Severe Thunderstorm Warning 28, NWS Jackson, MS

AREA FORECAST DISCUSSION...UPDATED...
NATIONAL WEATHER SERVICE JACKSON MS
1035 AM CST WED MAR 5 2003

VAPOR IMAGERY SHOWS STRONG SHORTWAVE TROUGH OVER NORTHERN MEXICO.
THIS WILL AID IN THUNDERSTORM DEVELOP BY MID TO LATE AFTERNOON OVER
THE REGION. WITH 850 TEMPS AT 15C...GOOD UPPER JET AND  TEMPS
ALREADY IN THE MIDDLE 60S ON THE COAST....EXPECT LOW LEVEL CLOUDS TO
MIX OUT THIS AFTERNOON. MORNING CAP ON AREA SOUNDINGS WILL ERODE
BY AROUND MID AFTERNOON. SO WITH THIS IN MIND HAVE INCREASED POPS
SLIGHTLY IN THE NORTH...UP TEMPS BY 1-2 CATEGORIES...ESPECIALLY IN
THE SOUTH WITH LOW TO MIDDLE 70S EXPECTED. IF WE GET SEVERE IT WILL
BE BY LATE AFTERNOON IN THE SOUTH AND ALSO MENTIONED A FEW STORMS IN
THE NORTHEAST. THE REST OF FORECAST FOR THIS AFTERNOON APPEARS TO
BE ON TRACK.

.JAN...
AR...NONE.
LA...NONE.
MS...NONE.
17

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MAIN FORECAST CHALLENGE IS THE RAIN SYSTEM TONIGHT AND WHETHER THIS
SYSTEM WILL PRODUCE A SIGNIFICANT AMOUNT OF SEVERE WEATHER IN THE
FORECAST AREA.

IN THE SHORT TERM...WEDNESDAY THROUGH FRIDAY...A MILD SOUTHWESTERLY
SUBTROPICAL JET CONTINUES TO AFFECT THE LOWER MISSISSIPPI VALLEY FOR
AT LEAST A FEW MORE DAYS.  BOTH THE ETA AND GFS MODELS FORECAST A
LOW PRESSURE CENTER TO FORM OVER MISSISSIPPI LATER THIS AFTERNOON.
ALTHOUGH THE INSTABILITY SHOULD BE SOMEWHAT MARGINAL WITH THIS
SYSTEM...THE LOCAL FORECAST AREA SHOULD BE IN THE RIGHT ENTRANCE
REGION OF A VERY STRONG JET STREAM (140 TO 150 KNOT CORE OVER
KENTUCKY AND INTO PENNSYLVANIA).  THE PROXIMITY TO THE RIGHT
ENTRANCE REGION OF THE JET WILL LEAD TO INCREASED UPPER LEVEL
DIVERGENCE OVER THE REGION AND WE WILL ALSO HAVE STRONG DEEP LAYER
WIND SHEAR.  I BELIEVE THE EXTENSIVE CLOUDINESS OVER THE FORECAST
AREA WILL KEEP HIGH TEMPERATURES SLIGHTLY BELOW AVN/NGM GUIDANCE
NUMBERS. THE ETA GUIDANCE NUMBERS SEEM TO BE RUNNING AT LEAST 10
DEGREES TOO HIGH FOR THE MAXIMUM TEMPERATURE TODAY.  THE GOOD NEWS
WITH THIS STORM SYSTEM IS THAT IT SHOULD BE A VERY FAST MOVER.  THE
MAIN LINE OF STORMS SHOULD PROGRESS QUICKLY THROUGH THE FORECAST
AREA IN THE LATE AFTERNOON THROUGH THE EVENING TIME FRAME.  WITH
MANY RIVERS STILL NEAR OR ABOVE FLOOD STAGE...WE DONT NEED A HEAVY
RAIN EVENT.  MORE GOOD NEWS IN THE SHORT TERM IS THAT THE ETA AND
GFS MODELS CONTINUE TO SHOW A DRY FORECAST FOR FRIDAY.  (A FEW DAYS
AGO THE GFS INDICATED THAT FRIDAY COULD BE A SIGNIFICANT RAIN DAY.)
WITH THE LATEST MODEL RUN AND TO BETTER BLEND WITH NEIGHBORING
OFFICE FORECASTS FOR FRIDAY...I TOTALLY REMOVED MENTION OF RAIN FOR
FRIDAY. FOR TEMPERATURES IN THE SHORT TERM...AS MENTIONED
EARLIER...I BELIEVE CLOUDS WILL HOLD THE TEMPERATURES SLIGHTLY BELOW
THE COOLEST GUIDANCE NUMBERS THIS AFTERNOON. THEN...AFTER THE FRONT
MOVES THROUGH TONIGHT...WE SHOULD HAVE LESS CLOUDS AND A BIGGER
DIURNAL TEMPERATURE RANGE.  TEMPERATURES MAY GET WELL INTO THE 70S
ON FRIDAY WITH LOTS OF SUNSHINE.

IN THE EXTENDED...SATURDAY THROUGH TUESDAY...THE UPPER LEVEL FLOW
BECOMES MORE WESTERLY TO WEST NORTHWESTERLY. THIS PATTERN SHOULD BE
DRIER THAN THE EXTREMELY MOIST AND CLOUDY PATTERN WE HAVE
EXPERIENCED THE LAST SEVERAL WEEKS.  AT THIS TIME...WILL LEAVE
EXTENDED PERIOD FORECAST DRY.  HOWEVER...LATEST GFS MODEL RUN SHOWS
POSSIBILITY OF SOME RAIN FOR TUESDAY. THE TEMPERATURES WILL FINALLY
BE SEASONABLY MILD AFTER A LONG BELOW NORMAL PERIOD.  HIGHS WILL
GENERALLY BE IN THE 70S.

PRELIM NUMBERS...
JAN 63/52/65/47/74 58--0
MEI 64/54/65/47/74 38-10

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

15

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
061200-

HAZARDOUS WEATHER OUTLOOK...CORRECTION FOR FLOODING SECTION...AREAL COVERAGE
NATIONAL WEATHER SERVICE JACKSON MS
1240 PM CST WED MAR 05 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL MISSISSIPPI...
NORTHEAST LOUISIANA...AND EXTREME SOUTHEAST ARKANSAS

.DAY ONE...TODAY AND TONIGHT...

...THUNDERSTORMS...
SCATTERED THUNDERSTORMS WILL DEVELOP THIS AFTERNOON ACROSS THE
REGION AS A COLD FRONT MOVES IN FROM THE WEST. A FEW OF THESE
THUNDERSTORMS MAY BECOME SEVERE BY 5 PM...MAINLY ACROSS THE
SOUTHERN PART OF THE REGION. THERE IS A SLIGHT RISK OF SEVERE
THUNDERSTORMS GENERALLY ALONG AND SOUTHEAST OF A WINNSBORO
LOUISIANA TO LEXINGTON TO COLUMBUS MISSISSIPPI LINE. THERE IS A
RISK OF SCATTERED SEVERE THUNDERSTORMS ACROSS EASTERN LOUISIANA
AND PORTIONS OF CENTRAL AND SOUTHERN MISSISSIPPI GENERALLY ALONG
AND SOUTH OF A LINE FROM SICILY ISLAND LOUISIANA TO MENDENHALL TO
QUITMAN MISSISSIPPI. THE PRIMARY TIME FOR SEVERE WEATHER WILL BE
FROM 4 PM TO MIDNIGHT. THE SEVERE WEATHER WILL END FROM WEST TO
EAST DURING THE EVENING HOURS. THE PRIMARY SEVERE WEATHER RISK
LATE THIS AFTERNOON AND THIS EVENING WILL BE DAMAGING WINDS UP TO
70 MPH AND LARGE HAIL.

A COLD FRONT WILL MOVE INTO NORTHWEST MISSISSIPPI THIS AFTERNOON
AND WILL MOVE THROUGH THE REGION TONIGHT. A VIGOROUS UPPER LEVEL
JET THAT WILL BE POSITIONED OVER THE REGION WILL PRODUCE STRONG
UPPER SUPPORT FOR THUNDERSTORM DEVELOPMENT. GULF MOISTURE WILL
PUSH INTO SOUTHERN AREAS THIS AFTERNOON AS LOW LEVEL SOUTHERLY
FLOW INCREASES AND VERTICAL WIND PROFILES SHOW GOOD SHEAR ON TAP
FOR LATE THIS AFTERNOON AND TONIGHT. THE WEAK LINK IN THE
SCENARIO TODAY WILL BE UNCERTAINTY OF INSTABILITY.

...FLOODING...
SHOWERS AND THUNDERSTORMS WILL DEVELOP DURING THE AFTERNOON AS A
COLD FRONT MOVES INTO THE AREA. A STRONG UPPER LEVEL JET THAT
WILL BE POSITIONED OVER THE REGION WILL PROVIDE ADDITIONAL
SUPPORT FOR THUNDERSTORM DEVELOPMENT. GULF MOISTURE WILL DEEPEN
AS SOUTHERLY LOW LEVEL FLOW INCREASES. PERIODS OF HEAVY RAINFALL
ARE POSSIBLE LATE THIS AFTERNOON AND TONIGHT IN STRONGER
THUNDERSTORMS. WATER MAY BRIEFLY POND ON ROADWAYS AND IN LOW
LYING AREAS. PERIODS OF HEAVY RAINFALL ARE MOST LIKELY SOUTH OF A
LINE FROM WINNSBORO LOUISIANA TO CANTON MISSISSIPPI TO COLUMBUS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY...

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER CALL TO ACTION STATEMENT...
THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND
EMERGENCY MANAGEMENT PERSONNEL MAY BE REQUIRED LATER TODAY AND
TONIGHT.

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