Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 260841 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 441 AM EDT SUN JUL 26 2015 .SHORT TERM...
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(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.
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&& .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 143 AM EDT SUN JUL 26 2015 HIGH PRESSURE ACROSS THE REGION IS MAKING FOR CALM AND MOSTLY CLEAR CONDITIONS. THE CAVEAT IS THAT A CALM AND CLEAR NIGHT CULTIVATES FOG FORMATION...ESPECIALLY IN THE VALLEYS. GIVEN THAT LAST NIGHT MANY SITES SAW AFFECTS FROM FOG AND LAMP GUIDANCE CONTINUES TO INTRODUCE THE IDEA TONIGHT...HAVE KEPT MVFR TO IFR VIS IN THE TAFS FOR SME...LOZ...AND SJS. IF LAST NIGHT WAS ANY INDICATION...SME AND SJS COULD BOTH DROP DOWN BELOW AIRPORT MINS BRIEFLY AROUND DAYBREAK. DID OPT TO BE MORE CAUTIOUS FOR KSME AND KJKL...GIVEN THAT ANY HIGH CLOUDS THAT MAY MOVE IN FROM THE NORTH COULD HELP NEGATE THE DROPS WE EXPERIENCED LAST NIGHT. OTHERWISE EXPECT SITES TO BOUNCE BACK TO P6SM BY 13Z. AS A BOUNDARY TO OUR NORTH CONTINUES TO SHIFT SOUTHWARD...SCT100 WILL LIKELY SPREAD ACROSS THE ENTIRE AREA...AND POSSIBLY BKN100 AT KSYM. ACCORDING TO THE LATEST FORECAST SOUNDINGS...SOME SCT050 CU COULD ALSO DEVELOP DURING THE AFTERNOON HOURS...THOUGH PRECIP CHANCES ARE STILL BELOW CRITERIA. BETTER STORM CHANCES EXIST MOSTLY PAST THE TAF PERIOD SO LEFT OUT ANY MENTION OF SH OR TSRA AT THIS TIME. WINDS THROUGH THE PERIOD WILL REMAIN LIGHT AND VARIABLE AT ALL SITES. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JMW LONG TERM...HAL AVIATION...JMW

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