Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 290753
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
353 AM EDT MON JUN 29 2015

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 352 AM EDT MON JUN 29 2015

THE NEW SHORT TERM DISCUSSION WILL BE ISSUED SHORTLY.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 351 AM EDT MON JUN 29 2015

UPPER LEVEL MODELS CONTINUE TO SUPPORT A LONGWAVE TROUGH ACROSS MUCH
OF THE EASTERN CONUS TO START OFF THE PERIOD...KEEPING THE OHIO
RIVER VALLEY IN NW FLOW REGIME FROM TUESDAY NIGHT THROUGH FRIDAY.
THE AXIS OF THE TROUGH WILL THEN SHIFT DIRECTLY OVER KY AS ANOTHER
SHORTWAVE DIGS SOUTHWARD FROM CANADA TO START OFF THE WEEKEND.
FINALLY...THE UPPER LEVEL LONGWAVE PATTERN WILL SLOWLY DAMPEN AS WE
HEAD INTO THE END OF THE EXTENDED PERIOD SUNDAY INTO MONDAY.
HOWEVER...BY THE WEEKEND MODELS SHOW QUITE A BIT OF
DISCONTINUITY...SO THE EXACT TIMING AND MAGNITUDE OF THE UPPER LEVEL
TROUGH WILL BE SOMEWHAT LOW CONFIDENCE.

WITH THE GENERAL NW FLOW...EXPECT SHORTWAVES TO CONTINUE TO TRAVEL
SE AND INTO THE OHIO RIVER VALLEY. THIS WILL RESULT IN SEVERAL
SURFACE LOW PRESSURE CENTERS AND FRONTAL BOUNDARIES PASSING THROUGH
THE REGION...CREATING THE ENERGY AND LIFT TO PRODUCE SHOWERS AND
THUNDERSTORMS. AS HAS BEEN THE CASE OVER THE LAST FEW WEEKS...EXPECT
MOST WIDESPREAD ACTIVITY TO BE RIGHT ALONG AND JUST AHEAD OF THE
FRONTAL BOUNDARY...PEAKING IN SEVERITY DURING THE AFTERNOON AND
EARLY EVENING HOURS IN CONJUNCTION WITH THE PEAK HEATING.

THE FIRST OF THESE BOUNDARIES WILL BE EXITING TUESDAY NIGHT AS THE
NEXT BOUNDARY TO OUR NORTH MAKES A SHIFT SOUTHWARD. THIS SECOND
BOUNDARY IS EXPECTED TO MAKE IT INTO THE REGION WEDNESDAY
NIGHT...AND ACCORDING TO THE LATEST 00Z RUN OF THE GFS40...SHOULD
BECOME STALLED OUT ACROSS THE REGION THROUGH THE DAY FRIDAY AS THE
UPPER LEVEL TROUGH BACK-BUILDS ACROSS THE OHIO RIVER VALLEY. ALONG
THIS BOUNDARY...EXPECT SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS...WITH ANY UPPER LEVEL WAVES OF ENERGY ENHANCING
CHANCES FOR A MCS TO PASS THROUGH THE REGION. THE FRONTAL BOUNDARY
WILL FINALLY SHIFT SE OF THE STATE BY FRIDAY EVENING...ASSUMING
MODEL TIMING PANS OUT. UNFORTUNATELY...ANOTHER WEAK FRONTAL BOUNDARY
WILL HAVE FORMED TO OUR NORTH...AND WE WILL STILL BE IN VERY CLOSE
PROXIMITY TO THE EXITING FRONT. UNDER SW FLOW BY THIS POINT...AND
STILL IN AN UPPER LEVEL LOW PRESSURE TROUGHING PATTERN...EXPECT LESS
ORGANIZED SCATTERED CONVECTION TO CONTINUE INTO THE WEEKEND...WITH
BEST CHANCES STILL EXPECTED OVER THE SE CWA CLOSER TO THE EXITING
FRONT.

BY SUNDAY...MODEL CONFIDENCE IN CONVECTION STARTS TO DECLINE AS
THERE IS LITTLE AGREEMENT IN THE PATTERN ALOFT. IF THE GFS IS
CORRECT...THE UPPER LEVEL TROUGH WILL BEGIN DAMPENING/WEAKENING...
BUT CONTINUED WARM SW FLOW AND A PASSING SHORTWAVE COULD BE THE
SPARK FOR YET MORE SHOWERS AND THUNDERSTORMS DURING THE
AFTERNOON/EVENING HOURS. BOTH THE ECMWF AND THE GFS DO SUPPORT A
LARGE UPPER LEVEL CLOSED LOW PUSHING SOUTH FROM NW CANADA TO CENTRAL
CANADA BY LATE IN THE WEEKEND. THIS ENERGY WILL TRANSLATE TO THE
SURFACE WITH A STRONG LOW PRESSURE SYSTEM DEVELOPING ACROSS
SOUTHCENTRAL CANADA...PULLING A STRONG FRONTAL BOUNDARY WHICH WILL
SWEEP ACROSS MUCH OF THE CENTRAL AND EVENTUALLY EASTERN CONUS. EXACT
TIMING IS STILL OBVIOUSLY IN LOW CONFIDENCE...BUT IF THIS PANS OUT
ANOTHER GOOD CHANCE OF WIDESPREAD SHOWERS AND THUNDERSTORMS WILL
IMPACT THE REGION AHEAD OF THE FRONTAL ZONE AS WE END THE EXTENDED
PERIOD MONDAY.

WITH A NW FLOW REGIME...COOLER AIR WILL BE PULLED IN FROM CANADA TO
START OUT THE EXTENDED PERIOD. THEN AS THE TROUGH BACK-BUILDS AND
GENERALLY SW FLOW TAKES HOLD DURING A PORTION OF THE PERIOD...WE
WILL ACTUALLY CONTINUE TO PULL COOLER AIR IN FROM THE NORTH...AS
WINDS BECOME MORE NW JUST TO OUR WEST. THIS...IN CONJUNCTION WITH
CLOUD COVER AND POTENTIAL RAIN...WILL KEEP TEMPERATURES MODERATED
THROUGH MUCH OF THE EXTENDED...AT LEAST INTO THE WEEKEND. EXPECT
HIGHS IN THE UPPER 70S TO LOW 80S. BY MONDAY...ENERGY WILL BE
REDIRECTED TOWARDS THE INCOMING UPPER LEVEL HIGH...CAUSING A BREAK
IN THE UPPER LEVEL WIND FLOW ACROSS THE REGION. THIS WILL ALLOW FOR
A BETTER PULL OF TRUE SW WIND FLOW IN THE MID AND LOW LEVELS...WHICH
COMBINED WITH ANY SUNSHINE...WILL BOOST TEMPS BACK UP INTO THE MID
AND MAYBE EVEN UPPER 80S FOR THE DAY. WITH PARTLY TO MOSTLY CLOUDY
SKIES EXPECTED TO STICK AROUND DURING THE NIGHT...EXPECT
TEMPERATURES TO REMAIN MODERATED AS WELL...STAYING AROUND THE MID
AND UPPER 60S FOR EARLY MORNING LOWS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 215 AM EDT MON JUN 29 2015

IN GENERAL EXPECTING VFR CONDITIONS THROUGH THE FORECAST PERIOD.
AN AREA OF SCATTERED SHOWERS ASSOCIATED WITH AN APPROACHING COLD
FRONTAL SYSTEM WILL OVERSPREAD THE REGION FROM WEST TO EAST AROUND
DAWN THIS MORNING. SCATTERED THUNDERSTORMS ARE THEN EXPECTED TO
REDEVELOP DURING THE AFTERNOON. THE PRECIPITATION MAY BRING
TEMPORARY LOCALIZED IFR CONDITIONS...ESPECIALLY IN AFTERNOON
THUNDERSTORMS. SOME OF THE THUNDERSTORMS MAY CONTAIN MARGINALLY
LARGE HAIL AND STRONG WINDS. OTHERWISE...LIGHT SOUTHERLY WINDS
WILL GRADUALLY VEER TO THE SOUTHWEST AND INCREASE TO AROUND
10 KTS...WITH HIGHER GUSTS TO AROUND 20 KTS IN THE AFTERNOON.


&&

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

$$

SHORT TERM...RAY
LONG TERM...JMW
AVIATION...HAL/RAY



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