616
FXUS63 KJKL 091643
AFDJKL
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
1143 AM EST TUE FEB 9 2010
.SHORT TERM
ARCTIC FRONTAL BOUNDARY WILL BE MOVING INTO THE AREA THIS AFTERNOON.
A NARROW BAND OF MODERATE TO HEAVY SNOW HAS DEVELOPED ALONG AND AHEAD
OF THIS FEATURE AS THE UPSTREAM UPPER LEVEL TROUGH BECOMES A BIT
MORE NEGATIVELY TILTED. UPSTREAM REPORTS OF A BURST OF SNOW WITH
ACCUMULATIONS OF AROUND AN INCH HAVE BEEN COMING IN AS THIS BAND
PASSES. THEREFORE MOVED UP TIMING OF ADVISORY IN THE SOUTHWEST TO
ACCOUNT FOR THIS POTENTIAL AS THE ARCTIC BOUNDARY PUSHES ACROSS THE
AREA THIS AFTERNOON. OTHERWISE...MADE SOME MINOR ADJUSTMENTS TO
HOURLY TEMPS AND WINDS USING MAINLY THE RAW NAM DATA AS IT APPEARS TO
HAVE A PRETTY GOOD HANDLE ON SHORT TERM TRENDS. WINDS WILL VEER TO
THE WEST...NORTHWEST THIS AFTERNOON BEHIND THE FRONT...AND BECOME
GUSTY.
THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS...
/TODAY THROUGH WEDNESDAY NIGHT/
COMPLICATED STORM SYSTEM CONTINUES TO BE CHALLENGING FOR THE SHORT
TERM. A COUPLE OF AREAS OF LOW PRESSURE...ONE OVER CENTRAL
MISSISSIPPI...WITH ANOTHER TRYING TO ORGANIZE NEAR THE TENNESSEE
VALLEY. BEST INVERTED TROUGH IS EXTENDING THROUGH CENTRAL KY...WHERE
THERE HAVE BEEN SLIGHTLY HIGHER PRECIP TOTALS. WARM AIR HAS NOSED IN
FASTER THAN EXPECTED...KEEPING THE MAJORITY OF PRECIPITATION
SOUTHWEST OF A MOUNT VERNON TO SOMERSET LINE AS JUST PLAIN
RAIN...WITH A MIXTURE OF SLEET/RAIN/FREEZING RAIN AS FAR NORTHEAST AS
THE MOUNTAIN PARKWAY.
AS THE TENNESSEE VALLEY LOW SLOWLY DEEPENS IN RESPONSE TO AN UPPER
LEVEL TROUGH DIGGING ACROSS THE PLAINS...WARMER AIR WILL CONTINUE TO
BE DRAWN UP FROM THE SOUTHWEST...GRADUALLY BRINGING ABOVE FREEZING
TEMPERATURES EVERYWHERE IN EASTERN KENTUCKY. SNOWFALL TOTALS HAVE
GENERALLY BEEN AROUND AN INCH OR LESS SO FAR...EVEN NEAR THE I-64
CORRIDOR. RADAR TRENDS HAVE SHOWN A DROP OFF IN THE PRECIPITATION
UPSTREAM...SO HAVE LOWERED TOTALS ACROSS THE BOARD INTO THE 1-3 INCH
RANGE...WITH SOME MINOR ICE AND SLEET ACCUMULATION.
ONCE THE SURFACE LOW PASSES NORTH INTO THE OHIO VALLEY...LATE THIS
AFTERNOON AND THIS EVENING...THE ASSOCIATED COLD FRONT WILL USHER IN
MUCH COLDER AIR. ANY LINGERING RAIN WILL TURN BACK TO SNOW THIS
EVENING...WITH THE SNOW PICKING UP ONCE AGAIN IN INTENSITY OVERNIGHT
AS GOOD UPSLOPE FLOW AND A FAVORABLE CONNECTION WITH LAKE MICHIGAN
DEVELOPS...ALONG WITH STEEPENED LAPSE RATES AND UPPER LEVEL SUPPORT
AS THE UPPER LEVEL LOW PASSES BY NEAR AND ALONG THE OHIO RIVER. SNOW
WILL LINGER INTO THE DAY ON WEDNESDAY...AND BEGIN TAPERING OFF
WEDNESDAY NIGHT. HAVE RESERVED THE WARNING CRITERIA SNOWFALL FROM
TUESDAY NIGHT INTO WEDNESDAY FOR ALL COUNTIES IN THE WARNING.
ADDITIONALLY...STRONG WINDS WILL ALLOW FOR BLOWING SNOW AND LIMITED
VISIBILITIES. WILL CONTINUE TO HIGHLIGHT THIS IN THE PRODUCTS AS
WELL.
LONG TERM
/THURSDAY THROUGH MONDAY/
IN THE WAKE OF THE MAJOR UPPER LOW MOVING OFF THE NEW ENGLAND COAST
THE MODELS ARE IN AGREEMENT WITH THE UPPER PATTERN OVER THE REGION
FLATTENING OUT WITH SOME SLIGHT HEIGHT RISES OVER THE OHIO VALLEY.
ATTENTION THEN TURNS TO THE SOUTHERN STREAM LOW THAT IS BEING BETTER
HANDLED BY THE MODELS LATELY. THIS LOW ROLLS INTO THE SOUTHERN PLAINS
THURSDAY NIGHT AND ACROSS THE DEEP SOUTH ON FRIDAY. THE GEM AND ECMWF
ARE MORE AMPLIFIED WITH THIS WHEN COMPARED WITH THE GFS. WILL FOLLOW
A BLEND FOR THIS FEATURE IN CONJUNCTION WITH HPC/S PREFERENCE AND
CONTINUITY FROM THE PAST COUPLE OF DAYS. THE NORTHERN STREAM HAS A
BIT MORE UNCERTAINTY AMONG THE MODELS WITH GEM MOST AGGRESSIVE
BRINGING A CLOSED LOW SOUTHWEST INTO THE UPPER MIDWEST BY FRIDAY
MORNING WHILE THE GFS AND ECMWF ARE FLATTER AND LESS WELL DEFINED
WITH THIS WAVE. THE NORTHERN AND SOUTHERN STREAMS MESH TOGETHER ON
SATURDAY GENERALLY RESULTING IN A LARGE NORTHEASTERN TROUGH IN ALL
MODELS...JUST WITH SIGNIFICANT VARIATIONS IN THE DETAILS. A BLEND OF
THE GFS AND ECMWF WAS PREFERRED WITH THIS DEVELOPMENT AND THROUGH THE
WEEKEND AS THE TROUGH SHARPENS UP AND PIVOTS EAST OF THE AREA. TO THE
NORTH A NODE OF THE LARGE NEW ENGLAND TROUGH WILL SET UP TO ROTATE
THROUGH THE EASTERN GREAT LAKES...QUICKER AND A BIT MORE SOUTH IN THE
ECMWF THAN THE GFS. CONTINUED TO FOLLOW A BLENDED SOLUTION INTO
MONDAY...TEMPERING THE MORE IMPACT-FULL...AT LEAST FOR EAST
KENTUCKY...FORECAST FROM THE GFS.
SENSIBLE WEATHER WILL FEATURE UPSLOPE SNOWS ENDING IN OUR HIGHEST
EASTERN TERRAIN BY MIDDAY THURSDAY AS COLD HIGH PRESSURE SETS UP OVER
THE OHIO VALLEY...TEMPORARILY CLEARING THE BULK OF THE CLOUDS AND
SETTING UP A CHILLY NIGHT. HIGH CLOUDS WILL RETURN QUICKLY ON FRIDAY
AHEAD OF THE NEXT SOUTHERN STREAM LOW THAT LOOKS TO BRUSH BY LATER
THAT DAY. WOULD NOT RULE OUT SOME LIGHT SNOW FROM THIS ON FRIDAY...
BUT FOR NOW HAVE LEFT IT DRY. A SLIGHTLY BETTER CHANCE OF LIGHT SNOW
LOOKS TO BE FRIDAY NIGHT AND SATURDAY...ESPECIALLY IN OUR NORTHEAST
COUNTIES...AS THE UPPER TROUGH SHIFTS THROUGH THE REGION. THIS WILL
HELP TO REINFORCE THE COLD AIR IN PLACE WITH SOME WEAK UPSLOPE FLOW
POSSIBLE AS WELL THROUGH THE WEEKEND. THERE REMAINS A HIGH LEVEL OF
UNCERTAINTY WITH THE UPPER LEVEL FEATURES FOR THE LATTER PORTION OF
THE WEEKEND AND INTO THE NEW WORK WEEK AND AS A RESULT THE SFC
PATTERN IS IN QUESTION. HOWEVER...COLD AIR APPEARS TO BE LOCKED IN
PLACE...SO IN CONJUNCTION WITH LOW POPS DID KEEP A SMALL CHANCE OF
LIGHT SNOW IN THROUGH THE TAIL END OF THE FORECAST.
MAINLY FOLLOWED HPC TEMPERATURE GUIDANCE THROUGH THE FORECAST PERIOD
WITH SOME ADJUSTMENTS TO ACCOUNT FOR TERRAIN EFFECTS. AS FOR POPS...
ENDED UP FAIRLY CLOSE TO THE MEX NUMBERS...NOT SURPRISING...GIVEN THE
GENERAL PREFERENCE FOR THE SOLUTION FROM THE GFS.
AVIATION
/06Z TO 06Z/
CLOUDS HAVE BEEN GRADUALLY LOWERING AS A WARM FRONT IS MOVING TOWARD
THE AREA AND THE PRECIP HAS BEEN MOISTENING UP THE LOWER LAYERS. THE
OVERRUNNING OUT AHEAD OF THE FRONT HAS BEEN RESPONSIBLE FOR SOME
FREEZING RAIN AND SNOW WHICH WILL TURN TO ALL SNOW AFTER ABOUT 12Z.
SOME OF THE NUMERICAL GUIDANCE HAS THE CONDITIONS DROPPING TO LIFR
THIS MORNING...BUT HAVE KEPT IT TO IFR UNTIL 12Z WHEN THE COLD FRONT
GETS CLOSER TO THE AREA. THE COLD FRONT WILL MOVE ACROSS THE AREA
THIS AFTERNOON AND THEN THERE WILL BE A DRY SLOT MOVING ACROSS THE
AREA AROUND 00Z. KEPT THE CIGS AT MVFR DURING THIS TIME BUT WAS EVEN
TEMPTED TO BRING THEM TO IFR...BUT THERE IS STILL QUITE A BIT OF
UNCERTAINTY ON THE TIMING. ONCE THE COLD FRONT MOVES ACROSS THE
AREA LATE THIS AFTERNOON...ANY RAIN WILL BE TURNING BACK TO
SNOW...WITH THE BULK OF THE SNOW EXPECT LATER ON TUESDAY
NIGHT/WEDNESDAY MORNING.
JKL WATCHES/WARNINGS/ADVISORIES
WINTER STORM WARNING UNTIL 7 PM EST WEDNESDAY FOR KYZ044-052-104-
106-107-109-110-119-120.
WINTER WEATHER ADVISORY UNTIL 7 PM EST WEDNESDAY FOR KYZ050-051-
058>060-068-069-088-108-111>118.
WINTER WEATHER ADVISORY UNTIL 7 PM EST WEDNESDAY FOR KYZ079-083-
084.
WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 7 PM EST
WEDNESDAY FOR KYZ080-085-086.
WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 7 PM EST
WEDNESDAY FOR KYZ087.
SHORT TERM...GEOGERIAN/RAY
LONG TERM....JJ
AVIATION...JJ
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