Severe Thunderstorm Warning 330, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
305 AM CDT FRI MAY 5 2000

UPPER LOW OVER WRN ARKANSAS WILL CONTINUE TO FILL THROUGH TONIGHT...
THEN SLOWLY GET ABSORBED INTO NRN JET STREAM BY SAT NIGHT/SUNDAY AS
WESTERN U.S TROUGH ON WATER VAPOR DAMPENS OUT OVER ROCKIES AS UPPER
RIDGE BUILDS OVER THE SOUTHERN HIGH PLAINS. BOUNDARY OVER WESTERN CWFA
THAT HAS BEEN AROUND THE PAST SEVERAL DAYS NOW LOOKS TO HAVE NEARLY
DISSOLVED OUT PER MSAS LI/SURFACE PRESSURE/MOISTURE CONVERGENCE DATA.

SHORTWAVES OF MODERATE MAGNITUDE WILL CONTINUE TO ROTATE AROUND THE FILLING
LOW FROM NE TEXAS THROUGH NRN LOUISIANA...INTO CENTRAL ARKANSAS THROUGH
TONIGHT WITH A WEAKER SHORTWAVE MOVING OVER SOUTHERN ZONES ON SATURDAY.
PREFER THE AVN MODEL WITH SHORTWAVE/QPF LOCATIONS/TIMING...ALBEIT ALL
MODELS WERE OVERDONE ON PRECIPITABLE WATERS. FLASH FLOOD WATCH OVER
NW ZONES WILL BE ALLOWED EXPIRE THIS MORNING. HEAVY RAIN THREAT LOOKS
TO BE MORE ISOLATED COMPARED TO PREVIOUS DAYS WITH AFOREMENTIONED
MESOSCALE BOUNDARY MUCH LESS DEFINED...BUT THIS AREA WILL NEED TO BE
WATCHED CLOSELY BY DAYSHIFT. TRENDING RAIN CHANCES NW-E/SE TODAY IN
REFERENCE TO UPPER LOW POSITION...300-310K ISENTROPIC TRENDS AND 700
MB OMEGA FIELDS. ALSO...WILL HIT THUNDER WORDING HARDEST OVER THE WEST
THROUGH SATURDAY CLOSER TO WHERE LI/S OF (-3-(-6))...CAPES (1000-2000
J/KG) AND FORCING FROM RIGHT ENTRANCE REGION OF WANING 250 MB JET MAX
WILL EXIST. ALL IN ALL...CONVECTION WILL BECOME MORE HIT N' MISS AND
DIURNALLY DRIVEN IN THE AFTERNOONS THROUGH THIS WEEKEND AS SYSTEM OVER
ARKANSAS FINALLY OPENS AND LIFTS INTO MO/IL.

TEMPERATURES WARMED YESTERDAY MORE THAN EXPECTED DUE TO INSOLATION
AS SHORTWAVE OUT WEST SLOWED UP. LOW LEVEL THICKNESSES SHOW WE WILL
BE AS WARM IF NOT A LITTLE WARMER TODAY AND SATURDAY. BOTH FAN/FWC
MOS ARE IN THE BALLPARK ON LOWS/HIGHS AND SEE NO REASON TO STRAY.

QPF DISCUSSION: HAVE GOOD INSTABILITY...PRECIPITABLE H2O AMOUNTS OF
1.10" TO 1.25" IN AXIS ALONG MISSISSIPPI RIVER...AND SHORTWAVE
SWINGING THROUGH. WILL PAINT HIGHER AMOUNTS ALONG AXIS OF BEST
INSTABILITY... LEANING TOWARDS AVN AMOUNTS AND PLACEMENT. BEST
AMOUNTS LOOK TO BE NORTHWESTERN ZONES...LEAST...SOUTHEAST.

IN THE EXTENDED...SOME DIFFERENCES IN MEDIUM RANGE MODELS (MAINLY
AVN/CANADIAN) FOR SUNDAY WITH CANADIAN DRYING THINGS OUT BUT AVN/MRF
HOLDING TO SOME SMALL CHANCES OVER WESTERN SECTIONS. WITH CONFIDENCE
LOW ON WHAT THIS WEAKENING SYSTEM WILL DO...WILL JUST HOLD TO CURRENT
EXTENDED THOUGHT.

PRELIM NUMBERS...
JAN 83/65/85/64 3231
MEI 85/63/86/62 2232

.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