Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 280850 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON KY 350 AM EST WED JAN 28 2015 .SHORT TERM...(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 THROUGH TUESDAY) ISSUED AT 446 PM EST TUE JAN 27 2015 THERE ARE TWO WEATHER SYSTEMS OF CONCERN TO AFFECT THE REGION DURING THE PERIOD. ONE FROM THURSDAY INTO FRIDAY...AND ANOTHER FROM LATE SATURDAY NIGHT INTO MONDAY. THERE IS DECENT MODEL AGREEMENT FOR THE FIRST SYSTEM. FOR THE SECOND SYSTEM...WHILE THE MODELS AGREE ON IT COMING INTO BEING...THERE IS A GOOD DEAL OF VARIATION IN ITS TRACK. THE FIRST SYSTEM IS A COLD FRONT WITH A PARENT LOW PASSING WELL TO OUR NORTH. PRECIP MAY OCCUR IN THE WARM AIR ADVECTION AHEAD OF THE FRONT...AS WELL AS ALONG THE FRONT...AND IN THE LINGERING LOW LEVEL MOISTURE AND STEEP LAPSE RATES WITH UPSLOPE FLOW BEHIND THE FRONT. PRECIP WILL LIKELY TAKE THE FORM OF RAIN SHOWERS ALONG AND AHEAD OF THE FRONT. THERE IS A VERY SMALL CHANCE FOR SOME WINTERY PRECIP IN OUR NW COUNTIES EARLY IN THE DAY THURSDAY...BUT THE PROBABILITY APPEARS TOO LOW TO WARRANT MENTION AT THIS POINT. ONCE THE LOW LEVELS CHILL ENOUGH...ANY LINGERING PRECIP SHOULD GO OVER TO SNOW SHOWERS ON THURSDAY NIGHT. THE SURFACE LOW WITH THE SECOND SYSTEM IS EXPECTED TO TRACK FURTHER SOUTH...BUT EXACTLY HOW FAR SOUTH IS THE BIG QUESTION. THE 12Z ECMWF IS FURTHER SOUTH WITH THE SUPPORTING UPPER LEVEL IMPULSE WHEN COMPARED TO THE GFS...RESULTING IN ITS SURFACE LOW BEING FURTHER SOUTH. THE ECMWF SURFACE LOW TRACK IS ENE ACROSS THE JKL FORECAST AREA...WHILE THE 12Z GFS TAKES IT EAST ACROSS IN AND OH. INTERESTINGLY...THE 12Z GFS ENSEMBLE MEAN IS MUCH FURTHER SOUTH... WITH THE LOW TRACKING FROM LOUISIANA TO THE CAROLINA. THE TRACK WILL HAVE A VERY LARGE IMPACT ON TEMPERATURES AND PRECIP TYPE. THE NORTHERN TRACK WOULD LEAVE US WITH MAINLY RAIN IN THE MAIN BATCH OF PRECIP...WHILE THE SOUTHERN TRACK OF THE GFS ENSEMBLE WOULD BRING SIGNIFICANT SNOW. HAVE USED A MODEL COMPROMISE WHICH IS CLOSE TO THE ECMWF. THIS GIVES SOME POTENTIAL FOR SNOW AT THE ONSET...WITH A CHANGE TO RAIN...AND THEN BACK TO SNOW AS THE SYSTEM DEPARTS. HOWEVER...IT IS A LOW CONFIDENCE FORECAST FOR TEMPS AND PRECIP TYPE...AND THE SYSTEM BEARS WATCHING. && .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...HAL AVIATION...GREIF

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