Severe Thunderstorm Warning 628, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
400 AM CDT SAT AUG 2 2003

ONLY MINOR ADJUSTMENTS WERE MADE TO THE PREVIOUS FORECAST PACKAGE AS
FORECAST THINKING REMAINS GENERALLY THE SAME. A STRONG UPPER TROUGH
WILL CONTINUE TO SLOWLY DIG SWD AND EWD OVER THE NEXT FEW DAYS WITH
THE FORECAST AREA BECOMING INCREASINGLY UNDER THE INFLUENCE OF LOW
LEVEL FRONTAL CONVERGENCE AND UPPER JET SUPPORT. CURRENT CONVECTIVE
COMPLEXES OVER THE OZARK REGION WILL MOST LIKELY DISSIPATE BEFORE
REACHING NW/NRN ZONES AS THEY OUTRUN SUPPORT. AFTER COORDINATION
WITH SPC...WILL KEEP JUST SLIGHT TO CHANCE POPS GOING (HIGHEST NRN
MOST ZONES) FOR TODAY...AND INCREASE PRECIP CHCS SOUTHWARD
OVERNIGHT. CONFIDENCE IN DETAILS IS RATHER LOW CONCERNING CONVECTIVE
INITIATION AND EVOLUTION TONIGHT...BUT NRN HALF OF THE FORECAST AREA
WILL BE MOST AT RISK TO BE AFFECTED BY A CONVECTIVE COMPLEX. THE
ENTIRE FORECAST AREA SHOULD BE AT RISK SUNDAY FOR ORGANIZED TSTM
ACTIVITY.

INTERESTING DIFFERENCES IN REGARD TO THE UPPER TROUGH POSITIONING
EXIST FOR SUNDAY WITH THE ETA MOST AGGRESSIVE IN DRIVING UPPER JET
CORE SWD OVER THE FORECAST AREA. THE UKMET SHOWS SOME SUPPORT FOR
THE ETA SOLUTION WHICH WOULD IMPLY A QUICKER END TO TSTM CHANCES
SUNDAY EVENING. HAVE ADJUSTED GRIDS JUST A LITTLE TO LOWER SUN
NIGHT POPS. IN ANY CASE...UNUSUALLY STRONG JET DYNAMICS FOR EARLY
AUGUST WILL INCREASE SVR TSTM CHANCES AND HWO WILL CONTINUE TO
INDICATE THIS INTO EARLY NEXT WEEK. IT LOOKS LIKE A SHORT LULL IN
THE ACTION MAY EXIST FOR MONDAY...BUT THE GFS FORECASTS ACTIVE WX
TO RESUME TUES/WEDNESDAY.

.JAN...
AR...NONE.
LA...NONE.
MS...NONE.

43

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
031931-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
231 PM CDT SAT AUG 02 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL MISSISSIPPI...
NORTHEAST LOUISIANA...AND EXTREME SOUTHEAST ARKANSAS

.DAY ONE...TONIGHT AND SUNDAY...

...THUNDERSTORMS...
SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER EXTREME
SOUTHEAST ARKANSAS...NORTHEAST LOUISIANA AND MUCH OF MISSISSIPPI
THROUGH LATE THIS EVENING AND INTO TONIGHT. ISOLATED SEVERE
STORMS WILL BE POSSIBLE OVER AREAS ALONG AND NORTH OF THE
INTERSTATE 20 CORRIDOR. ANY SEVERE STORMS THAT DEVELOP WILL BE
CAPABLE OF PRODUCING WIND GUSTS TO 60 TO 70 MPH. SOUTH OF
INTERSTATE 20...SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE
THROUGH LATE EVENING BEFORE DISSIPATING. WIND GUSTS TO 40
MPH...FREQUENT LIGHTENING AND BRIEF PERIODS OF HEAVY RAIN ARE
POSSIBLE WITH THESE STORMS. HOWEVER...EXPECT THAT THE STORMS THAT
OCCUR SOUTH OF INTERSTATE 20 TO BE NON SEVERE. ON SUNDAY...EXPECT
A REPEAT OF THE SCENARIO ABOVE.

THE MOIST AND VERY UNSTABLE AIRMASS REMAINS OVER THE REGION AND
WILL REMAIN IN PLACE THROUGH SUNDAY EVENING. A SERIES OF
DISTURBANCES MOVING THROUGH THE AREA ARE ALLOWING FOR THE
DEVELOPMENT OF LARGE AREAS OF THUNDERSTORMS. FURTHERMORE...THE
ATMOSPHERIC FLOW IN THE MIDDLE AND UPPER LEVELS HAS BECOME
FAVORABLE FOR SEVERE THUNDERSTORM DEVELOPMENT. AS THE
DISTURBANCES SLOWLY BEGIN TO MOVE THROUGH OVERNIGHT...THE
THUNDERSTORM ACTIVITY WILL GRADUALLY DIMINISH OVER THE
AREA...ONLY TO REDEVELOP SUNDAY AFTERNOON AS ANOTHER DISTURBANCE
MOVES THROUGH. ON SUNDAY...THE MIDDLE AND UPPER LEVEL FLOW AND
JET POSITIONING APPEAR TO BE MORE FAVORABLE FOR SEVERE
THUNDERSTORM DEVELOPMENT THAN TODAY. THEREFORE...KEEPING THE
MENTION OF SEVERE THUNDERSTORMS NORTH OF INTERSTATE 20 IN THE
FORECAST FOR SUNDAY AS WELL.

...FLOODING...
WITH THE PASSAGE OF THE STRONG TO SEVERE THUNDERSTORMS...PONDING
OF WATER ON AREA ROADS AND IN POOR DRAINAGE AREAS WILL BE
POSSIBLE AS HEAVY RAINS ACCUMULATE ON THE SURFACES.

.DAYS TWO THROUGH SEVEN...SUNDAY NIGHT THROUGH SATURDAY...

...DAYS TWO AND THREE...SUNDAY NIGHT THROUGH TUESDAY...
STRONG THUNDERSTORMS ARE EXPECTED ONCE AGAIN OVER EXTREME
SOUTHEAST ARKANSAS...NORTHEAST LOUISIANA AND MUCH OF MISSISSIPPI
ON MONDAY AND TUESDAY. A FEW OF THE THUNDERSTORMS WILL AGAIN
BECOME SEVERE OVER THE FORECAST AREA. WIND GUSTS TO 60 TO 70 MPH
CAN BE ANTICIPATED WITH ANY SEVERE STORMS THAT DEVELOP.

ANOTHER SERIES OF STRONG DISTURBANCES WILL CONTINUE TO ROTATE
AROUND THE LOW PRESSURE AREA THAT REMAINS ENTRENCHED OVER THE
OHIO RIVER VALLEY. AS THESE SYSTEMS MOVE SOUTHEAST AND INTO THE
AREA BOTH DAYS...THE ATMOSPHERIC FLOW WILL BE STRONG ENOUGH TO
SUPPORT THE CONTINUED DEVELOPMENT OF SCATTERED STRONG AND
ISOLATED SEVERE THUNDERSTORMS.

...DAYS FOUR THROUGH SEVEN...TUESDAY NIGHT THROUGH SATURDAY...
NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

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

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