Severe Thunderstorm Warning 58, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
231 PM CST SUN MAR 17 2002

MAIN FORECAST CONCERNS CONTINUE TO DEAL WITH ANYTHING RELATED TO THE
FRONTAL BOUNDARY OVER THE FORECAST AREA.

SYNOPSIS...
A FRONTAL BOUNDARY OVER THE MID-SOUTH WILL MOVE NORTH TONIGHT
THROUGH MONDAY.  A STORM SYSTEM WILL DEVELOP OVER THE SOUTHERN
PLAINS...THEN MOVE INTO THE LOWER MISSISSIPPI RIVER VALLEY TUESDAY.
AFTER THE SYSTEM EXITS THE AREA WEDNESDAY...HIGH PRESSURE WILL
DOMINATE WEATHER CONDITIONS.  SHOWER AND THUNDERSTORM POSSIBILITIES
WILL CONTINUE INTO EARLY THIS WEEK...WITH GREATER CHANCES EXPECTED
TUESDAY.

DISCUSSION...
THE ATMOSPHERE OVER MUCH OF THE FORECAST AREA...ESPECIALLY CENTRAL
AND SOUTH...REMAINS CAPPED.  OUR 12Z SOUNDING HAD A 9 DEGREE C
TEMPERATURE AT 700 MB...WITH A FAIRLY DEEP SUBSIDENCE INVERSION
BETWEEN 850 AND 750 MB.  FARTHER NORTH...A WEAKER CAP AND THE
WOBBLING FRONT MAY ALLOW A FEW MORE SHOWERS TO BE SEEN HERE.
WHILE I WOULD NOT EXPECT TO SEE A WHOLE LOT OF SHOWER ACTIVITY IN
THE CENTRAL AND SOUTH...STRANGER THINGS HAVE HAPPENED AND WILL LOOK
AT RADAR/OBSERVATIONAL TRENDS BEFORE SENDING.

IN THE SHORT TERM...SOUTHWESTERLY FLOW ALOFT WILL KEEP SENDING
DISTURBANCES ALONG THE FRONT AT LEAST THROUGH MONDAY.  MOST OF THE
QG FORCING FOR THE CONVECTION SHOULD REMAIN ALONG THE FRONT...
GENERALLY IN THE MID-SOUTH AS THE FRONT BEGINS LIFTING NORTH IN
EARNEST TONIGHT/MONDAY.  850 MB THETA-E VALUES OF AT LEAST 320K ARE
FORECAST REMAIN OVER THE AREA THROUGH THROUGH THE START OF NEXT
WEEK.  SO...WHILE I CANT RULE OUT ISOLATED/SCATTERED SHOWERS...THE
MAIN FOCUS FOR PRECIP WILL REMAIN ALONG THE FRONT.  CURRENT POP
TRENDS LOOK TO BE OK...BUT I MAY DO SOME MINOR TWEAKING.

THEN THINGS BEGIN TO CHANGE.  AFTER LIFTING NORTH...THE FRONT SHOULD
WAIT NEAR THE MISSISSIPPI RIVER FOR OUR NEXT SYSTEM...WHICH IS SEEN
ON THE WATER VAPOR LOOP ENTERING CALIFORNIA.  BY TUESDAY...THE
REGION BEGINS TO COME UNDER THE RIGHT-REAR ENTRANCE REGION OF AT
LEAST AT A 100 KT UPPER JET.  UPWARD VERTICAL VELOCITIES SHOULD
INCREASE OVER THE LOWER MISSISSIPPI VALLEY BY TUESDAY NIGHT IN
RESPONSE TO THIS SYSTEM BEGINNING TO LIFT OUT.  THIS SHOULD PUSH THE
FRONT INTO THE FORECAST AREA TUESDAY NIGHT...AND THROUGH THE AREA
WEDNESDAY.  GIVEN THE AMOUNT OF FORCING...MOISTURE...AND INSTABILITY
WITH THIS SYSTEM...SHOWERS AND THUNDERSTORMS SHOULD BE MORE
PLENTIFUL TUESDAY AFTERNOON AND NIGHT.

THE FRONT SHOULD EXIT THE STATE WEDNESDAY.  THEN SURFACE HIGH
PRESSURE WILL BUILD INTO THE REGION THURSDAY AND BEGIN TO MOVE EAST
BY SUNDAY.  A HIGHLY MERIDIONAL UPPER FLOW (RIDGE WEST/TROUGH EAST)
WILL BE NOTED THROUGH THE FIRST HALF OF THE WEEKEND...BEFORE
BREAKING DOWN SUNDAY AS A SYSTEM BEGINS DEVELOPING IN THE WESTERN
U.S.  A LITTLE BOUNDARY LAYER MOISTURE IS STILL PROGGED TO MOVE
THROUGH THE AREA FRIDAY.  HOWEVER...IT APPEARS THAT THE ONLY FORCING
WILL BE SOME SHEAR VORTICITY ASSOCIATED WITH WITH THE UPPER JET
ROUNDING THE BASE OF THE EASTERN U.S. TROUGH.  SO...CONFIDENCE IS
NOT HIGH IN GETTING PRECIP AT THE END OF THE WEEK.  WILL PLAN ON
SEVERELY CURTAILING PRECIP TOWARD THE END OF THE WEEK.

THANKS MOB AND LIX FOR COORDINATION THIS AFTERNOON.  PRELIMINARY
NUMBERS TO FOLLOW.

FCSTID = 10
JAN   64  82  63  81 /  30  40  30  40
MEI   65  83  63  81 /  30  30  30  30

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

BUTTS

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
181200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
323 PM CST SUN MAR 17 2002

...THUNDERSTORMS...
NO SEVERE THUNDERSTORMS ARE EXPECTED THROUGH TONIGHT. HOWEVER...
SCATTERED THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND OVERNIGHT
MAINLY ALONG AND NORTH OF INTERSTATE TWENTY. THUNDERSTORMS ARE
EXPECTED TO BE NUMEROUS ALONG AND NORTH OF A FRONTAL BOUNDARY
NEAR AN OXFORD TO GREENVILLE TO BASTROP LOUISIANA LINE. AN
ISOLATED THUNDERSTORM MAY DEVELOP FARTHER SOUTH OF THE FRONT DUE
TO ABUNDANT MOISTURE AND WARM AFTERNOON TEMPERATURES...HOWEVER
THESE SHOULD DISSIPATE BY SUNSET.

SOUTHERLY WINDS WILL CONTINUE TO PROVIDE A MOSTLY SHALLOW LAYER
OF MOISTURE FROM THE GULF OF MEXICO. THE AIRMASS REMAINS QUITE
DRY ALOFT. AS THE WARM AND MOIST AIR INTERACTS WITH THE
FRONT...THUNDERSTORMS COULD PERSIST OVERNIGHT ACROSS THE DELTA
REGION. THE MAIN THREAT FROM THESE THUNDERSTORMS WILL BE
LIGHTNING STRIKES AND HEAVY RAINS.

THE ACTIVATION OF STORM SPOTTERS...HAM RADIO AND EMERGENCY
MANAGEMENT PERSONNEL...IN SUPPORT OF SEVERE WEATHER
OPERATIONS...SHOULD NOT BE REQUIRED THROUGH TONIGHT.

...FLOODING...
MINOR PONDING OF WATER ON ROADS AND IN LOW LYING AREAS WILL BE
POSSIBLE THROUGH TONIGHT ALONG AND NORTH OF THE STALLED FRONTAL
BOUNDARY. THE FRONT MAY DRIFT EASTWARD INTO THE DELTA REGION
LATER TONIGHT AS RAINFALL INCREASES OVER ARKANSAS.  UPPER LEVEL
WINDS WILL BE SOUTHWESTERLY ABOVE THE FRONT OVER NORTH
MISSISSIPPI AND THIS WILL KEEP THUNDERSTORMS MAINLY NORTH OF THE
FRONT. THIS MEANS ANY ONE AREA COULD GET SEVERAL THUNDERSTORMS
PRODUCING PERIODS OF HEAVY RAINFALL.

THE SOIL ACROSS THE REGION REMAINS WET FROM SATURDAY/S RAINS. ANY
ADDITIONAL RAIN WILL RUN OFF QUICKLY AND CAUSE TEMPORARY PONDING
AND EVEN OVER SPILL FROM DITCHES AND SMALL STREAMS.

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