Severe Thunderstorm Warning 650, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
240 PM CST TUE NOV 7 2000

MODELS ARE FAIRLY SIMILAR TODAY AND WILL USE A CONSENSUS AMONG THEM
FOR THE FORECAST.

EVERYONE WHO HAS BEEN BEGGING FOR RAIN THE PAST SEVERAL MONTHS
SHOULD BE HAPPY IN LESS THAN 48 HOURS. WEAK SURFACE FRONT WHICH
PASSED THROUGH MUCH OF THE CWFA LAST NIGHT WAS STALLED NEAR I-59 AT
NOON. FRONT WILL SURGE BACK NORTHWEST AS A WARM FRONT THIS EVENING
AND STALL NEAR THE NORTHWESTERN EDGE OF THE CWFA TONIGHT. AVN IS THE
OUTLIER HERE AS IT ONLY BRINGS THE FRONT BACK AS FAR AS THE NATCHEZ
TRACE. WILL LEAN TOWARD THE SUPERIOR LOW LEVEL RESOLUTION OF THE
OTHER MODELS FOR THE HANDLING OF THIS BOUNDARY. IF THE AVN TURNS OUT
TO BE RIGHT...TEMP FORECASTS IN THE DELTA REGION ARE VULNERABLE TO A
10-15 DEGREE BUST.

AFTER FRONT STALLS...DEVELOPING SURFACE LOW IN THE GULF RIDES
NORTHWARD ALONG IT...REACHING KLCH WEDNESDAY EVENING AND PASSING
THROUGH WESTERN AND NORTHERN MS WEDNESDAY NIGHT /PER AVN AND ETA -
DISCARDED NGM SOLUTION WHICH IS SEVERAL HOURS SLOWER/. ISENTROPIC
LIFT BEGINS IN EARNEST TONIGHT...WITH PRECIPITABLE WATER VALUES
ABOVE 1.5 INCHES BEING ADVECTED IN AND LIFTED OVER THE BOUNDARY
BEFORE MORNING. TONGUE OF GREATER THAN 2 INCH PWAT VALUES ENTERS THE
SOUTHWEST CWFA DURING THE DAY WEDNESDAY AND EVENTUALLY AFFECTS THE
ENTIRE AREA AT SOME TIME DURING THE EVENT. ISENTROPIC LIFT BEGINS TO
WEAKEN WEDNESDAY EVENING...JUST IN TIME FOR POWERFUL UPPER DYNAMICS
TO ENTER THE PICTURE WEDNESDAY NIGHT.

SHOWERS ALREADY BREAKING OUT OVER SOUTHEAST CWFA AS PER RADARS. THIS
ACTIVITY SHOULD SPREAD NORTHWESTWARD AS THE BOUNDARY RETREATS AND
ISENTROPIC LIFT INCREASES. MOISTURE POURING IN ON SOUTHWEST WINDS
ALOFT WILL CONTRIBUTE TO THE MIX TONIGHT AND WEDNESDAY...WITH
FRONTOGENETIC AND MOISTURE PARAMETERS POINTING TO THE DELTA AS THE
MOST LIKELY AREA FOR HEAVIEST RAIN. THUNDER POTENTIAL LOOKS SOMEWHAT
LIMITED DUE TO TOO MUCH MOISTURE ALOFT...BUT FRONTAL FORCING SHOULD
BE SUFFICIENT TO OVERCOME THIS LIMITING FACTOR. HOWEVER...AM GOING
TO REMOVE MENTION OF SEVERE FROM THE LA/AR ZONES FOR WEDNESDAY.
COMPARISONS WITH MONDAY FALSE ALARM SHOW LESS IMPRESSIVE SHEAR
PARAMETERS...LESS MODEL FORECAST CAPE...AND THE SAME LIMITING FACTOR
OF WIDESPREAD CLOUDS PREVENTING DAYTIME HEATING AND DESTABILIZATION.
WITH A SIMILAR BUT WEAKER SCENARIO THAN MONDAY...WHICH PRODUCED NO
SEVERE WEATHER IN OUR CWFA...CANNOT JUSTIFY HAVING IT IN THE ZONES
THIS TIME. SEVERE WEATHER THREAT MAY INCREASE FOR SOUTHEAST MS
WEDNESDAY NIGHT AS UPPER DIVERGENCE ASSOCIATED WITH RIGHT ENTRANCE
REGION OF JET STREAK COMES INTO PLAY...BUT WILL WAIT FOR ANOTHER
MODEL RUN OR TWO BEFORE JUMPING ON THIS.

MID LEVEL TROUGH AND VORT LOBE SWING THROUGH ON THURSDAY...ENDING
THE RAIN FROM WEST TO EAST DURING THE DAY. PATTERN THEN LOOKS DRY
THROUGH THE WEEKEND...DISCARDING THE OPERATIONAL MRF WHICH IS NOT
SUPPORTED BY ENSEMBLES OR THE NOGAPS. TEMPS WILL FALL TO SLIGHTLY
BELOW SEASONAL NORMS BEHIND THE TROUGH - LOWS IN THE 40S AND HIGHS
IN THE 60S.

24 HR QPF DISCUSSION: PRECIP BEGINNING TO BUILD NORTHWARD BEHIND
WARM FRONT. WITH PRECIP H20 AMOUNTS ON THE RISE ACROSS THE FA(1"
ISOPLETH PUSHING NORTH ACROSS FA TODAY INTO TONIGHT)...PRECIP H20
AMOUNTS LOOK TO BE 1.5" OR ABOVE OVER THE AREA. WITH ELEVATED TSRA
LIKELY NORTH OF THE WARM FRONT...AND TRAINING CELLS...AGREEING WITH
HPC/S NUMBERS WITH HIGHEST PRECIP TOTALS NORTHWESTERN SECTIONS OF FA
WITH 24 HR PRECIP TOTALS OF 0.5" SOUTHEAST TO 2"+ NORTHWEST.

PRELIM NUMBERS - SUBJECT TO CHANGE...
JAN 062/072/060/062 7+86
MEI 064/074/063/067 8+87

.JAN...
AR...NONE.
LA...NONE.
MS...NONE.
06/16