Severe Thunderstorm Warning 67, NWS Paducah, KY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
209 PM CDT TUE APR 23 2002

MAIN FORECAST CHALLENGES WILL BE WITH TIMING AND INTENSITY
OF WARM FRONT/MCS CONVECTION OVERNIGHT AND WITH COLD FRONT WED
AFTERNOON.

CURRENT SATELLITE AND RADAR TRENDS SHOW DECAYING REMANTS /ANVIL
RAIN/ OF THIS MORNINGS MCS OVER WRN TN...WITH MAIN SFC WARM FRONT
ALONG SRN OK/AR AT 18Z. COLD POOL FROM AM CONVECTION RETARDING
SURFACE-BASED MOISTURE INFLUX.   THE DEQUEEN AR PROFILER...LOCATED
ON THE SOUTHERN END OF THE COLD POOL /LOWEST 1KFT UNDER NELY WINDS/
SHOWS DEEP MOISTURE IN PLACE /SFC-700 MB/. BLOOMFIELD MO ALSO SHOWS
DECENT MSTR MOVING BACK NEWD BTWN 650-700 MB UNDER W-SLY WINDS
15-25KT. AS THE AFTERNOON PROGRESSES...MOISTURE SHOULD EXPAND
DOWNWARD...AS ELEVATED WARM FRONTAL BOUNDARY MOVES TWD S CNTRL MO
AND NWRN TN OVERNIGHT.

ETA AND AVN ARE SIMILAR IN WIND SPEED AND STRENGTH...WITH ETA HAVING
SLIGHTLY HIGHER WINDS W-NWLY /45-50 KTS/ BTWN 500-600 MB THIS AFTN
ACROSS AR. SUSPECT CAPPING WILL STAY IN PLACE THROUGH MOST OF THE
EVENING FURTHER NEWD ACROSS THE PAH FORECAST AREA...WITH RAPID
DESTABILIZATION FROM LATE EVENING ON OVER SERN MO. BOTH ETA AND AVN
SEEM TO BE A LITTLE SLOW IN THE NWD TRANSLATION OF THE WARM FRONTAL
BOUNDARY IN THE LOWER MS VALLEY GIVEN THE FASTER FLOW ALOFT.

WILL CONSIDER A SLIGHTLY SLOWER TIMING OF PCPN DEVELOPMENT OVER WARM
FRONT THIS EVENING AS ADVERTISED...PROBABLY KEEPING MOST OF THE
SIGNIFCANT PCPN OUT OF THE NERN HALF OF THE CWA BEFORE DAYBREAK.

AT THIS TIME...EXPECT SHOWERS AND SCATTERED THUNDERSTORMS TO DEVELOP
IN MARGINAL INSTABILITY ALOFT FOR THE OVERNIGHT HOURS.

THE BIG KEY TO THE FORECAST OF LATE MORNING/EARLY AFTERNOON
CONVECTION WILL BE THE DEGREE OF CLEARING OF CLOUD DECK BEHIND ANY
WARM FRONTAL PCPN AND PROJECTED MCS FROM THE MID-MS VALLEY /SEE SPC
DAY TWO DISC/. THE DEGREE OF CLEARING WILL ONLY AID IN THE
DIFFERENTIAL HEATING AND INSTABILITY OF PARCELS LIFTED AHEAD OF THE
COLD FRONT THAT WILL SHARPEN AS THE DAY PROGRESSES/ Q SUB N DIV AND
FRONTOGENETIC FORCING SHARPEN IN THE 1000-850 MB FROM WED 18Z TO THU
00Z/. GIVEN DECENT 30-50KT W-SWLY SHEAR...INSTABILITY/LIS -6 TO -10/
AND DECENT CONVERGENCE...AGREE WITH SPC ASSESSMENT OF SQUALL LINE
DEVELOPMENT AND DAMAGING WIND POTENTIAL. IF AVN PANS OUT...SQUALL
ACTIVITY SHOULD MOVE INTO SERN MO/SRN IL +/- 2 HOURS FROM 18Z
/DEPENDING ON SFC HEATING/...THEN MOVE QUICKLY ACROSS THE ENTIRE CWA
BY 03Z THU.

WILL NOT MAKE ANY SIGNIFICANT CHANGES TO EXTENDED...WITH THE
EXCEPTION OF ADDING A CHANCE OF SHRA/TSRA ON MONDAY.

.PAH...NONE.

SMITH