Severe Thunderstorm Warning 439, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
205 PM CDT MON AUG 19 2002

FORECAST CONCERNS OVER THE NEXT COUPLE OF DAYS WILL BE THE CHANCES OF
DIURNAL CONVECTION THROUGH THE PERIOD WITH THE WESTWARD MOVEMENT OF
A SHORT WAVE AND THE AFFECTS OF THE UPPER RIDGE WITH AFTERNOON
TEMPERATURES.

ON LATEST VAPOR/IR/VIS/RUC ANALYSIS A SHORT WAVE WAS OBSERVED OVER ALABAMA
AS THE REGION WAS UNDER A BROAD FLAT RIDGE WITH SOME MIDLEVEL COOL
AIR(500MB -8C) COMING FROM THE NORTHWEST. A STRONG COLD FRONT WAS POSITIONED
WELL NORTH FROM THE CENTRAL PLAINS THROUGH THE MID TO UPPER
MISSISSIPPI VALLEY. THE AVN MODEL INITIALIZED BETTER THAN THE ETA
MODEL. SOME STRONG CONVECTION WAS NOTED ACROSS THE SOUTHEAST HALF.

LOOKING AT THE SHORT TERM...THE UPPER RIDGE WILL BE CENTERED NORTH
OF THE REGION. THIS WILL ALLOW EASTERLY FLOW TO BRING IN A SHORT WAVE
SLOWLY MOVING ACROSS THE REGION ON TUESDAY INTO WEDNESDAY. ON THE
SURFACE A WEAK FRONTAL BOUNDARY WILL DIP JUST NORTH OF THE COUNTY
WARNING AREA. ONCE AGAIN THE AVN MODEL SEEM TO HAVE A BETTER HANDLE
ON THE FEATURE. PRECIPITABLE WATER WILL HOLD AT 1.8 TO 2.0 INCHES
WITH DIURNAL CONVECTION EXPECTED THROUGH THE SHORT TERM. LOOKING AT
ISENTROPICS AS NOTED WITH THE MIDNIGHT SHIFT. UPGLIDE DYNAMICS DO NOT
LOOK VERY IMPRESSIVE WITH LIMITED LIFT CONFINED TO COASTAL AREAS SOUTH
AND EAST OF THE FORECAST AREA. PRESSURE DEFICITS ONLY AROUND 40 TO
50 MB. SO WILL STICK WITH THE LOW POPS FOR MOST AREAS AND SCATTERED
POPS FOR THE SOUTH HALF FOR TUESDAY AND WEDNESDAY. WILL GO CLOSE TO
MOS TEMPS AND MAKE SLIGHT ADJUSTMENTS TO MOS POPS. WILL PUT BEST POPS
OVER THE SOUTH HALF FOR TONIGHT.

EXTENDED DISCUSSION THURSDAY THROUGH MONDAY
THE GLOBAL AVN MODEL SHOWS THE CENTER OF THE UPPER RIDGE OVER THE
EASTERN TENNESSEE VALLEY ON THURSDAY MOVING TOWARD THE ATLANTIC
SEABOARD...WHILE THE REGION IS UNDER UNSETTLED EASTERLY FLOW. MODEL SHOWS
DECENT MEAN MOISTURE FOR SCATTERED DIURNAL CONVECTION THROUGH
FRIDAY. BY THE WEEKEND THE GLOBAL AVN IS SIMILAR TO YESTERDAY IN
DIVERTING THE NORTHERN PLAINS TROUGH NORTH OF THE REGION TOWARD THE
EASTERN SEABOARD. IT STILL BRINGS A WEAK FRONTAL BOUNDARY THROUGH ON
SATURDAY. ON SUNDAY THE TROUGH WE WILL BE UNDER NORTHWEST FLOW
BEHIND THE DEEPENING UPPER TROUGH WITH RIDGING IN THE PLAINS. WILL
PUT IN PARTLY CLOUDY WITH A GOOD CHANCE OF CONVECTION FOR THE
WEEKEND. ON MONDAY AS THE UPPER TROUGH SWINGS OFF INTO THE ATLANTIC
THE REGION WILL BE UNDER THE BROAD FLAT RIDGE ONCE AGAIN...BRINGING IN
GOOD MEAN MOISTURE FOR DIURNAL CONVECTION.  THE EUROPEAN
MODELS...CANADIAN AND NOGAPS WERE GENERALLY SIMILAR. THE CANADIAN SHOWS
598 DKM OVER THE TENNESSEE VALLEY...SPELLING WARM MUGGY CONDITIONS
FOR THE EXTENDED.

PRELIM NUMBERS...
JAN 73/93/73/93 3323
MEI 73/92/72/91 3323

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

17

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
201200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
328 PM CDT MON AUG 19 2002

...THUNDERSTORMS...
SCATTERED SHOWERS AND THUNDERSTORMS CAN BE EXPECTED ACROSS
PARTS OF CENTRAL AND SOUTH MISSISSIPPI THIS EVENING...GENERALLY
ALONG AND SOUTH OF A LINE FROM BROOKHAVEN TO JACKSON TO MERIDIAN.
 SHOWERS AND THUNDERSTORMS WILL BE ISOLATED TO THE NORTH AND EAST
OF THIS LINE. STORMS THAT FORM OVER EAST MISSISSIPPI WILL HAVE
THE POTENTIAL TO BECOME SEVERE AND PRODUCE DAMAGING WINDS TO 70
MPH. THE BEST THREAT FOR SEVERE STORMS WILL OCCUR EAST OF A LINE
FROM EUPORA TO JACKSON TO BROOKHAVEN.

A WEAK WEATHER DISTURBANCE WILL CONTINUE TO TRACK TO THE SOUTH
ACROSS EAST MISSISSIPPI THIS AFTERNOON AND EVENING. ACTIVITY WILL
DIMINISH SHORTLY AFTER SUNSET AND MOST WILL END BY MIDNIGHT.
STORMS THAT FORM OVER  PARTS OF EAST AND CENTRAL
MISSISSIPPI...GENERALLY EAST OF A LINE FROM EUPORA TO JACKSON TO
BROOKHAVEN...MAY PRODUCE DAMAGING WIND UP TO 70 MPH.

THE ACTIVATION OF EMERGENCY MANAGEMENT OFFICIALS...HAM RADIO
OPERATORS...AND STORM SPOTTER GROUPS WILL LIKELY NOT BE REQUIRED
THROUGH TONIGHT.

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