Area Forecast Discussion
Issued by NWS Jackson, KY

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KJKL 232055
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
355 PM EST TUE DEC 23 2014

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 353 PM EST TUE DEC 23 2014

THIS AFTERNOON SHOWERS AND THUNDERSTORMS ARE SPREADING ACROSS
PORTIONS OF EASTERN KY. WSR-88D SHOWING BEST CONCENTRATION OF SHOWERS
AND THUNDERSTORMS GENERALLY ALONG AND JUST EAST OF THE WESTERN CWA
BORDER. SHOWERS HAVE BEEN MOVING NE ALONG THIS AREA WITH SOME AREAS
SEEING AROUND A QUARTER OF A INCH WITH HIGHER AMTS POSSIBLE IN
HEAVIER STORMS. HRRR GUIDANCE SEEMS TO HAVE A DECENT HANDLE ON THESE
BANDS OF SHOWERS AND THUNDERSTORMS AND HAS THESE BANDS ACROSS
PORTIONS OF THE TN VALLEY PROGRESSING NORTH ACROSS EASTERN KY THIS
EVENING INTO TONIGHT. 18Z SURFACE ANALYSIS SHOWS LOW PRESSURE
CONTINUING TO DEVELOP ALONG THE LA COAST LINE THIS AFTERNOON. THIS
AREA OF LOW PRESSURE IS EXPECTED TO CONTINUE TO MOVE NORTH AND EAST
OVERNIGHT INTO WEDNESDAY. THIS WILL CONTINUE TO SPREAD RAIN ACROSS
THE REGION. THIS SURFACE LOW WILL ALSO BRING A STRONG COLD FRONT
ACROSS EASTERN KY TOMORROW AFTERNOON THIS WILL PROVIDE GOOD LIFTING
MECHANISM FOR SHOWERS AND THUNDERSTORMS WITH GUSTY WINDS POSSIBLE.
BEHIND THIS FRONT WOULD EXPECT THERE TO CONTINUE TO BE GUSTY WINDS
PARTICULARLY ACROSS THE HIGHER TERRAIN AND NW PORTIONS OF THE CWA.
MOVING INTO WEDNESDAY NIGHT LOW PRESSURE IS FORECAST TO MOVE NORTH
INTO THE GREAT LAKES REGION AND WE WILL QUICKLY GET INTO THE DRY
SLOT. THEREFORE MOISTURE DOES GET CUTOFF AND LOOKING AT FORECAST
SOUNDINGS THIS WOULD LEAD TO LITTLE IF ANY ICE ALOFT. DID OPT TO KEEP
A SLIGHT CHANCE OF RAIN MIXED WITH SNOW AND MAYBE SOME DRIZZLE ACROSS
THE HIGHER TERRAIN...HOWEVER CONFIDENCE IN ANY SNOW CONTINUES TO
DECREASE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 425 AM EST TUE DEC 23 2014

THE PERIOD WILL BEGIN WITH A DEEP CLOSED LOW AND ASSOCIATED SFC
SYSTEM CENTERED OVER THE GREAT LAKES REGION WITH A TROUGH EXTENDING
SOUTH INTO THE MS VALLEY. RIDGING IS EXPECTED TO BE OFF THE SOUTHEAST
US COAST WITH RIDGING ALSO OVER NORTHERN MEXICO AND INTO THE SOUTHERN
AND CENTRAL ROCKIES. A TROUGH IS EXPECTED TO BE WORKING ACROSS THE
NORTHWESTERN CONUS AT THAT POINT AS WELL. FROM THU INTO THE START OF
THE WEEKEND...THE DEEP LOW INITIALLY OVER THE GREAT LAKES WILL TRACK
NORTH ACROSS ONTARIO AND QUEBEC AND INTO THE MARITIMES WITH THE
TRAILING TROUGH AXIS MOVING ACROSS THE AREA EARLY IN THE PERIOD ON
WED NIGHT INTO EARLY ON THU. RIDGING SHOULD THEN WORK ACROSS THE
EASTERN CONUS FROM LATER ON CHRISTMAS DAY INTO FRIDAY. MEANWHILE THE
COLD FRONT TRAILING FROM THE SYSTEM MOVING THROUGH THE GREAT LAKES
INITIALLY SHOULD HAVE EXITED INTO WV OR SHOULD EXIT INTO WV VERY
EARLY IN THE PERIOD. A DRY SLOT SHOULD WORK ACROSS THE AREA EARLY IN
THE PERIOD PER RECENT MODEL CONSENSUS FOLLOWED BY SOMEWHAT DEEPER
WRAPAROUND MOISTURE LATER ON WED NIGHT. SFC HIGH PRESSURE WILL BUILD
IN BEHIND THE DEPARTING LOW PRESSURE SYSTEM FOR THU NIGHT INTO FRI
NIGHT.

FROM WED INTO FRIDAY...A TROUGH WILL HAVE DEVELOPED AND WORKED ACROSS
THE WESTERN CONUS AND SHOULD BE MOVING INTO THE PLAINS BY THE START
OF THE WEEKEND. AT THAT POINT...THE MOST RECENT GFS AND ECMWF RUNS
BEGIN TO DIFFER IN TIMING OF INDIVIDUAL WAVES BUT THERE IS A GENERAL
THEME OF LOWERING HEIGHTS ACROSS THE EASTERN SEABOARD AND SOUTHEAST
FROM THE WEEKEND INTO EARLY NEXT WEEK WITH A TROUGH OVER THE WESTERN
INTO THE CENTRAL CONUS BECOMING INCREASINGLY BROAD WITH TIME. THE
GENERAL CONSENSUS IS FOR A COLD FRONT TO ENTER THE LOWER OH AND
APPALACHIAN REGION FROM FRI NIGHT INTO SATURDAY AND THEN SHIFT SOUTH
OF THE REGION AS EARLY AS SAT AFTERNOON OR EVENING PER THE GFS AND
AS LATE SAT NIGHT INTO SUN PER THE ECMWF.

THE UPPER LEVEL TROUGH AND WRAPAROUND MOISTURE SHOULD LEAD TO SHOWER
AND DRIZZLE CHANCES FROM WED NIGHT INTO MIDDAY ON THURSDAY. SOME SNOW
COULD MIX IN AS WELL. LOCATIONS BELOW 2000 OR 2500 FEET ELEVATION
SHOULD REMAIN ABOVE FREEZING ON WED NIGHT. BEHIND THE DEPARTING
SYSTEM AND IN ADVANCE OF A SFC HIGH...THE LOW LEVEL FLOW WILL BECOME
TOO SOUTHWEST FOR IDEAL UPSLOPE FLOW BUT LOW LEVEL LAPSE RATES WILL
SUPPORT THE CHANCES FOR SHOWERS AND OR DRIZZLE. IN ADDITION...MODEL
FORECAST SOUNDINGS INDICATE THAT ICE CRYSTALS COULD BE LOST AT TIMES
LEADING TO LIGHT PRECIP POSSIBLY FALLING FROM CLOUDS WHERE ICE IS NOT
PRESENT...LEADING TO JUST RAIN OR DRIZZLE AT TIMES. THERE MAY BE
TIMES WHERE ICE IS PRESENT SO SOME FLURRIES OR LIGHT SNOW WOULD ALSO
BE POSSIBLE...BUT CHANCES FOR THIS ARE BEST ON THE RIDGES. A BIT OF
FREEZING DRIZZLE ALSO CANNOT BE RULED OUT LATE WED NIGHT INTO EARLY
ON THURSDAY FOR ELEVATIONS ABOVE 2000 OR 2500 FEET ELEVATION. THE
PRESSURE GRADIENT WILL REMAIN RATHER STEEP WELL INTO WED NIGHT...SO
WIND GUSTS AS HIGH AS 35 TO 40 MPH WILL BE POSSIBLE. A SLIGHTLY
STRONGER GUST CANNOT BE RULED OUT ABOVE 2500 FEET. AS THE MOISTURE
BECOMES INCREASINGLY SHALLOW AS CHRISTMAS DAY PROGRESSES ANY LINGERING
DRIZZLE SHOULD DISSIPATE WITH SOME PARTIAL CLEARING...ESPECIALLY IN
WESTERN SECTIONS. HIGH PRESSURE SHOULD LEAD TO DRY WEATHER FOR THU
EVENING INTO MOST OF FRIDAY NIGHT.

BOTH OF SCENARIOS FROM THE 0Z GFS AND 0Z ECMWF RUNS POINT TOWARD
MAINLY RAIN...POSSIBLY MIXING WITH OR CHANGING TO SNOW ON SAT INTO
SAT NIGHT. CURRENT MODEL RUNS HAVE A WAVE DEVELOPING ON SAT INTO SAT
NIGHT ALONG THE BOUNDARY THAT WILL HAVE PASSED TO OUR SOUTH WITH AN
INVERTED TROUGH EXTENDING TO ITS NORTH IN RESPONSE TO A SHORTWAVE
WORKING FROM HE SOUTHERN ROCKIES ACROSS THE SOUTHERN PLAINS AND INTO
THE SOUTHEASTERN CONUS FROM SAT NIGHT INTO SUN NIGHT. THE MODELS
TRACK THE SFC WAVE ACROSS THE SOUTHEASTERN STATES DURING THAT TIME. IF
DEEP ENOUGH MOISTURE LINGERS AS THIS SYSTEM DEPARTS ON SUN NIGHT INTO
EARLY ON MONDAY...SOME SNOW MIGHT MIX IN.

OVERALL..TEMPERATURES THROUGH THE PERIOD WILL REMAIN NEAR NORMAL TO
ABOVE NORMAL AS THE CORE OF THE COLDER AIRMASSES REMAINS MAINLY
BOTTLED UP OVER CANADA AND NEARER TO THE US/CANADIAN BORDER. THE
BIGGEST DEPARTURES SHOULD OCCUR FROM FRI INTO SATURDAY. SOME MODEL
GUIDANCE SUGGESTS THAT AT LEAST A GLANCING BLOW OF COLDER AIR MAY
AFFECT THE AREA AROUND THE MIDDLE OF NEXT WEEK...BUT THERE HAS BEEN
PLENTY OF MODEL DIFFERENCES FROM RUN TO RUN AND MODEL TO MODEL DURING
THAT TIME PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 100 PM EST TUE DEC 23 2014

THIS AFTERNOON MOST SPOTS ARE DRY...HOWEVER SHOWERS AND EVEN A FEW
THUNDERSTORMS ARE MOVING NE OUT OF MIDDLE TN. THESE SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO SLOWLY PROGRESS NE OVER THE NEXT FEW
HOURS AND AFFECT SME AND LOZ FIRST. THESE SHOWERS AND THUNDERSTORMS
WILL CONTINUE TO SPREAD ACROSS THE REGION THROUGH THE DAY INTO THE
OVERNIGHT. MOST AREAS THIS AFTERNOON HAVE BEEN BETWEEN VFR/MVFR CIGS
AND THIS WILL TREND TOWARD MVFR AND EVEN CLOSER TO IFR OVER MUCH OF
THE TAF PERIOD AS WE SEE MULTIPLE ROUNDS OF SHOWERS AND SLIGHT CHANCE
OF THUNDERSTORMS. HEAVIER SHOWERS COULD ALSO BRIEFLY REDUCE VIS TO
NEAR IFR CONDITIONS.


&&

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

$$

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





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.