Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 201046
AFDJKL

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

.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 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 646 AM EDT MON OCT 20 2014

A LINE OF SHOWERS IS CURRENTLY MOVING ACROSS THE OHIO RIVER INTO KY
AHEAD OF AN APPROACHING COLD FRONT. EXPECT THESE SHOWERS TO BE LIGHT
AND SCATTERED IN NATURE...AFFECTING MUCH OF EASTERN KY THROUGH THE
DAY AND INTO THE OVERNIGHT. WENT AHEAD AND INCLUDED VCSH AT THIS
TIME...GIVEN THE UNCERTAINTY OF WHERE AND WHEN EXACTLY THESE SHOWERS
WILL AFFECT A GIVEN TAF SITE. LATEST MODELS ARE STILL SHOWING CIGS
LIKELY LOWERING THROUGHOUT THE AFTERNOON AND INTO THE OVERNIGHT HOURS
AS WELL. EXPECT VFR CONDITIONS TO GENERALLY STAY INTACT UNTIL THE
OVERNIGHT TONIGHT...WHEN SOME MVFR CIGS ARE POSSIBLE. DESPITE A
FRONTAL PASSAGE...WINDS SHOULD GENERALLY REMAIN UNDER 10KTS BOTH
TODAY AND TONIGHT...SWITCHING FROM SW DURING THE DAY TODAY...TO MORE
WRLY LATE TONIGHT AFTER THE FRONTAL PASSAGE.

&&

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

$$

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






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