Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 260522 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1222 AM EST THU FEB 26 2015 .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...
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(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.
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&& .JKL WATCHES/WARNINGS/ADVISORIES...
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WINTER WEATHER ADVISORY UNTIL 7 AM EST THIS MORNING FOR KYZ079- 080-083>088-107-109-110-112>120.
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&& $$ UPDATE...JP SHORT TERM...GREIF LONG TERM...RAY AVIATION...SHALLENBERGER

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