Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 221137
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
637 AM EST MON DEC 22 2014

.UPDATE...
ISSUED AT 637 AM EST MON DEC 22 2014

DESPITE THE UNFAVORABLE CONDITIONS...A FEW SPRINKLES HAVE
DEVELOPED FROM BREATHITT COUNTY NORTHEAST INTO JOHNSON COUNTY. JOHNSON
COUNTY MESONET IS STILL AT 31 DEGREES...BUT PRECIPITATION IS PROBABLY
NOT HEAVY ENOUGH (AS OBSERVED HERE AT THE OFFICE) TO CAUSE MUCH OF AN
ISSUE AND ALL OF THIS SHOULD BE A VERY SHORT TERM ISSUE AS THIS WILL
ALL BE PUSHING OUT IN THE NEXT HOUR. ALSO...THE MESONET HAS BEEN
COMING UP AS THE CLOUDS SPREAD BACK IN. UPDATED TO THROW IN SOME
SPRINKLES FOR THE AFFECTED AREAS OVER THE NEXT HOUR OR TWO.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 315 AM EST MON DEC 22 2014

EASTERN KENTUCKY SITS BETWEEN TWO SYSTEM EARLY THIS MORNING WITH THE
FIRST SYSTEM PUSHING NORTH ACROSS THE CAROLINAS...WHILE THE SECOND
ONE DROPPING SOUTHEAST INTO THE CENTRAL PLAINS. MID LEVEL
SUBSIDENCE...COMBINED WITH LOWER LEVEL DOWNSLOPING SOUTHEAST FLOW HAS
KEPT EASTERN KENTUCKY DRY OVERNIGHT. THE SYSTEM OVER THE CAROLINAS
WILL SPREAD ATTEMPT TO SPREAD SOME MOISTURE BACK TO THE NORTHWEST AS
IT MOVES NORTH THIS MORNING...BUT GIVEN THE HOSTILE
ENVIRONMENT...COMBINED WITH LARGE DEWPOINT DEPRESSIONS...ITS ENOUGH
TO WARRANT A DRY FORECAST THROUGH THE DAY. WE SHOULD SEE A MIX OF SUN
AND CLOUDS TODAY AS CLOUDS HAVE A TOUGH TIME HANGING ON THROUGH THE
DAY. THIS WILL HELP BOOST TEMPERATURES UP INTO THE 50S TODAY. A MID
LEVEL WAVE ROUNDING THE BASE OF THE MID LEVEL TROUGH WILL PUSH
NORTHEAST ACROSS THE OHIO RIVER VALLEY TONIGHT. HOWEVER...SOUTHEAST
WINDS WILL PERSIST INTO TONIGHT. THE BEST FORCING APPEARS WILL STAY
TO OUR WEST AND NORTH TONIGHT. WITH OUR WESTERN COUNTIES ON THE
FRINGES. THUS..WILL BRING A SMALL CHANCE INTO OUR WESTERN ZONES
OVERNIGHT. WE MAY SEE A LULL THROUGH MUCH OF TUESDAY...BUT AS THE MID
LEVEL TROUGH ADVANCES EAST...ANOTHER STRONGER WAVE IS EXPECTED TO
PUSH NORTH ACROSS THE TENNESSEE VALLEY...LEADING OT INCREASING RAIN
CHANCES BY LATE IN THE DAY. A TRICKY TEMPERATURE FORECAST FOR
TUESDAY...BUT IF WE CAN STAY DRY ENOUGH THROUGH THE DAY...READINGS
INTO THE 60S SEEM LIKELY...BUT AN EARLIER ONSET TO RAIN OR MORE CLOUD
COVER...COULD LIMIT HOW WARM WE GET. PLAN TO LIMIT RAIN CHANCES ON
TUESDAY IN THE EAST AS SOME WEAK DOWNSLOPING CONTINUES AND COULD HOLD
OFF RAIN UNTIL TUESDAY NIGHT.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 315 AM EST MON DEC 22 2014

THE FOCUS OF THE EXTENDED PERIOD WILL BE THE TUESDAY NIGHT THROUGH
CHRISTMAS MORNING TIME FRAME. A POWERFUL STORM SYSTEM IS EXPECTED TO
FORM OVER THE SOUTHERN MISSISSIPPI RIVER VALLEY TUESDAY NIGHT INTO
WEDNESDAY...AS A STREAK IN THE POLAR JET PHASES WITH A SOUTHERN
STREAM JET STREAK OVER THE LOUISIANA MISSISSIPPI REGION. THIS
SOUTHERN STORM SYSTEM IS EXPECTED TO PUSH ACROSS THE TENNESSEE AND
OHIO VALLEY REGIONS AS A LARGE TROUGH OF LOW PRESSURE ALOFT MAKES
ITS WAY ACROSS THE NORTHERN PLAINS AND GREAT LAKES REGION. BOTH THE
ECMWF AND GFS MODELS WERE IN GOOD AGREEMENT WITH THE TIMING OF THIS
LARGE WEATHER SYSTEM...ALONG WITH THE EVOLUTION OF PRECIPITATION
ASSOCIATED WITH IT AND THE EASTWARD PROGRESSION OF THE SYSTEM.
TEMPERATURES WILL BE QUITE WARM TO BEGIN THE PERIOD...WITH READINGS
IN 50S EXPECTED BOTH TUESDAY NIGHT AND WEDNESDAY. PRECIPITATION WILL
START OUT AS PERSISTENT MODERATE TO AT TIMES LOCALLY HEAVY RAIN
SHOWERS. THIS RAIN WILL LAST THROUGHOUT CHRISTMAS EVE DAY. ONCE THE
UPPER LOW MOVES OFF TO THE EAST...WINDS WILL SHIFT TO THE WEST
CHRISTMAS EVE NIGHT INTO EARLY CHRISTMAS DAY. THIS WILL ALLOW SOME
COLDER AIR TO FILTER INTO THE BEHIND THE DEPARTING WEATHER SYSTEM.
AS A RESULT...THE RAIN WILL GRADUALLY MIX WITH SNOW LATE WEDNESDAY
NIGHT INTO EARLY THURSDAY MORNING. THE LATEST MODEL SOUNDINGS ARE
SUGGESTING THAT ICE CRYSTAL GROWTH ALOFT WILL BE LACKING...THEREFORE
MAKING FOR ONLY VERY MEAGER AMOUNTS OF SNOW OCCURRING ACROSS THE
AREA. BASED ON THAT...AND THAT FACT THE GROUND WILL BE QUITE
WARM...VERY LITTLE IF ANY SNOW ACCUMULATION IS EXPECTED.

THE OTHER ISSUE OF NOTE WITH THIS SYSTEM WILL BE THE WIND. AS THE
UPPER LOW PRESSES EASTWARD AND STRENGTHENS...THE SURFACE WINDS WILL
RESPOND IN KIND ACROSS EASTERN KENTUCKY. WINDS WILL BEGIN TO PICK UP
QUITE A BIT DURING THE AFTERNOON HOURS ON WEDNESDAY...WITH SOUTHERLY
WINDS OF 10 TO 20 MPH POSSIBLE. THE WINDS COULD GUST AS HIGH AS 30
TO 40 MPH FROM TIME TO TIME...PARTICULARLY AS THE UPPER LOW AND ITS
ATTENDANT SURFACE COLD FRONT MOVE PAST THE AREA.

TEMPERATURES TO BEGIN THE PERIOD WILL BE WELL ABOVE NORMAL...WITH
READINGS TOPPING OUT IN THE MID TO UPPER 50S ON WEDNESDAY AND NIGHT
TIME LOWS IN THE MID 30S WEDNESDAY NIGHT. AFTER THAT...THINGS WILL
RETURN TO NORMAL AS THE COLD AIR SETTLES OVER THE REGION. HIGHS EACH
DAY FROM CHRISTMAS DAY THROUGH THE WEEKEND ARE EXPECTED TO AT OR
SLIGHTLY BELOW NORMAL. THE EXCEPTIONS TO THIS COULD BE FRIDAY AND
FRIDAY NIGHT...WHEN ANOTHER WEATHER SYSTEM TRAVERSES THE REGION.
TEMPERATURES ON FRIDAY COULD WARM INTO THE LOWER 50S AS WINDS SHIFT
TO THE SOUTH AHEAD OF THE APPROACHING WEATHER SYSTEM. THE PERIOD OF
THE FORECAST...HOWEVER...IS WHERE THINGS GET A BIT OUT OF SORTS. THE
ECMWF MODEL HAS A LARGE...ROBUST...AND VERY MOIST WEATHER SYSTEM
MOVING ACROSS THE REGION DURING THE WEEKEND...WHILE THE GFS IS
FORECASTING A MUCH WEAKER AN NEARLY PRECIPITATION FREE WEATHER
SYSTEM DURING THIS SAME PERIOD OF TIME. FINALLY DECIDED TO INCLUDE A
SLIGHT CHANCE OF RAIN FOR THE SATURDAY SUNDAY TIME FRAME TO ACCOUNT
FOR THE FACT THAT BOTH MODELS ARE PRODUCING SOME SORT OF
PRECIPITATION FOR EASTERN KENTUCKY...WHILE AT THE SAME TIME
ACCOUNTING FOR THE ENORMOUS DIFFERENCES BETWEEN THE TWO MODELS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 637 AM EST MON DEC 22 2014

CLOUDS WILL HOLD OVER THE AREA THIS MORNING WITH SOME PATCHY MVFR
CONDITIONS POSSIBLE. HOWEVER...FOR THE MOST PART VFR CONDITIONS
SHOULD PREVAIL. DOWNSLOPING SOUTHEAST FLOW OFF THE HIGH TERRAIN
ERODE ANY MVFR CIGS BY 9 AM WITH VFR CONDITIONS EXPECTED THROUGH THE
REST OF THE DAY. THE CLOUDS MAY DISSIPATE FOR A TIME THIS
AFTERNOON...BEFORE HIGH/MID CLOUDS INCREASE AGAIN AHEAD OF OUR NEXT
WEATHER SYSTEM. THUS...PLAN TO STICK WITH VFR CONDITIONS THROUGH THE
TAF FORECAST PERIOD. SOME QUESTION AS TO IF/WHEN SHOWERS MOVE INTO
EAST KENTUCKY TONIGHT...WITH ANY SHOWERS MOST LIKELY IN OUR SOUTH
CENTRAL INTO NORTHERN KENTUCKY. WILL INCLUDE A VCSH IN THE SYM AND
SME TAFS TO ACCOUNT FOR SOME UNCERTAINTY.

&&

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

$$

UPDATE...KAS
SHORT TERM...KAS
LONG TERM...AR
AVIATION...KAS





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