Severe Thunderstorm Warning 199, NWS Jackson, KY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
300 PM EDT SAT JUL 17 2004

.DISCUSSION...

MAIN FORECAST CONCERN FOCUSED ON EVOLUTION OF UPPER LOW SEEN ON
WATER VAPOR SAT PIX...DIVING SOUTH ACROSS NW OHIO. ETA AND GFS
DIFFER SLIGHTLY ON THE FUTURE OF THIS SYSTEM...WITH THE GFS KEEPING
THE UPPER LOW SLIGHTLY FARTHER NORTH THAN THE ETA AND OPENING IT UP
SOONER. GENERALLY USED A MIX OF THE TWO MODEL SOLUTIONS AS THE ETA
HAS TRENDED FARTHER NORTH WITH THIS FEATURE.

ALREADY SEEING CONVECTION DEVELOP WITH HEATING OF THE DAY AND WHILE
SOME OF THIS CONVECTION WILL WEAKEN AFTER SUNDOWN...WITH A WEAK
UPPER LEVEL SHORTWAVE ROTATING THROUGH KY AROUND THIS UPPER
LOW...KEPT CHANCE OF POPS INTO THE OVERNIGHT HOURS...MAINLY BEFORE
06Z.

WITH UPPER LOW LINGERING ACROSS OHIO ON SUNDAY...EXPECT SCT
SHRA/TSRA TO ONCE AGAIN DEVELOP SUNDAY WITH THE BEST CHANCE DURING
THE AFTERNOON WHEN ANOTHER WEAK VORT LOBE ROTATES AROUND THIS UPPER
LOW AND WITH THE HEATING OF THE DAY. EXPECT LOTS OF CU
TOMORROW WITH THERMAL TROF OVERHEAD...THUS WENT A LITTLE LOWER THAN
GUIDANCE FOR HIGHS.

500MB COLD POOL IS FORECAST TO RESIDE OVER EASTERN KY MONDAY...THUS
ONCE AGAIN EXPECT SCT AFTERNOON CONVECTION TO BREAK OUT...WITH TEMPS
ONCE AGAIN BETWEEN 75 AND 80 DEGREES.  AS SURFACE RIDGE BEGINS TO
BUILD FOR MONDAY NIGHT...BROUGHT DOWN LOW TEMPS A COUPLE OF DEGREES
FOR BOTH MONDAY NIGHT AND TUESDAY NIGHT. AS FOR PCPN CHANCE ON
TUESDAY...FEEL CHANCES ARE VERY SMALL WITH UPPER TROF SHIFTING EAST
OF OUR AREA...BUT FOR CONSISTENCY KEPT A SLIGHT CHANCE OF AFTERNOON
TSRA/SHRA.

EXTENDED...

MRF AND GFS MODELS NOT IN VERY GOOD AGREEMENT REGARDING TIMING OF
COLD FRONT/SHORTWAVE TROUGH FOR WEDNESDAY. GFS WANTS TO PUSH THE
SYSTEMS THROUGH CENTRAL AND EASTERN KENTUCKY A BIT FAST THAN THE
MRF. DECIDED TO GO WITH MRF SOLUTION BASED ON PERSISTENT
DEEP...EASTERN TROUGH PATTERN OVER THE PAST FEW DAYS. TIMING OF
PRECIP FOR LATER IN THE WEEK (THURSDAY NIGHT THROUGH SATURDAY) IS A
BIT MURKY. GFS WANTS TO BRING IN PRECIP FOR SOUTHERN KY FOR
WEDNESDAY AFTERNOON AND EVENING...MRF DOES NOT SHOW THIS...IN
FACT...MRF CURRENTLY BRINGING MORE CLEARING AND DRYNESS FOR
WEDNESDAY EVENING AND A GOOD PORTION OF THURSDAY. HOWEVER...DUE TO
PASSAGE OF 500MB SW TROUGH...AND RESULTING NORTHWEST FLOW...HAVE NOT
RULED OUT A CHANCE FOR SOME SCATTERED PRECIP FOR THURSDAY EVENING.
BOTH MODELS IN FAIRLY GOOD AGREEMENT WITH TIMING AND EXTENT OF
PRECIP FOR FRIDAY AND SATURDAY. BOTH MRF AND GFS TRY TO BRING IN
PRECIP BEGINNING THURSDAY NIGHT AS A WEAK SHORTWAVE AND ASSOCIATED
SURFACE FRONT PASS BY. ONLY WENT WITH CHANCE POPS ON FRIDAY AND
SATURDAY DUE TO UNCERTAINTY OF AREAL EXTENT OF PRECIP.

1027 AM EDT SAT JUL 17 2004

.PREV DISCUSSIONS...

AREA OF TSRA/SHRA GRADUALLY DIMINISHING ACROSS EAST KY OCCURRING IN
AREA OF UPPER DIVERGENCE AND IN LEFT FRONT QUAD OF 60+ KT 300MB
JET. WEAK SHORTWAVE NOT FORECAST TO EXIT FAR EASTERN KENTUCKY UNTIL
21Z PER LATEST MESOETA...SO WILL KEEP HIGH CHANCE POPS IN FAR
EASTERN ZONES TODAY...BUT WILL TAPER THEM DOWNWARD IN THE WEST WHERE
SCT AFTERNOON SHRA/TSRA POSSIBLE CONSIDERING MOIST ILN SOUNDING.
ONCE SHORTWAVE MOVES EAST...EXPECT SOME CLEARING...SO FEEL TEMPS
SHOULD RECOVER TO NEAR CURRENT FORECAST HIGHS AND MADE ONLY MINOR
ADJUSTMENTS HERE.

&&

317 AM EDT SAT JUL 17 2004

CURRENT RADAR TRENDS TENDS TO SUPPORT THE GFS MODEL WITH THE
SHRA/TSRA RAPIDLY ENCROACHING ON ERN KY. GREATEST THREAT TODAY WILL
BE HEAVY RAIN. FORTUNATELY WE HAVE HAD SEVERAL RAIN-FREE DAYS AND
FFG IS HIGHER. WILL STILL HAVE TO WATCH FOR TRAINING CELLS AS THE
VERY EFFICIENT RAIN MAKERS COULD DROP 2-3 IN A SHORT TIME. UA
CHARTS INDICATED THE 50H TROF THAT IS SWEEPING SE INTO THE LONG WAVE
TROF. THIS FEATURE CORRESPONDS WELL WITH THE CURRENT PCPN PATTERN.

HAVE CHOSEN TO FOLLOW THE GFS THIS MORNING DUE TO CONSISTENCY AND
BETTER INITIALIZATION WITH THE PCPN PATTERN. HENCE...WILL HAVE
LIKELY POPS TODAY...DROPPING TO GOOD CHC TONIGHT. EARLY SUN WILL SEE
A SLIGHT REPRIEVE BEFORE THE AFTERNOON HEATING KICKS OFF MORE TSRA.
COOLER TEMPS IN THE OFFING WITH THE LONG WAVE TROF REMAINING NEARLY
STATIONARY THRU THE WEEKEND. AS THE LOW PASSES TO THE EAST OF THE
APPLAC MTNS WE GET INTO THE WRAP AROUND PCPN WHICH WILL BE MORE
SPOTTY AND DIMINISH BY EARLY NEXT WEEK AS THE SYSTEM TRACKS UP THE
EAST COAST AND HAS LESS INFLUENCE OR OUR WX.

&&

1107 PM EDT FRI JUL 16 2004

UPDATE TONIGHT TO REDUCE POPS IN THE SOUTHWEST...AND SOME MINOR
ADJUSTMENTS TO SKY AND DEW POINTS. OTHERWISE...TEMPS/WINDS WERE
ABOUT PERFECT...EVEN ON THE HOURLY OBS.

BASED ON CURRENT RADAR TRENDS...GFS HAS BEEN HANDLING PRECIP
PATTERNS MUCH BETTER THAN THE ETA. FROM ALL APPEARANCES ETA REALLY
HAS OVERDONE POPS...PARTICULARLY IN THE SOUTHWEST. IN THE
END...COMPROMISED ON POP VALUES USING A MIX OF THE GFS AND ETA...BUT
ALIGNED PRECIP/QPF PATTERN MORE WITH GFS. LEFT CHANCE POPS IN
FORECAST FOR ALL ZONES...CLOSER TO DAWN IN THE CENTRAL AND SOUTHERN
PORTIONS OF CWA. WITH MOST SHOWER AND THUNDERSTORM ACTIVITY TO
NORTHWEST...MOVING SLOWLY SOUTHEASTWARD...WITH WITH HIGHER POPS
EARLIER IN NORTHWEST.

&&

.JKL...WATCHES/WARNINGS/ADVISORIES...NONE.
&&

HYSELL/RICHEY

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON KY
451 AM EDT SAT JUL 17 2004

KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120-180900-
BATH KY-BELL KY-BREATHITT KY-CLAY KY-ELLIOTT KY-ESTILL KY-FLEMING KY-
FLOYD KY-HARLAN KY-JACKSON KY-JOHNSON KY-KNOTT KY-KNOX KY-LAUREL KY-
LEE KY-LESLIE KY-LETCHER KY-MAGOFFIN KY-MARTIN KY-MCCREARY KY-
MENIFEE KY-MONTGOMERY KY-MORGAN KY-OWSLEY KY-PERRY KY-PIKE KY-
POWELL KY-PULASKI KY-ROCKCASTLE KY-ROWAN KY-WAYNE KY-WHITLEY KY-
WOLFE KY-
451 AM EDT SAT JUL 17 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN KENTUCKY.

.DAY ONE...TODAY AND TONIGHT.

HEAVY RAINFALL WITH THE FORECAST THUNDERSTORMS TODAY AND TONIGHT HAS
THE POTENTIAL FOR LOCALIZED FLOODING.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

THERE IS A CHANCE FOR THUNDERSTORMS SUNDAY THROUGH MONDAY. EXPECT A
SLIGHT CHANCE FOR ADDITIONAL THUNDERSTORMS MONDAY NIGHT THROUGH
TUESDAY NIGHT AND AGAIN FROM THURSDAY THROUGH FRIDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO CALL IN RAINFALL AMOUNTS.

DUSTY