Severe Thunderstorm Warning 154, NWS Jackson, MS

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
1145 AM CST SAT MAR 18 2000

SURFACE TROUGH SLOWLY INCHING NORTH ACROSS S-SE PORTIONS OF THE
FORECAST AREA AND WAS JUST SOUTH OF A MCCOMB-HATTIESBURG LINE AS OF
17Z. THIS AREA OF MOISTURE CONVERGENCE HAS BEEN THE FOCUS FOR
NUMEROUS...STRONG THUNDERSTORMS AS MID LVL SHORTWAVE OVER DEEP SOUTH
TEXAS MOVES NORTHEAST INTO THE NW GULF OF MEXICO HELPING TO
DESTABILIZE THINGS ALONG WITH DAYTIME HEATING.

ANALYSIS OF 12Z AREA SOUNDINGS AND MODIFICATIONS TO THESE SOUNDING
WITH EXPECTED DAYTIME HIGHS/DEW PTS REVEALED CAPES RANGING FROM
AROUND 1000 J/K OVER CENTRAL/NORTH MISSISSIPPI TO OVER 2000 J/KG
OVER THE SOUTH. THIS COMBINED WITH 150-250 STORM RELATIVE HELICITIES
AND NEAR 7 DEG C/KM MID LEVEL LAPSE RATES MAY RESULT IN SCATTERED...
...SEVERE THUNDERSTORMS MAINLY SOUTH OF I-20 CORRIDOR. WET BULBS ZERO
HEIGHTS RANGE BETWEEN 7000-9000 FT OVER THIS AREA WHICH WILL BE
CONDUCIVE FOR LARGE HAIL FORMATION AS STORMS MAY ROTATE ALONG AND
JUST NORTH OF THE SURFACE TROUGH BOUNDARY. AGREE WITH SPC THAT A
WATCH COULD BE NEEDED IN SOUTH MISSISSIPPI AS THE DAY WEARS ON. WILL
GENERALLY INCREASE P^OPS NEAR SURFACE TROUGH TODAY AND TAKE OUT
TRANSITIONAL CLOUD WORDING ALL ZONES. OTHERWISE...REST OF FORECAST ON
TRACK.

.JAN...
MS...NONE.
AR...NONE.
LA...NONE.
05

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
190400-

AREA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
1120 AM CST SAT MAR 18 2000

A WARM FRONT IS DEVELOPING ALONG THE GULF COAST AS LOW PRESSURE
DEVELOPS OVER THE WESTERN GULF. A STRONG UPPER LEVEL SYSTEM OVER THE
SOUTHERN PLAINS WILL MOVE EASTWARD AND COMBINE WITH THE WARM FRONT
TO BRING INCREASING THUNDERSTORM COVERAGE OVER THE AREA THROUGH
TONIGHT.

FOR THIS AFTERNOON...THE BEST INSTABILITY AND MOISTURE WILL COMBINE
OVER SOUTHEAST PORTIONS OF THE AREA ALONG AND NORTH OF THE SURFACE
WARM FRONT. IN THIS AREA...THUNDERSTORMS MAY BECOME SEVERE WITH
LARGE HAIL BEING THE PRIMARY THREAT. WIDELY SCATTERED THUNDERSTORMS
ARE POSSIBLE ELSEWHERE...BUT INSTABILITY AND MOISTURE WILL BE TOO
LIMITED FOR ORGANIZED SEVERE THUNDERSTORM ACTIVITY.

FOR TONIGHT...A SLIGHT RISK OF SEVERE THUNDERSTORMS WILL EXIST
OVER THE ENTIRE AREA...ESPECIALLY LATE TONIGHT...AS THE UPPER LEVEL
SYSTEM APPROACHES FROM THE WEST RESULTING IN FAVORABLE WIND SHEAR
AND BETTER INSTABILITY. AS OF NOW...THE DEVELOPING SCENARIO IS
COMPLEX AND TIMING OF SEVERE WEATHER IS STILL QUESTIONABLE. PERSONS
OVER THE ENTIRE AREA SHOULD STAYED TUNED TO LATER FORECASTS AND
STATEMENTS TO KEEP ABREAST OF THE DEVELOPING SITUATION.

ACTIVATION OF STORM SPOTTERS...EMERGENCY MANAGEMENT PERSONNEL AND HAM
RADIO OPERATORS MAY BE NECESSARY THROUGH TONIGHT.

FOR MORE INFORMATION...PLEASE VISIT OUR INTERNET WEB SITE AT
HTTP://WWW.SRH.NOAA.GOV/JAN