Severe Thunderstorm Warning 93, NWS Paducah, KY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
200 PM CDT MON MAY 22 2000

PRIMARY FORECAST CHALLENGE IS LATE PM-EVENING TSM CHANCES AND THEIR
OVERNIGHT EVOLUTION. CURRENT SATELLITE IMAGERY REVEALS ENHANCED IR
TOPS FM GREAT LAKES TO HIGH PLAINS STATES...IN VCNTY OF SURFACE TROF
WHICH SEPARATES L60S TDS FM M-U50S TDS. 12Z UA ANALYSIS REVEALS PAH FA
IN H8 10C TDD ZONE...WHILE SURFACE TDS ARE IN L60S IN OPEN SW LOW
LAYER FLOW. FLOW ALOFT IS NWLY WITH INCOMING NOSE OF 30-40KT WINDS
NOTED AT H5.

NGM/ETA ARE COMING INTO AGREEMENT THAT AS PLAINS TROF SWINGS
SE...PARAMETERS WILL COME TOGETHER OVER PAH FA FOR POSSIBLE
EVOLUTION OF TSM COMPLEX IN LOWER OH VALLEY TONIGHT. OPEN SW FLOW FM
SURFACE-H8 PROVIDES AMPLE LOW LAYER MOISTURE...AND APPROACHING WEAK
SURFACE TROF SHOULD AID CONVERGENCE. NW FLOW PERTURBATION SHOULD
GREATLY ENHANCE UVM FIELD AS IT SWINGS INTO PLAY LATER TONIGHT...AND
PUSHES DEVELOPING COMPLEX EAST...THEREBY DIMINISHING POPS TUE AM.
THAT DIMINISHED POP SHOULD ONLY BE TEMPORARY...AT LEAST UNTIL PM
HOURS TUE...WHEN TRAILING FRONT IS DRAGGED SLOWLY INTO PAH FA LATE
TUE-TUE NIGHT AS PARENT LOW MOVES ACROSS NRN GREAT LAKES.

MODELS THEN BEGIN TO WAFFLE ON HOW FAR SOUTH TO TAKE FRONT...AS
HINTS OF DEVELOPING SRN PLAINS LOW STALLS BOUNDARYS SOUTHWARD
PROGRESSION. 12Z AVN IS A LITTLE QUICKER THAN ITS PREDECESSOR AND
MRF...SUGGESTING LINGERING OF POP SRN PTNS FA THRU WED...WITH FRONT
STALLING JUST TO THE SOUTH OF THE FA BY WED NIGHT-THU. WL THEREFORE
ATTEMPT TO ACCOMODATE THIS TWEEK IN POP TIMING IN EXTENDED PTN
FCST...WITH RE-INTRO OF POP STILL SLATED FOR FRIDAY WHEN SAID BOUNDARY
RETURNS NWARD AS WARM SECTOR.

FWC HAS PERFORMED WELL LAST 24 HOURS...SO WL FOLLOW FAIRLY CLOSELY.
IT SUGGESTS WE MAY APPROACH RECORD HIGHS TOMORROW...BUT PROBABLY NOT
EXCEED (92 PAH/95 EVV).

.PAH...NONE.
DH

ILZ075>078-080>094-INZ081-082-085>088-KYZ001>022-MOZ076-086-087-100-
107>112-114-221830-

THUNDERSTORM OUTLOOK...VALID UNTIL 600 AM TUESDAY
NATIONAL WEATHER SERVICE PADUCAH KY           SOUTHEAST MO/SOUTH IL
1133 AM CDT MON MAY 22 2000                     SOUTHWEST IN/WEST KY

THERE IS A SLIGHT CHANCE OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
TONIGHT OVER PORTIONS OF SOUTHEAST MISSOURI...SOUTHERN ILLINOIS...AND
SOUTHWEST INDIANA. THE CHANCE OF THUNDERSTORMS THIS AFTERNOON IS
MAINLY ALONG AND NORTH OF A LINE FROM POPLAR BLUFF MO THROUGH
HARRISBURG IL TO JUST EAST OF EVANSVILLE IN.

BY TONIGHT THE SLIGHT RISK OF SEVERE THUNDERSTORMS WILL ENCOMPASS THE
ENTIRE QUAD STATE AREA...INCLUDING ALL OF SOUTHERN ILLINOIS...
SOUTHEAST MISSOURI...SOUTHWEST INDIANA...AND WESTERN KENTUCKY.

HIGH PRESSURE SHIFTED JUST EAST OF THE AREA LAST NIGHT. THIS WILL
ALLOW A SLOW MOVING TROUGH...CURRENTLY EXTENDING FROM THE GREAT LAKES
TO THE TEXAS PANHANDLE...TO MOVE INTO THE REGION LATE THIS AFTERNOON
INTO TONIGHT. A STRONG SOUTHWEST FLOW AT THE SURFACE WILL ADVECT LOW
LEVEL MOISTURE INTO THE AREA. AS THE TROUGH APPROACHES THE REGION IT
WILL TAP INTO THE POOL OF MOISTURE. THESE PARAMETERS COMBINED WITH A
MODERATELY UNSTABLE ATMOSPHERE WILL SET THE STAGE FOR THUNDERSTORM
DEVELOPMENT...SOME OF WHICH MAY BECOME SEVERE.

A LIMITING FACTOR FOR SEVERE STORM DEVELOPMENT WILL BE
THE LOSS OF DAYTIME HEATING...AS THE BETTER CHANCE FOR PRECIPITATION
WILL BE AFTER SUNSET WHEN THE TROUGH MOVES IN. WIND SHEAR WILL BE
MINIMAL THROUGHOUT THE COLUMN WHICH WILL KEEP THE THREAT FOR TORNADIC
STORMS LOW.

THE DEVELOPING WIND FIELD WILL FAVOR TRAINING OF THUNDERSTORM
CELLS...WHICH MAY RESULT IN EXCESSIVE RAINFALL.

THE BEST TIMING FOR THUNDERSTORM DEVELOPMENT WILL BE LATE THIS
AFTERNOON OVER PORTIONS OF SOUTHEAST MISSOURI...SOUTHERN ILLINOIS...
AND SOUTHWEST INDIANA...THEN SPREADING OVER THE REST OF THE AREA...
INCLUDING KENTUCKY...AFTER SUNSET.

MOVEMENT OF STORMS WILL BE EAST AROUND 30 MPH.

SPOTTER ACTIVATION MAY BE REQUESTED BY LATE AFTERNOON AND OVERNIGHT.
EMERGENCY PERSONNEL SHOULD MONITOR NOAA WEATHER RADIO OR YOUR LOCAL
MEDIA OUTLET FOR ADDITIONAL STATEMENTS OR POSSIBLE WARNINGS
CONCERNING THE POTENTIAL FOR SEVERE WEATHER.

HOOPER