Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 200901
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
501 AM EDT MON OCT 20 2014

.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 VIRGINIAS 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. THIS WAS FURTHER COMPLICATED BY THE LACK OF 0Z DATA WHILE
CREATING THE FORECAST DUE TO A NCF ISSUE. THESE TWO ISSUES HAVE LED
TO 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.

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 VIRGINIAS...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 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 143 AM EDT MON OCT 20 2014

CONDITIONS WILL BE MAINLY VFR THROUGH THE AVIATION PERIOD ON THE
BACKSIDE OF HIGH PRESSURE RETREATING TO THE NORTHEAST. THERE IS A
POTENTIAL FOR PATCHY FOG LATE TONIGHT AT SME AND LOZ...BUT VIS
SHOULDN/T GET ANY WORSE THAN MVFR FROM THIS. CIGS WILL LIKELY DEVELOP
AND LOWER THROUGH THE AFTERNOON ON MONDAY...BUT LATEST SOUNDINGS ARE
SHOWING THE LOWEST CLOUD DECK AROUND 3 TO 4K FEET WITH ONLY SCT CIGS
AT BEST. LIGHT AND VARIABLE WINDS TONIGHT WILL AVERAGE AROUND 5 KTS
FROM THE SOUTHWEST THROUGH THE DAY MONDAY.

&&

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

$$

SHORT TERM...JMW
LONG TERM...HAL
AVIATION...JMW






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