FXUS63 KJKL 022000
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
300 PM EST WED DEC 2 2009

.SHORT TERM.../TONIGHT THROUGH THURSDAY/...UPDATED

SFC FEATURES SHOW LOW PRESSURE CENTERED OVER SOUTH CENTRAL KY THIS
AFTERNOON...WITH UPPER LEVEL CLOSED LOW ROUGHLY OVER LITTLE ROCK.
THERE IS A PRONOUNCED DRY SLOT PUSHING NORTHWARD INTO OUR AREA FROM
THE SOUTH. THIS FEATURE PRESENTS THE FORECAST CHALLENGE FOR THE
SHORT TERM...I.E. PROBABILITY OF RAIN FOR TONIGHT WITH THE USUALLY
VERY RELIABLE NAM IN THE IMMEDIATE SHORT TERM COMING IN DRIER THAN
THE GFS. THIS HAS RESULTED IN SIGNIFICANT DIFFERENCES IN MOS
GUIDANCE FOR POPS OVERNIGHT AS WELL...WITH THE NAM ADVERTISING
SLIGHT TO CHANCE POPS AND THE MAV MOS PREDICTING HIGH LIKELY TO CAT
POPS. CONSIDERING THE PROXIMITY AND TRACK OF THE LOW...PREFERRED TO
STAY CLOSER TO THE MORE ROBUST MAV MOS GUIDANCE AND USED A BLEND OF
THIS WITH PERSISTENCE. THEREFORE EXPECT RAIN TO REDEVELOP AS THIS
SYSTEM TRACKS NORTHEAST TONIGHT. WITH AMPLE MOISTURE ASSOCIATED WITH
THIS SYSTEM...EXPECT SHOWERS TAPER OFF TO DRIZZLE DURING THE DAY
THURSDAY. OTHERWISE...WITH EXTENSIVE CLOUD COVER THROUGH THE BULK OF
THE OVERNIGHT PREFERRED WARMER MOS GUIDANCE FOR OVERNIGHT LOWS AD
COOLER NUMBERS FOR HIGHS THURSDAY. THIS JIVES VERY WELL WITH
INHERITED GRIDS SO ONLY MINOR TWEAKS WERE MADE TO TEMPS...MORE FOR
CCF PURPOSES. HAD SOME REPORTS OF WIND DAMAGE IN TN...AND HAVE SEEN
DECENT INTERMITTANT GUSTS FROM AREA SFC OBS. THEREFORE WILL LET
CURRENT NPW RIDE THROUGH 6 PM.

.LONG TERM.../THURSDAY NIGHT THROUGH WEDNESDAY/...UPDATED

GOOD CHANCE OF DRIZZLE OR EVEN FLURRIES THU EVENING BUT FIGURE  
MOISTURE WILL BE TOO SHALLOW TO MEASURE OUT. A LITTLE BETTER CHANCE 
OF SNOW FRI NIGHT BUT MODELS BARELY BRUSH BY WITH ENOUGH MOISTURE 
BELOW 700 MB SO SLIGHT CHANCE STILL SUFFICIENT.
  
00Z GFS/ECMWF/CANADIAN MODELS AGREED PRETTY WELL THROUGH 144 HOURS 
(00Z TUE) IN A HIGH AMPLITUDE PATTERN HOLDING ON. BY THAT TIME A 5H 
RIDGE WOULD EXTEND NORTH INTO AK AND A LOW/TROUGH EXTENDING FROM NWT 
TO NV/OR. THEREAFTER THE DIFFERENCES INCREASE BUT GFS/ECMWF AGREE IN 
A STRONG SOUTHERN STREAM DOMINATING CONUS. TIMING OF THE EMBEDDED 
SHORTWAVE PASSING THROUGH THE MIDWEST AT MID-WEEK IS DIFFICULT FOR 
THESE MODELS ATTM AND WILL NOT LATCH ONTO ANY ONE FOR NOW.

12Z GFS AND ECMWF AGREE A LITTLE BETTER ON THE SHORTWAVE PASSING 
EAST KY EARLY ON WED WITH THE COLD FRONT AND ASSOCIATED PRECIPITATION
OCCURRING LATE ON TUE NIGHT. THIS IS GOOD ENOUGH TO BOOST POPS TO 
HIGH CHANCE BUT TIMING IS STILL LIKELY TO CHANGE SOME SINCE THE 
UPPER FLOW IS ALMOST ZONAL WITH FAST FLOW.

&&

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

RATHER LARGE LOW PRESSURE SYSTEM IS RIDING UP THE MID MISSISSIPPI
RIVER VALLEY AND WILL PUSH THROUGH THE OHIO VALLEY OVER THE NEXT 12
TO 24 HOURS. SIGNIFICANT 925MB TO 850 WIND MAX HAS DEVELOPED JUST
OFF THE SFC. HAD A GUSTS TO 33KT AT KPBX WITHIN THE LAST HOUR. IN
ADDITION...KJKL VAD WIND PROFILER IS READING 50 KT FROM THE SE ABOUT
1 KFT TO 1.5 KFT AGL. WITH AN EAST...SE SFC WIND OF 10KTS OR LESS
DECIDED TO INCLUDE SOME LLWS THROUGH THE REMAINDER OF THE AFTERNOON.
OTHERWISE...REGIONAL MOSAIC RADAR TRENDS SUGGEST SHOWERS AND LIGHT
RAIN WILL REDEVELOP DURING THE LATE AFTERNOON AND EARLY EVENING
HOURS. HAD PREDOMINANT MVFR CIGS ADVERTISED BUT CIGS HAVE REMAINED
ANCHORED IN THE VFR RANGE SO FAR. ONLY KSME CIGS HAVE FLIRTED WITH
MVFR AT TIMES. BUT UPSTREAM OBS DO SHOW LOWER CIGS HOWEVER...AND
FCST SOUNDINGS AND TIME SECTIONS WOULD INDICATE THESE LOWER CIGS
WILL ARRIVE EVENTUALLY. THEREFORE GRADUALLY LOWERED CIGS BACK DOWN
LATE THIS AFTERNOON AND THIS EVENING. SFC WINDS WILL VEER TO THE
SOUTH AND INCREASE TONIGHT...THEN GRADUALLY DECREASE AND VEER TO THE
WEST BY THURSDAY.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR KYZ088-118-
120.

&&

$$
SHORT TERM...RAY
LONG TERM...GV
AVIATION...RAY