Severe Thunderstorm Warning 335, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
250 PM CDT FRI MAY 5 2000

MODELS CLOSE ON SCENARIO FOR CLOSED UPPER LOW OVER AR THIS AFTERNOON.
UPPER LOW WILL WOBBLE OVER THAT STATE AND GRADUALLY FILL THROUGH
THIS FORECAST CYCLE. SOME MINOR DIFFERENCES APPEAR IN TIMING. IN THE
ETA...CLOSED LOW FILLS AROUND 06Z SAT AND LIFTS INTO MID MS RIVER
VALLEY NEAR MO/IL BY 18Z SUN. IN NGM...CLOSED LOW LINGERS A BIT LONGER
OVER AR AND BEGINS FILLING/LIFTING AFTER 18Z SAT. SHORTWAVES OF
MODERATE MAGNITUDE WILL CONTINUE TO ROTATE AROUND CLOSED LOW FROM NE
TX INTO LA...SE AR...AND W MS THROUGH TONIGHT. AT THE SAME TIME
...LOW/MID LEVEL FLOW REMAINS SSE...PUMPING MORE WARM...MOIST AIR
INTO REGION.

COULD SEE SOME STRONGER STORMS DEVELOPING THIS EVENING MAINLY OVER
NW AND SE ZONES. ATTM...MID/LOW LEVEL FLOW ALMOST UNIDIRECTIONAL WITH
LIMITED SPEED DIFFERENCE. THEREFORE...ENVIRONMENT'S SHEAR A BIT
LIMITED. YET AMS VERY WARM/MOIST/UNSTABLE. WHILE NW ZONES ALREADY
ANTICIPATING POTENTIAL SEVERE/HEAVY RAINFALL AS SHORTWAVES APPROACH
...ONGOING TSTMS PRODUCING HAIL/GUSTY WINDS/HEAVY RAIN OVER OUR SERN
ZONES WHERE SEA-BREEZE HELPED INITIATE CONVECTION. WORDING FORECASTS
TO REFLECT CONDITIONS TONIGHT.

AS UPPER SYSTEM SLOWLY ABSORBED INTO NRN JET STREAM BY SAT NIGHT
INTO SUN...UPPER LEVEL RIDGING INTENSIFIES OVER THE SRN PLAINS AND
ALONG THE SE ATLANTIC COASTAL REGION...LEAVING A GREATLY WEAKENED
UPPER TROUGH AXIS THROUGH THE ERN MS COUNTIES/AL. DUE TO THIS
FEATURE...WILL KEEP CLOUDS/SOME CHANCE OF SHOWERS OVER ERN ZONES ON
SUNDAY AFTERNOON/EVENING. ASIDE FROM POTENTIAL FOR CONVECTION
INDUCED BY DIURNAL HEATING WITH WARM TEMPS IN SOGGY AMS CRANKED OUT
BY MODELS' SOLUTIONS...ANALYSIS OF 305-310K ISENTROPIC DATA SUGGESTS
SOME WEAK LIFT OVER THIS REGION. EVENT'S OVER BY 00Z MON AS AMS
DRIES OUT APPRECIABLY AND DOWNGLIDE PATTERN SETS UP OVER AREA. BY
12Z MON...HIGH PRESSURE DOMINATES WEATHER. EXPECT FAIR CONDITIONS
EVERYWHERE AFT 00Z MON WITH PARTLY SUNNY SKIES BY 18Z MON.

QPF DISCUSSION: PRECIPITABLE H2O AMOUNTS OF 1.25" TO 1.50" ROUGHLY
ALONG MISSISSIPPI RIVER WITH GOOD LOW LEVEL SURGE OF GULF MOISTURE
SHOULD MAKE PRECIPITATION MORE DIURNAL IN NATURE OVER NEXT DAY OR
SO. BEST CONCENTRATED RAIN AMOUNTS SHOULD OCCUR IN WESTERN ZONES
WHERE MULTIPLE OUTFLOW BOUNDARIES AND SOME WEAKENING UPPER SUPPORT
PERSIST FOR ABOUT 24 HOURS LONGER. TROPICAL RAINS IN THE SOUTHEAST
PORTIONS SHOULD DIE WITH SUNSET. WILL GENERALLY INDICATE .25 TO .50
INCH AMOUNTS...LOCALLY HIGHER IN ARKLAMS REGION.

IN THE EXTENDED...MON LOOKS LIKE GENERALLY FAIR CONDITIONS IN PLACE
IN 12Z RUNS OF NOGAPS/ECMWF...ALONG WITH LAST RUN OF MRF. BY 12Z MON
(96 HRS) IN ECMWF AND NOGAPS CHANGES BEGIN AS NEXT LOW PRESSURE
SYSTEM BECOMES ESTABLISHED OVER CENTRAL PLAINS. BY 12Z TUE INTO WED
...LOW-LEVEL MOISTURE INCREASES IN SLY FLOW FROM GLFMX AHEAD OF THIS
NEXT BOUNDARY AND UPPER LEVEL SYSTEM. BY 12Z WED...APPEARS CDFNT
EXTENDS THROUGH THE ARLATX AND APPROACHING CWFA.

PRELIM NUMBERS...
JAN 65/86 65/87 3322
MEI 63/86 64/87 3222

.JAN...
MS...NONE.
AR...NONE.
LA...NONE.
05/16

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
060400-

AREA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
1015 AM CDT FRI MAY 5 2000

AN UPPER LEVEL LOW PRESSURE SYSTEM MOVING SLOWLY NORTHWEST ACROSS
THE OZARKS WILL GRADUALLY TAKE MOISTURE AWAY FROM THE LOWER
MISSISSIPPI VALLEY. HOWEVER...THE AIRMASS SHOULD REMAIN UNSTABLE
ENOUGH TO SUPPORT SCATTERED THUNDERSTORMS ESPECIALLY DURING THE
AFTERNOON AND EVENING HOURS. A SLIGHT INCREASE IN LOW LEVEL WINDS
ALONG WITH THE DIURNAL HEATING SHOULD SET OFF THE STORMS MAINLY
ALONG AND WEST OF A GRENADA TO JACKSON TO HATTIESBURG LINE THROUGH
ABOUT 10 PM.

LOCALLY HEAVY RAINFALL AND FREQUENT LIGHTNING STRIKES WILL DEVELOP
WITH ISOLATED CASES OF HAIL OR STRONG GUSTY WINDS. IN AREAS WHERE
RAINFALL BECOMES PERSISTENT...LOCALIZED FLOODING COULD DEVELOP
ESPECIALLY IN THE DELTA REGION.

ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS
...AND EMERGENCY
MANAGEMENT PERSONNEL SHOULD NOT BE NEEDED THIS AFTERNOON THROUGH
TONIGHT.

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