Severe Thunderstorm Warning 199, NWS Jackson, KY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
155 PM EDT WED SEP 20 2000

COMPLEX WEATHER PATTERN NEXT FEW DAYS AT LEAST. SHORT TERM PROBLEMS
INCLUDE CHCS FOR SVR WEATHER/SQUALL LINE DEVELOPMENT, TIMING OF THE
FRONT TONIGHT AND LINGERING SHOWERS IN THE MORNING. NEXT PROBLEMATIC
AREA COMES ALONG ABOUT FRIDAY WITH MOISTURE ADVECTING NWRD FROM
REMNANTS OF WHAT IS NOW TD#12. THEN SOME TIMING DIFFERENCES WITH THE
NEXT FROPA ALONG ABOUT SUNDAY. OVERALL THE MODELS ARE IN DECENT
AGREEMENT BUT DO HAVE TIMING DIFFERENCES. WILL GO WITH THE
ETA/MESO-ETA IN THE SHORT TERM...WILL LEAN A LITTLE MORE TOWARD THE
ECMWF OVER THE MRF IN THE EXTENDED.

LATEST SFC CHART SHOWING THAT THE COLD FRONT TO OUR NW HAS NOT MOVED
VERY MUCH OVER PAST 12 HOURS OR SO BUT SHOULD BEGIN TO ACCELERATE
AND MOVE ACRSS THE STATE TONIGHT. 8H/5H CHARTS ALONG WITH OTHER
MODEL DATA INDICATES THAT THIS IS A PRETTY DYNAMIC SYSTEM FOR THIS
TIME OF THE YEAR. 8H AND SFC MOISTURE HAS RAPIDLY INCREASED THRU THE
MORNING HOURS AND SFC CHART SHOWING A LARGE AREA OF 70+ DEWPOINTS TO
OUR SOUTH. SAT PICS SHOW THAT A LARGE CU AND AC FIELD HAVE ALSO
EXPLODED INTO EXISTENCE OVER MOST ALL OF TN AND KY. THINKING ATTM IS
THAT THIS FIELD MAY RESTRICT/LIMIT SVR THREAT OVER E KY TO SOME
EXTENT. RADARS SHOWING THAT SCT SHOWERS HAVE ALREADY DEVELOPED OVER
PORTIONS OF KY INCLUDING A FEW IN OUR CWA. THE SHOWERS ARE MOVING
RAPIDLY TO THE NE.

SQUALL LINE WILL STILL LIKELY FORM THIS AFTERNOON OVER THE MDT RISK
AREA AS INDICATED BY LATEST SPC PRODUCTS...MOVE EAST TONIGHT AND
WEAKEN AS IT MOVES ACRSS THE CWA. FCST SOUNDINGS ONLY SHOWING MDT
INSTABILITY DESPITE INCR RH AND PWS. STRONG SPEED SHEAR NOTED IN THE
LOWER LEVELS. WE ARE NOT VERY EXCITED ABOUT A LATE NIGHT SEVERED
THREAT.

SHORT TERM...WILL GO WITH LIKELY POPS TONIGHT. STILL DEBATING ON HOW
TO HANDLE TIMING OF THE FRONT/ZONE BREAK UP AND SVR THREAT. MODELS
HAVE BEEN CONSISTENT INDICATING THAT THE BEST LIFT WILL BE BETWEEN
06-12Z TNGHT ALONG WITH FROPA DURING THAT SAME GENERAL TIME FRAME.
HEAVY RAINS NOT TOTALLY OUT OF THE QUESTION EITHER BUT FEEL THAT FAST
MOVEMENT OF THE CELLS SHOULD LIMIT AMOUNTS. SOME STRATIFORM RAIN
BEHIND THE FRONT WILL LIKELY LINGER INTO THE EARLY MORNING
HOURS...BUT NONE OF THE PCPN SHOULD POSE ANY WIDESPREAD FLOODING
PROBLEMS CONSIDERING HOW DRY IT HAS BEEN OF LATE. 3HR FFG VALUES
AVERAGING AROUND 3 INCHES WHICH IS ABOUT AS HIGH AS THEY HAVE BEEN
ALL SUMMER.

WILL HAVE TO HOLD ONTO SOME LOW CHC POPS IN THE MORNING ESP IF ETA
PACKAGES ARE RIGHT. SLOW CLEARING AS THE DAY PROGRESSES.

MODELS ARE NOW COMING INTO HALF DECENT AGREEMENT THAT REMNANTS OF
TD#12 WILL MOVE ONSHORE SOMEWHERE OVER W FL PANHANDLE/AL AND THEN
MOVE NORTHWARD. NOT GOING TO GO HOG-WILD JUST YET ON THE POPS BUT
WILL GO MC ON FRI WITH SOME CHC POPS.

EXTENDED...MRF IS SLOWER THAN ECMWF/UKMET..ETC...IN MOVING THE NEXT
FROPA ACRSS THE CWA SUNDAY. WILL GO AHEAD AND INTRODUCE A CHC OF
SHRA/TSRA ON SAT AND HOLD ONTO IT FOR SUNDAY AS WELL BUT IF THE
FASTER EURO MODEL IS RIGHT IT MAY BE EAST OF US BY SUNDAY. WILL GO
PC AND COOLER ON MONDAY.

NGM/AVN MOS NUMBERS QUITE A BIT WARMER THAN FAN NUMBERS SO WILL MOST
LIKELY GO WITH A BLEND. POPS SEEM TO BE IN THE BALLPARK.

WORK ZONES OUT SHORTLY UNDER SDFOZFJKL. COORDINATION WELCOME.

.JKL...FIRE WEATHER WATCH ALL ZONVES FOR GUSTY WINDS THROUGH 21/0200Z.

HALL