FXUS63 KJKL 011723
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
1223 PM EST TUE DEC 1 2009

.SHORT TERM.../THE REST OF TODAY/

WILL UPDATE THIS MORNING MAINLY TO REMOVE MORNING WORDING FROM THE
FORECAST. PATCHES OF DENSE FOG HAVE LINGERED THIS MORNING...ALONG
WITH UPPER LEVEL SKY COVER ADVECTING IN AHEAD OF THE APPROACHING
SYSTEM. THIS WILL LIKELY HURT AFTERNOON HIGH TEMPERATURES AND HAVE
TWEAKED THEM DOWN TO THE LOW AND MID 50S. MIXING HEIGHTS WILL BE
QUITE SUPPRESSED UNDER SUBSIDENCE INVERSION WHICH SHOULD ALSO KEEP
TEMPS DOWN A BIT. OTHERWISE...THINGS LOOK ON TRACK AND WILL UPDATE
THE ZFP/HWO SHORTLY.

THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS...

/TODAY THROUGH THURSDAY/

EXPECT SOME FREEZING FOG AND SOME POSSIBLE BLACK ICE THIS MORNING.
HAVE ISSUED AN SPS TO HIGHLIGHT THIS HAZARD. THE TRACK OF THE
SURFACE LOW PRESSURE SYSTEM CONTINUES TO VARY FROM RUN TO RUN.
DECIDED TO GO WITH THE ECMWF...NAM...AND SREF THAT KEEPS THE TRACK OF
THE LOW ACROSS CENTRAL KENTUCKY. THE GFS IS A OUTLIER AS IT BRINGS
THE LOW DIRECTLY ACROSS EASTERN KENTUCKY. BASED ON THE LATEST MODEL
RUNS...DECIDED TO DELAY THE ONSET OF PRECIPITATION UNTIL WEDNESDAY
MORNING. ALSO RAISED THE POPS ON WEDNESDAY IN LINE WITH ALL THE
MODELS AND MOS GUIDANCE. THE DOWNSLOPING WILL GREATLY REDUCE THE
AMOUNT OF PRECIPITATION...HOWEVER THE FORCING WILL BE TOO GREAT AND
EVEN IN THE TYPICAL DOWNSLOPING AREAS WILL GET MEASURABLE RAINFALL.
BACKED OFF OF THE SNOW ON THE BACK SIDE OF THE FRONT DUE TO LACK OF
ICE CRYSTAL FORMATION. IT IS MORE LIKELY TO SEE SOME DRIZZLE BEHIND
THE FRONT.

.LONG TERM.../THURSDAY NIGHT THROUGH MONDAY/

AMPLIFIED UPPER LEVEL SYSTEM ACROSS THE GREAT LAKES AND SOUTHERN 
CANADA WILL BRING MAINLY A CHILL DOWN ACROSS THE AREA FOR THE END OF 
THE WEEK. THE MODELS HAVE TRENDED SLIGHTLY WARMER WITH THE INITIAL 
SHOT OF COLDER AIR ARRIVING THURSDAY NIGHT. THIS PUTS ICE CRYSTAL 
FORMATION IN JEOPARDY WITH A SHALLOW MOISTURE LAYER GETTING ONLY AS 
COOL AS -6 TO -7C. AS SUCH...WILL MENTION SOME PATCHY DRIZZLE FOR 
THURSDAY NIGHT. DEPENDING ON HOW COOL THE SURFACES GET IN THE HIGHER 
SOUTHEAST TERRAIN...THERE MAY BE A SMALL WINDOW OF FREEZING DRIZZLE 
POTENTIAL BEFORE THE MOISTURE BECOMES TOO SHALLOW. 

HIGH PRESSURE WILL BUILD IN AT THE SURFACE FOR FRIDAY...WITH DRY BUT 
COLD WEATHER EXPECTED. THE LEFTOVER TROUGH AXIS FROM THE GREAT 
LAKES/SOUTHERN CANADIAN SYSTEM WILL THEN MOVE THROUGH ON SATURDAY. 
THE LAST COUPLE OF RUNS OF THE ECMWF HAVE HAD MUCH MORE MOISTURE 
ASSOCIATED WITH THIS TROUGH COMPARED TO THE GFS. WILL MAINTAIN THE 20 
POPS FOR THIS FEATURE...AND IT STILL LOOKS LIKE THAT ANYTHING THAT 
DOES FALL WILL BE IN THE FORM OF SNOW WITH A REINFORCEMENT OF COLDER 
AIR. DRY WEATHER AND A SLOW MODIFICATION IN TEMPERATURES IS THEN 
EXPECTED FOR THE REST OF THE PERIOD AS THE FLOW BECOMES MORE ZONAL 
ALOFT. FOR TEMPERATURES...CONTINUED TO STAY BELOW GUIDANCE FOR THE 
HIGHS IN THE COLD AIR REGIME. DID ADJUST SOME OF THE LOWS UP A 
BIT...CLOSER TO GUIDANCE EARLY IN THE EXTENDED...DO TO LINGERING 
CLOUD COVER.

&&

.AVIATION.../18Z TO 18Z/...UPDATED

THE LAST OF THE FOG HAS DISSIPATED AND VFR CONDITIONS WILL PREVAIL
THROUGH DAWN ON WEDNESDAY. STRONG SOUTHERN SYSTEM APPROACHES
OVERNIGHT WITH GRADUALLY INCREASING HIGH LEVEL CLOUDS. THE EVENTUAL
CEILING FROM THESE CLOUDS WILL LOWER...GOING TO MVFR OR LOWER SHORTLY
AFTER DAWN. KSME/KLOZ WILL SEE ONSET OF PRECIPITATION RIGHT AROUND
SUNRISE WITH KJKL AND OTHER SITES EAST A BIT LATER. WILL BE
OPTIMISTIC AND KEEP THINGS PREDOMINANTLY MVFR...HOWEVER IFR WILL
DEFINITELY BE POSSIBLE IN THE MORE MODERATE RAIN SHOWERS THROUGH THE
END OF THE FORECAST PERIOD. SURFACE WINDS WILL ALSO INCREASE AND VEER
TO SOUTHEASTERLY AROUND DAWN...WITH GUSTS AS HIGH AS 15 TO 20 MPH ON
WEDNESDAY AFTERNOON.

&&

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

&&

$$

SHORT TERM...JJ/SCHOETTMER
LONG TERM....GEOGERIAN
AVIATION...SCHOETTMER