Area Forecast Discussion
Issued by NWS Jackson, KY

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349 FXUS63 KJKL 200818 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 418 AM EDT WED MAY 20 2015 .SHORT TERM...
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(THIS EVENING THROUGH WEDNESDAY NIGHT) ISSUED AT 345 AM EDT WED MAY 20 2015 03Z SURFACE ANALYSIS SHOWS FRONT HAS MOVED SOUTH OF THE TENNESSEE VALLEY AND CANADIAN HIGH PRESSURE BROADLY CENTERED ACROSS THE UPPER PLAINS. IN THE UPPER LEVELS THE RIDGING THAT HAS BEEN IN PLACE HAS FLATTENED WITH MORE OF A ZONAL FLOW IN THE WAKE. MUCH DRIER AND COOLER CONDITIONS PREVAIL BEHIND THE FRONT THAT USHERED IN NORTHERLY FLOW. WE HAVE BEEN ABLE TO STAY FAIRLY MIXED OVERNIGHT GIVEN THE PLACEMENT OF THE SURFACE HIGH...SO SEEING A MORE SUBTLE RIDGE/VALLEY SPLIT THIS MORNING. DID OPT KEEP MENTION OF VALLEY FOG...HOWEVER GIVEN THE MIXING MOST PLACES WILL SEE LITTLE IF ANY ISSUES THIS MORNING. TODAY WILL FEATURE MOSTLY SUNNY DAY WITH SOME HIGH CLOUDS STREAMING IN FROM THE WEST. A FEW MORE CLOUDS WILL WORK THERE WAY INTO THE FAR WEST LATE IN THE DAY. ALL EYES THEN TURN TO UPPER LEVEL DISTURBANCE CURRENTLY ACROSS THE PLAINS. THIS WILL BE THE NEXT FEATURE TO BRING POSSIBILITY OF SHOWERS ACROSS EASTERN KY TONIGHT INTO THURSDAY. A COUPLE OF ISSUES TO MENTION IS THE VERY DRY AIR IN PLACE AHEAD OF THIS SYSTEM AND THE FACT THAT THE UPPER LEVEL SYSTEM DOES WEAKEN/SHEAR OUT AS IT MOVES EAST...HOWEVER THAT SAID MODEL TRENDS CONTINUE TO INCREASE POP CHANCES WITH GFS BEING THE WEAKEST. GIVEN THIS TREND DID COME UP SOME WITH REGARDS TO POPS BUT STAYED IN THE HIGH RANGE OF CHANCE. ALSO DID KEEP ALL ACTIVITY AS JUST RAIN SHOWERS AT THIS POINT...HOWEVER NAM FORECAST SOUNDINGS DO HINT AT A BIT MORE INSTABILITY ACROSS THE SOUTH NEAR THE TN BORDER. THIS WILL HAVE TO BE LOOKED AT CLOSER IN SUBSEQUENT FORECAST UPDATES BUT WOULD THINK WE WOULD ONLY BE LOOKING AT ISOLATED CHANCES IF THAT. OTHERWISE DID BUMP PREVIOUS FORECAST HIGHS DOWN FOR THURSDAY GIVEN THE TREND FROM THE THE GUIDANCE AND THE CLOUD COVER/GENERAL NW FLOW IN PLACE. THESE HIGH TEMPS WILL BE NEARING 10 DEGREES BELOW NORMAL FOR THIS TIME OF YEAR WITH NORMAL THIS TIME OF YEAR 75 AT JKL AND 77 AT LOZ. .LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY) ISSUED AT 418 AM EDT WED MAY 20 2015 SURFACE HIGH PRESSURE BUILDING IN FROM THE WEST WITH A DRY AIR MASS WILL RESULT IN DRY WEATHER AND CLEAR TO PARTLY CLOUDY SKIES THURSDAY NIGHT AND FRIDAY. TEMPERATURES SHOULD BE BELOW NORMAL...ESPECIALLY MORNING LOWS DUE TO LOW DEW POINTS AND GOOD RADIATIVE COOLING. A COLD FRONT WILL APPROACH FROM THE NORTH FRIDAY EVENING...BUT IS EXPECTED TO DISSOLVE AS IT ARRIVES. MOISTURE WILL BE LIMITED...AND NO PRECIP IS EXPECTED. HIGH PRESSURE PASSING BY TO OUR NORTH BEHIND THE FRONT WILL BRING A REINFORCING PUSH OF COOL AND DRY AIR TO TAKE US INTO THE WEEKEND. BY SUNDAY THE HIGH WILL SLIP AWAY OFF THE EAST COAST AND OUR LOW LEVEL FLOW WILL TURN TO THE SOUTH...WHILE UPPER LEVEL RIDGING DEVELOPS OVER THE SOUTHEAST CONUS. THIS WILL BRING WARMING TEMPERATURES AND DEW POINTS. ENOUGH MOISTURE MAY RETURN TO SUPPORT A FEW SHOWERS/THUNDERSTORMS ON SUNDAY AFTERNOON AND EVENING. AS HEAT AND HUMIDITY BUILDS EARLY IN THE WEEK...AN OVERALL INCREASE IN POPS IS ALSO FORECAST. THE BETTER CHANCE OF RAIN WILL INITIALLY BE TO OUR NORTH AND WEST...FURTHER REMOVED FROM THE UPPER RIDGE. THE RIDGE SHOULD BE BREAKING DOWN BY TUESDAY AND A DISSIPATING COLD FRONT WILL APPROACH FROM THE NORTHWEST...WITH HIGHER POPS SHIFTING SOUTHEAST TOWARD KY. OTHERWISE...NOT MUCH IN THE WAY OF FEATURES CAN BE DISCERNED IN THE FLOW ALOFT...AND IT IS QUITE A DISTANCE OUT IN TIME...SO HAVE USED A DIURNAL TREND FOR PRECIP WITH PEAK POPS IN THE AFTERNOON AND EARLY EVENING HOURS.
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&& .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 100 AM EDT WED MAY 20 2015 SURFACE ANALYSIS SHOWS COLD FRONT HAS MOVED SOUTH OF THE REGION TONIGHT AND HIGH PRESSURE BUILDING SOUTHEAST. THIS HELP FOSTER GENERALLY VFR CONDITIONS FOR TAF SITES WITH AT MOST SOME HIGH THIN CIRRUS STREAMING ACROSS. OTHERWISE FOG DEVELOPMENT IS POSSIBLE ACROSS VALLEY LOCATIONS AND ESPECIALLY ALONG RIVER VALLEYS...BUT THIS IS NOT EXPECTED TO AFFECT THE TAF SITES. HIGH TO MID LEVEL CLOUDS ARE POSSIBLE LATE IN THE TAF PERIOD WITH APPROACHING DISTURBANCE. WINDS THROUGH THE PERIOD WILL REMAIN LIGHT AND GENERALLY OUT OF THE NORTH. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...DJ LONG TERM...HAL AVIATION...DJ

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