Severe Thunderstorm Warning 103, NWS Jackson, KY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
240 PM EDT THU AUG 23 2001

...UPDATED ZONES TO INCLUDE SEVERE THUNDERSTORM WATCH UNTIL 9 PM.
ALSO TWEAKED HIGH AFTERNOON TEMPS UP A CATEGORY. HAVE ALSO DECIDED
TO ISSUE A FLASH FLOOD WATCH FOR THE ENTIRE CWA...APPEARS BEST
THREAT WILL BE THE NORTHERN ZONES EARLY AND THE SOUTHERN ZONES LATE
SO DECIDED TO JUST GO AHEAD AND ISSUE FOR ENTIRE CWA. THE REST IS
THE SAME AS FOLLOWS BELOW...HALL

MAIN FCST CONCERN IN THE SHORT TERM IS HEAVY RAINFALL POTENTIAL THIS
EVENING AS WELL AS SEVERE TSRA. FCST SOUNDINGS AND SFC OBS SHOWING
THE AIRMASS BECOMING INCREASING UNSTABLE WITH VERY HIGH CAPES (NEAR
4000 J/KG ACCORDING TO THE MESOETA SOUNDINGS) AND LI INDICES TO NEAR
-8 THIS AFTERNOON. PWS ALSO INCR TO A LITTLE OVER 2.0 INCHES. HIGH
THETA-E AIR MOVING IN ALSO. SFC DEWPOINTS INCR INTO THE LOWER AND
MIDDLE 70S. A DEFINITE LOW LEVEL BNDRY IS MISSING HOWEVER TO HELP
FOCUS HEAVY RAINS. FEELING AT THIS TIME IS THAT STORMS/THE EVENT MAY
START OFF AS A SEVERE EVENT AND THEN AT LEAST TRY TO TURN INTO A
HEAVY RAIN EVENT. THE BIGGEST CHALLENGE AT THE MOMENT IS WHETHER OR
NOT TO ISSUE A FLASH FLOOD WATCH AND HOW MUCH SEVERE ACTIVITY WE
WILL SEE THIS AFTERNOON/EVENING. AS LONG AS THE STORMS MOVE RIGHT
ALONG WE ARE PROBABLY OK ALONG WITH RELATIVELY (EMPHASIS ON
RELATIVELY) HIGH FLASH FLOOD GUIDANCE VALUES. ON THE OTHER HAND...IF
TRAINING SETS UP THEN WE COULD GET INTO TROUBLE QUICKLY.

SFC CHART SHOWING A WEAK/DIFFUSE BNDRY NEAR THE OHIO RIVER BUT THE
MAIN FRONT IS FURTHER NORTH ACROSS FAR N OH/IN/IL. 8H CHART ALSO
SHOWS THE FRONT IN THE SAME LOCATION AND THE CHART ARGUES THAT THE
BNDRY MAY NOT MOVE AS FAR SOUTH AS FAST AS THE MODELS ARE ALL
INDICATING THAT IT WILL. (SOME CONCERN OVER THE BNDRY GETTING HUNG
UP DURING THE MIDDLE OF THE NIGHT OVER THE CENTRAL-SOUTHERN CWA AND
HELPING TO FOCUS TSRA/TRAINING OF CELLS). ETA MODELS AND TO SOME
EXTENT THE NGM ARE HITTING THE PCPN AND BEST LIFT THE HARDEST LATE
THIS AFTERNOON AND EVENING AND MAINLY OVER THE SOUTHERN 1/2 OF THE
CWA. HOWEVER THE LATEST RADAR AND SAT PICS INDICATE THAT THE STORMS
ARE NOW BEGINNING TO FIRE ALONG THE OLD BNDRY NEAR THE OHIO RVR. THE
AVN MODEL LOOKS RATHER WEAK ON THE WHOLE SYSTEM WITH MOST EMPHASIS
BEING PLACED OVER KS AND MO/IL SO WILL LEAN MORE TOWARD THE ETA
MODELS FOR THIS PACKAGE.

SHORT TERM SENSIBLE...DEBATING ON LIKELY POPS FOR THE WHOLE CWA
TONIGHT ALTHOUGH POPS MAY NEED TO BE LOWERED ACROSS THE NORTH AS THE
NIGHT WEARS ON. WITH PRETTY GOOD SVR STORM POTENTIAL WILL USE STRONG
WORDING IN THE ZONES ALONG WITH LOCALLY HEAVY RAINS POSSIBLE. WILL
MAKE A LAST MINUTE DECISION ON FLASH FLOOD WATCH. WHILE THE BEST
THREAT AREA APPEARS TO BE OVER THE SOUTHERN 1/2 OF THE CWA...THE
NORTHERN HALF WILL MOST LIKELY SEE THE BULK OF THE STORMS EARLY ON
SO IF WE GO WITH A FFA WE MAY HAVE TO GO FOR THE WHOLE CWA.

EXPECT MOST OF THE ACTIVITY TO MOVE THRU THE CWA DURING THE
LATE-OVERNIGHT BUT WOULD EXPECT SOME LINGERING SHRAS IN THE MORNING
OVER THE SOUTHERN ZONES. THEN SKIES SHOULD BECOME PC CWA WIDE ON
FRIDAY WITH TEMPS IN THE MID 80S. PC FRIDAY NIGHT. NEXT WAVE OF
ACTIVITY PUSHES BACK TOWARD THE CWA ON SAT BUT FEEL THAT IT WILL BE
SAT NIGHT BEFORE ANY PCPN MAKES IT THIS FAR EAST. THEREFORE WILL GO
WITH CHC POPS THEN.

EXTENDED...AVN/MRF/ECMWF ARE IN REASONABLE AGREEMENT OVERALL. WILL
KEEP CHC POPS GOING FOR SUNDAY. NEW AVN RUN IS SLOWER WITH THE NEXT
UPPER TROFF/SFC SYSTEM TO MOVE THRU THAN THE MRF IS. WILL THEREFORE
KEEP A MENTION OF POPS ON MONDAY ALSO. WILL GO WITH PC BUT DRY
TUE-THUR. NOT REAL TRUSTING OF THE SYSTEM THAT THE MRF GENS UP
THUR-FRI FROM THE SOUTH AND SPREADS PCPN N-NE. SOME OF THAT COULD
MAKE IS HERE BY THUR NIGHT IF ITS FOR REAL...WILL HAVE TO WAIT AND
SEE. LOWS OF 60-65 AND HIGHS 80-85 SHOULD WORK THRU THE PERIOD.

NGM/MAV MOS VERY SIMILAR AND DONT PLAN ON DEVIATING MUCH AT ALL.
WORK ZONES OUT BEFORE TOO LONG UNDER SDFOZFJKL. COORDINATION WELCOME.

THANKS TO MRX/CRW AND HPC FOR COORDINATION TODAY.

SPS HAS BEEN ISSUED FOR SLIGHT RISK OF SEVERE THUNDERSTORMS AND HVY
RAIN POTENTIAL.

.JKL...NONE.

HALL

KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120-240200-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE JACKSON KY
1212 PM EDT THU AUG 23 2001

...SEVERE THUNDERSTORMS AND HEAVY RAINS POSSIBLE THIS AFTERNOON AND
EVENING IN EASTERN KENTUCKY...

THE STORM PREDICTION CENTER IN NORMAN, OKLAHOMA...INDICATES THAT
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER ALL OF EASTERN
KENTUCKY THIS AFTERNOON AND EVENING.  THE PRIMARY THREAT WILL BE
DAMAGING WINDS...BUT LARGE HAIL CANNOT BE RULED OUT.

A COLD FRONT...EXTENDING FROM ILLINOIS...EASTWARD INTO NORTHERN OHIO...
WILL SLOWLY MOVE SOUTH TOWARD KENTUCKY THIS AFTERNOON AND EVENING.  THE
COMBINATION OF DAYTIME HEATING...AND SEVERAL UPPER LEVEL DISTURBANCES
MOVING THROUGH THE OHIO VALLEY...WILL CAUSE THUNDERSTORMS TO DEVELOP
THIS AFTERNOON AND EVENING. SOME OF THE STORMS COULD BECOME SEVERE
THIS AFTERNOON AND EVENING AND PRODUCE DAMAGING WIND GUSTS AND LARGE
HAIL.

HEAVY RAIN IS ALSO POSSIBLE TONIGHT OVER EASTERN KENTUCKY AS SHOWERS
AND THUNDERSTORMS WILL DEVELOP AND MOVE SOUTHEAST OVER THE SAME
AREAS. THE GREATEST THREAT FOR HEAVY RAINS APPEARS TO BE SOUTH OF A
PRESTONSBURG TO JACKSON TO SOMERSET LINE. LOCALIZED RAINFALL OVER
TWO INCHES IN AN HOUR WILL BE POSSIBLE AND THIS COULD LEAD TO FLASH
FLOODING OF SMALL STREAMS AND CREEKS.

PLEASE STAY TUNED TO NOAA WEATHER RADIO AND OTHER LOCAL MEDIA FOR FURTHER
DETAILS OR UPDATES.

FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT
HTTP://WWW.CRH.NOAA.GOV/JKL

PELTON