Severe Thunderstorm Warning 577, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
120 PM CDT FRI AUG 25 2000

LOOKING AT VAPOR IMAGERY UPPER RIDGE HAD SHIFTED SLIGHTLY WEST...AS
A WELL DEFINED SHORTWAVE...WHICH WAS ADVERTISED BY THE MODELS WAS MOVING
OVER THE EASTERN SECTIONS OF THE FORECAST AREA. ON THE SURFACE HIGH
PRESSURE WAS NOTED WITH DEWPOINTS IN THE 60S/70S. A WEAK OUTFLOW
BOUNDARY WAS MOVING SOUTHWARD OVER OUR EASTERN QUADRANT.

LOOKING AT THE SHORTTERM RANGE THE UPPER RIDGE WILL MAINTAIN ITSELF
THROUGH THE PERIOD...WITH A SERIES OF WEAK SHORTWAVES PASSING
THROUGH THE REGION ON THE EASTERN SIDE OF THE RIDGE. COOLER MID
LEVEL TEMPS AND TIME OF MAX AFTERNOON HEATING WILL FAVOR MORE ROUNDS
OF AFTERNOON AND EARLY EVENING THUNDERSTORMS THROUGH SUNDAY. ALSO A
BACK DOOR FRONT WILL BE HANGING ACROSS THE REGION TONIGHT THROUGH
SATURDAY NIGHT...BEFORE RETREATING TO THE EAST ON SUNDAY. THE FRONT
WILL PROVIDE SOME ADDED LOW LEVEL CONVERGENCE THROUGH SATURDAY
NIGHT...WHICH WILL MAKE POPS A LITTLE DIFFICULT...DEPENDING ON
FRONTAL POSITIONING. IT LOOKS LIKE THAT IT WILL MOVE TO THE WESTERN
SECTIONS OF MISSISSIPPI...BEFORE GRADUALLY RETREATING EAST.
MEAN MOISTURE WILL BE DECENT OVER THE REGION DURING THE PERIOD. SO
WITH THAT IN MIND WILL FOLLOW THE ETA SOLUTION...SINCE IT INTIALIZED
THE SURFACE AND UPPER FEATURES THE BEST.

THE BEST COVERAGE FOR TONIGHT SHOULD BE IN THE EAST AND SOUTH WITH
THE WEAK FRONT AND SEABREEZE AFFECTS TO CONTEND WITH ON POP COVERAGE.
FOR SATURDAY AND SATURDAY NIGHT THE BEST COVERAGE SHOULD BE IN THE
WEST AND SOUTH WITH FRONTAL AND SEABREEZE AFFECTS. ON SUNDAY...WHEN THE
FRONT RETREATS EAST OF THE REGION...WILL PUT THE BEST LOW POPS IN
THE SOUTH FOR SEABREEZE INTERACTION. AS NOTED WITH PREVIOUS DISCUSSION
THE AIRMASS BEHIND THE FRONT MAY BE COOL ENOUDH TO INHIBIT MOST
CONVECTION...DESPITE COOLER TEMPS ALOFT...BUT WILL PUT IN LOW POPS
ANYWAY. AS FAR AS TEMPERATURES ARE CONCERN WILL GO WITH THE WARMER
NGM MOS. THE ETA 2 METER TEMPS LOOKED TO BE TOO WARM WITH THE FRONT
HANGING AROUND ON SATURDAY. ALSO LOOKED TO BE A LITTLE WARM IN THE
NORTH HALF ON SUNDAY.

24 HOUR QPF DISCUSSION: FORECAST MODELS PUT VERY MINIMAL QPF VALUES
IN FORECAST FOR PERIOD ENDING AT 12Z SATURDAY. WITH ONLY 20 - 30%
COVERAGE OF AFTERNOON/EARLY EVENING THUNDERSTORMS EXPECTED...WE
ANTICIPATE NO MORE THAN .05 INCH BASIN AVERAGE IN EXTREME SOUTHERN
PORTIONS OF THE FORECAST AREA AND .01 ELSEWHERE.

EXTENDED DISCUSSION...LOOKING AT THE LONGTERM MONDAY THROUGH
WEDNESDAY...UPPER RIDGE WILL BE PREVALENT ACROSS THE REGION THROUGH
THE PERIOD. THE MRF TRIES TO BRING THE REMNANTS OF DEBBY OVER THE
REGION FROM THE EAST ON WEDNESDAY. LOOKING DEBBYS CURRENT TROPICAL
WAVE SITUATION...IT DOESNT SEEM LIKELY AT THIS TIME...SINCE STEARING
CURRENTS SHOULD TAKE IT WELL SOUTH OF THE REGION. IN THE LOW LEVELS
THE REGION WILL BE UNDER EAST SOUTHEAST FLOW. THE CANADIAN MODEL HAS
A LITTLE STRONGER UPPER RIDGE OVER THE REGION AND TAKES THE REMNANTS
OF DEBBY TO OUR SOUTH OVER THE GULF. THE NOGAPS MODEL WAS NOT AS STRONG
WITH THE UPPER RIDGE. LIKE THE CANADIAN MODEL IT KEEPS THE MOISTURE
FROM THE REMNANTS OF DEBBY IN THE GULF...BUT THE CANADIAN WAS FARTHER
SOUTH WITH IT. IT DID SHOW SOME LIGHT CONVECTIVE COVERAGE IN THE SOUTH
HALF...MAINLY DUE TO SEA BREEZE INTERACTION. SO WITH THAT IN MIND
WILL CONTINUE ISOLATED CONVECTION NORTH/CENTRAL AND WIDELY SCATTERED
CONVECTION SOUTH FOR THE PERIOD.

PRELIM NUMBERS...
JAN 71/98/71/99 132
MEI 69/99/69/99 222

.JAN...
AR...NONE.
LA...NONE.
MS...NONE.
17/19

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
260400-

AREA THUNDERSTORM OUTLOOK     ...UPDATED...
NATIONAL WEATHER SERVICE
JACKSON MS
400 PM CDT FRI AUG 25 2000

THROUGH THE REMAINDER OF THIS AFTERNOON INTO EARLY EVENING...THE BEST
CHANCE FOR THUNDERSTORMS WILL BE IN THE SOUTHERN AND EASTERN
SECTIONS OF THE FORECAST AREA. THE BEST CHANCE FOR ISOLATED SEVERE
THUNDERSTORMS WILL BE IN THE EASTERN HALF OF THE CENTRAL PORTIONS OF
THE FORECAST AREA FROM SOUTHEAST OF A LINE FROM KOSCIUSKO TO
HAZLEHURST TO MORGANTOWN.

ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND EMERGENCY
MANAGEMENT PERSONNEL MAY BE NECESSARY THROUGH TONIGHT.H

FOR MORE INFORMATION PLEASE VISIT OUR WEB SITE AT
WWW.SRH.NOAA.GOV/JAN. THIS INCLUDES AN EXPERIMENTAL GRAPHICAL
HAZARDOUS WEATHER OUTLOOK.