Severe Thunderstorm Warning 178, NWS Jackson, MS

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE JACKSON MS
659 AM CDT THU APR 24 2003

ILL BE SENDING OUT A QUICK UPDATE TO INCLUDE MENTIONING OF SEVERE
THUNDERSTORM WATCH NUMBER 154.  NO OTHER CHANGES ARE EXPECTED AT
THIS TIME.

BUTTS

---------- PREVIOUS DISCUSSION ----------
430 AM CDT THU APR 24 2003

FORECAST CHALLENGES THIS PACKAGE:
SEVERE WEATHER/FLOODING POTENTIAL THROUGH FRIDAY

A VERY ACTIVE WEATHER PATTERN IS SETTING UP ACROSS THE FORECAST AREA
OVER THE NEXT 24 HOURS OR SO.  THE LATEST SURFACE ANALYSIS HAS AN
AREA OF SURFACE LOW PRESSURE BETWEEN GOODLAND AND DODGE CITY
KANSAS.  A WARM FRONT WAS LOCATED OVER OUR NECK OF THE WOODS FROM
ABOUT TEXARKANA...SOUTHEAST TO ABOUT BROOKHAVEN...THEN TO NEAR THE
CITY OF MOBILE.  THE FINAL RESTING PLACE FOR THIS FRONT IS EXPECTED
TO PLAY A ROLE IN SEVERE WEATHER DEVELOPMENT.

AS EXPECTED...ROUND 1 HAS MOVED ALONG THE FRONTAL BOUNDARY.  AREA
RADARS SHOWS A NARROW LINE OF SHOWERS AND THUNDERSTORMS ALONG THE
MISSISSIPPI RIVER...AS WELL AS OVER SOUTHWEST ARKANSAS/NORTHWEST
LOUISIANA.  PEEKING UPSTREAM...ROUND 2 HAS ALREADY BEGUN OVER
SOUTH-CENTRAL KANSAS AND NORTHWEST OKLAHOMA.  WELL DEAL WITH THIS
ONE TODAY.

LOCATED BETWEEN THE POLAR AND SUBTROPICAL BRANCHES OF THE JET
STREAM...KINEMATIC FIELDS ARE EXPECTED TO INCREASE OVER THE FORECAST
AREA THROUGH THE DAY.  A 30 TO 50 KNOT LOW LEVEL JET WILL CONTINUE
TO PUMP MOISTURE INTO THE REGION...PUSHING 850 MB THETA-E VALUES
WELL ABOVE 325K.  STEEPENED LAPSE RATES ARE EXPECTED TO BE IN
PLACE...ESPECIALLY OVER OUR NORTHERN COUNTIES...AS MY ANALYSIS OF
THE MODEL FIELDS SHOW SEVERAL THERMAL TROUGHS MOVING THROUGH THE
MID-TROPOSPHERE.  FORCING WILL BE PROVIDED BY THE APPROACH OF A
SERIES OF STRONG UPPER-ATMOSPHERIC DISTURBANCES...THE WARM
FRONT...AND APPROACH OF A DRYLINE-ISH FEATURE.

GHCC MM5 DATA SHOWS FORECAST CAPE VALUES BETWEEN 1000 AND 3000
JOULES/KG (DEPENDING ON YOUR LOCATION) TODAY.  IN ADDITION...MODEL
FORECAST 0 TO 1 KM STORM-RELATIVE HELICITY VALUES ARE ABOUT 100...
LFC HEIGHTS ARE LOWERING (ESPECIALLY OVER NORTHERN AREAS)...AND A
MID-LEVEL DRY PUNCH WILL WORK ITS WAY INTO AREA BY AFTERNOON.  THIS
MORNINGS CONVECTION IS EXPECTED TO ACCOMPLISH TWO THINGS OVER THE
AREA.  ONE...ITLL REINFORCE THE WARM FRONT (OR...IT WONT ALLOW IT
TO MOVE OUTTA HERE QUICKLY).  AND TWO...ITS OUTFLOW BOUNDARIES WILL
PROVIDE ADDITIONAL INITIATION POINTS FOR CONVECTION.  POINT OF THE
STORY...SEVERE WEATHER APPEARS TO BE A POSSIBILITY OVER THE ENTIRE
AREA TODAY.

PUTTING ALL THIS TOGETHER ON A LOCAL SEVERE WEATHER COMPOSITE CHART
THIS MORNING...I FIND THE GREATEST RISK OF SEVERE WEATHER BETWEEN
700 AM AND MIDNIGHT WILL BE GENERALLY ALONG AND NORTH OF INTERSTATE
20.  ESPECIALLY IN THIS AREA...THE POSSIBILITY OF TORNADOES CANNOT
BE RULED OUT.

OTHER THAN THE SEVERE WEATHER RISK...GIVEN THE AMOUNT OF MOISTURE
RETURN...PARTS OF THE AREA COULD SEE HEAVY RAINFALL AND FLOODING.
AVERAGE RAINFALL AMOUNTS BETWEEN 2 AND 4 INCHES...WITH ISOLATED
AMOUNTS UP TO 6 INCHES MAY BE SEEN THROUGH TOMORROW MORNING.  THE
CURRENT FLASH FLOOD WATCH AREA LOOKS TO BE IN FINE SHAPE...AND WILL
NOT TWEAK.

AFTER TODAY/TONIGHTS CONVECTION...WE BEGIN DRYING OUT AS THE ENTIRE
STORM SYSTEM MOVES THROUGH THE AREA.  HOWEVER...IT LOOKS LIKE THERE
MAY BE ENOUGH SHALLOW MOISTURE TO COMBINE WITH LINGERING OUTFLOW
BOUNDARIES...PLENTY OF INSTABILITY...AND THE COLD FRONT...TO ALLOW
MORE STORMS TO DEVELOP BY AFTERNOON.  GIVEN THE AMOUNT OF
INSTABILITY...ISOLATED SEVERE STORMS COULD BE SEEN AGAIN.  ANY OF
THESE STORMS SHOULD DIMINISH FRIDAY NIGHT WITH WEAKENING INSTABILITY
AND THE DYNAMICAL SUPPORT MOVING AWAY FROM THE AREA.

DRY CONDITIONS SHOULD RETURN BY SATURDAY...AS RIDGING AGAIN TAKES
CONTROL OF WEATHER CONDITIONS IN OUR AREA.

NO CHANGES WERE MADE TO THE EXTENDED FORECAST.

GRIDS ARE OUT.  NUMBERS ARE BELOW.

FCSTID =   10
JAN   77  63  80  53 /  80  90  90  20
MEI   77  62  80  53 /  80  90  90  30

.JAN...
AR...NONE.
LA...FLASH FLOOD WATCH THROUGH TONIGHT LAZ015-016-023>026.
MS...FLASH FLOOD WATCH THROUGH TONIGHT MSZ042>066-072>074.

BUTTS

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
251200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
659 AM CDT THU APR 24 2003

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

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

...THUNDERSTORMS...
THUNDERSTORMS WILL OCCUR OVER NORTHEAST LOUISIANA...SOUTHEAST
ARKANSAS AND MUCH OF MISSISSIPPI TODAY AND TONIGHT. THE BEST
CHANCE FOR SEVERE STORMS WILL BE NORTH OF A LINE FROM WINNSBORO
LOUISIANA TO JACKSON MISSISSIPPI TO MERIDIAN. ISOLATED SEVERE
STORMS ARE POSSIBLE SOUTH OF THIS LINE. THE PRIMARY SEVERE
WEATHER RISK THROUGH THURSDAY NIGHT WILL BE LARGE HAIL. DAMAGING
WIND GUSTS AND TORNADO DEVELOPMENT ARE ALSO POSSIBLE. THE
LIKELIHOOD OF SEVERE STORM DEVELOPMENT WILL BE HIGHEST FROM THIS
AFTERNOON THROUGH MIDNIGHT TONIGHT.

DEEP GULF MOISTURE WILL BE FORCED INTO THE REGION BEHIND A WARM
FRONT THAT WILL LIFT NORTHWARD ACROSS MUCH OF THE AREA TODAY.
WEATHER  DISTURBANCES IN UPPER LEVELS OF THE ATMOSPHERE WILL
INTENSIFY THE LIFT NECESSARY FOR THUNDERSTORM DEVELOPMENT. UPPER
JET FLOW WILL ALSO INTENSIFY THIS AFTERNOON AND EVENING TO
PROMOTE ADDITIONAL SUPPORT FOR STRONG CONVECTION. THE COMBINATION
OF MOIST AND UNSTABLE AIR AND STRONG FORCING FROM ACTIVE WEATHER
FEATURES WILL RESULT IN THE LIKELIHOOD OF SEVERE THUNDERSTORM
DEVELOPMENT TODAY AND TONIGHT...ESPECIALLY FROM THIS AFTERNOON
THROUGH MIDNIGHT.

...FLOODING...
PERIODS OF HEAVY RAINFALL CAN BE EXPECTED ACROSS NORTHEAST
LOUISIANA... SOUTHEAST ARKANSAS AND MUCH OF MISSISSIPPI TODAY AND
TONIGHT. FLOODING RAINS WILL BE POSSIBLE OVER NORTHEAST LOUISIANA
AND SECTIONS OF CENTRAL AND SOUTHERN MISSISSIPPI...GENERALLY
SOUTH OF A LINE FROM DELHI LOUISIANA TO YAZOO CITY MISSISSIPPI TO
DEKALB. OCCASIONALLY HEAVY RAIN IS ALSO POSSIBLE OVER SOUTHEAST
ARKANSAS AND NORTH MISSISSIPPI...WHERE PONDING WATER MAY OCCUR ON
ROADWAYS AND IN LOW LYING AREAS.

DEEP MOISTURE WILL MOVE INTO PLACE ACROSS NORTHEAST LOUISIANA...
SOUTHEAST ARKANSAS AND MUCH OF MISSISSIPPI IN THE WAKE OF A WARM
FRONT THAT WILL STALL ACROSS NORTH AND EAST MISSISSIPPI TODAY.
MOISTURE WILL BE MOST ABUNDANT SOUTH OF THE WARM FRONT THIS
AFTERNOON AND EVENING. PERIODS OF HEAVY RAINFALL CAN BE EXPECTED
FROM THE AFTERNOON THROUGH MIDNIGHT AS STRONG THUNDERSTORMS
DEVELOP OVER THE REGION. THE POSSIBILITY OF THUNDERSTORMS MOVING
ACROSS THE SAME AREAS FOR EXTENDED PERIODS WILL INCREASE THE
POTENTIAL FOR FLOODING.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY...

...DAYS TWO AND THREE...
THE CHANCE OF SEVERE THUNDERSTORMS WILL CONTINUE FRIDAY AFTERNOON
AND EVENING OVER CENTRAL AND EAST SECTIONS OF
MISSISSIPPI...GENERALLY EAST OF INTERSTATE 55 AND NORTH OF A LINE
FROM HAZLEHURST TO QUITMAN.

THE WEATHER SYSTEM RESPONSIBLE FOR SEVERE STORM DEVELOPMENT TODAY
AND TONIGHT WILL FINALLY MOVE EAST OF MISSISSIPPI FRIDAY NIGHT.
UNTIL THE SYSTEM PASSES...THE AIR MASS OVER THE REGION WILL
REMAIN HUMID AND UNSTABLE...PARTICULARLY OVER EASTERN SECTIONS OF
MISSISSIPPI. THE CHANCE OF SEVERE STORM DEVELOPMENT WILL CONTINUE
DURING THE AFTERNOON AND EVENING FOR AREAS EAST OF INTERSTATE 55
AND NORTH OF A LINE FROM HAZLEHURST TO QUITMAN.

SEVERE WEATHER POTENTIAL WILL END FROM THE WEST FRIDAY EVENING AS
THE COLD FRONT FINALLY DRAGS EAST OF THE AREA.

...DAYS FOUR THROUGH SEVEN...
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...IN SUPPORT OF SEVERE WEATHER
OPERATIONS...MAY BE NEEDED TODAY AND TONIGHT.

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