000
FXUS63 KJKL 191738
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
138 PM EDT SUN MAY 19 2013

.UPDATE...
ISSUED AT 1238 PM EDT SUN MAY 19 2013

ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ACROSS
ALL BUT THE NW PART OF FORECAST AREA. THE SHOWERS AND THUNDERSTORMS
ARE MOST NUMEROUS OVER THE SOUTHWEST PART OF FORECAST AREA. THE
SPEED MAX THAT WAS ASSOCIATED WITH THE CONVECTIVE DEVELOPMENT OVER
SOUTH CENTRAL KY THIS MORNING IS SHIFTING INTO NE TN...AND EXPECT
THIS TO CONTINUE TO SUPPORT CONVECTION IN THE SOUTHERN PART OF THE
FORECAST AREA THROUGH MID TO LATE AFTERNOON. WITH THE SPEED MAX
CONTINUING TO WEAKEN AND SHIFT AWAY THIS EVENING...AND LOSS OF
DAYTIME HEATING EXPECT A RAPID DECREASE IN CONVECTION EARLY THIS
EVENING. THIS IDEA IS SUPPORTED BY THE 12Z NAM AND LATEST HRRR. HAVE
UPDATED NDFD FOR LATEST HOURLY TRENDS.

UPDATE ISSUED AT 1007 AM EDT SUN MAY 19 2013

UPPER LOW CURRENTLY OVER NORTH CENTRAL KY PER WATER VAPOR IMAGERY.
PERSISTENT CONVECTIVE DEVELOPMENT OCCURRING OVER SOUTH CENTRAL KY
LOOKS TO BE ASSOCIATED WITH A LOCAL UPPER LEVEL SPEED MAXIMUM ON THE
SW SIDE OF THE UPPER LOW. MODELS HAVE A HANDLE ON THIS SPEED MAX AND
IT LOOKS TO SHIFT EAST BY 18Z AS THE LOW MOVES OFF TO NORTHEAST.
THOUGH THE SPEED MAX IS FORECAST TO WEAKEN...ITS SHIFT TO THE EAST
COMBINED WITH DESTABILIZATION DUE TO DAYTIME HEATING IS EXPECTED TO
RESULT IN AN INCREASE IN CONVECTION THIS AFTERNOON. HAVE DECIDED TO
KEEP THE 30 PERCENT RAIN PROBABILITIES IN THE FAR NORTH...BUT HAVE
INCREASED PROBABILITIES ELSEWHERE TO 40 TO 50 PERCENT. THE 06Z METMOS
AND MAVMOS ACTUALLY HAVE HIGHER PROBABILITIES...BUT FOR NOW THOUGHT
SCATTERED SHOWERS AND THUNDERSTORMS WAS MORE IN LINE WITH WHAT IS
EXPECTED FOR THIS AFTERNOON. THE ALLEN COUNTY KY MESONET HAS ALREADY
REPORTED 1.44 INCHES OF RAIN THIS MORNING WITH RAINFALL RATES NEAR 1
INCH PER HOUR. WILL MENTION LOCALLY HEAVY RAIN IN THE HWO. HAVE
UPDATED NDFD AND ZFP.

UPDATE ISSUED AT 702 AM EDT SUN MAY 19 2013

FRESHENED UP THE HOURLY TEMPERATURES AND DEW POINTS ACCORDING TO THE
LATEST TRENDS IN OBSERVATIONS.

&&

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 246 AM EDT SUN MAY 19 2013

THE UPPER LEVEL LOW IS CURRENTLY PARKED ACROSS NORTHEASTERN
KENTUCKY...WITH MOST SHOWER ACTIVITY STAYING ACROSS EASTERN TENNESSEE
AND SOUTHWEST VIRGINIA. THIS FEATURE WILL GRADUALLY SHIFT EAST AND
DAMPEN WITH TIME AS UPPER LEVEL RIDGING WORKS IN FROM THE WEST. THE
MODELS HAVE BEEN OVERDOING THE CONVECTIVE COVERAGE LATELY...SO WILL
DOWNPLAY THE GIVEN POPS THROUGH THE NEXT 36 HOURS.

EXPECT SCATTERED SHOWERS AND A FEW THUNDERSTORMS TO POP UP THIS
AFTERNOON WITH HEATING...BEFORE DIMINISHING EARLY THIS EVENING. HIGHS
WILL TOP OUT IN THE UPPER 70S TO AROUND 80 DEGREES. ANY CONVECTION
WILL DWINDLE QUICKLY TONIGHT WITH BETTER CLEARING LIKELY AND
CONSEQUENTLY FOG. LOWS WILL BOTTOM OUT IN THE LOWER 60S ONCE AGAIN.

THE UPPER LEVEL RIDGE WILL BUILD IN OVERHEAD ON MONDAY...WITH HIGHS
REACHING WELL INTO THE 80S. WILL MAINTAIN THE INHERITED SLIGHT
CHANCE POPS FOR MOST LOCATIONS AT BEST GIVEN THE CAPPING THAT WILL BE
IN PLACE.

.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 405 AM EDT SUN MAY 19 2013

THE START OF THE PERIOD WILL BE DOMINATED BY UPPER LEVEL RIDGING THAT
IS EXPECTED TO EXTEND FROM THE WESTERN GULF OF MEXICO NORTH INTO THE
OHIO VALLEY. AT THAT POINT...A LARGE CLOSED UPPER LEVEL LOW IS
EXPECTED TO BE ANCHORED OVER THE NORTHERN PLAINS. AT THAT POINT...THE
MAIN BAND OF WESTERLIES IS EXPECTED TO LINE FROM THE PACIFIC
NORTHWEST NORTHEAST INTO CENTRAL CANADA AND THEN SOUTHEAST TOWARD THE
NORTHEASTERN CONUS. THIS MEANS THAT THE CLOSED LOW WILL ONLY SLOWLY
MOVE TOWARD THE EAST AND NORTHEAST INTO THE GREAT LAKES AND OPEN UP
THROUGH THU INTO FRI WHEN IT SHOULD GET PICKED UP BY THE WESTERLIES
AND MOVE INTO THE NORTHEAST OR MID ATLANTIC STATES. ALTHOUGH THERE IS
A GENERAL CONSENSUS ON THE OVERALL UPPER LEVEL PATTERN DIFFERENCES
REMAIN IN TIMING AND TRACK OF THIS SYSTEM AS IT MOVES FROM THE PLAINS
AND INTO THE GREAT LAKES. THIS LEADS TO TIMING DIFFERENCES IN THE
PASSAGE OF THE ASSOCIATED FRONT AND HOW QUICKLY IT DEPARTS TO THE
SOUTHEAST OF THE AREA.

OVERALL...CONVECTIVE ACTIVITY SHOULD BE MINIMAL EARLY IN THE PERIOD
AS THE RIDGING SHOULD BRING CAPPING AND COVERAGE OF CONVECTION
SHOULD ON AVERAGE NOT BE MORE THAN ISOLATED MON EVENING. RIDGING
SHOULD ALLOW FOR SOME CLEARING ON MON NIGHT AND AREAS OF FOG MAY FORM
AND THESE COULD BECOME DENSE DEPENDING ON THE DEGREE OF CLEARING.
DIURNAL HEATING MAY BE SUFFICIENT FOR ISOLATED TO POSSIBLY SCATTERED
ON TUE NEAR THE VA LINE...BUT MOST LOCATIONS SHOULD EXPERIENCE NOT
MUCH MORE THAN A DIURNAL INCREASE IN CU. THE CHANCES FOR CONVECTION
WILL INCREASE AT MIDWEEK AS THE RIDGING DEPARTS TO THE EAST AND
DISTURBANCES ROTATING AROUND THE UPPER LEVEL SYSTEM WORK INTO THE
LOWER OH VALLEY REGION. AT THE SAME TIME...THE SFC COLD FRONT
ASSOCIATED WITH THE UPPER LEVEL SYSTEM TO MOVE INTO THE LAKES SHOULD
ALSO APPROACH.

ALTHOUGH THE SFC BOUNDARY SHOULD WORK ACROSS THE REGION THU NIGHT
INTO FRIDAY...THE GFS RUNS HAVE REMAINED SLOWER WORKING THE SFC
BOUNDARY AND UPPER LEVEL SYSTEM SOUTH AND EAST RESPECTIVELY AND TRACK
THE UPPER SYSTEM CLOSER TO THE AREA. FOR THIS REASON...CHANCES FOR
CONVECTION WERE CONTINUED INTO WELL INTO FRI AND FRI NIGHT AS WAS IN
THE PREVIOUS FORECAST. THE ECMWF SOLUTION WOULD MEAN A DRIER END TO
THE WORK WEEK. AT THIS POINT...IT APPEARS THE BOUNDARY WILL HAVE
PASSED FAR ENOUGH SOUTH AND EAST AND THE UPPER LEVEL SYSTEM WILL HAVE
DEPARTED TO THE EAST ENOUGH FOR SAT TO BE DRY.

DIURNAL TEMPERATURE RANGES SHOULD GENERALLY BE SUPPRESSED FROM
MIDWEEK ON. HOWEVER...UNDER THE INFLUENCE OF THE DEPARTING RIDGE...
THE COMBINATION OF TEMPS IN THE UPPER 80S ON AVERAGE AND DEWPOINTS IN
THE LOW TO MID 60S SHOULD YIELD ABOUT AS WARM OF A HEAT INDEX AS HAS
BEEN EXPERIENCED SO FAR THIS SPRING. HOWEVER...THE WARMEST OF THESE
SHOULD CLIMB TO NO HIGHER THAN 90. RECORD HIGHS AT JKL AND LOZ WILL
LIKELY END UP APPROACHED AND POSSIBLY EXCEEDED. RECORD HIGHS FOR TUE
AT JKL AND LOZ ARE 85/1987 AND 88/1962 RESPECTIVELY. THE MAV MOS
NUMBERS APPEARED MUCH TOO WARM AND NUMBERS CLOSER TO THE MET/CONSALL
WERE MORE APPROPRIATE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 138 PM EDT SUN MAY 19 2013

UPPER LEVEL LOW PRESSURE OVER NE KY IS BRINGING SCATTERED SHOWERS AND
THUNDERSTORMS TO THE FORECAST AREA...WITH THE THUNDERSTORMS MOST
NUMEROUS OVER SOUTHERN PARTS OF THE FORECAST AREA. AT TAF ISSUANCE
TIME SHOWERS AND THUNDERSTORMS ARE ABOUT TO END AT LOZ AND SME...BUT
MVFR FOG AND CEILINGS WILL PERSIST UNTIL 19Z AT THESE LOCATIONS.
THUNDERSTORMS ARE MORE ISOLATED FURTHER NORTH...WITH MAINLY ISOLATED
SHOWERS FROM JKL NORTH. OUTSIDE OF SHOWERS AND THUNDERSTORMS VFR
CONDITIONS WILL PREVAIL INTO THE EVENING HOURS. FOG AND LOW CLOUD IS
EXPECTED TO DEVELOP TONIGHT...ESPECIALLY IN AREAS THAT RECEIVED RAIN
TODAY. EXPECT IFR TO LOW IFR CONDITIONS BY EARLY MONDAY
MORNING...IMPROVING TO VFR BY MONDAY AFTERNOON.

&&

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

$$

UPDATE...SBH
SHORT TERM...GEOGERIAN
LONG TERM...JP
AVIATION...SBH