE SIMILAR CONDITIONS AS THE BOUNDARY SLOWLY
MOVES SOUTH THROUGH FRIDAY AFTERNOON. MAINTAINED LOCALLY HEAVY
RAINFALL. LAPSE RATE WILL HOLD AT AROUND 6-7C/KM ACROSS THE REGION.
WILL KEEP SOME HAIL AND WIND CHANCES FOR HAIL/WIND TO PROB HAZARDS
AND WILL CONTINUE TO MENTION SEVERE IN THE HWO. THE MODELS HAVE
SLOWED DOWN THE TIMING OF WHEN THE RAIN DEPARTS THE REGION. IT LOOKS
LIKE MOST OF THE RAINS SHOULD BE OUT BY FRIDAY EVENING...EXCEPT FOR
WEST OF THE MS RIVER. THIS ACTIVITY SHOULD EXIT THE REGION BY
MIDNIGHT. THE FRONTAL BOUNDARY WILL BEGIN TO RETURN NORTH BY
SATURDAY NIGHT. THIS WILL BRING BACK OUR CHANCES OF RAIN FROM WEST
TO EAST AS ANOTHER DISTURBANCE COMES ACROSS THE REGION IN NORTHWEST
FLOW ALOFT.

AS FAR AS TEMPS ARE CONCERN WENT GENERALLY WITH MAV GUIDANCE
DURING THE DAYS AND MOS GUIDANCE AT NIGHT. AS FOR POPS WENT WITH
MAV GUIDANCE...SINCE THE MODELS WERE GENERALLY SIMILAR./17/

.PREVIOUS EXTENDED DISCUSSION...

LONG TERM(SATURDAY THROUGH THURSDAY)...NOT YOUR TYPICAL STRETCH OF
SUMMER TIME WEATHER IN STORE FOR THIS PERIOD. DEEP LONGWAVE TROUGH
AXIS ON THE E COAST MEANS NWLY FLOW FOR THE LOWER MS VALLEY AND THUS
SEVERAL FRONTS COME INTO PLAY. A WELL DEFINED FRONTAL BOUNDARY
POSITIONED ALONG THE GULF COAST OR FARTHER SOUTH ON SATURDAY BEGINS
TO RETURN NWD SATURDAY NIGHT/SUNDAY ON BOTH GFS/ECMWF SOLUTIONS. BEST
RAIN CHANCES WILL BE SWRN PORTIONS OF CWFA INITIALLY WITH A GRADUAL
SPREADING NEWD ON SUNDAY. THE BETTER MOISTURE ARRIVES ON MONDAY AS
EVIDENCED BY 2.1 INCH PWATS AND WHEN BEST QPF AMOUNTS COULD AVERAGE 2-3
INCHES INTO MONDAY NIGHT. WE TEMPORARILY GET INTO THE WARMER SECTOR
ON TUESDAY HOWEVER ANOTHER COLD FRONT PUSHES INTO THE MID SOUTH
TUESDAY EVENING. RATHER IMPRESSIVE 30-40KTS OF 850MB FLOW DEVELOPS
AHEAD OF THIS FRONT WITH 6C 7-500MB LAPSE RATES FOR POTENTIAL STRONG
TO SEVERE STORMS. THE FRONT FINALLY SETTLES AND STALLS INTO SRN MS
WEDNESDAY REMAINING THERE THROUGH THURSDAY FOR A POTENTIAL HEAVY RAIN
EVENT IN A STATIONARY AXIS OF NEAR 345C 850MB THETA E AIR AND 35-40 K
INDEXES...CAN YOU BELIEVE THIS IS REALLY AUGUST?? WILL PROBABLY ADD A
LINE OR TWO IN THE HWOJAN FOR STRONG STORMS AND HEAVY RAIN RISK.

MEX MOS TEMP GUIDANCE APPEARS ON TRACK FOR THE MOST PART WITH SOME
LEANING TOWARD ENSEMBLE MEAN HIGHS. POPS REMAIN ABOVE NORMAL FOR MUCH
OF THE LONG TERM AT LEAST UNTIL LATER NEXT WEEK. GFS ENSEMBLE MEAN
PROGS SHOW ONLY A SLIGHT RETROGRESSION OF THE OVERALL PATTERN THROUGH
MID AUGUST SO TROPICS SHOULD REMAIN A NON FACTOR FOR THE TIME BEING./40/

&&
.AVIATION...
A FRONTAL BOUNDARY MOVING INTO THE REGION SHOULD BRING SCATTERED TO
NUMEROUS SHOWERS AND THUNDERSTORMS TO THE AREA THROUGH EARLY THIS
EVENING. ACTIVITY SHOULD TEND TO LAST LONGEST SOUTH OF INTERSTATE
TWENTY AND ALONG AND WEST OF THE MISSISSIPPI RIVER WHERE SOME LATE
NIGHT REDEVELOPMENT IS POSSIBLE. SOME OF THE STORMS WILL CONTAIN
GUSTY WINDS...FREQUENT LIGHTNING...HAIL AND HEAVY TURBULENCE.
BESIDES THESE THREATS...ANTICIPATED LOCALLY IFR/LIFR CONDITIONS IN
AND AROUND STORMS. GRADUALLY CLEARING CONDITIONS TONIGHT AND WET
GROUND (IN MANY CASES) WILL ALLOW FOR AT LEAST PATCHY FOG TO FORM BY
SUNRISE. RISK OF THIS OCCURRENCE WILL BE HIGHEST IN NORTHERN ZONES
SUCH AS GLH/GWO/GTR/MEI. /BB/

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       71  90  64  91 /  52  52  10  14
MERIDIAN      69  91  60  91 /  49  42   8   6
VICKSBURG     72  91  66  92 /  51  52  13  23
HATTIESBURG   72  89  65  91 /  55  58  11  16
NATCHEZ       72  88  68  88 /  52  57  15  34
GREENVILLE    70  91  63  92 /  51  39  10  20
GREENWOOD     70  90  64  91 /  41  33   8  12

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
317 PM CDT THU AUG 7 2008

ARZ074-075-LAZ007>009-016-MSZ018-019-025-034>036-040>045-047>052-
055>058-065-066-082030-
ASHLEY-CHICOT-MOREHOUSE-WEST CARROLL-EAST CARROLL-MADISON LA-
BOLIVAR-SUNFLOWER-LEFLORE-WASHINGTON-HUMPHREYS-HOLMES-ISSAQUENA-
SHARKEY-YAZOO-MADISON MS-LEAKE-NESHOBA-WARREN-HINDS-RANKIN-SCOTT-
NEWTON-LAUDERDALE-SIMPSON-SMITH-JASPER-CLARKE-COVINGTON-JONES-
317 PM CDT THU AUG 7 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR .

.DAY ONE...TONIGHT AND FRIDAY

STRONG TO SEVERE THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON AND
EVENING. WIND GUSTS UP TO 60 MPH AND PENNY SIZED HAIL WILL BE
THE PRIMARY RISKS WITH SEVERE THUNDERSTORM ACTIVITY. FREQUENT
DANGEROUS LIGHTNING AND PERIODS OF HEAVY RAINFALL PRODUCING 1 TO 2
INCH AMOUNTS IN SHORT PERIODS OF TIME CAN BE ALSO BE EXPECTED. SLOW
MOVING STORMS REDEVELOPING OVER THE SAME AREAS MAY LEAD TO LOCALIZED
FLOODING IN URBAN AND OTHER POOR DRAINAGE AREAS.

SCATTERED TO NUMEROUS THUNDERSTORMS...AND ONE TO TWO CLUSTERS OF
THUNDERSTORMS...ARE EXPECTED TO DEVELOP AND MOVE SOUTHEAST ACROSS
THESE AREAS THIS AFTERNOON AND EVENING. AN UPPER LEVEL DISTURBANCE
APPROACHING THE REGION FROM THE NORTHWEST WILL COMBINE WITH POCKETS
OF MODERATE TO HIGH INSTABILITY TO FUEL POTENTIAL SEVERE THUNDERSTORM
DEVELOPMENT. HIGH AMOUNTS OF ATMOSPHERIC MOISTURE WILL ALLOW FOR
TORRENTIAL RAINFALL WITH SOME STORMS...ALTHOUGH WIDESPREAD FLASH
FLOODING PROBLEMS ARE NOT ANTICIPATED. THERE IS THE POTENTIAL FOR
STORMS TO TEMPORARILY END IN SOME AREAS BY EARLY THIS EVENING...AND
THEN REDEVELOP AGAIN LATER TONIGHT. IF THIS OCCURS THEN LOCATIONS
AFFECTED BY THE SECOND ROUND OF RAIN WILL HAVE AN INCREASED RISK OF
ASSOCIATED FLOODING PROBLEMS.

.DAYS TWO THROUGH SEVEN...FRIDAY NIGHT THROUGH WEDNESDAY

THE STALLING FRONTAL BOUNDARY OFF THE GULF COAST WILL BE RETURNING
NORTHWARD BY MONDAY WITH MORE STRONG THUNDERSTORMS AND THE POTENTIAL
FOR HEAVY RAINS AND FLOODING INTO TUESDAY AND POSSIBLY WEDNESDAY.

.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 THROUGH TONIGHT.

LAZ015-023>026-MSZ053-054-059>064-072>074-082030-
RICHLAND-FRANKLIN LA-CATAHOULA-TENSAS-CONCORDIA-CLAIBORNE-COPIAH-
JEFFERSON-ADAMS-FRANKLIN MS-LINCOLN-LAWRENCE-JEFFERSON DAVIS-
MARION-LAMAR-FORREST-
317 PM CDT THU AUG 7 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR .

.DAY ONE...TONIGHT AND FRIDAY

THERE IS A SLIGHT RISK OF STRONG TO LOCALLY SEVERE THUNDERSTORMS LATE
THIS AFTERNOON THROUGH MIDNIGHT. WIND GUSTS UP TO 50 MPH AND DIME
SIZED HAIL WILL BE THE MAIN RISKS...ALTHOUGH SEVERE STORMS CONTAINING
WINDS TO 60 MPH AND HAIL UP TO...OR LARGER...THAN PENNIES WILL ALSO
BE POSSIBLE. IN ADDITION...FREQUENT DANGEROUS LIGHTNING AND PERIODS
OF HEAVY RAINFALL PRODUCING 1 TO 2 INCH AMOUNTS IN A SHORT PERIOD CAN
BE EXPECTED TO MOVE INTO THE AREA BY LATE THIS AFTERNOON. SLOW MOVING
STORMS REDEVELOPING OVER THE SAME AREAS MAY LEAD TO LOCALIZED
FLOODING IN URBAN AND OTHER POOR DRAINAGE AREAS.

SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO FORM THIS
AFTERNOON ACROSS PORTIONS OF NORTHEAST LOUISIANA AND SOUTHERN
MISSISSIPPI SOUTH OF INTERSTATE TWENTY. A FEW OF THESE STORMS COULD
USE MODERATE TO HIGH ATMOSPHERIC INSTABILITY TO BECOME POTENT. THE
RISK FOR SEVERE WEATHER SHOULD INCREASE SOMEWHAT BY EARLY THIS
EVENING AS THERE IS POTENTIAL FOR THUNDERSTORMS CLUSTERS PREVIOUSLY
TO THE NORTH TO MOVE DOWN INTO THE REGION AND PRODUCE WINDS OVER 45
MPH.

SCATTERED THUNDERSTORMS ON FRIDAY COULD BE STRONG TO SEVERE ACROSS
THE AREA WITH LOCALLY HEAVY RAINFALL ALSO A RISK. THE PRIMARY IMPACT
FROM THE STORMS WOULD BE GUSTY WINDS OF 50 TO 60 MPH...FREQUENT
LIGHTNING STRIKES AND POSSIBLE HAIL. RAINFALL AMOUNTS COULD EASILY
TOTAL 1 TO 2 INCHES IN LESS THAN ONE HOUR TO PRODUCE LOCALIZED
FLOODING OF POOR DRAINAGE AND LOW LYING AREAS AS WELL. THE MOVEMENT
OF DRIER AIR INTO THE AREA LATE IN THE AFTERNOON SHOULD END THE STRONG
STORM THREAT BEFORE EVENING.

.DAYS TWO THROUGH SEVEN...FRIDAY NIGHT THROUGH WEDNESDAY

THE STALLING FRONTAL BOUNDARY OFF THE GULF COAST WILL BE RETURNING
NORTHWARD BY MONDAY WITH MORE STRONG THUNDERSTORMS AND THE POTENTIAL
FOR HEAVY RAINS AND FLOODING INTO TUESDAY AND POSSIBLY WEDNESDAY.

.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 THROUGH FRIDAY AFTERNOON.

MSZ026>033-037>039-046-082030-
GRENADA-CARROLL-MONTGOMERY-WEBSTER-CLAY-LOWNDES-CHOCTAW-OKTIBBEHA-
ATTALA-WINSTON-NOXUBEE-KEMPER-
317 PM CDT THU AUG 7 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR .

.DAY ONE...TONIGHT AND FRIDAY

STRONG TO SEVERE THUNDERSTORMS WILL BE POSSIBLE THROUGH THE REMAINDER
OF THIS AFTERNOON AND THROUGH EARLY THIS EVENING. WIND GUSTS UP TO 60
MPH AND PENNY SIZED HAIL WILL BE THE PRIMARY RISKS WITH SEVERE
THUNDERSTORM ACTIVITY. FREQUENT DANGEROUS LIGHTNING AND PERIODS OF
HEAVY RAINFALL PRODUCING 1 TO 2 INCH AMOUNTS IN SHORT PERIODS OF TIME
CAN BE ALSO BE EXPECTED. SLOW MOVING STORMS REDEVELOPING OVER THE
SAME AREAS MAY LEAD TO LOCALIZED FLOODING IN URBAN AND OTHER POOR
DRAINAGE AREAS.

SCATTERED TO NUMEROUS THUNDERSTORMS ARE EXPECTED TO CONTINUE TO
PROGRESS SOUTHEAST ACROSS THESE AREAS THIS AFTERNOON AND THEN EXIT
EARLY THIS EVENING AS DRIER AIR FILTERS IN FROM THE NORTH. HIGH
AMOUNTS OF ATMOSPHERIC MOISTURE WILL ALLOW FOR TORRENTIAL RAINFALL
WITH SOME STORMS...ALTHOUGH WIDESPREAD FLASH FLOODING PROBLEMS ARE
NOT ANTICIPATED.

.DAYS TWO THROUGH SEVEN...FRIDAY NIGHT THROUGH WEDNESDAY

THE STALLING FRONTAL BOUNDARY OFF THE GULF COAST WILL BE RETURNING
NORTHWARD BY MONDAY WITH MORE STRONG THUNDERSTORMS AND THE POTENTIAL
FOR HEAVY RAINS AND FLOODING INTO TUESDAY AND POSSIBLY WEDNESDAY.

.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 THROUGH THIS EVENING.

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

50

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