Severe Thunderstorm Warning 639, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
340 PM CDT FRI SEP 22 2000

MID/UPPER LEVEL SHORTWAVE ENERGY OVER ERN TX NOTED ON WATER VAPOR
IMAGERY IS HEADING EAST INTO LOWER MS VALLEY REGION WHERE STRONG LOW
LEVEL THETAE RIDGE AND INSTABILITY AXIS EXIST. AIRMASS SOMEWHAT
DEPLETED OVER CNTRL AND ERN PORTIONS OF THE FORECAST AREA FROM
PREVIOUS CONVECTION...BUT AIRMASS IS RECOVERING AND SHOWER/TSTM
ACTIVITY GRADUALLY DEVELOPING EASTWARD. WILL PUT FAIRLY HIGH POPS
FOR MAINLY THIS EVENING.

STRONG TROFFING OVER THE WRN/CNTRL CONUS WILL MAINTAIN WARM/MOIST
SOUTHERLY FLOW ACROSS THE FORECAST AREA NEXT SEVERAL DAYS AS A
STRONG COLD FRONT DROPS SOUTHWARD INTO THE SOUTHERN PLAINS AND MID
MS VALLEY. APPEARS THAT SURFACE FOCUSING FOR PRECIPITATION WILL BE
LACKING THROUGH SUNDAY. STILL THOUGH...EXPECT THERE WILL BE ENOUGH
INSTABILITY GIVEN SOME INSOLATION TO TRIGGER WIDELY SCATTERED TO
SCATTERED AFTN/EVNG SHOWER/TSTM ACTIVITY IN HIGH PRECIPITABLE WATER
AIRMASS. WILL KEEP SMALL POPS AND ABOVE AVERAGE TEMPS GOING.

FORECAST BECOMES RATHER COMPLICATED BY LATE SUNDAY AFTN INTO SUNDAY
NIGHT AS MUCH WILL DEPEND ON TIMING OF COLD FRONT PUSHING SOUTHEAST
TOWARDS THE LOWER MS VALLEY AND SHORTWAVE ENERGY. MODELS INDICATE
THAT STRONG MID LEVEL RIDGING WILL TAKE PLACE ALONG THE GULF COAST.
THIS WILL HELP LEND TO AN UNSEASONABLY STRONG BAROCLINIC ZONE FROM NRN TX
INTO THE OH/TN VALLEY REGION. THE LONGWAVE PATTERN SUGGESTS THAT THE
COLD FRONT WILL BE SLOW TO PUSH SOUTHWARD INTO THE LOWER MS VALLEY
WITH MOST MID/UPPER LEVEL ENERGY REMAINING NORTH OF THE AREA.
OVERALL CONFIDENCE NOT HIGHT AND CHANCE POPS LOOK GOOD AT THIS
TIME...WITH BEST POPS OVER NRN ZONES.

QPF DISCUSSION...BEST PRECIPITATION COVERAGE WILL TAKE PLACE IN 1ST
6 HR PERIOD WITH SCATTERED SHOWER/TSTM COVERAGE. EXPECT AROUND
QUARTER TO ONE HALF INCH AVERAGE DURING 00Z TO 06Z PERIOD...OVER
MAINLY CNTRL/ERN BASINS. TOTAL BASIN AVERAGES FOR 06Z TO 00Z SUNDAY
PERIOD SHOULD BE AROUND ONE TENTH OF AN INCH OR LESS.

IN THE EXTENDED...CONFIDENCE REMAINS ON THE LOW SIDE CONCERNING COLD
FRONTAL POSITION MONDAY. MODELS AND NCEP INDICATE DEVELOPMENT OF WAVE
ALONG THE E-W COLD FRONT AS IT HANGS UP MONDAY ACROSS THE LOWER MS
VALLY WITH RESISTANCE FROM RIDGING ACROSS THE NRN GULF. WILL KEEP
SLIGHTLY COOLER TEMPS IN FOR MONDAY. MODELS INDICATE STRONGER
TROFFING IN FOR ERN US TUESDAY AND WEDNESDAY AND COOL/DRY HIGH
PRESSURE SHOULD BUILD ACROSS THE FORECAST AREA.

PRELIM NUMBERS...

JAN 73/89/71/91 5323
MEI 71/88/69/91 6323

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

43

P

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
230400-

AREA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
1045 AM CDT FRI SEP 22 2000

A WEAK FRONT ACROSS NORTHERN MISSISSIPPI THIS MORNING WILL CONTINUE
LIFTING NORTHWARD. MEANWHILE...AN UPPER LEVEL DISTURBANCE IN
SOUTHWEST LOUISIANA WILL CROSS MUCH OF THE AREA THROUGH EARLY
TONIGHT. SCATTERED THUNDERSTORMS WILL DEVELOP IN THE TROPICAL AND
UNSTABLE AIRMASS SOUTH OF THE FRONT WITH LOCAL...RATHER SHORT-LIVED
DOWNPOURS...GUSTY WINDS AND LIGHTNING STRIKES. MOST OF THESE SHOULD
DISSIPATE BEFORE MIDNIGHT.  NO SEVERE THUNDERSTORMS ARE EXPECTED.

ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND EMERGENCY
MANAGEMENT PERSONNEL WILL NOT BE NECESSARY THROUGH TONIGHT.

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