Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 261814 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 214 PM EDT SUN JUL 26 2015 .UPDATE... ISSUED AT 214 PM EDT SUN JUL 26 2015 HIGHER DEWPOINTS HAVE ALLOWED FOR A BIT BETTER INSTABILITY IN THE ACROSS THE CUMBERLAND PLATEAU...AND HAS KICKED OFF A STRAY SHOWER OR TWO. FORTUNATELY...IT LOOKS LIKE THIS ACTIVITY SHOULD STAY JUST TO OUR SOUTH THROUGH THE AFTERNOON. THUS...NO CHANGES TO THE FORECAST PLANNED AT THIS TIME. UPDATE ISSUED AT 925 AM EDT SUN JUL 26 2015 UPDATED TO LOWER SKY COVER TODAY WITH JUST A FEW HIGH CLOUDS DRIFTING ACROSS THE AREA. GIVEN THE LACK OF INSTABILITY THIS EVENING...HAVE OPTED TO REMOVE THUNDER CHANCES. LATEST HI RES MODELS SHOW A DYING AREA OF SHOWERS MOVING IN WELL AFTER SUNSET THIS EVENING. THIS SUPPORTS THE REMOVAL OF DAYTIME POPS AND THUNDER. THIS WILL SET THE STAGE FOR ANOTHER MILD DAY WITH HIGHS AGAIN PUSHING THE UPPER 80S IN PLACES. UPDATE ISSUED AT 705 AM EDT SUN JUL 26 2015 CONDITIONS REMAIN CALM ACROSS THE CWA WITH HIGH PRESSURE OVERHEAD. FOG IS OBSERVED ACROSS THE CWA...LOCALLY DENSE IN SOME LOCATIONS. AS THE SUN BEGINS TO RISE OVER THE NEXT COUPLE OF HOURS...EXPECT THE FOG TO BEGIN BURNING OFF. A BOUNDARY TO OUR NORTH HAS PRODUCED SHOWERS AND CLOUD COVER OVER NORTH CENTRAL OH AND INDIANA EARLIER IN THE OVERNIGHT PERIOD. NOW...MOST OF THESE SHOWERS HAVE DISSIPATED...BUT THE CLOUD COVER IS CONTINUING TO SHIFT TO THE SE. THESE CLOUDS WILL MOVE ACROSS THE CWA THROUGHOUT THE DAY...INCREASING WITH DAYTIME HEATING...BUT SHOULD REMAIN VFR IN NATURE. OVERALL...NO MAJOR CHANGES WERE NEEDED FOR THIS UPDATE. LOADED THE LATEST OBSERVATIONAL DATA FOR TEMPS...DEW POINTS...AND WINDS INTO THE ONGOING FORECAST TO MAKE SURE THE NEAR TERM GRIDS REFLECTED THE CURRENT CONDITIONS. && .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 339 AM EDT SUN JUL 26 2015 HIGH PRESSURE REMAINS IN CONTROL DURING THIS EARLY MORNING...WITH CALM CONDITIONS PROMOTING FOG ONCE MORE IN THE VALLEY LOCATIONS. EXPECT THIS TO BURN OFF THROUGH THE MORNING AS THE SUN BEGINS TO RISE. FOCUS THEN SHIFTS TO A WEAK BOUNDARY CURRENTLY NORTH OF THE OHIO RIVER OVER NORTH CENTRAL INDIANA AND OHIO. LATEST GFS IS SHOWING THIS BOUNDARY SINKING SLIGHTLY FARTHER SOUTH DURING THE DAY TODAY...BUT REMAINING NORTH OF THE OHIO RIVER. THE QUESTION WITH THIS BOUNDARY WILL BE PRECIPITATION CHANCES...PARTICULARLY IF THEY WILL MAKE IT ACROSS THE OHIO RIVER AND INTO OUR CWA. UNFORTUNATELY...EVERY MODEL HAS A DIFFERENT OPINION ON THIS...BUT THE ONE THING THAT IS AGREED UPON IS THAT WHATEVER DOES OCCUR WILL BE LIGHT AND BRIEF IN NATURE. ENDED UP JUST INCLUDING SLIGHT POPS ACROSS THE NORTHERN CWA STARTING IN THE AFTERNOON AND CONTINUING INTO THE EVENING. BY NIGHTFALL...THE BOUNDARY WILL SHIFT SOUTHWARD INTO OUR CWA BUT WILL LOSE CONSIDERABLE STRENGTH AS IT DOES SO. THIS...COUPLED WITH LOSS OF DAYTIME INSTABILITY...WILL KEEP ANY POPS IN THE SLIGHT CHANCE CATEGORY THROUGH THE NIGHT...IF THEY EXIST AT ALL. WHAT IS LEFT OF THE BOUNDARY WILL STRETCH FROM WESTERN KY SE TO THE SOUTHERN ATLANTIC SEABOARD DURING THE DAY TOMORROW...LEAVING MUCH OF EASTERN KY UNDER HIGH PRESSURE BY THE AFTERNOON. DESPITE THIS...HIGHER POPS THAN TODAY ARE EXPECTED ACROSS OUR AREA. THE REASON FOR THIS LIES IN THE UPPER LEVELS...WHERE A SHORTWAVE WILL BEGIN STRENGTHENING INTO AN UPPER LEVEL TROUGH OVER THE EASTERN SEABOARD. ALL MODELS ARE SURPRISINGLY IN GOOD AGREEMENT THAT THIS FEATURE WILL PULL ENOUGH MID AND UPPER LEVEL MOISTURE INTO THE REGION THAT POPS WILL BE POSSIBLE SUNDAY NIGHT AND THROUGH THE DAY MONDAY...ESPECIALLY ACROSS THE HIGHER APPALACHIAN TERRAIN. THIS WILL INCLUDE SOUTHEAST KY AND POINTS TO OUR EAST. EITHER WAY...PWAT VALUES ARE QUITE LOW...AND THERE IS LITTLE HELP FROM THE LLVL WINDS AS FAR AS PRODUCING ANY DECENT SHEER OR LIFT...SO NOT EXPECTING ANYTHING STRONG OUT OF THIS SYSTEM. AS FAR AS TEMPERATURES DURING THE SHORT TERM...THE APPROACHING BOUNDARY WILL BE TOO WEAK TO SWAY TEMPERATURES MUCH. CONTINUED SUNSHINE TODAY WILL BOOST TEMPS BACK INTO THE UPPER 80S...AND THE SLIGHT INFLUX IN MOISTURE WILL UNFORTUNATELY LEAD TO HIGHER HUMIDITY VALUES. CLOUDS WILL LIKELY HELP INSULATE OVERNIGHT...WITH EARLY MORNING LOWS EXPECTED TO STAY AROUND 70 DEGREES. THEN FOR MONDAY...SCATTERED CLOUDS AND SHOWERS WILL LIKELY PLAY A ROLE IN TEMPERATURES THROUGHOUT THE DAY...BUT OVERALL DON/T EXPECT THERE TO BE ENOUGH IMPACT TO SUBSTANTIALLY LOWER TEMPS FROM WHAT THEY REACHED TODAY. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 441 AM EDT SUN JUL 26 2015 EARLY IN THE PERIOD...UPPER LEVEL RIDGING WILL BUILD IN FROM THE WEST...WHILE SURFACE HIGH PRESSURE RESIDES JUST TO OUR NORTHEAST. THE NAM AND GFS HAVE BEEN CONSISTENT IN ALLOWING LOW LEVEL DRYING TO NUDGE INTO OUR REGION IN ASSOCIATION WITH THE SURFACE HIGH... RESULTING IN DRY WEATHER THROUGH WEDNESDAY. THE ECMWF MAINTAINS A MORE HUMID AIR MASS AND GENERATES PRECIP IN OUR AREA UNDER THE PERIPHERY OF THE UPPER RIDGE. HAVE OPTED TO LEAN CLOSER TO THE AMERICAN MODELS...THINKING THAT THEY ARE BETTER HANDLING THE SMALLER SCALE INTRUSION OF LOW LEVEL DRIER AIR...AND THAT RISING GEOPOTENTIAL HEIGHTS WILL ALSO HELP TO INHIBIT DEEP CONVECTION. ALL THREE MODELS SHOW THE UPPER RIDGE FLATTENING AND RETROGRADING TO THE WEST AT MIDWEEK AS THE TROUGH CURRENTLY IN THE PACIFIC NORTHWEST RIDES OVER THE RIDGE AND THROUGH SOUTHEAST CANADA AND THE NORTHEAST CONUS. THIS WILL ALLOW ANOTHER COLD FRONT TO MOVE SOUTHEAST THROUGH THE AREA WEDNESDAY NIGHT AND THURSDAY. EVEN THE GFS SHOWS ENOUGH MOISTURE INCREASE TO ALLOW FOR A POTENTIAL OF SHOWERS/THUNDERSTORMS WITH THE FRONT. THE MODELS HAVE TRENDED A BIT FASTER WITH THE SYSTEM SINCE YESTERDAY...AND THIS HAS BEEN TAKEN INTO ACCOUNT FOR THE POP. BEHIND THE MIDWEEK FRONT...A DRIER AIR MASS IS SHOWN FOR LATE IN THE WEEK...WHICH IF IT MATERIALIZES WILL ALLOW FOR SOME COOL NIGHTS AND SUNNY/WARM DAYS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 214 PM EDT SUN JUL 26 2015 MAINLY VFR CONDITIONS WILL BE SEEN OVER THE NEXT 24 TO 36 HOURS. ANOTHER ROUND OF VALLEY FOG MAY DEVELOP LATE TONIGHT...WITH A SMALL POSSIBILITY OF A FEW TAF SITES BRIEFLY GOING DOWN TO MVFR VISIBILITIES. HOWEVER...CONFIDENCE IS LOW RIGHT NOW AS CLOUD COVER REMAINS UNCERTAIN TONIGHT. THUS WILL PLAN TO LET THE VFR CONDITIONS RIDE FOR NOW. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KAS SHORT TERM...JMW LONG TERM...HAL AVIATION...KAS

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