FXUS63 KJKL 060826
AFDJKL
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
326 AM EST SUN DEC 6 2009
.SHORT TERM.../TODAY THROUGH MONDAY NIGHT/...UPDATED
A FAIRLY QUIET SHORT TERM FORECAST IS IN STORE...CONSIDERING WHAT WE
HAVE BEEN THROUGH AND WHAT IS COMING UP IN THE WEEK AHEAD. HIGH
PRESSURE WILL DOMINATE AT THE SURFACE THROUGH TONIGHT BEFORE
SCOOTING OFF TO THE EAST IN RESPONSE TO AN APPROACHING WEAK SURFACE
LOW OVER THE SOUTHERN GREAT LAKES. MEANWHILE...STRONG ZONAL FLOW
ALOFT WILL HAVE A FEW WEAK WAVES EMBEDDED. THE IMPACT ON SENSIBLE
WEATHER WILL RESULT IN MOSTLY SUNNY SKIES EARLY GIVING WAY TO PARTLY
CLOUDY SKIES LATER TODAY AND CONTINUED INCREASING CLOUDS OVERNIGHT.
MODEL TIME HEIGHTS/SOUNDINGS INDICATE VERY LITTLE CHANCE THAT ANY
SORT OF PRECIPITATION IS GOING TO HIT THE GROUND LATE TONIGHT INTO
MONDAY MORNING AS SATURATION DOES NOT MAKE IT BELOW MID LEVELS WITH
THE PASSAGE OF THIS SYSTEM. FEEL THE MAJORITY OF AREAS WILL SEE
VIRGA...HOWEVER CANNOT COMPLETELY RULE OUT SOME MEASURABLE
PRECIPITATION SO WILL CONTINUE SLIGHT CHANCE POPS. IF PRECIP DOES
FALL AROUND DAWN...WET BULBING WOULD ALLOW FOR MOSTLY LIGHT SNOW.
PRECIPITATION WOULD QUICKLY CHANGE OVER TO RAIN BY MID MORNING AS
TEMPS WARM. AS THE SYSTEM QUICKLY PASSES...WILL MENTION SOME
SPRINKLES LINGERING MONDAY EVENING.
AS FAR AS TEMPERATURES ARE CONCERNED...WENT BELOW THE LOWEST GUIDANCE
FOR TODAY AS A SLOW START COMBINES WITH INCREASING SKY COVER AND LOW
MIXING HEIGHTS. EXPECT TEMPS TO STRUGGLE TO THE LOW 40S...HOWEVER
WOULDNT BE SURPRISED IF THEY DONT MAKE IT OUT OF THE UPPER 30S
DEPENDENT ON SKY COVER. THANKS TO ILN FOR COLLABORATION. FOR
TONIGHT...RIDGES RECOVER UNDER SOUTHWEST FLOW AND VALLEYS SHOULD FALL
TO THE MID 20S...ESPECIALLY IN THE EAST. THIS WILL PROVIDE THE SETUP
FOR A NICE RIDGE/VALLEY SPLIT ON THE ORDER OF 7 TO 10 DEGREES. HIGH
TEMPERATURES STRUGGLE ON MONDAY UNDER HEAVY SKY COVER AND DONT SEE US
GETTING OUT OF THE LOW TO MID 40S. TUESDAY NIGHT SEES TEMPERATURES
RIGHT AROUND THE FREEZING MARK...WITH THE COLDEST VALLEYS IN THE
UPPER 20S.
.LONG TERM.../TUESDAY THROUGH SATURDAY/...UPDATED
MODELS REMAIN RATHER CONSISTENT WITH THE PATTERN THROUGH THE PERIOD
WITH SOME RIDGING FROM THE GULF OF MEXICO NORTHWEST TOWARD THE GREAT
LAKES AT THE START OF THE PERIOD WITH AN UPPER LOW OVER THE HUDSON
BAY REGION AND A TROUGH EXTENDING SOUTHWEST INTO THE NORTHERN
ROCKIES. THIS TROUGH...HOWEVER AT THAT POINT IS NOT EXPECTED TO BE
IN PHASE WITH A SHORTWAVE OR SHORTWAVES OVER THE CENTRAL AND
SOUTHERN ROCKIES. THE WSW FLOW ALOFT SHOULD ALSO HAVE ADDITIONAL
EMBEDDED SHORTWAVES. AT THE SFC...AN AREA OF HIGH PRESSURE IS
EXPECTED TO BE OVER THE MIDDLE TO UPPER OH VALLEY REGION...AND
EXITING TO THE EAST AT THE START OF THE PERIOD. ALSO AT THE SFC WILL
BE AN AREA OF LOW PRESSURE OVER THE SOUTHERN ROCKIES/FOUR CORNERS
REGION. THE GFS HAS BEEN CONSISTENT OVER THE LAST COUPLE OF RUNS
WITH THE INITIAL DEPTH AROUND 12Z TUE...THOUGH THE CANADIAN/
NAM/ECMWF AND 12Z/5TH GFS ENSEMBLE MEAN ARE ABOUT 8 TO 10 MB WEAKER
WITH THE PRESS. THE MODELS ARE IN GOOD AGREEMENT THOUGH WITH A LEAD
SHORTWAVE MOVING INTO THE TN AND OH VALLEY ON TUE AFTERNOON AND THEN
THE OVERALL EVOLUTION OF THE PATTERN WITH THE SOUTHERN ROCKIES
TROUGH LIFTING ENE AND THEN TAKING ON A NEGATIVE TILT BY WED WITH
THE LOW REDEVELOPING AND STRENGTHENING AS IT MOVES FROM THE PLAINS
INTO THE MS VALLEY BY 12Z WED AND THEN INTO THE GREAT LAKES AND
ONTARIO WED INTO THU. AT THAT POINT THE ECMWF MAY BE A STRONG
OUTLIER WITH THE SFC PRESS AND SOMETHING 5 TO 10 MB WEAKER WITH THE
PRESS MAY BE MORE REASONABLE...BUT STILL VERY POTENT.
THIS COMBINATION WILL LEAD TO A GRADUALLY STRENGTHENING LLJ TO THE
50 TO 70KT+ RANGE AND POTENT ISENTROPIC LIFT BY TUE NIGHT. MODELS
PROJECT THE PW TO CLIMB TO ABOUT 1.1 INCHES ON AVERAGE OR ABOUT 240
PERCENT OF NORMAL. IN ADDITION...LAPSE RATES AT THE MID LEVEL
BETWEEN 750 MB AND 650 MB ALSO STEEPEN A BIT WITH PLENTY OF DYNAMICS
AND SHEAR. THE MODELS ALSO HINT AS SOME POSSIBLE COUPLING OF A JET
STREAK TO OUR NORTH AND ONE MOVING INTO THE TN AND LOWER OH VALLEY
AROUND 6Z ON TUE NIGHT. THIS COMBINATION WILL LEAD TO A VERY REAL
POSSIBILITY OF QPF EXCEEDING ONE INCH SOMEWHERE IN THE OH/TN VALLEY
REGION...POSSIBLY AFFECTING THE NORTHERN CWA...WITH AT LEAST A
HALF OF AN INCH IN THE SOUTH WITH THE PROGRESSION OF THE SYSTEM
BEING A LIMITING FACTOR.
OPTED TO ADD A SLIGHT CHANCE OF THUNDER AS MENTIONED ABOVE.
DEPENDING ON THE EVENTUAL WIND DIRECTIONS ALOFT AND STRAIGHT OF THE
PRESS GRADIENT SOME GUSTS ON DOWNSLOPING OR MOUNTAIN WAVE ACTION
CANNOT BE COMPLETELY RULED OUT ON TUE NIGHT ALONG THE VA
BORDER...BUT AT THIS POINT IN APPEARS THAT WED WILL BE BREEZY POST
FRONT. AT LEAST FOR A TIME AROUND 18Z OR SO ON WED AFTERNOON
SUSTAINED WINDS OF 15 TO 25 MPH WITH GUSTS INTO THE ADVISORY RANGE
APPEAR POSSIBLE. AT THIS POINT WE WILL CONTINUE TO HIGHLIGHT THIS IN
THE HWO. WITH THE ISENTROPIC LIFT KICKING IN A LITTLE QUICKER ON TUE
AFTERNOON COMPARED TO SOME MODEL RUNS AND 21Z SREF POPS INTO THE
HIGH CHANCE TO LIKELY RANGE BY 0Z WED AND INCREASING MOS POPS IN THE
WEST BY LATE TUE AFTERNOON...OPTED TO RAISE POPS IN THE NORTHWEST
TWO THIRDS LATE IN THE DAY ON TUE...WITH AN AREA OF CHANCE POPS IN
THE TYPICAL RAIN SHADOW REGION NEAR THE VA BORDER. OPTED FOR CAT
POPS ON TUE NIGHT WITH SUCH A POTENT SYSTEM MOVING IN AND SOME OF
THE REASONS MENTIONED ABOVE. DEPENDING ON THE TIMING OF THE ONSET OF
PRECIP...MAX T ON TUE MAY BE SUPPRESSED BELOW MOS VALUES...
ESPECIALLY THE WARMER MOS NUMBERS.
IT STILL LOOKS LIKE TEMPS WILL SURGE UPWARD SOMETIME EITHER LATE TUE
INTO EARLY WED...BUT PROBABLY MORE LIKELY TUE NIGHT INTO EARLY WED
IN ADVANCE OF THE COLD FRONT...WITH POSSIBLY A COUPLE OF DEGREE RISE
IN THE DRY SLOT ON WED AM...BEFORE MUCH COLDER AIR WORKS IN ON COLD
ADVECTION ON WED AFTERNOON. AGAIN...GUSTS SHOULD BE AT THEIR PEAK IN
THE DRY SLOT PERIOD.
A WEAKER SYSTEM SHOULD APPROACH LATE IN THE PERIOD AND TRANSITION
INTO THE AREA LATE IN THE PERIOD WITHIN A RATHER BROAD MEAN TROUGH
OVER MUCH OF THE EASTERN NOAM BEHIND A DEPARTED POTENT MIDWEEK
SYSTEM. THE COLDEST NIGHTTIME PERIOD APPEARS TO BE THU NIGHT WHEN
SOME CLEARING SHOULD FINALLY CLEAR AND A SFC HIGH MOVES INTO THE
REGION. LITTLE CHANCE WAS MADE BEYOND WED.
&&
.AVIATION.../06Z TO 06Z/
MVFR CIGS HAVE MOVED TO THE EAST OF THE CWA AND UNDER CLEAR SKIES
TEMPERATURES HAVE QUICKLY DROPPED TO THE LOWER 20S AND TEENS. DESPITE
THE VERY DRY AIR IN PLACE...VISIBILITIES HAVE DROPPED TO THE VFR/MVFR
THRESHOLD AT KLOZ/KSME LIKELY DUE TO RESIDUAL MOISTURE LEFT OVER FROM
TODAY/S SNOW. HAVE INCLUDED A TEMPO GROUP AT THESE TWO SITES FOR MVFR
VISIBILITIES UP TO DAWN. THIS AFTERNOON SHOULD BE CHARACTERIZED BY
MOSTLY CLEAR SKIES WITH INCREASING UPPER LEVEL SKY LATE IN THE DAY.
SURFACE WINDS SHOULD BE VERY LIGHT OUT OF THE EAST BY LATE THIS
AFTERNOON.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...SCHOETTMER
LONG TERM...JP
AVIATION...SCHOETTMER
