Tornado Warning 3, NWS Paducah, KY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
200 PM CST THU JAN 21 1999

LATEST SURFACE ANALYSIS SHOWS AN AREA OF LOW PRESSURE OVER OKLAHOMA
WITH A WARM FRONT EXTENDING ACROSS CNTRL MO AND SRN IL INTO NW KY.
AIRMASS SOUTH OF THIS FRONT HAS BECOME MODERATELY UNSTABLE.
TEMPERATURES AND DEWPOINTS IN THE 60S HAS RESULTED IN SURFACE-BASED
CAPE VALUES OF 500 TO 1500 J/KG.  12Z UA SOUNDINGS SHOWED AIRMASS
WAS STRONGLY CAPPED.  HOWEVER...UPWARD VERTICAL MOTIONS ASSOCIATED
WITH MID-LEVEL SHORTWAVE TROF MOVING ACROSS THE PLAINS HAS RESULTED
IN CAP WEAKENING.  THIS IS SEEN IN 18Z LZK AND JAN SOUNDINGS.

SHOWERS AND THUNDERSTORMS ARE ONCE AGAIN BEGINNING TO DEVELOP ACROSS
PORTIONS OF FA...GENERALLY INVOF WARM FRONT.  WITH INSTABILITY IN
PLACE AND CONTINUED UPWARD VERTICAL MOTION EXPECTED OVER REGION...
EXPECT ADDITIONAL STORMS WILL DEVELOP WITH SOME OF THESE STORMS
POSSIBLY BECOMING SEVERE.

MODELS INDICATE THE SHORTWAVE TROF WILL SLOWLY NORTHEAST AWAY FROM
REGION WHILE A SECOND STRONGER SHORTWAVE TROF DROPS INTO THE
LONGWAVE TROF THAT HAS ALREADY DEVELOPED OVER THE SOUTHERN PLAINS.
THIS SECOND SHORTWAVE TROF WILL THEN ROTATE EWD TOWARD THE FA FRI
AND SATURDAY.  AS A RESULT...A COLD FRONT WILL SWEEP ACROSS THE
REGION FRI AFTN INTO FRIDAY NIGHT.  MODELS CONTINUE TO SHOW A DRY
PUNCH WILL MOVE ALSO INTO THE REGION LATE FRIDAY AFTN/EVENING.  WITH
INSTABILITY EXPECTED TO REMAIN IN PLACE AND WIND FIELDS ALSO
EXPECTED TO INCREASE...BELIEVE THREAT OF SEVERE THUNDERSTORMS WILL
INCREASE AS FRONT AND DRY PUNCH MOVE INTO REGION.

CLOUDS SHOULD CONTINUE ACROSS THE FA UNTIL SATURDAY WITH WRN
PORTIONS OF FA BEGINNING TO SEE SOME SUN BY EARLY SAT AFTN.  A FEW
SHOWERS MAY ALSO CONTINUE...MAINLY OVER NRN AND ERN SECTIONS OF FA
EARLY SATURDAY.

FWC/FAN TEMPERATURE GUIDANCE ARE IN CLOSE AGREEMENT.  HOWEVER...
BELIEVE LOWS TONIGHT WILL BE WARMER THAN GUIDANCE ACROSS SRN
SECTIONS OF FA AS DEWPOINTS ARE CURRENTLY APPROACHING THE 60S.
HIGHS TOMORROW MAY ALSO BE A FEW DEGREES WARMER THAN GUIDANCE.

WILL HOLD OFF ON FLASH FLOOD WATCH ATTM AS CURRENT THINKING IS THAT
HEAVY RAINS SHOULD GENERALLY BE FRIDAY AND FRIDAY NIGHT.

.PAH...NONE.

JH/JK

ILZ075>078-080>094-INZ081-082-085>088-KYZ001>022-MOZ076-086-087-100-
107>112-114-211857-

THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE PADUCAH KY
1057 AM CST THU JAN 21 1999

THE ENTIRE QUAD-STATE REGION OF SOUTHEAST MISSOURI...SOUTHERN
ILLINOIS...SOUTHWEST INDIANA AND WESTERN KENTUCKY IS UNDER A SLIGHT
RISK FOR SEVERE THUNDERSTORMS THROUGH FRIDAY.

A WARM FRONTAL BOUNDARY WHICH MOVED THROUGH THE REGION WITH WIDELY
SCATTERED THUNDERSTORMS EARLY THIS MORNING WILL CONTINUE TO PUSH
NORTH INTO NORTHERN ILLINOIS AND INDIANA TODAY.  ALTHOUGH MODERATE
INSTABILITY EXISTS SOUTH OF THE FRONT ACROSS OUR AREA...WARM
TEMPERATURES ALOFT ARE HELPING TO CAP THUNDERSTORM DEVELOPMENT FOR
THE TIME BEING.  BREAKS IN THE CLOUDS THIS AFTERNOON COULD HELP TO
WEAKEN THE CAP...RESULTING IN SOME WIDELY SCATTERED LATE AFTERNOON
AND EARLY EVENING THUNDERSTORMS.  WITH LOW LEVEL WINDS INCREASING
TONIGHT AND BETTER DYNAMICS APPROACHING FROM THE WEST...MORE
WIDESPREAD THUNDERSTORMS ARE LIKELY.  THE MAIN THREAT FROM ANY STORMS
THAT DEVELOP THROUGH FRIDAY MORNING WILL BE LARGE HAIL.  THE STORMS
WILL MOVE TOWARD THE NORTHEAST AROUND 35 MPH.

ON FRIDAY...AN UPPER LEVEL STORM SYSTEM WILL SWING TOWARD THE
MISSISSIPPI VALLEY.  THIS WILL LIKELY RESULT IN THE DEVELOPMENT OF A
SQUALL LINE TO OUR WEST AND SOUTHWEST FRIDAY AFTERNOON.  THIS SHOULD
THEN PROGRESS NORTHEAST TOWARD THE QUAD-STATE LATER FRIDAY AFTERNOON
AND EVENING.

SPOTTER ACTIVATION MAY BE REQUIRED LATER THIS AFTERNOON AND
TONIGHT...WITH LIKELY ACTIVATION BY LATER FRIDAY.

JK/JH