Severe Thunderstorm Warning 677, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
300 AM CDT SAT OCT 13 2001

MODELS IN GENERAL AGREEMENT ON SYNOPTIC FEATURES ALTHOUGH
DIFFERENCES IN TIMING REMAIN. UPPER LOW TO DIG INTO ERN TX TODAY AS
100+ KT UPPER JET MAX LIFTS NWD JUST W OF MS RIVER. MODELS INDICATE
SLIGHT NEGATIVE TILT TO UPPER TROUGH THIS AFTERNOON. LOW LEVEL
DYNAMICS INCREASE WITH 850 MB JET MAX INTO WRN ZONES THIS MORNING.
850 MB WIND SPEEDS FORECAST 40-50 KT RANGE WRN AREAS THIS
MORNING...SPREADING ACROSS REST OF FORECAST AREA BY 18Z TODAY. AS
UPPER LOW DIGS OVER ERN TX...UPPER FLOW NEARLY PARALLEL WITH COLD
FRONT. THIS TO INCREASE THREAT OF TRAINING ECHOES THIS AFTERNOON.
PRECIPITABLE WATER VALUES FORECAST FROM 1.5 TO 2+ INCHES TODAY LOOK
SUFFICIENT FOR POSSIBILITY OF FLOODING PROBLEMS IF TRAINING CELLS
OCCUR. WILL ISSUE FLOOD WATCH FOR WRN ZONES FOR TODAY. WILL NOT
INCLUDE ERN ZONES AT THIS TIME SINCE UPPER SYSTEM TO ACCELERATE
LATER TODAY...REDUCING THE CHANCE OF TRAINING CELLS ERN AREAS. NCEP
RAIN ESTIMATES OF 1-2 INCHES WRN ZONES THROUGH 18Z TODAY LOOK A BIT
OVERDONE BUT GENERAL TOTALS FROM 1-2 INCHES 18Z THROUGH 00Z SUNDAY
WRN ZONES LOOK UNDERDONE. EXPECT AVERAGES FROM 1/2 TO 1 INCH THROUGH
MIDDAY WEST THEN 2-3 INCHES W AND CENTRAL AREAS BY 00Z SUNDAY...WITH
LOCALLY HIGHER AMOUNTS.

UPPER TROUGH MOVING NEAR MS RIVER AROUND MIDNIGHT. MODELS AGREE THAT
SIGNIFICANT UPPER DIVERGENCE TO CONTINUE NRN HALF OF FORECAST AREA
THROUGH 06Z SUNDAY...ENDING BY 12Z SUNDAY MORNING. 850 MB FLOW
VEERING TO THE W OVER WRN ZONES BY MIDNIGHT...SHIFTING W/NW ALL
ZONES BY 12Z SUNDAY. COLD 500 MB TEMP TROUGH PIVOTING FROM NE LA
INTO W CENTRAL AND NW MS TONIGHT...MOVING N OF THE AREA EARLY SUNDAY
MORNING. AIR MASS REMAINING UNSTABLE EARLY TONIGHT SO WILL KEEP
HIGHS POPS INTO SECOND PERIOD.

AIR MASS DRYING RAPIDLY BEHIND COLD FRONT...REMAINING DRY THROUGH
FRIDAY.

.PRELIM NUMBERS...
JAN 078/062/075/048  +9-0
MEI 079/067/075/048  ++10

.JAN...
MS...FLOOD WATCH WRN MS FOR TODAY
LA...FLOOD NE LA WATCH FOR TODAY
AR...FLOOD SE AR WATCH FOR TODAY

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
141200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
706 AM CDT SAT OCT 13 2001

...THUNDERSTORMS...
THUNDERSTORMS WILL BE WIDESPREAD OVER NORTHEAST
LOUISIANA...SOUTHEAST ARKANSAS AND MOST OF MISSISSIPPI THROUGH
THE AFTERNOON AND EARLY EVENING. SCATTERED THUNDERSTORMS WILL BE
SEVERE AND MAY PRODUCE LARGE HAIL AND DAMAGING WIND.

STRONG LOW LEVEL SOUTHERLY FLOW WILL CONTINUE TO PULL MOISTURE
INTO THE REGION AHEAD OF A STRONG UPPER LEVEL LOW AND ASSOCIATED
COLD FRONT THAT WILL APPROACH THE REGION TODAY. ABUNDANT MOISTURE
AND INCREASED INSTABILITY WILL LEAD TO ORGANIZED THUNDERSTORMS
THIS MORNING AND CONTINUE THROUGHOUT THE DAY. THE STRONGEST
STORMS WILL DEVELOP WEST OF A LINE FROM GRENADA TO KOSCIUSKO TO
MONTICELLO DURING THE MORNING AND AFTERNOON...SPREADING TO EAST
MISSISSIPPI BY EARLY AFTERNOON. THE MAIN SEVERE WEATHER THREAT
WILL BE DAMAGING WINDS TO 70 MPH AND HAIL TO ONE INCH. STRONGER
THUNDERSTORMS WILL HAVE THE POTENTIAL TO PRODUCE TORNADOES.

THUNDERSTORM ACTIVITY WILL DIMINISH OVER SOUTHEAST
ARKANSAS...NORTHEAST LOUISIANA AND WEST MISSISSIPPI BY EARLY
EVENING AS THE COLD FRONT REACHES THE MISSISSIPPI RIVER.
THUNDERSTORMS WILL DIMINISH IN INTENSITY AND COVERAGE ACROSS EAST
MISSISSIPPI LATER TONIGHT AS THE SYSTEM LIFTS OUT OF THE REGION.

ALL SHOULD MONITOR FUTURE FORECASTS AND STATEMENTS CONCERNING
THIS DEVELOPING WEATHER SITUATION.

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT PERSONNEL
WILL LIKELY BE NEEDED TODAY AND EARLY TONIGHT.

...FLOODING...
FLOODING IS POSSIBLE OVER SOUTHEAST ARKANSAS...NORTHEAST
LOUISIANA AND WEST MISSISSIPPI WEST OF A LINE FROM GRENADA TO
KOSCIUSKO TO MONTICELLO TODAY.

AN APPROACHING WEATHER SYSTEM WILL STALL AS IT MOVES INTO EAST
TEXAS EARLY TODAY. SHOWERS AND THUNDERSTORMS WILL INCREASE OVER
NORTHEAST LOUISIANA...SOUTHEAST ARKANSAS AND WEST MISSISSIPPI.
AREAS WEST OF A LINE FROM GRENADA TO KOSCIUSKO TO MONTICELLO MAY
BEGIN TO SEE THUNDERSTORMS MOVE REPEATEDLY ACROSS THEIR
AREA...RESULTING IN THE THREAT OF FLOODING THROUGH THE AFTERNOON.

AREAS EAST OF THE LINE FROM GRENADA TO KOSCIUSKO TO MONTICELLO
WILL ALSO SEE INCREASING SHOWERS AND THUNDERSTORMS EARLY
TODAY...WITH PERIODS OF HEAVY RAINFALL. THE STORM SYSTEM WILL
BEGIN TO SPEED UP AS IT CROSSES INTO EAST MISSISSIPPI THIS
AFTERNOON AND THE THREAT OF FLOODING WILL BE LESS.
HOWEVER...WATER MAY BEGIN TO POND ON ROADWAYS AND IN LOW LYING
AREAS.

RAINFALL WILL DIMINISH FROM THE WEST DURING THE EARLY EVENING AS
THE COLD FRONT CROSSES THE MISSISSIPPI RIVER.

...NON PRECIPITATION...
SOUTH WIND FROM 15 TO 25 MPH CAN BE EXPECTED OVER NORTHEAST
LOUISIANA...SOUTHEAST ARKANSAS AND MOST OF MISSISSIPPI TODAY.
CAUTION IS ADVISED ON AREA LAKES.

A STRONG COLD FRONT WILL MOVE ACROSS TEXAS THIS MORNING AND WILL
MOVE NEAR THE MISSISSIPPI RIVER DURING THE LATE AFTERNOON. THE
STRONG SURFACE LOW PRESSURE SYSTEM ASSOCIATED WITH THE FRONT WILL
PRODUCE GUSTY SOUTH WIND DURING THE MORNING AND AFTERNOON.

BOATERS SHOULD EXERCISE CAUTION ON AREA LAKES AND WATERWAYS.
DRIVERS OF CAMPERS...VANS AND OTHER HIGH PROFILE VEHICLES SHOULD
ALSO USE CAUTION WHEN ON THE ROAD TODAY.

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