Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 201713
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
113 PM EDT MON OCT 20 2014

.UPDATE...
ISSUED AT 113 PM EDT MON OCT 20 2014

SOME LIGHT SHOWERS ARE MOVING ACROSS THE AREA TODAY AS A SERIES OF
WEAK SHORT WAVES WILL BE MOVING ACROSS THE AREA OVER THE NEXT 12 TO
18 HOURS. ONLY LIGHT PRECIPITATION IS EXPECTED FROM THESE SHOWERS.
UPDATED THE FORECAST TO TRY TO BETTER TIME THE PRECIPITATION. THE
REST OF THE FORECAST IS ON TRACK.

UPDATE ISSUED AT 958 AM EDT MON OCT 20 2014

UPDATED THE FORECAST TO UP THE PROBABILITY OF PRECIPITATION FOR TODAY
BASED UPON THE CURRENT RADAR AND THE HIGH RESOLUTION RAPID REFRESH
MODEL. THE REST OF THE FORECAST IS ON TRACK.

UPDATE ISSUED AT 724 AM EDT MON OCT 20 2014

THE LINE OF SHOWERS MOVING INTO KY IS STILL SHOWING SIGNS OF
STRENGTHENING...WITH FAIRLY GOOD COVERAGE ACROSS THE NORTH CENTRAL
PORTION OF THE STATE. AFTER SENDING OUT THE PREVIOUS
UPDATE...DECIDED TO GO BACK AND RE-EVALUATE OUR ONGOING POP FORECAST TO
MAKE SURE IT WAS LINING UP WITH THE RECENT RAINFALL TRENDS. ENDED UP
USING A BLEND OF RADAR TRENDS AND LATEST MODEL GUIDANCE TO COME UP
WITH A FORECAST THAT SHOULD BETTER SUIT THE PROGRESSION OF THE LINE
OF SHOWERS INTO EASTERN KY DURING THE DAY TODAY.

UPDATE ISSUED AT 635 AM EDT MON OCT 20 2014

FORECAST SEEMS TO BE ON TRACK SO FAR THIS MORNING FOR THE MOST PART.
THE LINE OF RAIN SHOWERS IS SHOWING SOME SIGNS OF STRENGTHENING AND
BETTER ORGANIZATION AS WE CONTINUE TO TRACK IT/S MOVEMENT ACROSS THE
OHIO RIVER INTO KY. HOWEVER...LATEST OBSERVATIONS ARE STILL ONLY
INDICATING LIGHT RAIN WITH VERY LITTLE VISIBILITY RESTRICTION. MAIN
UPDATE WAS TO TWEAK TEMPERATURES IN THE NEAR TERM. LOADING IN THE
OBSERVATIONAL DATA TO THE ONGOING TEMPERATURE FORECAST PROVED TO DROP
CURRENTLY FORECASTED TEMPERATURES DOWN SEVERAL DEGREES IN SOME
LOCATIONS. BLENDED THIS OUT FOR SEVERAL HOURS...WITH TEMPERATURES
EXPECTED TO START HEATING FROM THIS POINT FORWARD AS THE SUN BEGINS
TO RISE.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 359 AM EDT MON OCT 20 2014

THE REX BLOCK PATTERN CONTINUES OVER THE CONUS THIS MORNING...WITH
MUCH OF THE EASTERN CONUS BEING INFLUENCED BY A STRONG TROUGHING
PATTERN. THIS TROUGH WILL CONTINUE TO BE OUR MAIN WEATHER DRIVER FOR
THE SHORT TERM TODAY THROUGH TUESDAY. DURING THE DAY TODAY...A
SHORTWAVE EMBEDDED IN THE LONGWAVE PATTERN WILL CONTINUE TO
STRENGTHEN AS IT MOVES FROM THE UPPER GREAT LAKES THIS MORNING TO
THE LOWER GREAT LAKES BY LATE THIS AFTERNOON AND EVENING. BY
TOMORROW NIGHT IT WILL STRENGTHEN INTO A CLOSED LOW...THEN DIVE
SOUTHWARD DURING THE DAY TUESDAY...REACHING THE VIRGINIA/S BY TUESDAY
EVENING. HERE IT WILL STALL OUT BEFORE SLOWLY MOVING UP THE NEW
ENGLAND SEA BOARD DURING THE EXTENDED PERIOD.

FOR TODAY...AS THE SHORTWAVE STRENGTHENS...IT WILL DRIVE A SURFACE
LOW PRESSURE SYSTEM FROM THE UPPER GREAT LAKES TO THE LOWER GREAT
LAKES. FROM THIS SURFACE SYSTEM WILL EXTEND A COLD FRONT. AS THE LOW
MOVES...THE COLD FRONT WILL SWEEP FROM NW TO THE SE...AND EVENTUALLY
TRAVERSE EASTERN KY LATE TONIGHT AND INTO TUESDAY MORNING. AS
SUCH...UPPER LEVEL CLOUDS HAVE ALREADY PROTRUDED INTO THE REGION
THIS MORNING IN ADVANCE OF THIS SYSTEM. A WEAK SCATTERED LINE OF
RAIN SHOWERS IS NOT FAR BEHIND...CURRENTLY MOVING ACROSS MUCH OF
NORTHERN OH...IN...AND WESTERN KY. SO FAR THESE SHOWERS ARE SHOWING
UP ON THE RADAR AS VERY LIGHT...WITH LITTLE IMPACTS EXPECTED.
UNFORTUNATELY...LATEST MODELS ARE HAVING A HARD TIME COMING TO A
CONCLUSION ABOUT THE PRECIP AS IT REACHES EASTERN KY AND CONTINUES
AHEAD OF THE FRONT TODAY AND TONIGHT. THE EXACT LOCATION OF WHERE
THE BEST QPF AND POPS WILL BE LOCATED CONTINUES TO DIFFER FROM MODEL
TO MODEL. THERE IS A SLIGHT LACK IN CONSISTENCY BETWEEN OFFICES FOR
POPS OVER THE NEXT 24 HOURS. TRIED TO MATCH UP AS BEST AS POSSIBLE.
REGARDLESS...THIS IS A MOISTURE DEPRIVED SYSTEM...SO ANY RAIN THAT
DOES OCCUR IS NOT EXPECTED TO CAUSE MUCH IN THE WAY OF IMPACTS AND
SHOULD BE MOVING THROUGH THE AREA FAIRLY FAST.

ONCE THE FRONTAL BOUNDARY MOVES THROUGH US BY TOMORROW
MORNING...EXPECT THE RETURN OF A MORE NORTHERLY FLOW PATTERN AND
COOLER TEMPERATURES. AFTERNOON TEMPS WILL ONLY TOP OFF IN THE UPPER
50S TO AROUND 60 ONCE MORE. ALTHOUGH THE FRONTAL BOUNDARY WILL HAVE
EXITED...THE UPPER LEVEL LOW WILL BE ON ITS TRANSITION SOUTHWARD
TOWARDS THE VIRGINIA/S...PULLING THE SURFACE LOW PRESSURE SYSTEM WITH
IT. STRONG NORTHERLY FLOW WILL ALLOW FOR WRAP AROUND MOISTURE TO
CONTINUE TO FLOW INTO EASTERN KY OFF THE BACKSIDE OF THE LOW. THIS
MOISTURE WILL BE VERY WEAK...BUT UPSLOPE FLOW IN THE FAR EAST COULD
BE ENOUGH TO PRODUCE LIGHT SHOWERS IN THIS AREA BOTH TONIGHT AND
THROUGH THE DAY TOMORROW. EXPECT LITTLE IMPACT FROM THIS...WITH ONLY
VERY LIGHT ACCUMULATIONS EXPECTED.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 501 AM EDT MON OCT 20 2014

AN UPPER TROUGH AXIS IS FORECAST TO BE OVER THE APPALACHIANS AT THE
START OF THE PERIOD...IN THE PROCESS OF FORMING A LARGE CLOSED LOW
AT ITS BASE AS IT SLOWLY SHIFTS EASTWARD. AT THE SURFACE...A LARGE
LOW PRESSURE SYSTEM IS EXPECTED TO BE MEANDERING NEAR THE MID
ATLANTIC COAST. IT WILL PUT OUR LOCAL AREA IN A REGION OF COLD AIR
ADVECTION AND UPSLOPE FLOW...FAVORING LOW LEVEL INSTABILITY WITH
CLOUDS AND POSSIBLY SHOWERS. AS THE ENTIRE SET-UP SLOWLY SHIFTS
EASTWARD...IT SHOULD TAKE ANY SHOWERS WITH IT BY WEDNESDAY. A SURFACE
RIDGE WILL THEN BE OUR DOMINANT FEATURE INTO FRIDAY. BY FRIDAY
EVENING BOTH THE GFS AND ECMWF INDICATE A SHORTWAVE TROUGH NEARING
FROM THE NORTHWEST. THE 00Z ECMWF HAS SOME LIGHT PRECIP WITH THIS ON
FRIDAY NIGHT...BUT THIS WAS NOT THE CASE IN THE PREVIOUS RUN...AND
THE GFS IS STILL BASICALLY DRY. WILL STICK WITH POPS BELOW THE 20
PERCENT THRESHOLD AT THIS POINT...KEEPING THE FORECAST DRY. A COOL
AIR MASS AND SUFFICIENT RADIATING AT NIGHT WILL PRESENT A
POSSIBILITY OF FROST FOR THE FIRST FEW NIGHTS...MAINLY IN VALLEYS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 113 PM EDT MON OCT 20 2014

SOME LIGHT SHOWERS ARE MOVING ACROSS THE AREA TODAY IN ASSOCIATION
WITH A SERIES OF WEAK SHORT WAVES MOVING ACROSS THE AREA OVER THE
NEXT 12 TO 18 HOURS. ONLY LIGHT PRECIPITATION IS EXPECTED FROM THESE
SHOWERS HOWEVER THEY WILL BE ABLE TO SLOWLY LOWER THE CIGS DURING THE
EVENING AND WILL BE ABLE TO GET THEM DOWN TO ABOUT 1500 FT BY 9Z. THE
STRATUS CLOUDS SHOULD BURN OFF DURING THE MORNING AND RETURN TO VFR.

&&

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

$$

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





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