Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 260854
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
354 AM EST FRI DEC 26 2014

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 307 AM EST FRI DEC 26 2014

EARLY THIS MORNING...AN UPPER LEVEL RIDGE WAS CENTERED NEAR CUBA WITH
THE RIDGE AXIS EXTENDING NORTH INTO THE SOUTHEASTERN US...APPALACHIANS
TO THE CENTRAL GREAT LAKES REGION. MEANWHILE AS TROUGH WAS OVER THE
ROCKY MOUNTAIN REGION WITH A CLOSED LOW OVER THE FOUR CORNERS REGION.
A DEEP CLOSED LOW WAS ALSO OVER EASTERN CANADA. AT THE SFC...HIGH
PRESSURE WAS CENTERED OVER THE CENTRAL AND SOUTHERN APPALACHIAN
REGION. ASSOCIATED WITH THIS RIDGE WAS A VERY DRY AIRMASS AND THE
OBSERVATIONS FROM THE HIGHER TERRAIN ABOVE 2500 FEET HAVE EXPERIENCED
THE SUBSIDENCE INVERSION SURFACING. THESE HIGHER RIDGES ARE IN THE
LOWER 40S WITH DEWPOINTS IN THE SINGLE DIGITS ABOVE ZERO TO THE LOWER
TEENS. AS EXPECTED...THE POSITION OF THIS HIGH IS FAVORABLE FOR A
RIDGE/VALLEY TEMPERATURE SPLIT AND THIS IS EVIDENCED BY CURRENT
OBSERVATION RANGING FROM THE MID 20S IN THE NORMALLY COLDER VALLEY
LOCATIONS TO THE LOWER 40S. THE RIDGES IN THE LOWER TERRAIN ARE
CURRENTLY NEAR THE FREEZING MARK. OBSERVATIONS FROM EARLIER INDICATED
SOME VALLEY FOG.

OTHER THAN THE PATCHY EARLY VALLEY FOG AND POSSIBILITY OF THIS BEING
PATCHY FREEZING FOG...THROUGH AROUND DAWN. SOME OF THIS MAY DISSIPATE
AND JUST GO INTO FROST FORMATION...SO HAVE ONLY KEPT THIS AS PATCHY.
THE UPPER LEVEL AND SFC RIDGE WILL DOMINATE TODAY INTO TONIGHT. SOME
OF THE VERY DRY AIR ALOFT WILL MIX DOWN ESPECIALLY IN THE SOUTHEASTERN
COUNTIES AND SOME LOW MIN HUMIDITY IS ANTICIPATED...ESPECIALLY ABOVE
2000 FEET. MIN RH OF 20 TO 30 PERCENT SHOULD BE COMMON OVER THE
SOUTHEASTERN COUNTIES...WITH MIN RH FROM THE HIGH SINGLE DIGITS TO
THE TEENS ABOVE 2000 FEET. FURTHER TO THE WEST TEMPERATURES SHOULD BE
COLDER AND DEWPOINT NOT AS LOW. THE SFC AND UPPER LEVEL RIDGE WILL
DEPART TO THE EASTERN SEABOARD LATER TODAY AND INTO TONIGHT...BUT WITH
THE RELATIVELY DRY AIR REMAINING IN PLACE...ANOTHER RIDGE/VALLEY
TEMPERATURE SPLIT IS ANTICIPATED.

MEANWHILE...THE TROUGH INITIALLY OVER THE ROCKIES WILL BEGIN TO MOVE
EAST INTO THE PLAINS THROUGH SATURDAY. A LEAD SHORTWAVE AND A
NORTHERN STREAM TROUGH SHOULD INTERACT TO LEAD TO A WAVE OR SERIES OF
WAVES OF LOW PRESSURE MOVING NORTHEAST ALONG A BAROCLINIC ZONE THAT
CURRENTLY EXTENDS FROM THE NORTHERN GREAT LAKES TO THE CENTRAL PLAINS
TO THE SOUTHERN ROCKIES. AS THE WAVE OF LOW PRESSURE TRACKS INTO THE
CENTRAL GREAT LAKES THIS TRAILING BUT WAVY SFC COLD FRONT SHOULD
REACH THE LOWER OH VALLEY AND POSSIBLY ENTER THE COMMONWEALTH BEFORE
THE END OF THE PERIOD. HOWEVER...GIVEN THE CURRENTLY DRY AIRMASS IN
PLACE THAT IS EXPECTED TO LINGER INTO EARLY ON SATURDAY...IT WILL
TAKE A WHILE FOR MOISTURE ADVECTION TO BE SUFFICIENT FOR RAIN SHOWERS
TO ENTER EASTERN KY. IN FACT...THESE SHOULD BE CLOSER TO THE FRONT
INITIALLY AND MOST OF...IT NOT THE ENTIRE CWA SHOULD REMAIN DRY
THROUGH SUNSET ON SATURDAY. HOWEVER...THE WEEKEND SHOULD END RATHER
WET WITH STEADIER RAIN SPREADING INTO THE AREA JUST AFTER THE END OF
THE PERIOD.

THE DRY AIRMASS WILL WARM RATHER WELL TODAY AND MAX T SHOULD AVERAGE
10 TO 15 DEGREES ABOVE NORMAL. TEMPERATURES ON SATURDAY SHOULD BE
SLIGHTLY MILDER AND EVEN FURTHER ABOVE NORMAL. EVEN OVERNIGHT LOWS
TONIGHT SHOULD AVERAGE ABOUT 10 DEGREE ABOVE NORMAL ON THE RIDGES AND
A COUPLE OF DEGREES ABOVE NORMAL FOR VALLEY LOCATIONS.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 349 AM EST FRI DEC 26 2014

THE PERIOD WILL BEGIN WITH A SLOW MOVING COLD FRONT SLOWLY PROGRESS
EAST AS SURFACE HIGH MOVES EAST INTO THE ATLANTIC. THIS SLOW MOVING
FRONT WILL HAVE SEVERAL AREAS OF LOW PRESSURE MOVE ALONG THE
BOUNDARY. ONSET OF PRECIP COULD BE SLOWED DUE TO
DOWNSLOPING...HOWEVER MOISTURE WILL EVENTUALLY DEEPEN AS WE MOVE INTO
SUNDAY. NO TREAT OF WINTER PRECIP AS TEMPERATURES ARE EXPECTED TO BE
ABOVE NORMAL DURING THIS PERIOD. THIS FRONTAL BOUNDARY AND ELONGATED
TROUGH WILL MOVE EAST WITH THE TROUGH BEGINNING TO FLATTEN OUT SUNDAY
NIGHT. HIGH PRESSURE WILL PROGRESS EAST BEHIND THE COLD FRONT AND
THIS WILL ALSO USHER IN COOLER CLOSER TO NORMAL TEMPERATURES ON
MONDAY INTO TUESDAY. THIS HIGH PRESSURE WILL KEEP WEATHER FAIRLY
QUIET AND TEMPS GENERALLY BELOW NORMAL THROUGH MUCH OF THE LONG TERM
PERIOD. TUESDAY NIGHT THERE IS A WEAK SHORT WAVE THAT CROSSES THE
AREA WITH MAINLY A BIT MORE CLOUD COVER ACROSS THE REGION. THIS WILL
KEEP FROM GAINING MAX COOLING AND COULD EVEN BRING POTENTIAL OF SOME
FLURRIES...HOWEVER CONFIDENCE IS LOW ON THIS AT THIS POINT GIVEN HOW
DRY IT WILL BE. ALSO BASED ON MODEL SOUNDING THE MOISTURE IS QUITE
SHALLOW. HIGH WILL CONTINUE TO BUILD EAST BRINGING MOSTLY CLEAR SKIES
AS WE MOVE INTO LATER WEDNESDAY AND WEDNESDAY NIGHT. GIVEN THAT HIGH
WILL BE MOSTLY CRESTING ACROSS THE REGION AND MOSTLY CLEAR SKIES
WOULD EXPECT THIS TO ONE OF THE COLDER NIGHTS WITH GOOD RADIATIONAL
COOLING. RIGHT NOW GOING WITH LOW TEMPS IN THE UPPER TEEN TO LOWER
20S WED NIGHT. MOVING INTO THURSDAY MORE UNCERTAINTY EXISTS WITH
500MB SHORTWAVE EJECTING OUT OF THE FOUR CORNER AND HOW QUICKLY
MOISTURE SPREADS NE AHEAD OF DEVELOPING LOW PRESSURE SYSTEM ACROSS
SOUTHERN TX. RIGHT NOW JUST KEPT SLIGHT CHANCE OF MIX RAIN/SNOW
BEFORE CHANGING TO RAIN ON THURSDAY...HOWEVER CONFIDENCE IS LOW ON
HOW MUCH OF THIS SYSTEM WILL BE OCCURRING ON THURSDAY VERSUS FRIDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 135 AM EST FRI DEC 26 2014

HIGH PRESSURE WILL BRING MOSTLY VFR TO THE ENTIRE REGION THROUGH THE
PERIOD. THE ONLY EXCEPTION TO THIS IS SOME MVFR OR LOCALLY LOWER FOG
IN THE DEEPER NON TAF SITE VALLEY LOCATIONS.


&&

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

$$

SHORT TERM...JP
LONG TERM...DJ
AVIATION...JP





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