Severe Thunderstorm Warning 151, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
330 AM CDT TUE APR 3 2001

LATEST SURFACE ANALYSIS INDICATES WARM FRONTAL BOUNDARY TO THE NORTH
OF THE CWFA OVER THE TN VALLEY. SOUTHERLY FLOW IS IN FULL
SWING...BRINGING ABUNDANT GULF MOISTURE TO THE REGION. DEWPOINTS ARE
ON THE ORDER OF 20 TO 25 DEGREES HIGHER THAN THIS TIME LAST NIGHT.
TEMPS ARE ANYWHERE BETWEEN 15 AND 25 DEGREES HIGHER THAN LAST NIGHT.
LOW LEVEL STRATUS IS EVIDENT OVER THE ENTIRE CWFA...AND 88D IS
SHOWING INCREASED SHOWER ACTIVITY OVER EXTREME NORTH PORTIONS. LAPS
AND MSAS DATA INDICATING WEAK SHORTWAVE ENERGY MOVING ACROSS THAT
REGION. AVN SEEMS TO PICK UP ON THIS FEATURE ALSO WITH SOME MOISTURE
CONVERGENCE INDICATED IN THAT REGION.

MODELS SEEM TO AGREE ON MOST OF THE MAJOR FEATURES. DIFFERENCES LIE
IN THE DETAILS. ETA HAS BLOWN UP HUGE LIFT OVER THE EXTREME
SOUTHWEST CWFA DURING CURRENT TIME PERIOD...WHERE NOTHING IS
EVIDENT. ALSO THINK ETA IS CONTINUING TO OVER FORECAST QPF...WITH
BULLSEYE AMOUNTS ASSOCIATED WITH PREVIOUS MENTIONED LIFT THUS
KEEPING HIGHER QPFS OVER THE AREA. SO WITH ALL OF THIS SAID...WILL
LEAN TOWARDS THE AVN SOLUTION.

FAIRLY ZONAL FLOW AT 500MB CURRENTLY. FLOW WILL BECOME MORE
NORTHWESTERLY IN NATURE AS UPPER LEVEL RIDGE BUILDS OVER THE GULF
COAST STATES AND MOVES EAST. SHORTWAVE ENERGY FROM MEXICO WILL MOVE
EAST OVER THE CWFA...THE FIRST WAVE WILL APPROACH DURING THE
AFTERNOON HOURS TODAY...AND WILL MOVE EAST ALONG THE I-20
CORRIDOR...WITH A COUPLE MORE SHORTWAVES TO FOLLOW IN THE SAME
GENERAL AREA THROUGH EARLY TOMORROW NIGHT.

AT THE SURFACE...FRONT OVER TN VALLEY WILL SLOWLY MOVE SOUTH THOUGH
60 HOURS AS HIGH PRESSURE BUILDS OVER THE EASTERN SEABOARD
...EVENTUALLY BECOMING DIFFUSE IN THE EXTENDED PERIOD.
BOUNDARY WILL PROVIDE A SURFACE FOCUSING MECHANISM FOR CONVECTION.
WITH SEVERAL OTHER FACTORS IN PLACE...HEATING (DAYTIME MAXS NEAR
80)...ABUNDANT MOISTURE(60 TO 70 DEGREE DEWPOINTS)...WEAK UPPER JET
DYNAMICS...30 TO 40KT LLJ DYNAMICS IN THE FIRST 24 HOURS...AND
INSTABILITY FORM EASTWARD MOVING SHORTWAVES...EXPECT CONVECTION TO
START BREAKING OUT...WITH POPS INCREASING NEAR THE SOUTHWARD MOVING
BOUNDARY.

THE PROBLEM WILL BE THE PLACEMENT AND COVERAGE OF POPS...ESPECIALLY
IN THE FIRST 12 HOURS WITH NO DEFINITE FOCUSING MECHANISM (EXCEPT
HARD TO TIME AND PLACE SHORTWAVES). FURTHER INTO THE FORECAST PRECIP
SHOULD BE FOCUSED ALONG OR NEAR SOUTHWARD MOVING BOUNDARY. BY 00Z
WED...BOUNDARY SHOULD BE ENTERING THE NORTHERN TIER OF THE CWFA AND
WILL SLOWLY MOVE SOUTH TO CENTRAL ZONES BY WED MORN...AND BECOMING
VERY HARD TO DEFINE LATE WEDNESDAY AS HIGH PRESSURE BUILDS FROM THE
EAST.

FOR TODAY...HIGHEST POPS WILL BE IN THE NORTH. SHORTWAVES SHOULD BE
TRACKING EAST ALONG THOSE AREAS...AND SHOWERS ALREADY BREAKING OUT
THINK THIS IS WARRANTED. DECREASING POPS SOUTHWARD.
TONIGHT...BOUNDARY WILL BE APPROACHING THE NORTHERN TIER OF ZONES.
HIGHER POPS ARE AGAIN WARRANTED IN THAT REGION AND DECREASING
SOUTHWARD.
WEDNESDAY...WEAKENING BOUNDARY WILL BE OVER CENTRAL ZONES. HIGHEST
POPS IN THAT REGION.
WEDNESDAY NIGHT...BOUNDARY BECOMING DIFFUSE WITH HIGH PRESSURE
BUILDING IN FROM THE EAST. LOW END CHANCE POPS LOOK PRETTY GOOD.

GUIDANCE LOOKS PRETTY GOOD ON TEMPS AND WILL NOT STRAY TO FAR.
PRETTY UNIFORM OVER THE CWFA WITH HIGHS NEAR 80 AND LOWS IN THE 60S.
HAVE VERY LOW CONFIDENCE IN POP FORECAST. HARD TO DEFINE AND TIME
SHORTWAVES...AND A MEANDERING BOUNDARY...AM NOT TOO CONFIDENT ON
LIKELY POPS FORECAST FOR SOME AREAS. WILL PLAY IT CONSERVATIVE
...UNTIL TRENDS CAN BE ESTABLISHED AND MODELS COME MORE
INTO LINE WITH ONE ANOTHER.

CURRENT EXTENDED LOOKS GOOD AND WILL ONLY MAKE COSMETIC CHANGES AS
NEEDED.

.PRELIM NUMBERS
JAN 81/65/81/63 3343
MEI 81/63/81/60 3343

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

32

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>
074-041200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
600 AM CDT TUE APR 03 2001

...THUNDERSTORMS...
SCATTERED SEVERE THUNDERSTORMS ARE POSSIBLE OVER PARTS OF NORTH
MISSISSIPPI THIS MORNING AND EARLY AFTERNOON. THE THREAT OF SEVERE
THUNDERSTORMS WILL DECREASE SOUTHWARD.

THE COMBINED EFFECTS OF AN UPPER LEVEL JET STREAM AND SIGNIFICANT
LOW LEVEL FLOW FROM THE GULF WILL PRODUCE SEVERE THUNDERSTORMS NEAR
THE NORTH MISSISSIPPI BORDER. SCATTERED THUNDERSTORMS WILL
CONTINUE INTO THE EVENING AS A FRONT DRIFTS SOUTHWARD INTO NORTHERN
MISSISSIPPI TONIGHT. HOWEVER...THE THREAT OF SEVERE WEATHER WILL
DECREASE THIS AFTERNOON AS THE JET STREAM SHIFTS TO THE EAST AND LOW
LEVEL FLOW BEGINS TO DECREASE.

SCATTERED THUNDERSTORMS CAN BE EXPECTED OVER MUCH OF NORTHEAST
LOUISIANA AND CENTRAL AND SOUTH MISSISSIPPI TODAY AND THIS EVENING.
SEVERE WEATHER IS NOT EXPECTED IN THESE AREAS.

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