Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 220803 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 403 AM EDT MON SEP 22 2014 .SHORT TERM...
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(TODAY THROUGH TUESDAY) ISSUED AT 402 AM EDT MON SEP 22 2014 SUBSTANTIAL DRY AIR HAS MOVED IN ACROSS MUCH OF EASTERN KY AFTER A DEPARTING COLD FRONT FROM EARLIER IN THE DAY. HOWEVER...A DISTURBANCE CURRENTLY MOVING ACROSS THE UPPER GREAT LAKES REGION HAS CAUSED A BROAD DECK OF MVFR CLOUDS. ACCORDING TO THE LATEST IMAGERY...THESE CLOUDS ARE CONTINUING TO PUSH SSE-WARD AND ARE EXPECTED TO ENTER INTO EASTERN KY OVER THE NEXT SEVERAL HOURS. THE LEADING EDGE OF THIS CLOUD DECK IS ALREADY PUSHING INTO SJS OBSERVATION SITE IN THE FAR EASTERN PORTION OF THE CWA. THE LATEST OBSERVATIONS UPSTREAM...ALONG WITH THE LATEST MODEL SOUNDINGS AND LAMP GUIDANCE...ALL POINT AT THIS CLOUD DECK REMAINING MVFR. DURING THE DAY TODAY...STRONG SUBSIDENCE WILL TAKE HOLD ACROSS THE REGION UNDER SURFACE HIGH PRESSURE AND RISING UPPER LEVEL HEIGHTS AS A LONGWAVE TROUGH DEPARTS EAST FROM THE AREA. THIS WILL LEAD TO A THINNING OF CLOUDS THROUGHOUT THE MORNING AND AN INFLUX OF COLD DRY CANADIAN AIR. WINDS WILL REMAIN OUT OF THE NORTH BOTH AT THE SURFACE AND UPPER LEVELS AS THE STRONGLY DISPLACED NORTHERN JET CONTINUES MOVE EASTWARD ACROSS THE REGION FOLLOWING THE LONGWAVE PATTERN. EXPECT HIGHS TODAY TO BE MUCH LOWER THAN THAT OF YESTERDAY...ONLY REACHING THE UPPER 60S IN MOST LOCATIONS. SIMILARLY...WITH THE LOSS OF DAYTIME HEATING...RADIATIONAL COOLING WILL BE AT A MAXIMUM UNDER MOSTLY CLEAR SKIES. THIS WILL ALLOW FOR TEMPS TO DROP WELL BELOW NORMAL...INTO THE LOW TO MID 40S ACROSS THE REGION FOR LOWS. SOME OF THE DEEPEST RIVER VALLEYS WILL LIKELY SEE FOG DEVELOPMENT AS THE DEW POINTS REMAIN HIGHER IN THESE LOCATIONS. THE NORTHERN JET WILL PUSH OFF EAST OF THE AREA BY TUESDAY/TOMORROW. WHILE WINDS WILL REMAIN NORTHERLY...THEY WILL NOT BE QUITE AS STRONG IN THE MID AND UPPER LEVELS. CONTINUED SUNSHINE ACROSS THE AREA WILL ALSO WORK TO MODIFY TEMPS SLIGHTLY HIGHER AS STRONG HIGH PRESSURE REMAINS OVERHEAD. DAYTIME HIGHS ARE EXPECTED TO REACH THE LOW 70S IN SOME LOCATIONS...WHILE SOME OF THE HIGHER ELEVATIONS MAY CONTINUE TO SEE UPPER 60S. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 329 PM EDT SUN SEP 21 2014 A STRONG UPPER LEVEL RIDGE WILL MOVE INTO THE MISSISSIPPI RIVER VALLEY BY 12Z TUESDAY. SURFACE HIGH PRESSURE WILL REMAIN STRONG OVER THE REGION...WITH WINDS BOTH AT THE SURFACE AND ALOFT PULLING DRY AND COLDER AIR IN FROM CANADA. AFTERNOON HIGHS TUESDAY WILL LIKELY FALL SHORT OF THE AGGRESSIVE MAV GUIDANCE...ENDING UP CLOSER TO THE MET NUMBERS. THIS WILL PUT THEM RIGHT AROUND THE 70 DEGREE MARK. THE UPPER LEVEL RIDGE WILL REMAIN BLOCKED OVER THE REGION THROUGH THE REMAINDER OF THE WEEK. AS SUCH...DRY AIR WILL PERSIST ACROSS MUCH OF THE OHIO RIVER VALLEY...THOUGH THE LOSS OF STRONGEST NRLY WIND FLOW AT BOTH THE SURFACE AND ALOFT WILL LEAD TO AIR MASS MODIFICATION AND RISING TEMPERATURES THROUGHOUT THE EXTENDED. MODELS ARE NOT IN VERY GOOD AGREEMENT HEADING THROUGH NEXT WEEKEND. DEEP SOUTHEAST FLOW MAY DEVELOP WITH MOISTURE ADVANCING INTO THE AREA FROM THE ATLANTIC. WHILE DOWNSLOPING FLOW MAY LIMIT POTENTIAL PRECIPITATION...IF THE FLOW IS DEEP ENOUGH...SOME MOISTURE MAY STILL MAKE IT OVER THE HIGH TERRAIN LEADING TO POSSIBLE SHOWERS BY SUNDAY. HOWEVER...THIS PERIOD REMAINS VERY MUCH UNCERTAIN. MORE SHALLOW SOUTHEAST FLOW WOULD LIMIT THIS PRECIPITATION THREAT AS DOWNSLOPING WOULD DOMINATE. THUS...WILL ONLY INCLUDE SOME SLIGHT CHANCES FOR RAIN AS WE HEAD INTO THE END OF THE EXTENDED.
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&& .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 204 AM EDT MON SEP 22 2014 SUBSTANTIAL DRY AIR HAS MOVED IN ACROSS MUCH OF EASTERN KY AFTER A DEPARTING COLD FRONT FROM EARLIER IN THE DAY. HOWEVER...A DISTURBANCE CURRENTLY MOVING ACROSS THE UPPER GREAT LAKES REGION HAS CAUSED A BROAD DECK OF MVFR CLOUDS. ACCORDING TO THE LATEST IMAGERY...THESE CLOUDS ARE CONTINUING TO PUSH SSE-WARD AND ARE EXPECTED TO ENTER INTO EASTERN KY WITHIN THE NEXT SEVERAL HOURS. GIVEN THE LATEST OBSERVATIONS UPSTREAM...AND WITH SUPPORT FROM THE LATEST MODEL SOUNDINGS AND LAMP GUIDANCE...DECIDED TO INCREASE CLOUD DECK HEIGHTS BACK TO MVFR AS THEY MOVE ACROSS THE REGION. OTHERWISE...PATCHY FOG SHOULD ONLY BE CONFINED TO THE DEEPEST VALLEYS AND IN SOME LOCATIONS THAT RECEIVED RAINFALL TODAY...BUT SHOULD GENERALLY STAY OUT OF THE TAF SITES. BY LATE TOMORROW MORNING...STRONG SUBSIDENCE WILL TAKE HOLD...WITH CLOUDS LIFTING TO VFR AND THINNING OUT THROUGH THE AFTERNOON. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JMW LONG TERM...KAS/JMW AVIATION...JMW

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