Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 280926 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 426 AM EST WED JAN 28 2015 .SHORT TERM...
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(TODAY THROUGH THURSDAY) ISSUED AT 350 AM EST WED JAN 28 2015 08Z SFC ANALYSIS SHOWS HIGH PRESSURE MOVING THROUGH THE OHIO VALLEY. THIS HIGH IS PROVIDING A DECENT NIGHT OF RADIATIONAL COOLING FOR THE VAST MAJORITY OF THE AREA WITH THE ONLY EXCEPTION FOUND IN FAR EASTERN PARTS OF THE STATE WHERE NORTHEAST LOW LEVEL FLOW IS KEEPING SOME STRATUS AROUND. IN FACT...A FEW SNOW SHOWERS HAVE BEEN FALLING OUT OF THESE AS SEEN IN THE KPBX OBS AND THE RADAR IMAGES FROM RLX. IN THE CLEAR AREAS TEMPERATURES HAVE BEEN FALLING STEADILY WITH THE RIDGES AND THE VALLEYS LEADING THE PACK...THOUGH AS THE NIGHT HAS WORN ON THE DEEPER VALLEYS HAVE DROPPED THE FURTHEST...WHILE THE MORE OPEN LOCATIONS HAVE BEEN LAGGING...THUS FAR. READINGS AT 3 AM VARY FROM THE MID TEENS ON THE RIDGES AND THOSE SHELTERED VALLEYS WHILE LOWER 20S ARE FOUND IN MORE OPEN PLACES LIKE SME AND LOZ AS WELL AS SOUTHERN VALLEYS OF EKQ AND 1A6. DEWPOINTS...MEANWHILE...ARE GENERALLY IN THE MID TEENS TO NEAR 10 ABOVE AS WINDS REMAIN LIGHT... GENERALLY FROM THE NORTH TO NORTHEAST. THE MODELS ARE IN PRETTY GOOD AGREEMENT ALOFT FOR THE SHORT TERM PORTION OF THE FORECAST AS THEY ALL DEPICT THE RETREAT OF THE DEEP NORTHEAST TROUGH AND WITH IT THE ENERGY STREAM THAT RAN FROM NNW TO SSE OVER OUR EASTERN BORDER. BRIEF RIDGING WILL FOLLOW INTO THURSDAY MORNING FOR KENTUCKY THOUGH ANOTHER DEVELOPING TROUGH WILL BE TRAILING QUICKLY BEHIND THESE HIGHER HEIGHTS. THIS TROUGH SLIPS INTO THE SOUTHERN OHIO VALLEY BY MIDDAY THURSDAY WITH A COUPLE OF BATCHES OF TRAILING ENERGY THAT WILL EVENTUALLY FORM A DEEPER TROUGH FOR THE NORTHEAST COAST BY WEEK/S END. GIVEN THE MODEL SIMILARITIES IN THE SHORT TERM...HAVE FAVORED A BLENDED SOLUTION WITH A LEAN TOWARD THE NAM12 FOR WX DETAILS ON THURSDAY. SENSIBLE WEATHER WILL FEATURE A CHILLY START TO THE DAY WITH SOME SINGLE DIGITS POSSIBLE AT DAWN. PLENTY OF SUNSHINE WILL ALLOW READINGS TO CLIMB SMARTLY INTO THE MID 30S IN THE NORTH AND LOWER 40S SOUTH EVEN AS HIGH CLOUDS START TO ARRIVE AHEAD OF THE NEXT CLIPPER SYSTEM. THESE HIGH CLOUDS...AND WINDS STARTING TO REACT TO THE SFC LOW...WILL LIKELY NOT PREVENT A DECENT DROP OFF IN TEMPERATURES FOLLOWING SUNSET FOR THE BULK OF THE AREA TONIGHT. EXPECT THE EASTERN VALLEYS TO FALL OFF THE FURTHEST AND BE THE LAST TO ENGAGE WITH THE INCREASING SOUTHERN SFC FLOW...WAITING UNTIL CLOSER TOWARDS DAWN TO BREAK THEIR TEMPERATURE FALL AND START TO RISE. MEANWHILE... RIDGES AND MORE OPEN LOCATIONS IN THE WEST WILL ONLY SLOWLY DROP OFF THROUGH THE FIRST PART OF THE NIGHT. EXPECT THE THICKENING CLOUDS AND INCREASING SOUTHERN WINDS TO ALLOW TEMPS TO CLIMB IN THE HOURS BEFORE DAWN MOST PLACES ALONG WITH RISING DEWPOINTS. PCPN CHANCES SHOULD ARRIVE FROM NORTHWEST TO SOUTHEAST DURING THURSDAY MORNING WITH PLACES LIKELY WARMING QUICK ENOUGH TO PREVENT A MIX AT THE ONSET. THIS WILL STILL NEED TO BE WATCHED BUT AT THIS POINT IS NOT ENOUGH OF A CONCERN TO HIGHLIGHT IN THE GRIDS...ZONES...OR HWO. AS THE SFC LOW PASSES TO THE NORTH LATER THURSDAY...ITS FRONT WILL PUSH THROUGH A BAND OF RAIN FOR MOST OF THE AREA THAT AFTERNOON. COLDER AIR DOES FOLLOW ON WEST TO NORTHWEST WINDS FOR LATE IN THE AFTERNOON AND INTO THE EVENING THURSDAY. AS A RESULT...SOME SNOW MAY MIX IN WITH THE LINGERING RAIN BY 00Z FRIDAY IN THE NORTHWEST PARTS OF THE AREA. HAVE ADDED A MIX FOR THIS IN THE WX GRIDS TOWARDS THE END OF THE SHORT TERM PERIOD. AGAIN USED THE BCCONSSHORT AS A STARTING POINT FOR TEMPERATURES... DEWPOINTS...AND WINDS THROUGH THIS EVENING AND THE SUPERBLEND THEREAFTER. DID MAKE SOME FAIRLY SUBSTANTIVE...TERRAIN BASED... ADJUSTMENTS TO HOURLY AND MINIMUM TEMPERATURES...AS WELL AS WINDS... TONIGHT AHEAD OF THE INBOUND FRONTAL SYSTEM. AS FOR POPS...ENDED UP CLOSE TO A COMBINATION OF THE MAV AND MET NUMBERS THROUGH THE DAY THURSDAY...THOUGH WITH ADDED TIMING DETAILS IN THE SPATIAL COVERAGE OF THE POP/WX GRIDS DURING THE AFTERNOON...IN PARTICULAR. .LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY) ISSUED AT 425 AM EST WED JAN 28 2015 CLIPPER SYSTEM WILL BE EXITING TO THE EAST OF THE REGION AS WE MOVE INTO THURSDAY NIGHT. THERE WILL BE A CHANGE OVER FROM RAIN TO MIX AND THEN TO ALL SNOW. GIVEN LIMITED MOISTURE WITH THIS SYSTEM WOULD THINK ACCUMULATIONS WOULD BE QUITE LIGHT. DO KEEP THE MENTION OF SLIGHT CHANCES RIGHT ALONG THE RIDGES INTO EARLY FRIDAY GIVEN THE NW FLOW THAT SETUP ACROSS THE REGION THROUGH THAT PERIOD. THIS SURFACE LOW WILL RESTRENGTHEN ACROSS NEW ENGLAND STATES AS SURFACE HIGH DIVES ACROSS THE OHIO VALLEY THROUGH THE DAY FRIDAY. SKIES ARE EXPECTED TO CLEAR OUT THROUGH THE DAY AS HIGH PRESSURE AND DRIER AIR BUILD ACROSS EASTERN KY. THIS FRONT DOES BRING COLDER AIRMASS WITH TEMPS DROPPING INTO THE TEENS FRIDAY NIGHT. SATURDAY HIGH PRESSURE WILL SHIFT EAST AND THIS WILL BRING RETURN FLOW TO THE REGION. THIS WILL TRANSLATE TO REASONABLE REBOUND IN TEMPS WITH HIGHS REACHING INTO THE UPPER 30S TO LOWER 40S ACROSS MOST SPOTS. THEN ALL FOCUS SHIFTS TO DEVELOPING STORM SYSTEM ACROSS THE DESERT SW AND PLAINS SATURDAY. THIS DEVELOPING LOW PRESSURE SYSTEM COMBINED WITH UPPER LEVEL TROUGH THAT DEVELOPS ACROSS THE PLAINS WILL BE THE NEXT BIG WEATHER MAKER TO AFFECT EASTERN KY THIS COMING WEEKEND. THAT SAID THE FORECAST UNCERTAINTY FOR THIS STORM SYSTEM HAS BEEN QUITE NOTICEABLE FROM RUN TO RUN. PREVIOUS RUNS OF THE GFS IN REGARDS TO THIS SYSTEM SUGGESTED MORE PROGRESSIVE LOW PRESSURE SYSTEM...HOWEVER LATEST 00Z/28 IS A BIT MORE INLINE WITH THE LATEST 00Z/28 ECMWF. IT SHOULD ALSO BE NOTED THAT EVEN THE 00Z/28 GFS ENSEMBLE MEAN IS MORE PROGRESSIVE THAN THE OPERATIONAL SOLUTION AND LOOKING AT SOME OF THE PERTURBATIONS THE SURFACE LOW LOCATIONS VARY QUITE A BIT. THESE DIFFERING SOLUTIONS WILL HAVE IMPLICATIONS ON TIMING AND AMTS OF PRECIP. THIS TIMING WILL ALSO PLAY A BIG ROLL IN TIMING OF PRECIP CHANGE OVER TO SNOW SUNDAY NIGHT AND HOW MUCH SNOW WE ACTUALLY SEE. GIVEN UNCERTAINTY HAVE TRIED TO FOLLOW A MODEL BLEND APPROACH AT THIS POINT AND ALSO TRIED TO STAY IN REASONABLE COLLABORATION WITH SURROUNDING OFFICES. KEEP IN MIND RIGHT NOW MUCH OF THE QPF ASSOCIATED WITH THIS SYSTEM STILL LOOKS TO FALL IN THE FORM OF RAIN ON SUNDAY WHERE BETTER MOISTURE AND LIFT WILL TAKE PLACE DURING THAT PERIOD. GIVEN ALL THE UNCERTAINTY THINK THERE IS STILL POTENTIAL FOR ACCUMULATING SNOW SUNDAY NIGHT INTO MONDAY AND THIS WILL HAVE TO BE FINE TUNED IN SUBSEQUENT FORECAST UPDATES. MOVING INTO MONDAY WOULD EXPECT TEMPS TO GENERALLY DROP THROUGH THE DAY AND THE AMT OF DROP WILL DEPEND ON TIMING AND EVOLUTION OF THIS SYSTEM. THAT SAID THIS SYSTEM DOES LOOK TO USHER IN WELL BELOW NORMAL TEMPERATURES MONDAY NIGHT WITH LOWS DROPPING INTO THE TEENS AND EVEN SINGLE DIGITS IN SOME SPOTS. HIGH PRESSURE WILL MOVE EAST THROUGH THE DAY TUESDAY BRINGING SOME RETURN FLOW AND HIGHS GENERALLY IN THE LOW TO MID 30S SOUTH AND UPPER 20S TO LOWER 30S NORTH.
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&& .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 115 AM EST WED JAN 28 2015 ASIDE FROM SOME LOW CLOUDS OVER SJS...SKC CONDITIONS WILL PREVAIL THROUGH THE REST OF THE NIGHT BEFORE HIGH CLOUDS START TO PUSH IN FROM THE WEST AHEAD OF THE NEXT CLIPPER. WINDS THROUGH THE PERIOD WILL BE GENERALLY LIGHT FROM THE NORTH TO NORTHEAST INITIALLY THEN SWITCHING AROUND TO THE SOUTH BY MIDDAY WEDNESDAY. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GREIF LONG TERM...DJ AVIATION...GREIF

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