Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 010202 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1002 PM EDT TUE SEP 30 2014 .UPDATE... ISSUED AT 1002 PM EDT TUE SEP 30 2014 BASED ON THE LATEST TEMPERATURE AND DEW POINT TRENDS...THE LATEST GUIDANCE...AND COMPARISONS IN TEMPERATURES...DEW POINTS...AND FOG/CLOUDS TO THAT OF LAST NIGHT...DECIDED TO ADJUST THE OVERNIGHT LOWS FOR TONIGHT/TOMORROW MORNING SOMEWHAT ACROSS THE CWA. OVERALL...TRENDED DOWN SEVERAL DEGREES FROM PREVIOUS FORECAST...WITH LOWER DEW POINTS EARLIER IN THE AFTERNOON AND SLIGHTLY LESS FOG POTENTIAL OVERNIGHT EXPECTED TO PLAY A FACTOR IN ALLOWING TEMPS TO DROP SEVERAL DEGREES LOWER THAN THAT OF LAST NIGHT. UPDATE ISSUED AT 804 PM EDT TUE SEP 30 2014 FORECAST SEEMS TO BE FAIRLY WELL IN SHAPE SO FAR THIS EVENING. UPDATED THE NEAR TERM GRIDS WITH THE LATEST OBSERVATIONAL DATA FOR TEMPS...DEW POINTS AND WINDS. WILL CONTINUE TO MONITOR THESE PARAMETERS AS WE HEAD LATER INTO THE EVENING/OVERNIGHT TO BETTER ASSESS THE FOG POTENTIAL. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT) ISSUED AT 255 PM EDT TUE SEP 30 2014 THE FORECAST MODELS WERE ALL IN VERY GOOD AGREEMENT REGARDING THE WEATHER PATTERN FOR THE NEXT FEW DAYS. A WELL DEVELOPED RIDGE OF HIGH PRESSURE ALOFT WILL REMAIN IN PLACE OVER THE GREAT LAKES...OHIO VALLEY AND TENNESSEE VALLEY REGIONS OVER THE NEXT 36 HOURS. THE RESULT WILL BE LIGHT AND VARIABLE WINDS...MOSTLY CLEAR SKIES...AND DRY WEATHER. TEMPERATURES DURING THIS TIME WILL BE ABOVE NORMAL FOR THE TIME OF YEAR DUE TO THE INFLUENCE OF THE HIGH PRESSURE AND THE ABUNDANT SUNSHINE THAT WILL BATH THE REGION. HIGHS ON WEDNESDAY WILL BE TOPPING OUT IN THE UPPER 70S AND LOWER 80S...WITH OVERNIGHT LOWS TONIGHT AND TOMORROW NIGHT DROPPING INTO THE LOW TO MID 50S FOR MOST LOCATIONS. THE WEATHER ISSUE OF NOTE THE NEXT COUPLE OF NIGHTS WILL FOG. CONDITIONS REMAIN PRIMED FOR ANOTHER NIGHT OR TWO OF WIDESPREAD FOG. BASED ON THE LATEST TIME HEIGHT CROSS SECTIONS AND MODEL SOUNDINGS...AND PREVAILING CONDITIONS...THE FOG WILL LIKELY BECOME DENSE AGAIN FOR A LARGE PORTION OF THE AREA. UPCOMING SHIFTS WILL NEED TO MONITOR THE SITUATION TO DETERMINE IF ANY PRODUCTS NEED TO BE ISSUED TO DEAL WITH THE FOG. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 255 PM EDT TUE SEP 30 2014 AT THE MID AND UPPER LEVELS MODELS ARE IN REASONABLE AGREEMENT WITH LARGE SCALE FEATURES. SHORT WAVE RIDGING IN PLACE OVER THE OHIO VALLEY AT THE START OF THE EXTENDED WILL RAPIDLY YIELD TO A LARGE TROUGH AND LOW PRESSURE SYSTEM THAT IS EXPECTED TO BULL DOZE ITS WAY INTO THE EASTERN CONUS BY LATE FRIDAY...SATURDAY. THIS SYSTEM WILL PROVIDE OUR AREA WITH A SOLID SHOT OF COLDER AUTUMN LIKE AIR AND DOMINATE OUR WEATHER PATTERN THROUGH THE REMAINDER OF THE EXTENDED. CHALLENGE WILL CENTER AROUND SHORT WAVE ACTIVITY THAT ROUNDS THE BOTTOM OF THE LARGER EASTERN CONUS TROUGH THROUGH THE REMAINDER OF THE EXTENDED...OR MORE SPECIFICALLY THE TIMING OF THESE IMPULSES THROUGH OUR AREA. SENSIBLE WEATHER WILL FOCUS MAINLY AROUND STRONG COLD FRONTAL SYSTEM THAT WILL SWEEP ACROSS MUCH OF THE EASTERN CONUS...AND THROUGH THE OHIO VALLEY FRIDAY. A FEW IMPULSES BEHIND THIS FIRST SYSTEM WILL SERVE MAINLY TO REINFORCE THE MUCH COOLER AIR THAT WILL SETTLE OVER THE FORECAST AREA THROUGH THE BULK OF THE EXTENDED. A FAST MOVING COLD FRONT WILL PRODUCE SHOWERS AND A CHANCE OF THUNDERSTORMS FRIDAY. SHOULD FORECAST SOUNDINGS BE REALIZED AND IN PARTICULAR SOMETHING SIMILAR TO THE 12Z GFS SOLUTION...THERE COULD BE A POTENTIAL FOR A FEW STRONGER THUNDERSTORMS AS THE COLD FRONT PUSHES ITS WAY ACROSS OUR FORECAST AREA. WITH H850 LLJ APPROACHING 50 KTS COMBINED WITH SFC BASED INSTABILITY DIRECTLY AHEAD OF THE FRONT... LIS OF -3/CAPES ABOUT 1000 J/KG...THOUGHTS ARE THAT SOME STRONGER WINDS MAY MIX DOWN TO THE SFC IN AND NEAR ANY THUNDERSTORMS. WITH SHEAR PROFILES SHOWING THE MAJORITY OF THE BULK SHEAR EXISTING IN THE LOWER 3 KM OF THE SOUNDING...THE POTENTIAL FOR SOME BOWING CELLS/LINE SEGMENTS CAN NOT BE RULED OUT. HOWEVER...GREATER SFC BASED INSTABILITY WOULD BE REQUIRED FOR ANY SIGNIFICANT SEVERE THREAT. WINDS WILL BECOME GUSTY BEHIND THE FRONT AS WELL...AS COLDER AIR COMES RUSHING IN LATE FRIDAY. WITH STRONG MIXING THESE GUSTY WINDS APPEAR TO LINGER INTO FRIDAY NIGHT....EARLY SATURDAY MORNING BEFORE SUBSIDING. TEMPERATURES WILL COOL CONSIDERABLY. HIGHS WILL LIKELY ONLY CLIMB INTO THE 50S SATURDAY AND ONLY GRADUALLY MODERATE FROM THERE AS REINFORCING SHOTS OF COOLER AIR WORK THERE WAY INTO THE REGION FROM TIME TO TIME...THE NEXT MOST IMMEDIATE BEING A FRONT THAT MOVES ACROSS THE CWA MONDAY. GIVEN THAT THE MODELS CONTINUE TO ADVERTISE A THEME OF THE GFS BEING WARMER AND THE ECMWF MUCH COLDER FROM SAT THROUGH THE END OF THE PERIOD...THE BLEND OF GUIDANCE SEEMED TO BE THE BEST COURSE OF ACTION AT THIS TIME. HOWEVER...THE WARMER GFS IS TRENDING TOWARDS THE COOLER ECMWF OVERALL. THE BOTTOM LINE IS THE PERIOD BEGINS MILD AND THEN ENDS WITH BELOW NORMAL TEMPERATURES. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 710 PM EDT TUE SEP 30 2014 CONDITIONS LOOK RIPE FOR ANOTHER PERIOD OF DENSE FOG AT THE TAF SITES BEGINNING BETWEEN 5 AND 6Z TONIGHT AND LASTING THROUGH 13 AND 15Z ON WEDNESDAY. THE FOG WILL BE AT ITS WORST BETWEEN ROUGHLY 7 AND 12Z...THEN BEGIN LIFTING AND DISSIPATING BETWEEN 12 AND 13Z. LIFR CONDITIONS CAN BE EXPECTED DURING THE PEAK OF FOG COVERAGE AT THE TAF SITES. THE EXCEPTION MAY BE LONDON...WHO BASED ON CURRENT OBS COMPARED TO THAT OF LAST NIGHTS...ARE TRENDING A BIT DRIER...AND THEREFORE LED TO ONLY INCLUDING IFR CONDITIONS AT THIS TIME. WINDS WILL GO CALM OVERNIGHT AND BE LIGHT AND VARIABLE ON WEDNESDAY UNDER MOSTLY SUNNY SKIES. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JMW SHORT TERM...AR LONG TERM...RAY AVIATION...JMW

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