FXUS63 KJKL 090947
AFDJKL
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
447 AM EST WED DEC 9 2009
.SHORT TERM.../TODAY THROUGH THURSDAY NIGHT/...UPDATED
THE PRECIP PART OF THE EVENT ASSOCIATED WITH THE POTENT MIDWEST LOW
NOW OVER WESTERN IL IS WINDING DOWN...BUT NOT BEFORE RAINFALL TOTALS
AVERAGING IN THE 1.5 TO 2.5 INCH RANGE IN MANY AREAS GENERALLY FROM
SME TO JKL TO INEZ AND NORTH TO THE INTERSTATE 64 CORRIDOR AND THEN
ANOTHER AREA FROM SE MCCREARY COUNTY EAST THROUGH MUCH OF HARLAN
COUNTY. SOME AREAS NEAR THE KY 80 CORRIDOR OVER THE S FK KY RIVER
BASIN APPEAR TO HAVE HAD OVER 2 INCHES AS WELL WHEN COMBINING KY
MESONET...IFLOWS AND RAWS AND ASOS/AWOS DATA. THERE IS STILL SOME
THREAT FOR AREAL FLOODING ALONG THE LARGER STREAMS AND CREEKS AS THE
RAIN FROM THE PAST 18 HOURS COLLECTS IN THEM. DOWNSTREAM OF THESE
SIGNIFICANT RISES WILL ALSO OCCUR ON THE AREA RIVERS...ESPECIALLY THE
SOUTH FORK OF THE KY AND THE MAIN STEM AS WELL AS THE RED RIVER AND
POSSIBLY PARTS OF THE UPPER CUMBERLAND.
THE MAIN CONCERN HOWEVER FOR TODAY IS WITH THE WEST SOIL DUE TO
RECENT HEAVY RAIN COMBINED WITH THE POTENT POST FRONTAL SUSTAINED
WINDS AND WIND GUSTS ANTICIPATED STARTING ALONG THE FRONT BETWEEN
NOW AND ABOUT 12Z TO 13Z WHEN IT CLEARS THE EASTERN CWA AND THEN FOR
SEVERAL HOURS TODAY THROUGH ABOUT MID AFTERNOON. DURING THIS PERIOD
WIND GUSTS OF 50KT OR HIGHER ARE ANTICIPATED FOR A FEW HOURS. HOWEVER...
STRONG WINDS WILL REMAIN ALOFT EVEN EARLY IN THE EVENING...AND SO
WILL THE POTENTIAL FRO GUSTS AS THE LOW DEPARTS TO THE NE AND HIGH
PRESSURE BUILDS TOWARD THE TN AND OH VALLEY. THE PRESS GRADIENT
BETWEEN THE SYSTEMS WILL REMAIN RATHER TIGHT EVEN INTO MIDDAY ON THU
WHEN HEIGHT RISES AND HIGH PRESS WORK INTO THE REGION. IN SUMMARY...THE
HIGH WIND WARNING APPEARS WELL WARRANTED AND WILL BE CONTINUED WITH
THE EXPIRATION TIME AS IS.
ON THE STRONG AND GUSTY POST FRONTAL WINDS TODAY...A COLDER AIRMASS
WILL ADVECT INTO THE REGION WITH HIGHS IN THE 12Z TO 15Z TIMEFRAME
AND THEN FALLING TEMPS AFTER THAT. THE WIND GUSTS AS MENTIONED ABOVE
WILL MIX DOWN LIKELY MOST READILY IN THE DRY SLOT EVIDENT ON THE WV
AND IR IMAGERY OVER MUCH OF EASTERN ARKANSAS DON INTO LA AND NE INTO
CENTRAL KY. THE FRONT HAS BEEN RATHER INACTIVE RECENTLY AS FAR AS
SHOWER ACTIVITY WITH THE SYSTEM SHEARING TO THE NE. WE HELD ONTO SOME
SLIGHT TO LOW END CHANCE POPS JUST IN CASE FOR EARLY IN THE MORNING.
THE WRAPAROUND MOISTURE COMBINED WITH COLDER TEMPS ALOFT WILL ARRIVE
THROUGH THE AFTERNOON TO EARLY EVENING AND LEAD TO A SLIGHT CHANCE TO
CHANCE FOR SHOWERS AGAIN LATER IN THE DAY. AS TEMPS COOL ALOFT AND AT
THE SFC...SOME SNOW MAY MIX WITH THE RAIN FROM WEST TO EAST...WITH
ANY PRECIP PRIMARILY SNOW ALONG THE WESTERN TIER BY 22Z OR SO. THERE
COULD BE SOME ENHANCEMENT ALONG THE ESCARPMENT AND OTHER N TO SOUTH
ORIENTED RELATIVE RIDGE-LINES ACROSS THE AREA WITH THE SNOW SHOWER
ACTIVITY THAT SHOULD BE AT ITS HEIGHT BETWEEN 0Z AND 6Z. RATHER LOW
PW OF 0.25" OR LESS AND SHALLOW LAYER FOR CONVECTION SHOULD LIMIT ANY
AMOUNTS AND DURATION OF THIS EVENT...BUT A LIGHT DUSTING OF THE WHITE
STUFF IS POSSIBLE...ESPECIALLY RIDGETOPS. TEMPS WILL CONTINUE TO FALL
THROUGH TONIGHT WITH THE COLD ADVECTION WITH THE WEST AND HIGH
TERRAIN THE COLDEST AND BIG SANDY VALLEY THE WARMEST.
8H TEMPS OF -12C TO -15C EVEN WITH A DRY AIRMASS MOVING IN ASSOCIATED
WITH THE RIDGING SHOULD LEAD TO TEMPS STRUGGLING TO REACH 30 IN MANY
AREAS OR BELOW MOS VALUES. WITH THE RIDGE OF HIGH PRESSURE AND SFC HIGH
TO BUILD IN AND SLACKENING GRADIENT ON THU NIGHT ALONG WITH DEWPOINTS
OF AROUND 10 OF LESS EXPECTED TEMPS WILL LIKELY FALL BELOW MOS
VALUES AND SOME UPPER SINGLE DIGIT READINGS CANNOT BE RULED OUT
ACROSS THE HIGHER TERRAIN AND IN NORMALLY COLDER SPOTS.
.LONG TERM.../THURSDAY THROUGH TUESDAY/
MODELS HAVE DIVERGED A BIT IN THEIR RESPECTIVE SOLUTIONS OVER THE
PAST 24 HOURS...ESPECIALLY WITH RESPECT TO LOWER LEVEL FEATURES.
MAIN CHANGES TO THE EXTENDED PORTION OF THE FORECAST WERE TO TREND
TOWARDS LATEST ECMWF WHILE KEEPING SOME CONTINUITY WITH NATIONAL
GUIDANCE. IN GENERAL OUR AREA REMAINS UNDER THE INFLUENCE OF ZONAL
FLOW. BUT THE ECMWF CONTINUES TO TREND SLOWER AND WEAKER WITH
INITIAL SHORT WAVE TRACKING THROUGH THE CONUS OVER THE WEEKEND...
AND CONSEQUENTLY WITH RETURN OF MOISTURE LATE SATURDAY INTO SUNDAY.
TRIMMED TIMING OF POPS BACK SIGNIFICANTLY SATURDAY...FOCUSING
HIGHEST POPS IN A SATURDAY NIGHT...EARLY SUNDAY WINDOW. STILL CAN
NOT RULE OUT SOME MIXED PRECIPITATION CLOSER TO THE ONSET OF PRECIP
SATURDAY EVENING NORTH OF THE MOUNTAIN PARKWAY. BUT WITH THE OVERALL
SLOWER TREND IN EVOLUTION OF EVENTS...FELT THIS POTENTIAL WAS TOO
LOW TO MENTION IN THE FORECAST ATTM. THEREFORE KEPT THE BULK OF
PRECIPITATION AS RAIN FOR NOW. WILL READDRESS AS WE GET CLOSER TO
THE WEEKEND...AND MODELS HOPEFULLY CONGEAL ON A SOLUTION.
OTHERWISE...MORE SIGNIFICANT SHORT WAVE TROUGH MOVES INTO THE REGION
LATE MONDAY INTO TUESDAY. THERE CONTINUES TO BE SIGNIFICANT TIMING
ISSUES WITH THIS SECOND SYSTEM SO USED A BROAD BRUSH APPROACH FOR
THE LATTER PORTION OF THE FORECAST...GOING GENERALLY WITH CHANCE
POPS AND A SMALLER DIURNAL TREND TO TEMPS WITH ON AVERAGE MORE CLOUD
COVER THAN NOT.
&&
.AVIATION.../06Z TO 06Z/
MVFR ON AVERAGE IN THE SHOWERS AND OVER CENTRAL KY HAS BEEN OBSERVED
WITH BRIEF VFR IN A FEW SPOTS IN BETWEEN BANDS OF SHOWERS. OVERALL IN
SHOWERS THROUGH 9Z TO 10Z...WE EXPECT MVFR TO BE THE RULE FOR VIS AND
CIG...THOUGH SOME BRIEF IFR OR LIFR IS POSSIBLE IN THE MORE INTENSE
SHOWERS OR ANY THUNDERSTORMS THAT MIGHT DEVELOP. THE HIGH TERRAIN
ALONG THE VA BORDER WILL EXPERIENCE LIFR OR VLIFR THROUGH THE FROPA.
WINDS WILL INCREASE 9Z TO 12Z AS THE FRONT PLOWS THROUGH THE
REGION...SOME GUSTS TO TO 45 KTS OR MORE WILL BE POSSIBLE WITH THESE
SHOWERS OR STORMS ALONG THE FRONT...AND STRONG POST-FRONTAL WINDS
FROM THE SOUTHWEST GUSTING UP TO 50 KTS OR MORE ARE EXPECTED BEHIND
THE FRONT THROUGH 0Z TO 3Z OR SO. POST FRONTAL CLOUDS COULD SCATTER
A BIT AND VFR VIS/CIGS WILL BE POSSIBLE FOR A BRIEF PERIOD OF TIME...
HOWEVER WEST SOUTHWEST WINDS OF 30 TO 35 MPH AND GUSTS UP TO 60 MPH
WILL MAKE IT NEARLY IMPOSSIBLE FOR ANY SMALL AIRCRAFT TO FLY. EXPECT
A STRATOCU DECK AROUND THE VFR/MVFR THRESHOLD TO BUILD BACK IN 17Z TO 21Z
WITH SOME LINGERING RAIN AND SNOW SHOWERS TRANSITING TO SNOW SHOWERS
AND FLURRIES POSSIBLE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL 10 PM EST THIS EVENING FOR KYZ044-
050>052-058>060-068-069-079-080-083>088-104-106>120.
&&
$$
SHORT TERM...JP
LONG TERM...RAY
AVIATION...JP
