Severe Thunderstorm Warning 463, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
330 PM CDT FRI JUL 21 2000

TSTMS ARE FIRING UP IN THETAE RIDGE/INSTABILITY AXIS ALONG
JONESVILLE-MEADVILLE-COLUMBIA CORRIDOR...NICELY DEPICTED ON VISIBLE
IMAGERY/RADAR IMAGERY/LIGHTNING LOOPS. THE ETA AND AVN HAVE GOOD
HANDLE ON CURRENT SITUATION WITH DYING MCS PROPAGATING ACROSS ERN
AR/NRN MS. FOR THIS EVENING...APPEARS THAT TSTM ACTIVITY WILL HAVE A
HARD TIME DEVELOPING FARTHER NORTH ACROSS THE FORECAST AREA GIVEN
SFC MOISTURE DIVERGENCE OVER CNTRL/NE MS AND GIVEN FACT THAT DEEP
CONVECTION HAS YET TO INITIATE ALONG DYING MCS OUTFLOW. CURRENT
THINKING IS TO KEEP HIGH-END CHANCE POPS OVER SRN MOST COUNTIES WITH
SMALL EVENING POPS OVER CNTRL/NRN ZONES. IN ANY CASE...WILL MAKE
LAST MINUTE DECISION REGARDING EVENING POPS BASED ON LATEST
CONVECTIVE TRENDS.

FOR SATURDAY...AVN/ETA MAINTAIN STRONG INSTABILITY AXIS AND WEAK SFC
BOUNDARY ACROSS SW THIRD OF AREA AND EXPECT MORE SCATTERED TSTM
DEVELOPMENT ALONG THIS AXIS. WILL KEEP HIGH-END CHANCE POPS GOING
FOR WINNSBORO TO BROOKHAVEN TO HATTIEBURG CORRIDOR. TSTM DEVELOPMENT
A LITTLE MORE QUESTIONABLE FARTHER NORTHEAST WITH MUCH DEPENDENT ON
HARD-TO-TIME SHORTWAVE ENERGY. WILL CONTINUE CHANCE POPS THERE AS
MCSS CONTINUE TO PROPAGATE SOUTHEAST FROM THE SRN/CNTRL PLAINS.

SAT NIGHT THRU SUN NIGHT...MODELS IN GENERAL AGREEMENT IN DEEPENING
OF ERN US TROF THUS BRINGING SIGNIFICANT MID LEVEL HEIGHT FALLS OVER
THE LOWER MS VALLEY. WITH RIGHT ENTRANCE REGION OF UPPER JET OVER
OH/TN VALLEY REGION COMING INTO PLAY...WILL NEED TO GO ABOVE
GUIDANCE POPS...ESPECIALLY GIVEN AMPLIFYING PATTERN AND SEASONABLY
STRONG UPPER JET ENERGY INTERACTING WITH HIGH PRECIPITABLE WATER
AIRMASS.

CONCERNING TEMPERATURES...WITH MID LEVEL TROFFING TAKING PLACE
ACROSS THE LOWER MS VALLEY...EXPECT TEMPS TO GET BACK CLOSER TO
SUMMER AVERAGES AS SUGGESTED BY LATEST GUIDANCE AND WILL CONTINUE
DOWNWARD TREND.

QPF DISCUSSION...FOR NEXT 24 HRS...WILL COLOR IN SMALL BASIN
AVERAGES FOR SCT TSTM ACTIVITY OVER SW THIRD OF AREA THIS EVENING
AND ONCE AGAIN FOR SAT AFTN PERIOD.

IN THE EXTENDED...SURFACE FRONT SHOULD HANG UP ALONG GULF COAST THRU
PERIOD IN NORTHWEST FLOW BRINGING BEST CHANCES FOR TSTM ACTIVITY OVER
SRN PORTIONS OF THE FORECAST AREA AND WILL TREND POPS DOWNWARD FROM
THERE. TEMPS WILL BE CLOSE TO AVERAGE WITH HIGHS CONSIDERABLY LOWER
THAN IN RECENT WEEKS.

JAN 068/094/070/091 2324
MEI 068/093/068/090 1324

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

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