FXUS63 KJKL 292000
AFDJKL
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
300 PM EST SUN NOV 29 2009
.SHORT TERM.../TONIGHT THROUGH TUESDAY/...UPDATED
FORECAST IS PRETTY STRAIGHT FORWARD THIS CYCLE. MODELS ARE IN VERY
GOOD AGREEMENT THROUGH THE SHORT TERM PERIOD. A WELL DEFINED UPPER
LEVEL TROUGH AND ASSOCIATED COLD FRONTAL BOUNDARY WILL MOVE OUT OF
THE MID WEST AND THROUGH EASTERN KENTUCKY BY EARLY MONDAY. REGIONAL
RADAR MOSAIC IS SHOWING CONSIDERABLE SHOWER ACTIVITY BEING GENERATED
WITH THIS FEATURE...IN LINE WITH ADVERTISED MODEL SOLUTIONS. WITH
GOOD AGREEMENT...AND INITIALIZATION CONFIDENCE WAS HIGH ENOUGH TO
INCREASE POPS FOR LATE TONIGHT INTO EARLY MORNING MORNING.
THEREAFTER...SHORT WAVE RIDGING DEVELOPS...AND TRANSITS THE AREA FOR
THE LATTER PORTION OF THE PERIOD. THIS AND SFC HIGH PRESSURE WILL
KEEP OUR WEATHER DRY AND SEASONABLY COOL THROUGH TUESDAY.
.LONG TERM.../TUESDAY NIGHT THROUGH SUNDAY/...UPDATED
EAST KENTUCKY FINDS ITSELF BETWEEN WEATHER MAKING SYSTEMS AT THE
START OF THE FORECAST PERIOD AS EAST CONUS TROUGH SLIDES OFF TO THE
EASTERN COAST AND CLOSED LOW OVER THE SOUTHWEST BEGINS TO EJECT
EASTWARD. THIS EASTWARD EJECTION WILL BE IN RESPONSE TO RAMPED UP
100-110 KNOT SUBTROPICAL JET CORE TRAVERSING THE SOUTH CONUS.
MEANWHILE...THE POLAR JET BEGINS TO CARVE OUT ANOTHER TROUGH OVER
THE NORTHERN PLAINS...DRAGGING A TRULY POLAR AIRMASS WITH IT.
DIFFERENT DEGREES OF PHASING...STILL NOT CLEAR BETWEEN POLAR AND
SUBTROPICAL JET...SHOULD DEVELOP AND INTENSIFY A SURFACE LOW
SOMEWHERE AROUND THE WESTERN GULF COAST. THIS LOW WILL THEN RIDE TO
THE NORTHEAST TOWARD EAST KENTUCKY THEN UP THROUGH NEW ENGLAND BY
THURSDAY NIGHT. THE SYSTEM SWINGS A POWERFUL COLD FRONT THROUGH THE
AREA WEDNESDAY NIGHT BRINGING THE POLAR AIRMASS WITH IT.
THE RESULTANT SENSIBLE WEATHER WILL BE CHARACTERIZED BY INCREASING
CHANCES FOR PRECIPITATION...MOSTLY IN THE FORM OF RAIN...FROM SOUTH
TO NORTH ON WEDNESDAY AFTERNOON LASTING THROUGH THURSDAY. ISENTROPIC
LIFT OVER A WARM FRONT...WITH THE AID OF THE LEFT EXIT REGION OF A
100 KNOT H3 JET WILL HELP TO ENHANCE RAINFALL ON WEDNESDAY. HAVE
INCLUDED A PERIOD OF LIKELY POPS LATE WEDNESDAY INTO WEDNESDAY
EVENING AS SURFACE LOW TRAVERSES THE REGION. THERE IS...AND WILL BE
...CONTINUED MODEL DISAGREEMENT ON WHERE THE SURFACE LOW ACTUALLY
TRACKS. THIS FINAL TRACK OF THE LOW WILL BE KEY TO EXACTLY WHERE AND
WHEN A CHANGE OVER TO RAIN AND SNOW SHOWERS BEGINS. AT THIS POINT IT
LOOKS AS THOUGH WEDNESDAY NIGHT WILL SEE THE BEST CHANCE FOR SOME
SNOW SHOWERS WITH SOME LINGERING CHANCES INTO THURSDAY AFTERNOON. DO
NOT EXPECT ANY ACCUMULATION AT THIS POINT. OVERALL...MODELS HAVE
COME INTO BETTER AGREEMENT ON THE EVOLUTION OF THIS SYSTEM WITH
GENERAL AGREEMENT FROM ECMWF/GFS/CMC. HOWEVER INDIVIDUAL DETAILS DO
EXIST AND THE COLDEST GFS SOLUTION WOULD SUGGEST A LONGER PERIOD OF
SNOW WITH SOME POSSIBLE ACCUMULATION. THE WARMER ECMWF SOLUTION
SUGGESTS ONLY A BRIEF CHANGEOVER TO SNOW WITH MOSTLY FLURRIES AT THE
END. HAVE CONTINUED TO GO MIDDLE OF THE ROAD UNTIL EVENT NEARS. ONE
OTHER ITEM OF NOTE IS THAT A PERIOD OF FAIRLY STRONG DOWNSLOPE FLOW
OVER THE SOUTHEAST TERRAIN SHOULD LIMIT PRECIP HITTING THE GROUND ON
WEDNESDAY AND WEDNESDAY EVENING IN THE SOUTHEAST TERRAIN. HAVE
CONTINUED TO DEPICT THIS IN THE GRIDS.
AS FAR AS TEMPERATURES ARE CONCERNED...TUESDAY SHOULD BE A PLEASANT
DAY UNDER PARTLY CLOUDY TO MOSTLY SUNNY SKIES AND HIGHS RIGHT AROUND
50 DEGREES. TUESDAY NIGHT SHOULD GENERALLY BE IN THE MID 30S FOR
LOWS WITH A SUBTLE SPLIT BETWEEN RIDGES AND VALLEYS. WITH THE
APPROACH OF THE SYSTEM ON WEDNESDAY...TEMPERATURES SHOULD STRUGGLE A
BIT UNDER AMPLE CLOUD COVER AND INCREASING RAIN COVERAGE. AT THIS
POINT HIGHS IN THE UPPER 40S SEEM REASONABLE. THE SYSTEM DRAGS THE
POWERFUL COLD FRONT THROUGH ON WEDNESDAY NIGHT WITH GRADUALLY
FALLING TEMPERATURES IN THE LOW TO MID 30S. WILL SEE LITTLE IN THE
WAY OF RECOVERY ON THURSDAY AS STRONG COLD AIR ADVECTION COMBINES
WITH CONTINUED HEAVY SKY COVER. SURFACE HIGH PRESSURE BUILDS INTO
THE AREA OVER THE WEEKEND HIGHS IN THE LOWER 40S AND LOWS IN THE IN
THE UPPER 20S TO AROUND 30 DEGREES. ONCE AGAIN...IT IS IMPORTANT TO
UNDERSTAND THAT THESE TEMPERATURES ARE BASED ON A COMPROMISE BETWEEN
MODEL SURFACE LOW TRACKS. CHANGES IN THIS TRACK WILL HAVE A
SIGNIFICANT IMPACT ON TEMPERATURES AND COULD RESULT IN MORE OR LESS
SNOWFALL.
&&
.AVIATION.../18Z TO 18Z/
MID AND HIGH CLOUDS ARE RAPIDLY OVERSPREADING THE AREA. UPSTREAM
SATELLITE LOOP DOES SHOW A FEW BREAKS. BUT IN GENERAL CLOUDS WILL
CONTINUE TO INCREASE AND LOWER WITH TIME. SHOWERS WILL ENTER THE
PICTURE IN ERNST LATE THIS EVENING...THOUGH COULD NOT RULE OUT SOME
ISOLATED SHOWER ACTIVITY AROUND KSME AND KLOZ CLOSER TO SUNSET. A
COLD FRONTAL BOUNDARY WILL MOVE THROUGH EASTERN KENTUCKY TOWARDS DAWN
ON MONDAY. CIGS AND VSBYS WILL DROP INTO MVFR RANGE AS FRONTAL
SHOWERS ARRIVE...WITH CIGS THEN FALLING FURTHER INTO THE IFR RANGE
POST FRONTAL. HIGHER RIDGETOP TERMINALS WILL LIKELY SEE LIFR CIGS.
SHOWERS AND AT LEAST PARTIAL CLEARING SHOULD OCCUR A JUST BEYOND THE
END OF THE FORECAST PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...RAY
LONG TERM...SCHOETTMER
AVIATION...RAY
