Hail and Damaging Winds in Kentucky, June 21, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
334 AM EDT TUE JUN 21 2011

.SHORT TERM.../TODAY THROUGH THURSDAY/...UPDATED

EARLY THIS MORNING...A MID TO UPPER LEVEL RIDGE WAS CENTERED OVER
THE FL PENINSULA WITH THE RIDGE AXIS EXTENDING NORTH ACROSS THE
SOUTHERN APPALACHIANS INTO CENTRAL KY AND FURTHER NORTH TOWARD THE
SOUTHERN GREAT LAKES. A SHORTWAVE WAS MOVING FROM THE LOWER MS VALLEY
REGION TOWARD THE TN VALLEY REGION OVER THE RIDGE AND IN ADVANCE OF
THE MAIN UPPER LEVEL TROUGH THAT EXTENDED SOUTH ACROSS THE PLAINS
FROM A CLOSED UPPER LEVEL LOW IN THE PLAINS. A SFC LOW WAS CENTERED
IN THE PLAINS REGION NEAR THE KS/NB BORDER. THE SFC WARM FRONT
EXTENDED EAST TOWARD THE SOUTHERN GREAT LAKES AND THEN SE INTO
NORTHEASTERN KY AND THEN SE OVER THE EASTERN CWA NEAR THE KY/WV
BORDER AND THEN INTO THE CAROLINAS. MID AND HIGH LEVEL CLOUDS HAVE
GENERALLY THINNED OVERNIGHT...THOUGH THEY HAVE REMAINED MOST
PERSISTENT TO THE WEST OF JKL OVER WESTERN PARTS OF THE CWA. EASTERN
VALLEYS HAVE DECOUPLED AND FOG HAS FORMED THERE. THIS SHOULD PERSIST
UNTIL AROUND DAWN AND THEN BEGIN TO LIFT...GENERALLY BEFORE THE START
OF THE TODAY PERIOD.

THE UPPER LEVEL RIDGE AXIS THAT WILL BE OVER THE REGION EARLY IN THE
DAY WILL SHIFT TO THE EAST BY AFTERNOON. MODELS INDICATE THE SHORTWAVE/
VORT MAX OUT AHEAD OF THE MAIN TROUGH WILL MOVE NORTHEAST FROM THE
TN VALLEY AND ACROSS THE REGION NEAR OR JUST PRIOR TO PEAK HEATING
AND THIS COMBINED WITH UPPER LEVEL RIDGING SHIFTING EAST AND PLENTY
OF LOW LEVEL MOISTURE FROM RECENT RAIN AND INITIAL DAYTIME
HEATING...ISOLATED TO SCATTERED CONVECTION SHOULD DEVELOP BY EARLY TO
MID AFTERNOON. MODELS PROG LI IN THE -4 TO -6C RANGE WITH CAPE ON
THE ORDER OF 1500 TO 2500 J/KG. IN FACT...IF ENOUGH DAYTIME HEATING
CAN OCCUR OR MORE WERE TO OCCUR THAN CURRENTLY FORECAST...A FEW
STRONG TO SEVERE STORMS COULD RESULT WITH GUSTY WINDS AND HAIL BEING
THE MAIN THREATS. IN ADDITION...PW IN THE 1.5 TO 1.75 INCH RANGE AND
RELATIVELY HIGH FREEZING LEVELS SHOULD LEAD TO PLENTY OF WARM RAIN
PROCESSES AND THIS COULD RESULT IN BRIEF HEAVY RAIN AND POSSIBLY
LOCALLY HEAVY RAINFALL IF STORMS WERE TO TRAIN OR MOVE REPEATEDLY
OVER THE SAME AREAS. HAVE RAISED POPS FOR TODAY INTO THE CHANCE RANGE
AS THE 0Z WRF AND 0Z GFS AS WELL AS THE SREF MEAN ALL BRING QPF INTO
THE REGION. MOS GUIDANCE IS IN THE SCATTERED RANGE OR HIGHER AS IS
THE 21Z SREF POPS.

OTHERWISE...THE UPPER LEVEL TROUGH EXTENDING SOUTH FROM A CLOSED LOW
MOVING FROM THE PLAINS AND INTO THE UPPER MS VALLEY REGION WILL
SLOWLY APPROACH THE AREA BUT THE MEAN TROUGH AXIS MAY NOT PASS EAST
OF THE AREA UNTIL AFTER THE SHORT TERM PERIOD AS SHORT WAVES MOVE
DOWN ACROSS THE PLAINS AND TOWARD THE OH AND TN VALLEY REGIONS. IN SW
FLOW AHEAD OF THE MAIN TROUGH...ADDITIONAL WEAK AND HARD TO TIME
SHORTWAVES WILL LIKELY MOVE ACROSS THE AREA LATE TONIGHT AND INTO THE
DAY ON WED. AT THE SAME TIME...THE REGION WILL REMAIN IN THE WARM
SECTOR OF THE SFC LOW ALSO TRACKING FROM THE PLAINS TO THE UPPER MS
VALLEY REGION AND ON INTO THE GREAT LAKES BY LATE WED NIGHT INTO THU.
THE COLD FRONT SHOULD FINALLY MOVE ACROSS THE CWA LATE IN THE PERIOD.
WITH ALL OF THIS IN MIND...AN EXTENDED PERIOD FOR CHANCES OF AT
LEAST ISOLATED TO SCATTERED CONVECTION...IF NOT PERIODS OF GREATER
COVERAGE SHOULD RESULT FROM TONIGHT THROUGH THU. DRIER AIR...
PARTICULARLY AT THE LOW LEVELS WILL MOVE INTO THE REGION LATE IN THE
PERIOD...BEHIND THE FRONT WITH MUCH LOWER CHANCES FOR PRECIPITATION.
THE HIGHEST CHANCE FOR SHOWERS AND THUNDERSTORMS AHEAD OF THE
BOUNDARY APPEARS TO BE FROM LATE TONIGHT INTO EARLY WED EVENING. THE
APPROACHING UPPER LEVEL TROUGH AND POSSIBLY WEAKER LEAD SHORTWAVES
ALONG WITH THE POTENTIAL FOR SOME RIGHT ENTRANCE REGION DYNAMICS TO
GET INVOLVED FOR A WHILE SHOULD PROVIDE PLENTY OF LIFT FOR CONVECTION
OF THE MOIST AIRMASS PROGGED TO BE IN PLACE DURING THAT TIME.

RECENT RAINFALL AND RECENT MOS GUIDANCE PERFORMANCE TRENDS ALL ARGUE
FOR GOING TO THE LOWER END OF GUIDANCE FOR MAX T TODAY. INITIAL
SUNSHINE SHOULD LEAD TO PLENTY OF EVAPOTRANSPIRATION AND THIS
COMBINED WITH ADVECTION OF A MORE MOIST AIRMASS INTO THE REGION AND
THE SHORTWAVE MOVING INTO THE AREA SHOULD LEAD TO A SUBSTANTIAL CU
FIELD DEVELOPING BY EARLY TO MID AFTERNOON ALONG WITH SOME MID AND
HIGH CLOUDS MOVING INTO THE AREA ASSOCIATED WITH THE SHORTWAVE.
PLENTY OF CLOUDS AND GOOD COVERAGE OF PRECIP SHOULD SUPPRESS DIURNAL
TEMPERATURE RANGES THROUGH THE PERIOD...WITH LOWS GENERALLY IN THE
MID TO UPPER 60S AND HIGHS IN THE MID TO UPPER 80S TODAY AND THEN
LOWER 80S ON WED.

.LONG TERM.../THURSDAY NIGHT THROUGH MONDAY/

WEATHER PATTERN LOOKS TO REMAIN UNSETTLED HEADING THROUGH THE
UPCOMING WEEKEND AND INTO EARLY NEXT WEEK. BROAD MID/UPPER LEVEL
TROUGHING WILL REMAIN OVER THE GREAT LAKES SOUTH INTO THE OHIO
VALLEY THROUGH THE EXTENDED. AS IT LOOKS PRESENTLY...A BAROCLINIC
ZONE WILL REMAIN ANCHORED ACROSS THE KENTUCKY REGION FROM LATE IN
THE WEEK THROUGH THE WEEKEND. SEVERAL MORE SHORTWAVES WILL LIKELY
PROGRESS THROUGH THE MID LEVEL TROUGH...GENERATING ADDITIONAL
CHANCES FOR SHOWERS AND THUNDERSTORMS INTO EARLY NEXT WEEK. GIVEN
THIS UNSETTLED PATTERN AND UNCERTAINTY WITH REGARDS TO TIMING OF
INDIVIDUAL FEATURES...OPTING TO CARRY LOW CHANCE POPS THROUGH THE
EXTENDED FORECAST. GIVEN THE UNSETTLED NATURE OF THINGS...OPTED TO
GO COOLER FOR HIGHS THROUGH THE EXTENDED AS WELL...SIMILAR TO WHAT
WE HAVE BEEN EXPERIENCING THE PAST SEVERAL DAYS. OBVIOUSLY...IF
QUIETER WEATHER PREVAILS AND LESS CLOUD COVER...WE COULD END UP
WARMER...BUT ODDS ARE THAT WE WILL KEEP SOME CLOUD COVER ALONG WITH
REPEATED ROUNDS OF SHOWERS AND THUNDERSTORMS THROUGH THE EXTENDED
PERIOD.

&&

.AVIATION.../06Z TO 06Z/

THE PRESSURE GRADIENT HAS BEEN SUFFICIENT UP TO THIS POINT TO KEEP
LIGHT SOUTHERLY WINDS AT THE TAF SITES AS WELL AS MORE OPEN TERRAIN
AND RIDGTEOP LOCATIONS. DEEPER SHELTERED VALLEYS HAVE DECOUPLED AND
ARE EXPERIENCING SOME FOG. WITH CLOUD COVER NEAR 20KT EXPECTED FOR
THE BULK OF THE TIME THROUGH 12Z...FEEL THAT FOG SHOULD NOT BE A
PROBLEM AT THE TAF SITES...THOUGH IFR OR LOWER IS POSSIBLE IN DEEPER
VALLEY AIRPORT LOCATIONS. OTHERWISE...MODELS INDICATE A WEAK UPPER
LEVEL DISTURBANCE WILL PASS ACROSS THE REGION NEAR OR JUST PRIOR TO
PEAK HEATING AND THIS COMBINED WITH UPPER LEVEL RIDGING SHIFTING EAST
AND WITH PLENTY OF LOW LEVEL MOISTURE FROM RECENT RAIN SHOULD LEAD
TO ISOLATED TO SCATTERED CONVECTION BY EARLY TO MID AFTERNOON. WITH
THE MAIN UPPER LEVEL TROUGH AND A COLD FRONT APPROACHING ISOLATED TO
SCATTERED CONVECTION IS POSSIBLE DURING THE LAST 12 TO 15HRS OF THE
PERIOD. BRIEF IFR WOULD BE POSSIBLE IN ANY TSRA.

&&

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

&&

SHORT TERM...JP
LONG TERM...KAS
AVIATION...JP

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON KY
404 AM EDT TUE JUN 21 2011

KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120-221100-
FLEMING-MONTGOMERY-BATH-ROWAN-ESTILL-POWELL-MENIFEE-ROCKCASTLE-
JACKSON-PULASKI-LAUREL-WAYNE-MCCREARY-WHITLEY-KNOX-BELL-HARLAN-
ELLIOTT-MORGAN-JOHNSON-WOLFE-MAGOFFIN-FLOYD-LEE-BREATHITT-KNOTT-
OWSLEY-PERRY-CLAY-LESLIE-LETCHER-MARTIN-PIKE-
404 AM EDT TUE JUN 21 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EASTERN KENTUCKY.

.DAY ONE...TODAY AND TONIGHT.

THUNDERSTORMS ARE POSSIBLE TODAY AND TONIGHT. ANY THUNDERSTORMS TODAY
OR TONIGHT WILL BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL. A FEW
THUNDERSTORMS THIS AFTERNOON AND INTO EARLY THIS EVENING COULD BECOME
STRONG TO SEVERE...WITH STRONG TO DAMAGING WINDS AND HAIL THE MAIN
THREATS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

THUNDERSTORMS ARE POSSIBLE FROM WEDNESDAY THROUGH MONDAY. SOME OF THE
THUNDERSTORMS ON WEDNESDAY AND THURSDAY COULD BECOME STRONG TO SEVERE
AND PRODUCE LOCALLY HEAVY RAINFALL...STRONG TO DAMAGING WINDS AND HAIL
BEING THE MAIN THREATS.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO REPORT HEAVY RAINFALL OR ANY INCIDENTS OF
SEVERE WEATHER THROUGH THURSDAY THAT OCCUR TO THE NATIONAL WEATHER
SERVICE IN JACKSON KY.

JP