000 FXUS63 KJKL 100310 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON KY 1010 PM EST THU FEB 9 2012 .UPDATE... ISSUED AT 952 PM EST THU FEB 9 2012 02Z SFC ANALYSIS SHOWS HIGH PRESSURE IN PLACE OVER EAST KENTUCKY. THIS IS ATTEMPTING TO CLEAR THE SEMI-LOW CLOUD DECK IN PLACE OVER THE NORTHERN HALF OF THE CWA...WITH SOME SUCCESS. WHERE THE CLOUDS REMAIN THE TEMPERATURES ARE HOLDING UP IN THE LOWER AND MIDDLE 30S...BUT IN THE MORE CLEAR LOCATIONS TO THE SOUTH READINGS HAVE FALLEN INTO THE UPPER 20S. THE CLOUDS SHOULD CONTINUE TO SLOWLY ERODE TO THE NORTH... WHILE THE SOUTH STAYS MOSTLY CLEAR. DO EXPECT MORE IN THE WAY OF CLOUDS TO MOVE IN FROM THE WEST LATE TONIGHT. DUE TO THE DIFFERENCE IN CLOUD COVER OVERNIGHT...EXPECT THE TEMPERATURES TO VARY BY SKY COVER IN ADDITION TO A SMALL RIDGE TO VALLEY SPLIT. HAVE REPRESENTED THIS IN THE HOURLY TEMPERATURE GRIDS AS WELL AS THE MINIMUM ONES. ACCORDINGLY...THIS UPDATE PRIMARILY CHANGED TEMPERATURES AND SKY COVER. THESE CHANGES WARRANTED AN UPDATE TO THE ZONES AND OTHER PRODUCTS AND THEY HAVE BEEN ADJUSTED ACCORDINGLY. UPDATE ISSUED AT 815 PM EST THU FEB 9 2012 DID A QUICK UPDATE TO THE FORECAST PRIMARILY TO BETTER CAPTURE THE CURRENT SKY COVER AND TRENDS. THE SKY WILL BE TRICKY THROUGH THE NIGHT AS THE LOWER CLOUD DECK HAD BEEN ERODING FROM THE SOUTH JUST AS HIGH CLOUDS ARE INBOUND ALOFT. IN ADDITION...THE LATEST TIME HEIGHTS FROM THE NAM12 AND OTHER GUIDANCE SUGGEST THAT THE LOWER BATCH OF CLOUDS WILL HOLD IN OVER THE AREA...AND/OR BUILD BACK SOUTH LATER TONIGHT. HAVE TAKEN THIS ALL INTO CONSIDERATION AND REDREW THE SKY GRIDS TO EXHIBIT THIS KIND OF FLUX THROUGH THE NIGHT. DID ALSO UPDATE THE TEMPERATURE AND DEWPOINTS TO BETTER REFLECT THE LATEST OBSERVATIONS AND TRENDS. UPDATES HAVE BEEN ISSUED TO THE WEB AND NDFD. NO ZONE UPDATE AT THIS TIME. && .SHORT TERM.../TONIGHT THROUGH SATURDAY/ WINTER WEATHER WILL AFFECT EASTERN KENTUCKY FROM FRIDAY EVENING INTO SATURDAY. ON THE CURRENT WATER VAPOR IMAGERY A WELL DEFINED SHORT WAVE IS EMERGING FROM THE SOUTHERN ROCKIES INTO THE SOUTHERN PLAINS...WHILE ANOTHER SHORT WAVE IS DROPPING SOUTH FROM CANADA INTO THE NORTHERN PLAINS. THE NORTHERN WAVE IS DRIVING A STRONG COLD FRONT SOUTHWARD INTO THE UNITED STATES. THE SOUTHERN PLAINS SHORT WAVE IS FORECAST TO MOVE EAST INTO THE LOWER MS VALLEY BY 00Z SATURDAY. A BAND OF PRECIPITATION WILL DEVELOP IN ADVANCE OF THE WAVE...SWEEPING ACROSS EAST KY FRIDAY AFTERNOON AND EVENING. WHILE THE PRECIPITATION MAY START AS RAIN IT WILL QUICKLY CHANGE OVER TO SNOW FRIDAY EVENING AIDED BY GOOD DYNAMICS AND WET BULBING. THE NORTHERN STREAM SHORT WAVE WILL ALSO BE DIVING SOUTHEAST...DRIVING A COLD FRONT INTO KENTUCKY. THE COLD FRONT WILL MOVE ACROSS THE REGION FRIDAY NIGHT AND BE EAST OF KY BY 12Z SATURDAY. COLD AIR ADVECTION AND UPSLOPE FLOW WILL RESULT IN MORE SNOW SHOWERS DEVELOPING BY SATURDAY MORNING AND THEN CONTINUING INTO THE DAY ON SATURDAY. AFTER LOOKING AT ALL AVAILABLE MODEL DATA AND COORDINATING WITH NEIGHBORING WFOS HAVE DECIDED TO GO WITH A WINTER WEATHER ADVISORY FOR THE ENTIRE CWA. THE MAIN QUESTION TO BE RESOLVED WAS PRECIPITATION TYPE WITH THE SOUTHERN STREAM SYSTEM FOR FRIDAY AFTERNOON INTO FRIDAY EVENING. THERE ARE COME DISCREPANCIES IN THE MODELS REGARDING THE THERMAL STRUCTURE OF THE ATMOSPHERE WITH THIS. HAVE LEANED TOWARDS THE COOLER NAM...ECMWF AND GEM. THE GFS APPEARS MUCH TOO WARM...BOTH WITH MODEL SOUNDINGS AND WITH ITS ASSOCIATED MOS TEMPERATURES. THE GFS WARMS THE BOUNDARY LAYER TOO MUCH CONSIDERING LITTLE WAA AND EXTENSIVE CLOUDS ON FRIDAY...AND IT DOES NOT COOL THE BOUNDARY LAYER QUICK ENOUGH AFTER PRECIPITATION ONSET. WILL FORECAST A RAIN SNOW MIX TO START THE EVENT FRIDAY AFTERNOON...AND THEN QUICKLY TRANSITION TO ALL SNOW FRIDAY EVENING. BEST LIFT AND SNOW SHOULD COME IN TWO DISTINCT PERIODS. BEST LIFT WILL BE FROM 21Z TO 03Z...AND THEN AGAIN FROM 09Z TO 15Z WITH SNOW SHOWER ACTIVITY. THE BEST UPWARD VERTICAL VELOCITY COINCIDES WITH THE DENDRITIC GROWTH ZONE FOR FRIDAY EVENING...SUPPORTING IDEA OF SNOW EVEN WITH SURFACE TEMPERATURES ABOVE FREEZING. TOTAL SNOW ACCUMULATIONS LOOK TO BE 1 TO 2 INCHES FOR MOST OF THE AREA...WITH 2 TO 4 INCHES ABOVE 2000 FEET NEAR THE VIRGINIA BORDER. CONSIDERING THE RAPID TEMPERATURE DROP FRIDAY NIGHT...AND COLD AIR ADVECTION CONTINUING FOR SATURDAY ALONG WITH ADDITIONAL SNOW SHOWER ACTIVITY WILL LIKELY SEE SOME QUITE HAZARDOUS ROAD CONDITIONS. .LONG TERM.../SATURDAY NIGHT THROUGH THURSDAY/ THE EXTENDED FORECAST PERIOD BEGINS SATURDAY NIGHT WITH AN ACTIVE PATTERN IN PLACE AS A 500MB DEEP TROUGH BEGINS TO EXIT THE EAST COAST. THEN...A VERY BRIEF...AND WEAK...SHORTWAVE RIDGE WILL WILL MOVE THROUGH THE AREA ON MONDAY AND INTO EARLY MONDAY NIGHT. THE UPPER LEVEL PATTERN WILL CONTINUE TO TAKE A SPLIT FLOW APPROACH A CLOSED LOW WILL TRACK SOUTH ALONG THE WEST COAST CUT OFF FROM THE MAIN STREAM AS ANOTHER COUPLE OF SHORTWAVES MOVE EAST OVER THE NORTHERN PLAINS AND INTO THE OHIO VALLEY BY LATE TUESDAY NIGHT NIGHT. THIS COUPLED WITH ANOTHER SURGE OF GULF MOISTURE WILL SET THE STAGE FOR ANOTHER DEVELOPING SYSTEM ALONG THE WINDWARD SIDE OF THE APPALACHIANS WITH PRECIP MOVING INTO EASTERN KENTUCKY BY EARLY TUESDAY MORNING. THE PRECIP CHANCES WILL REMAIN INTO LATE WEDNESDAY AS THE PATTERN TAKE A PROGRESSIVE ZONAL LOOK OVER THE LOWER 48 AS ANOTHER WEAK IMPULSE FOLLOWS ON THE HEELS OF THE PREVIOUS WAVE. AFTER...AGAIN...A BRIEF SHORTWAVE RIDGE ON THURSDAY...THE PATTERN GAINS A BIT MORE AMPLITUDE AS ANOTHER SYSTEM DEVELOPS AND MOVES INTO THE AREA LATE THURSDAY INTO THURSDAY NIGHT. FOR MUCH OF THE EXTENDED...WILL LEAN TOWARDS THE EURO AS ITS CONSISTENCY HAS EXCEEDED THE GFS AND WILL ADJUST THE INITIALIZATION IF NEEDED TO MORE REFLECT THE EURO. A BIT SLOWER SOLUTION WOULD SUGGEST THE NEED FOR POPS TO LAST A BIT LONGER SATURDAY NIGHT AS THE SYSTEM ON SATURDAY MOVES OUT OF THE AREA. SOME SHALLOW MOISTURE STILL REMAINS AND IN AN CONTINUING UPSLOPE EVENT...AT LEAST SOME FLURRIES IS WARRANTED. DEPENDING ON HOW LONG THE LEFT OVER CLOUDS REMAIN OVER EASTERN KENTUCKY SATURDAY NIGHT TO HOLD IN SOME HEAT...SUNDAY LOW TEMPERATURES CAN BE DROPPING INTO THE LOWER TEENS IN THE VALLEYS...WITH SOME SHELTERED VALLEYS POSSIBLY REACHING SINGLE DIGITS. THEN...THE DEVELOPING SYSTEM MOVING INTO THE AREA EARLY TUESDAY MORNING...WITH SOME OF THE COLDER AIR STILL IN PLACE...MODEL SOUNDINGS SUGGEST PRECIPITATION STARTING OUT AS SNOW. THIS IS STILL A BIT TOO FAR OUT TO BE CONCERNED ABOUT ACCUMULATION WHICH AT THIS POINT IS MINIMAL ANYWAY AS THE OMEGA FALLS BELOW THE DENDRITIC GROWTH ZONE AND IS ONLY DURING THE PERIOD FROM 06Z TO 12Z WITH A BIT OF DRY AIR AT THE SURFACE TO OVERCOME BEFORE SURFACE TEMPS WARM ABOVE FREEZING AFTER 12Z. WILL LIKELY PUT A SNOW OR RAIN/SNOW IN THE GRIDS. THE REMAINING MOISTURE BEHIND THIS SYSTEM AND THE WEAK IMPULSE THAT WILL FOLLOW LATE TUESDAY NIGHT INTO WEDNESDAY MORNING WILL LIKELY LEAVE SOME LINGERING SHOWER ACTIVITY. ACCORDING TO MODEL SOUNDING DATA...THE AIR MASS OVER THE AREA DURING THIS TIME WILL PROBABLY NOT BE COLD ENOUGH TO SUPPORT SNOW...ESPECIALLY IN THIS PROGRESSIVE PATTERN WITH NO REAL GOOD COLD AIR PUSH FROM THE NORTH. SO WILL KEEP P TYPE LIQUID SHOWER ACTIVITY. CONCERNING THE DEVELOPING SYSTEM ON THURSDAY...LITTLE CONFIDENCE CAN BE DISPLAYED IN THE FORECAST FOR DAY 7 AND INTO DAY 8 AS BOTH THE GFS AND EURO WERE SHOWING A NICE TIGHTLY PACK NEGATIVELY TILTED WAVE IN THE PREVIOUS RUN AND HAVE NOW BACKED OFF SIGNIFICANTLY. CONCERNING TEMPERATURES...MODELS TOWARDS THE MIDDLE AND END OF THE EXTENDED LEAN TOWARD TEMPERATURES RETURNING TO NORMAL AND SLIGHTLY ABOVE SEASONAL AVERAGES. AFTER THE RUN OF THE INITIALIZATION AND GLANCING OVER THE 12Z EURO...THE INITIALIZATION DOES TAKE A SLIGHTLY SLOWER APPROACH...SIDING WITH THE EURO. THE ONE OTHER CONCERN IS THE TUESDAY MORNING TIME FRAME. TEMPERATURES CAME IN COLD ENOUGH TO SUPPORT SNOW IN THE 06Z TO 12Z TIME FRAME...BUT MODELS SUGGEST WEAK OMEGA IN GROWTH ZONE SO NOT MUCH ACCUMULATION IS EXPECTED AND ANY ACCUMULATION THAT REACHES A HALF INCH WILL BE ON THE RIDGES ABOVE 2000 FEET. THE OTHER CONCERN IS THE SYSTEM AT THE END OF THE PERIOD...WHERE THE 12Z EURO HAS COMPLETELY BACK OFF ON KEEPING THE NORTHERN AND SOUTHERN STREAM SEPARATE AND LEAVING EASTERN KENTUCKY DRY. THIS IS QUITE A TURN AROUND FROM ITS PREVIOUS RUN...SO FELT NO IMPROVEMENT COULD BE ADDED TO THE INITIALIZATION AND WENT WITH ITS RESULTS IN THE DAY 7 AND 8 PERIOD. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING) ISSUED AT 815 PM EST THU FEB 9 2012 THE MAIN CHALLENGE THROUGH THE NEXT 18 TO 24 HOURS WILL BE THE THREAT OF MVFR CLOUDS FOR MUCH OF EAST KENTUCKY AS A LAYER OF MOISTURE APPEARS TRAPPED NEAR THE CRITICAL THRESHOLD OF 3K FEET. CURRENTLY THE CLOUD DECK HAS LIFTED JUST INTO THE VFR CATEGORY AT MOST SPOTS WHERE IT HAS NOT OUTRIGHT CLEARED...LIKE THE FAR SOUTH. EXPECT THESE CLOUDS TO BE IN A STATE OF FLUX THROUGH THE NIGHT WITH SOME LOWERING INTO THE MVFR RANGE POSSIBLE DURING THE LATE NIGHT HOURS. HAVE INCLUDED THIS CONCEPT IN THE AVIATION GRIDS AND TEXT TAFS. THE CLOUDS WILL LIKELY LIFT DURING THE FIRST PART OF THE MORNING ON FRIDAY...BUT BY LATE IN THE DAY LOWER ONES WILL BE INBOUND FROM THE WEST ALONG WITH A THREAT OF RAIN OR SNOW SHOWERS. FOR NOW...HAVE ADDED THESE LOWER CLOUDS AND A VCSH TO THE LAST COUPLE OF HOURS OF THE TAFS. WINDS THROUGH THE PERIOD WILL BE LIGHT AND VARIABLE...BECOMING MORE SOUTHWESTERLY AHEAD OF THE PRECIPITATION DUE TO ARRIVE LATE FRIDAY. && .JKL WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 6 PM FRIDAY TO NOON EST SATURDAY FOR KYZ044-050>052-058>060-068-069-079-080-083>087-104-106>117- 119. WINTER WEATHER ADVISORY FROM 6 PM FRIDAY TO 5 PM EST SATURDAY FOR KYZ088-118-120. && $$ UPDATE...GREIF SHORT TERM...SBH LONG TERM...SHALLENBERGER AVIATION...GREIF