Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 260659
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
159 AM EST THU FEB 26 2015

.UPDATE...
ISSUED AT 158 AM EST THU FEB 26 2015

UPDATED THE FORECAST TO HIGHLIGHT A BANDED AREA OF PRECIP THAT HAS
DEVELOPED ALONG A LINE FROM MT VERNON AND NORTHEAST THROUGH WEST
LIBERTY. THIS HAS DEVELOPED ALONG A 700MB LINE OF FRONTOGENESIS
AND WILL SATURATE THE LOWER LEVELS IN A SHORT PERIOD OF TIME. WITH
THIS...THE HRRR AND SREF INDICATE OF A PERIOD OF TIME RESIDENCE
TIME THROUGH THE NEXT COUPLE OF HOURS. THIS WILL BE ENOUGH PERIOD
OF TIME FOR GREATER THAN AN INCH TO POSSIBLY TWO INCHES ALONG THIS
LINE...ESPECIALLY WITH THE LOW THAT IS SLOW TO EXIT TO THE EAST. A
NEW ZFP HAS BEEN SENT OUT FOR THIS UPDATE AND THE WSW HAS BEEN
EXTENDED TO A TIER OF COUNTIES TO THE NORTH.

UPDATE ISSUED AT 1125 PM EST WED FEB 25 2015

GRIDS HAVE BEEN FRESHENED UP BASED ON RECENT RADAR TRENDS AND NEAR
TERM GUIDANCE. SNOW HAS BEEN REPORTED TO BE REACHING THE GROUND
FROM MCCREARY COUNTY OVER TO KNOX COUNTY AND LESLIE COUNTY TO
LETCHER COUNTY. SOCIAL MEDIA WOULD INDICATE ABOUT HALF AN INCH OR
SO OF NEW SNOW IN HARLAN COUNTY. THE ONLY OTHER CHANGE WITH THIS
UPDATE WAS TO INCREASE QPF SLIGHTLY ALONG THE VA BORDER WHICH LED
TO SOLID 2 TO 3 INCH AMOUNTS FROM BELL COUNTY THROUGH HARLAN
COUNTY INTO LETCHER COUNTY. AT 2000 FEET AND ABOVE IN THESE
COUNTIES AS WELL AS PIKE COUNTY IN THE FLATWOODS AREAS TOTALS
AROUND 4 INCHES WILL BE POSSIBLE. THERE IS STILL SOME UNCERTAINTY
IN THE NORTHWARD EXTENT OF THE SHARP CUTOFF WITH SOME WAFFLING
FROM RUN TO RUN OF THE HRRR. HOWEVER...THE AVERAGE OF THE PAST FEW
HOURS STILL SUPPORTS THE CURRENT AREAL EXTENT OF THE ADVISORY.

UPDATE ISSUED AT 800 PM EST WED FEB 25 2015

SOME MINOR ADJUSTMENTS HAVE BEEN MADE TO HOURLY GRIDS FOR THE
OVERNIGHT PERIOD INTO EARLY ON THURSDAY. INITIALLY THESE WERE
BASED ON RECENT OBSERVATION AND RADAR TRENDS AS WELL AS THE RECENT
22Z AND 23Z HRRR RUNS WITH A CONSIDERATION OF 21Z SREF QPF AS
WELL. THIS LED TO COOLING OFF THE HIGHER TERRAIN WHERE WETBULBING
APPEARS TO ALREADY HAVE BEGUN AND QPF WAS NUDGED UP A TAD FOR
THESE HIGHER TERRAIN LOCATIONS BORDERING VA. THE TOP OF BLACK MTN
HAS AN RH NEAR 75 PERCENT.

AT THIS POINT...WE ARE IN THE WAIT FOR THE ATMOSPHERE TO CONTINUE
MOISTENING UP FROM THE TOP DOWN. UPSTREAM OF EASTERN KY...THE
SNOW IS NOW REACHING THE GROUND IN THE KTYS AND KGKT OR KNOXVILLE
AND SEVIERVILLE/GATLINBURG AREAS AS WELL AS AT KCSV AND KOQT.
BASED ON THIS...THE RECENT HRRR SEEMS TO HAVE A DECENT HANDLE ON
NORTHWARD PROGRESS OF THE AREA OF SNOW. THIS SHOULD BRING THE SNOW
INTO THE SOUTHERN PART OF THE CWA AROUND WHITLEY...HARLAN AND BELL
COUNTIES AROUND OR SHORTLY BEFORE 10 PM AND THEN GRADUALLY SPREAD
NORTH AND EAST. HOWEVER...THE 18Z OPERATIONAL RUNS AND THE RECENT
NEAR TERM GUIDANCE SUCH AS THE HRRR RUNS INDICATE THAT THE SNOW
WILL PROBABLY NOT MAKE IT MUCH FURTHER NORTH THE NORTHERN END OF
THE ADVISORY AS THERE WILL BE A SHARP NORTH OR NORTHWEST CUTOFF.
IN FACT...ACROSS THE NORTHERN TIER OF THE ADVISORY AMOUNTS COULD
RANGE FROM NOT MORE THAN A DUSTING IN THE NORTHERN OR NORTHWESTERN
END OF THE COUNTIES TO AN INCH OR MORE IN THE SOUTHERN END OF
THESE COUNTIES. IT STILL APPEARS THAT 2 TO 3 INCHES SHOULD BE
COMMON FROM SOUTHERN WHITELY COUNTY THROUGH BELL COUNTY NORTHEAST
ACROSS HARLAN AND LETCHER COUNTIES TO SOUTHERN PIKE COUNTY.
AMOUNTS AROUND 4 INCHES CANNOT BE RULED OUT ABOVE 3000 FEET.

POPS WERE RAISED FROM LIKELY TO CATEGORICAL FOR NEARLY ALL OF THE
AREA OF THE COUNTIES ON THE NORTHERN END OF THE ADVISORY. THE
SLIGHTLY HIGHER QPF LED TO SLIGHTLY HIGHER SNOWFALL FOR ELEVATIONS
OF 2000 FEET AND ABOVE FROM BELL COUNTY NORTHEAST TO EXTREME
SOUTHERN PIKE COUNTY. ATTM...THE ADVISORY CONTINUES TO REMAIN
VALID AND NO CHANGES ARE EXPECTED AT THIS TIME.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 500 PM EST WED FEB 25 2015

20Z SFC ANALYSIS SHOWS AN AREA OF LOW PRESSURE APPROACHING FROM
THE NORTHWEST WHILE ANOTHER IS MOVING IN FROM THE SOUTHWEST. IT IS
THIS SOUTHERN ONE WITH ITS WELL DEVELOPED PCPN SHIELD THAT WILL
GIVE MUCH OF THE AREA A DECENT CHANCE OF ACCUMULATING SNOW LATER
TONIGHT. UNDER OVERCAST SKIES TEMPERATURES ARE PEAKING INTO THE
MID 30S WHILE THE DEWPOINTS ARE STILL IN THE MID TEENS MOST
PLACES...THOUGH LOW 20S ARE FOUND IN THE FAR SOUTHWEST PARTS OF
THE CWA. WINDS ARE GENERALLY FROM THE NORTHEAST AT AROUND 5 MPH.

THE MODELS ARE IN GOOD AGREEMENT ALOFT WITH A DAMPENING BUT STILL
RATHER ROBUST SOUTHERN STREAM WAVE MOVING THROUGH THE SOUTHERN
APPALACHIANS. THIS IS TRAILED BY A ANOTHER...MORE BROAD...UPPER
LEVEL TROUGH THAT WILL CROSS THE OHIO VALLEY LATER THURSDAY AND
INTO THURSDAY NIGHT. AT THE SAME TIME...ANOTHER WEAKER WAVE WILL
PASS SOUTH OF KENTUCKY IN THE SOUTHERN STREAM. THESE STREAMS
REMAIN SEPARATE ENOUGH THROUGH THE SHORT TERM PORTION OF THE
FORECAST THAT THEIR SFC REFLECTIONS WILL LIKEWISE REMAIN ON THE
WEAKER SIDE OF POTENTIAL. GIVEN THE MODEL AGREEMENT ALOFT...AND
THE HIGHER RESOLUTION OF THE NAM12 AND HRRR...HAVE FOLLOWED THOSE
LATTER MODELS MOST CLOSELY FOR WX SPECIFICS.

SENSIBLE WEATHER WILL FEATURE THE EXPANDING NORTHERN FRINGE OF THE
SOUTHERN LOW STRAFING EASTERN KENTUCKY WITH SNOW ARRIVING SHORTLY
AFTER SUNSET AND THEN QUICKLY SPREADING NORTHEAST INTO THE LATTER
PART OF THE EVENING. THE DYNAMICS OF THIS SYSTEM AS SEEN IN THE
HIGHER RESOLUTION MODELS SUGGEST THAT THE SNOW COULD COME DOWN
BRIEFLY HEAVY WHEN IT SETS IN. THE LAST COUPLE OF RUNS OF THE
HRRR AND THE 18Z NAM12 DID PUSH SOME OF THE HIGHER QPF AND OMEGA A
TAD FURTHER NORTH INTO EASTERN KENTUCKY. SO WITH THIS AGREEMENT
AND THE POTENTIAL FOR QUICK ACCUMULATIONS HAVE DECIDED TO ADD
SEVERAL MORE COUNTIES TO THE INITIAL ADVISORY FROM MARTIN WEST TO
OWSLEY COUNTY. OTHERWISE...THE FORECAST IS ON TRACK WITH BETWEEN 1
AND 2 INCHES OF ACCUMULATION POSSIBLE MOST PLACES IN THE
ADVISORY...A BIT LESS IN THE WEST AND NORTH WITH HIGHER AMOUNTS
CLOSER TO THE VIRGINIA BORDER...PARTICULARLY FOR ELEVATIONS ABOVE
2500 FEET.

THE SNOW WILL TAPER TO FLURRIES AND POSSIBLE END FOR A TIME OVER
MOST OF THE AREA BY MIDDAY THURSDAY BEFORE THE APPROACH OF THAT
NEXT MID LEVEL TROUGH AND A SFC ARCTIC FRONT. SIMILAR TO SOME OF
THE FRONTS WE HAVE SEEN SO FAR THIS WINTER...WE EXPECT SNOW SHOWER
DEVELOPMENT ALONG AND BEHIND IT INTO THE NIGHT THURSDAY WITH BEST
LIFT AND FORCING TAKING PLACE IN THE EVENING. UP TO AN INCH OF
ADDITIONAL ACCUMULATION WILL BE POSSIBLE FROM THIS SET UP...BUT
MOST PLACES WILL SEE JUST A DUSTING OR TWO OF ACCUMULATION. ARCTIC
TEMPERATURES WILL SEND READINGS INTO THE TEENS MOST PLACES BY
FRIDAY MORNING.

USED THE CONSSHORT TO JUMP START THE T/TD/WIND GRIDS THROUGH THE
DAY THURSDAY...WITH SOME TERRAIN BASED ADJUSTMENTS. AFTER THAT
FAVORED THE SUPERBLEND INTO FRIDAY MORNING FOR A STARTING POINT.
AS FOR POPS...ENDED UP ON THE HIGH SIDE OF GUIDANCE THROUGH THE
PERIOD.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 345 PM EST WED FEB 25 2015

BROAD MID AND UPPER LEVEL TROUGH ACROSS THE ENTIRE CONUS WILL DEEPEN
OVER THE FAR SOUTHWEST...BAJA THROUGH THE WEEKEND PLACING OUR AREA
IN A GENERAL SOUTHWEST FLOW REGIME FOR THE BULK OF THE EXTENDED.
THIS WILL TEND TO KEEP STORM TRACKS SOMEWHAT CENTERED OVER THE OHIO
VALLEY REGION AS A SERIES OF DISTURBANCES RIDE NORTHEAST ACROSS THE
EASTERN CONUS. OVERALL IT APPEARS WE WILL BE GETTING INTO A VERY
ACTIVE WEATHER PATTERN...TYPICAL FOR THE APPROACH OF EARLY SPRING.
ACTUAL SENSIBLE WEATHER...PRECIPITATION TYPES...AMOUNTS ETC. WILL
DEPEND MORE ON EXACT TRACK OF SURFACE LOWS THROUGH THE REGION.
CONSIDERING THE CURRENT SNOWPACK ALONG WITH THE WATER CONTENT
PRESENT ACROSS A LARGE PART OF THE AREA...POTENTIAL HYDRO ISSUES
WILL NEED TO BE CONSIDERED SHOULD MUCH OF ANY PRECIPITATION WE
REALIZE THROUGH THE PERIOD FALL IN THE FORM OF RAIN.

MODEL SOLUTIONS APPEAR TO BE IN FAIRLY GOOD AGREEMENT THROUGH THE
EXTENDED. A SERIES OF STORM SYSTEMS SHOOT OUT OF THE INTER-MOUNTAIN/
SOUTH CENTRAL PLAINS AREA IN RAPID FIRE FASHION THROUGH THE PERIOD.
THE FIRST SHOULD AFFECT OUR AREA SUNDAY INTO MONDAY...THE SECOND
TUESDAY THROUGH EARLY WEDNESDAY AND THEN THE THIRD LATE WEDNESDAY
NIGHT INTO THURSDAY. ATTM MODEL CONSENSUS IS FOR SFC LOWS TO TRACK
GENERALLY TO OUR NORTHWEST...KEEPING OUR AREA IN THE WARM SECTORS OF
THESE SYSTEMS. HOWEVER...THE COLDER AIR THAT FILTERS IN BEHIND EACH
PASSING SYSTEM MAY ALLOW FOR THE A WINTRY MIX AT THE ONSET OF EACH
NEW ROUND OF WEATHER. THIS MAY BE ESPECIALLY TRUE NEXT TUESDAY
MORNING. AFTER A VERY COLD START FOR FRIDAY...EXPECT TEMPERATURES TO
GRADUALLY MODERATE TOWARDS MORE NORMAL LEVELS THROUGH THE EXTENDED
THOUGH OVERALL WE WILL REMAIN BELOW NORMS FOR THIS TIME OF THE
YEAR.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1222 AM EST THU FEB 26 2015

LOW LEVEL CIGS AND SNOWFALL WILL CONTINUE TO CREEP NORTH AND
NORTHEASTWARD THROUGH THE NIGHT AS THE LOW PRESSURE SYSTEM TRACKS
EAST ACROSS THE APPALACHIAN RANGE TONIGHT. THESE BELOW IFR CIGS
AT TIMES AND LOW VISIBILITY WILL CONTINUE AT MOST OF THE TAF SITES
BESIDES SYM THROUGH 14Z. WINDS WILL GENERALLY BE LIGHT AND
VARIABLE OR MAINLY OUT OF THE NORTH. HEADING INTO THE
AFTERNOON...THE SNOW WILL TRANSITION INTO UPSLOPE SNOW SHOWERS
THROUGH THE AFTERNOON WITH MAINLY FLURRIES AND A PERSISTENT MVFR
CIGS THROUGH THE REST OF THE TAF PERIOD. WINDS WILL INCREASE OUT
OF THE NORTHWEST THROUGH THIS PERIOD AS WELL.


&&

.JKL WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 7 AM EST THIS MORNING FOR
KYZ058>060-068-069-079-080-083>088-106>120.

&&

$$

UPDATE...SHALLENBERGER
SHORT TERM...GREIF
LONG TERM...RAY
AVIATION...SHALLENBERGER



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