FXUS63 KJKL 050357
AFDJKL
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
1057 PM EST FRI DEC 4 2009
.SHORT TERM.../THE REST OF TONIGHT/...UPDATED
MODELS HAVE BEEN CONSISTENT IN THEIR QPF AND COLD TEMPS...INCLUDING
THE NEW 00Z RUN OF THE WRF. AREA RADARS WERE PICKING UP AN INCREASE
IN VIRGA AT MID EVENING AS WE MOISTEN FROM THE TOP DOWN. A COMPROMISE
OF RECENT RUNS OF THE GFS AND WRF IS SUPPORTIVE OF UP TO 2 INCHES
FROM BELL COUNTY NORTHEAST TO MARTIN COUNTY. WOULD NOT BE SURPRISED
TO SEE A FEW 3 INCH AMOUNTS... ESPECIALLY ACROSS THE HIGHER
ELEVATIONS WHERE TEMPS HAVE BEEN RUNNING BELOW FREEZING FOR QUITE A
WHILE. HAVE EXPANDED THE WSW NW ANOTHER TIER OF COUNTIES FROM WHERE
IT WAS IN THE AFTERNOON FORECAST ISSUANCE.
THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS...
/TONIGHT THROUGH SUNDAY/
A RIDGE OF HIGH PRESSURE AT THE SFC FROM DFW TO PIT HAS ALLOWED A
GOOD PORTION OF THE OH RVR VALLEY TO CLEAR OUT TODAY. CONTINUED COLD
AIR ADVECTION FROM THE WEST AND NW HAS KEPT ANY SIGNIFICANT RISE IN
TEMPERATURES IN CHECK. AT 50H... A LONG WAVE TROF EXTENDS FROM THE
WRN GT LKS TO THE TX PANHANDLE. STRONG MID LVL WINDS FROM THE SW AT
70-75 KTS WILL DIRECT A DEVELOPING SFC LOW IN THE WRN GULF ACROSS FL
AND UP THE EASTERN SEABOARD. AS THE LOW TRACKS NORTH IT WILL DRAW
ATLANTIC MOISTURE INLAND AND WILL ALSO DRAW ADDITIONAL COLD AIR FROM
THE PLAINS. THIS MIX WILL PROVIDE A GOOD CHANCE FOR ACCUMULATING SNOW
FOR OUR MOUNTAIN COUNTIES ALONG THE VIRGINIA BORDER. HAVE ISSUED A
WINTER WEATHER ADVISORY FOR 1-2 INCHES OF SNOW IN THE HIGHER
ELEVATIONS OF HARLAN...LETCHER AND PIKE COUNTIES. TO THE WEST OF THAT
THE SNOW WILL TAPER OFF FROM AROUND A HALF AN INCH TO JUST TRACE
AMOUNTS NEARER INTERSTATE 75. THE LIGHT SNOW WILL CONTINUE INTO
SAT AS THE EAST COAST LOW PUSHES OFF THE DELMARVA COAST... EVENTUALLY
DRAWING ALL AVAILABLE MOISTURE WITH IT AND OUT OF KY. HIGH PRESSURE
WILL ONCE AGAIN ESTABLISH ITSELF OVER THE TN/OH RIVER BASINS WITH
DAYTIME TEMPS ON SAT ONLY REACHING THE MID 30S. CLEARING SAT NIGHT
WILL DROP THE OVERNIGHT TEMPS TO THEIR LOWEST VALUES OF THE SEASON
WITH LOWER 20S THE NORM AND SOME OF OUR COLDER LOCATIONS EVEN INTO
THE UPPER TEENS. THE HIGH WILL DRIFT TO THE MID ATLANTIC STATES FOR
THE LATTER PART OF THE WEEKEND AND WITH SW FLOW... THE MERCURY SHOULD
REACH THE MID 40S SUN AFTERNOON.
.LONG TERM.../SUNDAY NIGHT THROUGH FRIDAY/
04/00Z AND 12Z MODELS OFFER NO BIG SURPRISES SYNOPTICALLY NEXT WEEK
AND FEW CHANGES HAVE BEEN MADE TO THE FORECAST DURING THE PERIOD.
04/00Z ECMWF IS THE PREFERRED MODEL WHERE ANY DIFFERENCES EXIST. THE
DEGREE OF COOLING BEHIND OUR MIDWEEK SYSTEM IS THE BIGGEST QUESTION
MARK... WITH THE GFS BEING 6 TO 7C DEGREES COOLER AT 850 MB THAN THE
ECMWF AT 12Z THURSDAY. THE FAST PROGRESSIVE FLOW SHOULD MEAN LESS
OVERALL INTRUSION OF COLDER AIR THIS FAR SOUTH... THUS THE PREFERENCE
FOR THE WARMER ECMWF.
AS FOR SENSIBLE WEATHER... A WEAK SYSTEM IS STILL ON TAP TO BRING A
THREAT FOR PRECIP TO OUR AREA ON MONDAY. ANTECEDENT CONDITIONS ARE
VERY DRY AND THERE IS NOT A LOT OF MOISTURE ASSOCIATED WITH THE
SYSTEM SO CONTINUED TO ONLY OFFER A SLIGHT CHANCE OF SHOWERS DURING
THE DAY. THICKNESSES UP NORTH INDICATE THE POTENTIAL FOR A LITTLE
SNOW TO MIX IN... IF ANYTHING OCCURS AT ALL. OTHERWISE... A BRIEF
LULL IN RAIN CHANCES MONDAY NIGHT WILL BE FOLLOWED BY CHANCE POPS ON
TUESDAY AS OUR NEXT... MUCH MORE ROBUST SYSTEM APPROACHES FROM THE
WEST. PROGS INDICATE A VERY POTENT LOW LEVEL JET WITH THIS SYSTEM...
WITH GUSTY SOUTH TO SOUTHEASTERLY WINDS AT THE SURFACE. IN FACT...
WINDS MAY BE THE BIGGEST THREAT WITH THIS SYSTEM. A RESULTING RAIN
SHADOW SHOULD MEAN A DELAYED ONSET TO THE PRECIP... HOWEVER...
DYNAMICS WILL LIKELY OVERCOME THIS AND WE INCREASED POPS INTO THE
LIKELY RANGE FOR TUESDAY NIGHT. PROGS INDICATE A SLIGHTLY MORE
PROGRESSIVE SYSTEM SO DROPPED POPS BEHIND THE FRONT ON WEDNESDAY BUT
THERE REMAINS A CHANCE OF RAIN SHOWERS THROUGH THE DAY WITH WRAP
AROUND MOISTURE AFFECTING THE AREA AS THE UPPER TROUGH PASSES BY TO
OUR NORTHWEST. ANY LINGERING RAIN WILL MIX WITH AND CHANGE TO SNOW
WEDNESDAY NIGHT... BUT ANY PRECIP SHOULD BE VERY LIGHT BY THAT TIME.
HIGH PRESSURE WILL THEN SLIDE ACROSS THE OHIO VALLEY LEAVING DRY
CONDITIONS THURSDAY AND THURSDAY NIGHT BUT PROGS ARE ADAMANT THAT
ANOTHER SYSTEM WILL THREATEN THE AREA BY FRIDAY IN THE PROGRESSIVE
FLOW ALOFT SO WILL BRING IN FRIDAY WITH A 20 PERCENT CHANCE OF
SHOWERS.
THE 04/12Z GFSX GUIDANCE TEMPS SEEM VERY REASONABLE WITH THE
EXPECTED PATTERN NEXT WEEK... EVEN FOR TEMPS ON THURSDAY WHERE THE
MOST UNCERTAINTY LIES. THE GUIDANCE AGREES WELL WITH THE INHERITED
FORECAST NUMBERS TOO SO MADE FEW CHANGES OVERALL.
&&
.AVIATION.../00Z TO 24Z/
VFR TO CONTINUE THIS EVENING BUT WILL REACH IFR MOST AREAS BY DAYBREAK.
EASTERN KY BY 12Z WILL BE INFLUENCED AT THE NORTHWEST FRINGE OF A
FRONTAL SYSTEM SKIRTING THE AREA OFFSHORE OF THE CAROLINAS. THE CURRENT
LIGHT NORTH OR NORTHEAST WIND BELOW 5K FT WILL GRADUALLY DEEPEN SAT
MORNING WITH UPSLOPE ALLOWING TERRAIN TO BECOME SHROUDED IN CLOUDS
WITH LIGHT SNOW REACHING GROUND LEVEL. IFR/MVFR WILL NOT LAST LONG ON
SAT AS THE SYSTEM MOVES INTO THE ATLANTIC AND AFTERNOON CONDITIONS
IMPROVE. SAT NIGHT/SUNDAY WILL CONTINUE VFR UNDER HIGH PRESSURE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 3 AM TO 7 PM EST SATURDAY FOR
KYZ087-088-110-113-115-117>120.
&&
$$
SHORT TERM...DUSTY/HAL
LONG TERM....ABE
AVIATION...GV
