Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 300211
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
1011 PM EDT WED OCT 29 2014

.UPDATE...
ISSUED AT 1011 PM EDT WED OCT 29 2014

CURRENT TRENDS ACROSS THE REGION FEATURE THE CLOUD COVER UP NORTH
SLOW TO MOVE SOUTH INTO THE AREA. HIGH PRESSURE CENTERED OVER THE
CENTRAL PLAINS WITH A RIDGE AXIS NUDGING INTO THE TN VALLEY STILL
SEEMS TO BE KEEPING SOME GRADIENT OVER THE AREA. AS SUCH THE CLOUD
COVER HAS BEEN SLOW TO MOVE SOUTH DISSIPATING AS THIS OCCURS. THE
WEAKENING GRADIENT STILL LOOKS TO OCCUR OVERNIGHT SO HAVE KEPT THE
CLOUDS FROM MOVING SOUTH TO LATER IN THE NIGHT AND KEPT THE CLOUD
COVER MAINLY IN THE NORTHEAST AND EAST. CONDITIONS THROUGH THE NIGHT
STILL FAVOR SOME FROST AND FOG SO HAVE KEPT BOTH IN THE WEATHER
GRIDS. HOWEVER...THIS FORECAST MAY CHANGE THROUGH THE NIGHT IF
EXTENSIVE CLOUD COVER DOES MAKE IT FURTHER SOUTH THAN ANTICIPATED.
WITH THIS...THE SLOW APPROACH OF THE CLOUD COVER HAS AFFECTED THE
VALLEY TEMPS AND HAVE ADJUSTED THEM ACCORDINGLY AS SOME EXTREME
VALLEYS HAVE DROPPED OFF EARLY TONIGHT. WITH THESE CHANGES TO TEMPS
AND CLOUD COVER...HAVE SENT A NEW ZFP.

UPDATE ISSUED AT 701 PM EDT WED OCT 29 2014

MAIN FORECAST CONCERN FOR TONIGHT WILL BE THE CLOUD COVER NORTH INTO
OHIO AS IT SLOWLY PUSHES SOUTH. HOW MUCH CLOUD COVER THAT MOVES SOUTH
INTO EASTERN KENTUCKY OVERNIGHT WILL DICTATE HOW MUCH FOG WE WILL GET
AS WELL AS ANY FROST. ONCE THE LEADING EDGE OF THE MOISTURE BANKS
AGAINST THE MOUNTAIN RANGES TO THE EAST...THIS CLOUD COVER WILL
FILTER FURTHER SOUTH IN A LOW LEVEL STRATUS LAYER. FOR NOW...THE
GOING FORECAST LOOKS ON TRACK AND WILL LEAVE THE CLOUD COVER AS IS
BASED ON CURRENT TRENDS. IT IS WORTH MENTIONING THAT THE MODELS DO
NOT HAVE THIS WIDE SPREAD CLOUD COVER IN THEIR SOLUTIONS...THOUGH
HISTORICALLY...THE MODELS DO HAVE TROUBLE IDENTIFYING THIS SCENARIO.
FOR NOW HAVE UPDATED THE GRIDS WITH THE NEWEST OBSERVATIONS AND A NEW
ZFP WILL NOT BE NEEDED.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 315 PM EDT WED OCT 29 2014

SHORT TERM IS BASICALLY A TRANSITION PERIOD LEADING UP TO THIS
WEEKENDS MAJOR STORM SYSTEM. GENERAL WEST TO NORTHWEST STEERING FLOW
WILL GUIDE SFC HIGH PRESSURE ACROSS OUR AREA OVERNIGHT. LOW PRESSURE
AND ASSOCIATED STRONG COLD FRONTAL SYSTEM WILL APPROACH THE FORECAST
AREA QUICKLY THURSDAY NIGHT INTO EARLY FRIDAY MORNING.

FOR SENSIBLE WEATHER...SFC HIGH PRESSURE AND WEAK MID LEVEL SHORT
WAVE RIDGING WILL KEEP OUR WEATHER DRY BUT WILL NOT BE STRONG ENOUGH
TO PREVENT A TEMPORARY INCREASE IN CLOUD COVER OVERNIGHT AS A LARGE
AREA OF SC ROTATES INTO THE OHIO VALLEY REGION. SKIES CLEAR BACK OUT
THURSDAY TO PROVIDE OUR AREA WITH ONE MORE DAY OF SEASONABLE AUTUMN
LIKE WEATHER BEFORE BIG CHANGES OCCUR. WE WILL SEE THE THREAT OF RAIN
SHOWERS INCREASE TOWARDS DAWN ON FRIDAY...MAINLY FOR OUR WESTERN MOST
COUNTIES. FOR TEMPS...WEST TO NORTHWEST FLOW WILL TEND TO KEEP OUR
TEMPERATURES ON THE COOL SIDE OF NORMS. SAW NO REASON TO DEVIATE FROM
BLENDED MODEL GUIDANCE. SO JUST NUDGED INHERITED TEMPS TOWARDS MODEL
CONSENSUS.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 400 PM EDT WED OCT 29 2014

PERIOD WILL START OFF WITH A STRONG CLOSED LOW MOVING SOUTH THROUGH
CANADA...ACROSS THE UPPER GREAT LAKES...AND NOSE-DIVING INTO THE
OHIO RIVER VALLEY REGION FRIDAY EVENING AND OVERNIGHT. THIS LOW IS
CONTINUING TO SHOW A STRENGTHENING TREND OVER THE LAST FEW RUNS OF
THE GFS...NAM...AND ECMWF. THIS WILL BE THE MAIN SYSTEM TO AFFECT
THE WEATHER INTO THE WEEKEND...BUT SHOULD BE FAIRLY PROGRESSIVE. THE
LOW WILL ROTATE EASTWARD THROUGH THE REGION ALONG A TROUGH
AXIS...AND EXIT BY SATURDAY EVENING...WITH HEIGHTS EXPECTED TO RISE
THROUGHOUT THE REST OF THE EXTENDED PERIOD. MODELS ARE ALL IN FAIRLY
GOOD AGREEMENT WITH THIS SYSTEM...AND CONTINUE TO BE SO THROUGH THE
REMAINDER OF THE EXTENDED AS WELL. THIS HAS LED TO HIGHER CONFIDENCE
FOR THIS FORECAST.

CONCERNING THE STRONG LOW MOVING INTO THE REGION...THIS COULD BRING
DRASTIC CHANGES TO THE WEATHER PATTERN ACROSS EASTERN KY. LATEST
FORECAST SOUNDINGS ARE STILL TRENDING COLDER...SHOWING A VERY STRONG
JET STREAK OF NRLY CANADIAN WINDS BEING PULLED INTO THE REGION. THIS
CAA SHOULD DROP TEMPS BELOW FREEZING ACCORDING TO BOTH THE NAM AND
GFS BY 06 SATURDAY THROUGH MID MORNING SATURDAY. HIGHEST ELEVATIONS
/I.E. BLACK MOUNTAIN...COULD LOWER BELOW FREEZING BY 3Z/.
MEANWHILE...TIME HEIGHTS ARE ALSO SHOWING A GOOD AREA OF OMEGA AND
LIFT AROUND THE SAME TIME PERIOD...INDICATIVE OF SOME GOOD SNOW
POTENTIAL. ORIGINALLY...IT SEEMED AS THOUGH ANY ACCUMULATION WOULD
BE CONFINED TO THE HIGHEST ELEVATIONS /WHERE THE BEST UPSLOPE LIFT
AND COLDEST TEMPS WOULD OCCUR/. HOWEVER...BASED ON THE CURRENT
TRENDS...TEMPS SHOULD DROP BELOW FREEZING ACROSS MUCH OF THE
CWA...SO SOME SNOW ACCUMULATIONS ARE POSSIBLE EVEN IN THE WESTERN
CWA. HIGHEST AMOUNTS ARE STILL EXPECTED IN THE UPSLOPE REGIONS.

THE CLINCHER WILL BE THE CHANGE OVER. IT APPEARS AS THOUGH MODELS
ARE IN FAIR AGREEMENT THAT THE PRECIP ASSOCIATED WITH THIS SYSTEM
AND COLD FRONTAL PASSAGE WILL ENTER INTO THE REGION QUITE
QUICKLY...AS EARLY AS 15Z FRIDAY. AT THIS POINT...TEMPS WILL STILL
BE ABOVE FREEZING...WITH PRECIP EXPECTED TO FALL IN THE FORM OF
RAIN. AS THE SYSTEM CONTINUES TO AFFECT EASTERN KY...AND TEMPS FALL
OVERNIGHT...TEMPS WILL FALL TO BELOW FREEZING...AND INSTABILITY
SHOWS SIGNS OF INCREASING. IN FACT...AS INSTABILITY HEIGHTENS FRIDAY
EVENING...IT IS POSSIBLE TO HEAR A FEW RUMBLES OF THUNDER IN THE
HEAVIEST SHOWERS JUST BEFORE TEMPS DROP OFF OVERNIGHT AND THE RAIN
CHANGES TO SNOW.

TEMPS WILL QUICKLY JUMP BACK ABOVE FREEZING DURING THE DAY
SATURDAY...MELTING THE SNOW THAT HAS FALLEN. BY THIS POINT...DRY AIR
SHOULD BE WORKING INTO THE REGION AS THE UPPER LEVEL LOW PULLS EAST
OF EASTERN KY AND UPPER LEVEL HEIGHTS BEGIN TO INCREASE. SNOW WILL
CHANGE BACK TO RAIN...AND THEN SLOWLY TAPER OFF DURING THE DAY
SATURDAY. SOME LINGERING SHOWERS MAY STILL BE POSSIBLE HOWEVER IN
THE FAR EAST AS WRAP AROUND MOISTURE CONTINUES TO FLOW BACK INTO THE
REGION. THIS MOISTURE SHOULD FINALLY DEPART BY LATE SATURDAY NIGHT.
HIGH PRESSURE SHOULD THEN TAKE HOLD OVER THE REGION INTO THE
BEGINNING OF NEXT WEEK...WITH TEMPERATURES EXPECTED TO SLOWLY
REBOUND. YET ANOTHER COLD FRONT IS EXPECTED TO IMPACT THE REGION BY
LATE IN THE PERIOD TUESDAY INTO WEDNESDAY...BRINGING ANOTHER SHOT OF
PRECIP ACROSS THE CWA. LUCKILY...THIS SYSTEM LOOKS NO WHERE
NEAR AS POTENT AS THE ONE EXPECTED FOR THIS WEEKEND.

AS FAR AS SNOW TOTALS AND TEMPERATURE EXPECTATIONS FOR THIS
WEEKEND...UPSLOPE FLOW WILL KEEP HIGHEST SNOW AMOUNTS IN THE HIGHEST
ELEVATIONS...BUT IT IS POSSIBLE FOR MANY LOCATIONS TO EXPERIENCE SOME
ACCUMULATING SNOW. THE KEY WILL BE THE GROUND TEMPERATURE AS
WELL...AS TO HOW MUCH OF THE SNOW STICKS AND HOW MUCH MELTS. STORM
TOTAL SNOWFALL IS SHOWING BETWEEN 2.5 AND 3.0 INCHES OF SNOW IN THE
HIGHEST TERRAIN...WITH BETWEEN 0.2 AND 1.0 INCHES ELSEWHERE ACROSS
THE CWA. AS TEMPS RISE ABOVE FREEZING SATURDAY AND PRECIP BEGINS TO
FALL AS RAIN...WHAT HAS ACCUMULATED WILL LIKELY QUICKLY MELT. EVEN
AFTER THE PRECIP HAS PASSED...TEMPS SHOULD CONTINUE TO DROP AT OR
BELOW FREEZING THROUGH THE BEGINNING OF THE WEEK. AS A RESULT...HAVE
ADDED THE MENTION OF FROST FOR SATURDAY NIGHT/SUNDAY MORNING. BY THE
END OF THIS WEEKEND...THE GROWING SEASON SHOULD BE DONE FOR THE YEAR.
DAYTIME TEMPS BOTH SATURDAY AND SUNDAY SHOULD GENERALLY BE IN THE 40S
/COLDEST SATURDAY/...WITH BUILDING HEIGHTS ALLOWING FOR REBOUNDING
TEMPS INTO THE BEGINNING OF THE WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 701 PM EDT WED OCT 29 2014

FORECAST CHALLENGE CONCERNS AN AREA OF MOISTURE THAT APPEARS TO DROP
SOUTHEAST INTO OUR AREA OVERNIGHT. MOISTURE IS AT ABOUT THE 3K FT AGL
LEVEL AND WOULD AGREE WITH UPSTREAM OBS AS A LARGE AREA OF SC IS
ROTATING SOUTHWARD INTO THE OHIO VALLEY. QUESTION IS HOW FAR SOUTH
WILL THIS AREA OF CLOUD COVER EXTEND. THIS APPEARS TO BRING AT LEAST
MVFR CIGS TO SYM AND SJS. WHERE SKIES ARE CLEARER...LOZ AND SME...FOG
WILL DEVELOP AND WILL DROP VIS FOR THESE LOCATIONS IN THE TAFS. VFR
CONDITIONS WILL THEN RETURN INTO THE DAY ON THURSDAY.


&&

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

$$

UPDATE...SHALLENBERGER
SHORT TERM...RAY
LONG TERM...JMW
AVIATION...RAY/SHALLENBERGER






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