Severe Thunderstorm Warning 502, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
245 PM CDT THU JUN 28 2001

THE PERSISTENT UPPER LEVEL LOW THAT HAS BEEN AFFECTING MUCH OF THE
SOUTHEASTERN STATES WAS LOCATED IN SOUTHEAST MISSOURI THIS MORNING
WITH A TROUGH SOUTHWARD INTO NORTHEASTERN LOUISIANA. SCATTERED
CONVECTION IS OCCURRING THIS AFTERNOON ACROSS THE FORECAST AREA WITH
MOST WIDESPREAD COVERAGE SOUTH OF INTERSTATE 20. BOTH THE ETA AND
AVN MODELS ARE CONSISTENT IN FORECASTING LITTLE MOVEMENT TO THE
UPPER LOW THROUGH SATURDAY AFTERNOON. BY 00Z SUNDAY THE AVN AND ETA
MODELS ONLY TRACK THE LOW SEVERAL HUNDRED MILES WEST FROM THE
CURRENT POSITION IN SOUTHEAST MISSOURI INTO VICINITY OF SOUTHWEST
MISSOURI AND NORTHEAST ARKANSAS.

AT THE SURFACE: WITH A HIGH PRESSURE CENTER OFF THE COAST OF THE
SOUTHEASTERN UNITED STATES...LOW LEVEL FLOW INTO THE LOWER
MISSISSIPPI VALLEY WILL CONTINUE TO BE OUT OF THE SOUTH...BRINGING
WARM HUMID AIR INTO THE REGION. HOWEVER...THE PRESSURE GRADIENT WILL
CONTINUE TO BE VERY WEAK SO THE LOW LEVEL WIND FLOW WILL BE LIGHT.

WITH THE WARM HUMID AIR AT THE LOWER LEVEL AND UNSEASONABLY COOL AIR
AT 500 MB (ASSOCIATED WITH THE UPPER LEVEL LOW) EXPECT SCATTERED
THUNDERSTORM ACTIVITY TO CONTINUE ACROSS THE FORECAST AREA FOR THE
NEXT SEVERAL DAYS. THE GREATEST COVERAGE OF THUNDERSTORMS WILL OCCUR
DURING THE AFTERNOON AND EARLY EVENING HOURS. HOWEVER...FOR THIS
UNUSUAL SUMMER WEATHER PATTERN WITH AN UPPER LEVEL LOW IN SOUTHERN
MISSOURI AND A 500 MB TROUGH JUST WEST OF THE FORECAST
AREA...CONVECTION WILL BE POSSIBLE AT ANY TIME OF THE DAY OR NIGHT.

FOR TEMPERATURES...WILL STAY CLOSEST TO THE AVNS NUMBERS. BELIEVE
PLENTIFUL CLOUDINESS WILL KEEP THE MAXIMUM TEMPERATURES CLOSER TO
THE COOLER NUMBERS OF THE AVN GUIDANCE. LOW TEMPERATURES WILL
CONTINUE TO BE UNSEASONABLY COOL THE NEXT SEVERAL DAYS...GENERALLY
IN THE 65 TO 70 DEGREE RANGE.

24 HOUR QPF FORECAST: ALTHOUGH SCATTERED CONVECTION WITH UP TO 50
PERCENT COVERAGE OF RAIN IS EXPECTED THROUGH THE PERIOD ENDING AT
00Z FRIDAY...OVERALL AREAL QPF AMOUNTS SHOULD BE LESS THAN ONE TENTH
OF AN INCH WITH MOST PRECIPITATION OCCURRING FRIDAY AFTERNOON
BETWEEN 18Z AND 00Z (1300 - 1900L) RAINFALL AMOUNTS SHOULD TEND TO
BE HIGHER WEST OF THE MISSISSIPPI RIVER...BUT LOCALIZED 1-2 INCH
AMOUNTS COULD OCCUR ANYWHERE IN THE FORECAST AREA IN ISOLATED
STRONGER STORMS.

EXTENDED FORECAST: THE UPPER LEVEL LOW THAT HAS AFFECTED THE LOCAL
FORECAST AREA WEATHER FOR THE PAST WEEK IS EXPECTED TO DRIFT
SOUTHWESTWARD TOWARDS CENTRAL TEXAS BY SUNDAY AND WILL FINALLY
DISSIPATE BY TUESDAY. HOWEVER...THE AIRMASS WILL CONTINUE TO BE VERY
WARM...HUMID...AND UNSTABLE. A WEEK FRONT WILL GRAZE NORTHERN
PORTIONS OF MISSISSIPPI BY WEDNESDAY. WILL LEAVE CHANCE OF RAIN OUT
OF NORTHERN ZONES FOR DAY 7 (THURSDAY) BUT BELIEVE AIRMASS WILL
CONTINUE TO BE UNSTABLE ENOUGH TO SUPPORT AFTERNOON AND EVENING
CONVECTION ACROSS REMAINDER OF THE FORECAST AREA THROUGH THE ENTIRE
PERIOD. MAXIMUM TEMPERATURES SHOULD CONTINUE TO BE SLIGHTLY BELOW
NORMAL THROUGH THURSDAY WITH MINIMUM TEMPERATURES NEAR NORMAL.

PRELIM NUMBERS...
JAN 68/87 69/88  2524
MEI 67/89 68/90  2424

.JAN...
MS...NONE.
LA...NONE.
AR...NONE.
15

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
291200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
320 PM CDT THU JUN 28 2001

...THUNDERSTORMS...
ISOLATED THUNDERSTORMS MAY BE SEVERE OVER PARTS OF SOUTH AND EAST
MISSISSIPPI THIS AFTERNOON AND EARLY EVENING.

SCATTERED THUNDERSTORMS OVER NORTHEAST LOUISIANA...SOUTHEAST
ARKANSAS AND MUCH OF MISSISSIPPI WILL DIMINISH THIS EVENING AS
AFTERNOON HEATING ENDS AND THE AIR MASS SLOWLY STABILIZES.

A LOW PRESSURE CENTER IN THE UPPER LEVELS OF THE ATMOSPHERE WILL
REMAIN PARKED OVER THE REGION THROUGH FRIDAY. THIS SYSTEM WILL
PROVIDE EXTRA LIFT TO PROMOTE THUNDERSTORM FORMATION THIS
AFTERNOON AND EVENING. COOLING TEMPERATURES EARLY TONIGHT WILL
REDUCE LIFT AND STABILIZE THE AIR MASS ENOUGH TO REDUCE THE
CHANCE OF THUNDERSTORM DEVELOPMENT OVERNIGHT.

THE BEST CHANCE OF SEVERE STORMS WILL BE OVER SOUTH AND EAST
MISSISSIPPI WHERE THE AIR MASS WILL BE MOST UNSTABLE THIS
AFTERNOON AND EARLY EVENING. THE PRIMARY SEVERE WEATHER THREAT
WILL BE DAMAGING WIND. LARGE HAIL UP TO NICKEL SIZE IS ALSO
POSSIBLE.

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT PERSONNEL
MAY BE NEEDED THROUGH THE EARLY EVENING BUT WILL NOT BE NECESSARY
TONIGHT.

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