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000
FXUS63 KJKL 161419
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
1019 AM EDT SUN JUN 16 2013

.UPDATE...
ISSUED AT 1017 AM EDT SUN JUN 16 2013

UPDATED THE FORECAST TO BETTER REFLECT CURRENT CONDITIONS AND MODEL
TRENDS. DECREASED THE CLOUD COVER A LITTLE...HOWEVER REALLY EXPECTING
VARIABLE CLOUDINESS WITH THE CONVECTIVE ACTIVITY TODAY. THE MOST
INTENSE ACTIVITY IS JUST NORTH OF THE BLUEGRASS AND THIS SHOULD BE
SAGGING SOUTHWARD AND THE FRONT CONTINUES PUSHING SOUTH. THE HRR
MODEL IS WANTING TO DEVELOP SOME ACTIVITY OUT AHEAD OF THIS LINE
WITH THE AREA WEST OF I 75 BEING FAVORED INITIALLY. THE REST OF THE
FORECAST IS ON TRACK.

UPDATE ISSUED AT 730 AM EDT SUN JUN 16 2013

NO MAJOR CHANGES TO ONGOING FORECAST...JUST UPDATED GRIDS WITH
CURRENT OBSERVATIONS. A COUPLE THINGS TO NOTE HOWEVER. FIRST IS THE
INCOMING PRECIPITATION THAT IS WORKING ITS WAY INTO THE CWA VIA RADAR
IMAGERY. MOST OF THIS PRECIPITATION IS ELEVATED/VIRGA AND NOT BEING
REPORTED BY OBSERVATION PLATFORMS. OPTED TO KEEP ONGOING POPS...WHICH
HAVE LESS THAN SLIGHT CHANCE POPS THROUGH 12Z...INCREASING TO SLIGHT
CHANCES BY 13Z. IT IS POSSIBLE THAT SOMEONE COULD SEE A LIGHT
SPRINKLE BEFORE SLIGHT CHANCE POPS COME IN TO PLAY...BUT IT SHOULD
HAVE LITTLE EFFECT/IMPACT IF IT OCCURS. SECOND...LATEST GUIDANCE IS
SHOWING THE POTENTIAL FOR SOME FOG DEVELOPMENT AT TAF SITES OVERNIGHT
TONIGHT...AS AN ABUNDANT AMOUNT OF MOISTURE SITS OVER MUCH OF THE
AREA WITH LIGHT WINDS. OBVIOUSLY IF PRECIP IS ONGOING...THIS CAN
LIMIT FOG POTENTIAL. HOWEVER...FOR THOSE AREAS THAT ARE NOT
EXPERIENCING SUCH PRECIP /ESPECIALLY IN THE VALLEYS/ BR COULD BE A
POSSIBILITY. NEXT SHIFTS MAY WANT TO CONTINUE TO ASSESS THIS POTENTIAL
AND INCLUDE IN FORECAST AS NEEDED...BUT DID GO AHEAD AND TREND DOWN
WITH BR IN THE 12Z TAFS BASED ON GUIDANCE.

&&

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 447 AM EDT SUN JUN 16 2013

ZONAL FLOW ACROSS MUCH OF THE EAST AND NORTH CENTRAL THROUGH THE
SHORT-TERM. A SERIES OF SHORTWAVES WILL MOVE FROM WEST TO EAST AND
ACROSS/NEAR THE CWA TODAY THROUGH MONDAY...THE FIRST ONE IMPACTING
US DURING THE DAY TODAY. CLOUD COVER HAS BEEN ON THE INCREASE
OVERNIGHT...AND WILL CONTINUE TO SPREAD ACROSS THE REGION DURING THE
DAY. A FAIRLY DECENT AREA OF CONVECTION DEVELOPED OVERNIGHT OVER MO
AND IL...EXPANDING NORTH INTO THE GREAT LAKES REGION. AS THE SYSTEM
CONTINUES NE...A MORE SUBTLE OUTFLOW BOUNDARY SHOULD BRING A DECENT
SHOT AT PRECIP ACROSS THE NORTHERN COUNTIES BEFORE PUSHING SE DURING
THE COURSE OF THE DAY. AS IT TRAVERSES THE CWA...SOME PRETTY
REASONABLE LAPSE RATES AND INSTABILITY COULD BE ENOUGH TO SPAWN SOME
DECENT SCATTERED THUNDERSTORMS...ESPECIALLY THIS AFTERNOON. THAT
BEING SAID...SHEAR IS NEARLY UNIDIRECTIONAL...SO NOT EXPECTING ANY
LARGE MESOCYCLONES...MORE OF A PULSY STORM ENVIRONMENT IN WHICH WIND
AND POTENTIALLY HAIL WILL BE THE MAIN THREAT.

CONVECTIVE POTENTIAL WILL BE ON THE DOWNWARD TREND THROUGHOUT THE
EVENING/OVERNIGHT AS OUTFLOW CONTINUES TREK EASTWARD AND AWAY FROM
EASTERN KY...AND DAYTIME HEATING HAS LESS OF A CONTRIBUTING FACTOR.
THAT BEING SAID...MOISTURE RIPE ENVIRONMENT AND DEVELOPING LLVL JET
WILL ALLOW SOME ISO/SCT RESIDUAL SHOWERS/CONVECTION. UNFORTUNATELY
MODELS ARE HAVING A HARD TIME COMING INTO AGREEMENT ON WHERE THIS
RESIDUAL CONVECTION WILL TAKE PLACE...BUT ARE LEANING TOWARDS THE
BEST CHANCES MOVING SOUTHEAST OVER THE MORE MOUNTAINOUS REGION.

NEARLY 24 HOURS AFTER THE FIRST SHORTWAVE ENCOMPASSED THE OHIO RIVER
VALLEY...A SECOND MORE POTENT SHORTWAVE WILL BEGIN TO BEAR DOWN ON
THE REGION BY MONDAY MORNING. THOUGH MODELS SEEM TO BE IN FAIRLY
GOOD AGREEMENT WITH THE PLACEMENT OF THE SHORTWAVE...LIKE OVERNIGHT
THERE IS STILL A LOT OF UNCERTAINTY AT PLAY AS FAR AS EASTERN KY/S
INFLUENCE UNDER THIS SYSTEM AND THE SEVERE WEATHER POTENTIAL.
LOOKING AT BASICS...SURFACE COLD FRONT /VIA THE LATEST GFS RUN/ WILL
BE MOVING THROUGH IN A FAIRLY W TO E ORIENTATION BY LATE MORNING.
THIS WILL PLACE THE BEST AREA OF CONVECTION AHEAD OF THE FRONT...IN
THE SOUTHERLY PORTIONS OF THE REGION...WHERE WINDS WILL START OUT
SRLY AND THEN BACK MORE WESTERLY DURING THE DAY. WITH A DECENT AMOUNT OF
MOISTURE IN THE LOW LEVELS...AND DRY IN THE MID/UPPER
LEVELS...DAYTIME HEATING WILL ALLOW FOR A FAIR AMOUNT OF CAPE TO BE
TAPPED INTO. QVECTOR CONVERGENCE VECTORS ALSO INDICATE A GOOD AREA
OF LIFT TRAVERSING MUCH OF KY WITH MID LEVEL LAPSE RATES EXPECTED TO
BE IN THE 6 TO 6.5 RANGE BY AFTERNOON.  ALL THINGS PUT
TOGETHER...CONVECTION WILL OCCUR. THE QUESTION HOWEVER IS THE
LOCATION AND TIMING OF THE SET UP AS WELL AS WHETHER OR NOT ANY OF
THESE STORMS WILL PRODUCE SEVERE CONDITIONS. LOOKING AT
SOUNDINGS...EXPECT HAIL AND WINDS TO BE THE MAIN THREAT WITH
CONVECTION THAT OCCURS. MAIN AREA OF MOISTURE WILL THEN BEGIN
WORKING ITS WAY INTO THE REGION MONDAY EVENING.

.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 447 AM EDT SUN JUN 16 2013

SURFACE HIGH PRESSURE SLIPPING AWAY TO THE EAST WILL ALLOW A RETURN
OF LOW LEVEL MOISTURE AS THE PERIOD STARTS. AT THE SAME TIME...A
SHORT WAVE TROUGH WILL MOVE IN FROM THE WEST. SURFACE LOW
DEVELOPMENT OF SOME EXTENT IS EXPECTED...WITH A TRACK THROUGH THE
OHIO OR TENNESSEE VALLEY ON TUESDAY. HOWEVER...FORECAST MODELS STILL
DO NOT AGREE ON THE STRENGTH OR EXACT TRACK OF THE LOW...LEAVING
SOME UNCERTAINTY. THE GREATEST POP AT THIS POINT SEEMS TO BE ON
MONDAY NIGHT AS THE SHORTWAVE APPROACHES. A COLD FRONT WILL ALSO BE
DROPPING IN FROM THE NORTH...AND AS THE SHORTWAVE AND SURFACE LOW
PASS...THE DRIER AND SLIGHTLY COOLER AIR MASS WILL SETTLE SOUTH INTO
THE FORECAST AREA TUESDAY NIGHT AND WEDNESDAY...WITH FAIR WEATHER
THEN LASTING INTO THURSDAY.

THE HIGH PRESSURE SYSTEM AT THE HEART OF THE COOLER AND DRIER AIR
MASS WILL SLIP AWAY OFF THE NEW ENGLAND AND MID ATLANTIC COAST ON
THURSDAY...WITH LOW LEVEL MOISTURE AGAIN MAKING A RETURN LOCALLY BY
THURSDAY NIGHT ON THE BACK SIDE OF THE HIGH. LATE IN THE WEEK WE
WILL BE ON THE NORTHEAST PERIPHERY OF AN UPPER HIGH CENTERED OVER
THE SOUTH CENTRAL CONUS. WITH SUFFICIENT MOISTURE AND TRIGGERS...
THIS POSITION CAN BE CONDUCIVE TO MCS DEVELOPMENT...BUT THEY CAN BE
VERY DIFFICULT TO FORECAST...ESPECIALLY AT LONG RANGE. THE GFS DOES
SHOW A SHORTWAVE TROUGH ARRIVING AS A TRIGGER THURSDAY NIGHT...BUT
IT IS NOT APPARENT IN THE ECMWF. THE MODELS ALSO DISAGREE ON THE
NORTHEASTWARD EXTENT OF THE UPPER RIDGE AT THE END OF THE PERIOD.
THINK THAT THE BEST FORECAST AT THIS POINT IS A LENGTHY PERIOD OF
LOW POPS TO DEAL WITH THE UNCERTAINTY THURSDAY NIGHT ONWARD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 730 AM EDT SUN JUN 16 2013

RAIN COOLED AREAS FROM A CONVECTIVE SYSTEM CURRENTLY LOCATED IN THE
LOWER GREAT LAKES REGION HAS LEFT A RESIDUAL SFC BOUNDARY ACROSS THE
REGION JUST NORTH OF THE OHIO RIVER. MODELS APPEAR TO ADVERTISE
REGENERATION OF CONVECTION ALONG THIS BOUNDARY LATER TODAY WHICH THEN
MOVES EAST/SOUTHEAST THROUGH THE DAY. SHOULD THIS PLAY OUT THERE
APPEARS TO BE A GOOD CHANCE THAT CONVECTION WILL CLIP PORTIONS OF OUR
FORECAST AREA. WITH EXPECTED MOVEMENT...AFFECTS OF ANY NEW CONVECTION
WOULD APPEAR TO FAVOR KJKL MORE SO THAN KLOZ AND KSME...BUT WOULD NOT
RULE OUT SOME VCSH AT ALL TAF SITES. AT THIS TIME...EXACT SET UP AND
TIMING OF PRECIP IS STILL SOMEWHAT UNCERTAIN...THEREFORE CONFIDENCE
IN ANYTHING HIGHER THAN VCSH IS LOW. AS WE HEAD INTO THE OVERNIGHT
HOURS...CONTINUED MOIST AIR MASS IN ADDITION TO CALM WINDS COULD BE
ENOUGH TO PRODUCE FOG IN THE VALLEYS...POTENTIALLY AFFECTING TAF
SITES. THOUGH THIS IS NOT REFLECTED IN THE FORECAST AT THE
MOMENT...LATEST GUIDANCE IS SUGGESTING A DOWNWARD TREND AROUND 7Z FOR
ALL TAF SITES. OBVIOUSLY IF RAIN IS STILL ONGOING AT TAF SITES...THIS
WILL HINDER BEST FOG DEVELOPMENT.


&&

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

$$

UPDATE...JJ
SHORT TERM...JMW
LONG TERM...HAL
AVIATION...JMW