Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 010023 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON KY 823 PM EDT TUE MAR 31 2015 .UPDATE...
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ISSUED AT 810 PM EDT TUE MAR 31 2015 23Z SFC ANALYSIS SHOWS A DRY COLD FRONT DROPPING THROUGH EASTERN KENTUCKY. THIS IS SUPPORTING BREEZY AND DRY CONDITIONS THROUGH THE AREA THIS EVENING. THIS HAS LED TO SEVERAL WILD FIRES DEVELOPING THROUGH THE AREA EARLIER IN THE DAY THAT CONTINUE...AS SEEN ON THE DUAL POL RADAR LOOPS...CC IN PARTICULAR. THE WINDS WILL SLOWLY SETTLE THROUGH THE REST OF THE EVENING AS THE PRESSURE GRADIENT RELAXES AND THE MIXING HEIGHTS FALL. ACCORDINGLY...HAVE ALLOWED THE RED FLAG WARNING AND SPS FOR FIRE WEATHER CONCERNS EXPIRE. HOWEVER...DID CONTINUE THE CAUTIOUS WORDING IN THE HWO FOR THE REST OF THE EVENING FOR NEAR CRITICAL CONDITIONS. ALSO FINE TUNED THE T/TD GRIDS PER THE LATEST SHORTBLEND GUIDANCE...OBS...AND TRENDS. FINALLY...TOOK SKY COVER DOWN ANOTHER NOTCH WITH THIS UPDATE. THESE GRIDS HAVE BEEN SENT TO THE NDFD AND WEB SERVERS WHILE AN UPDATED ZFP AND HWO WERE ISSUED.
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&& .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT) ISSUED AT 345 EDT TUE MAR 31 2015 CURRENT CONDITIONS ACROSS THE AREA FEATURE MAINLY CLEAR SKIES WITH A AN UPSTREAM DRY COLD FRONT MOVING SOUTHEAST. AS OF 19Z...THE FRONT IS MOVING ACROSS THE OH RIVER AND INTO EASTERN KENTUCKY. WITH THIS...A STRONG GRADIENT WILL BE PRESENT WITH SOME 20 TO 25 KNOT GUSTS AND THIS WILL CONTINUE WITH AND BEHIND THE FRONT. EXPECTING WINDS TO DECREASE AND DECOUPLE BY 23Z THIS EVENING. PROFILES THIS EVENING CONTINUE WITH A DEEP DRY LAYER AND WILL KEEP SKIES MOSTLY CLEAR THROUGH TONIGHT AS WELL. WHILE THE CENTER OF HIGH PRESSURE WILL NOT HAVE MOVED INTO THE AREA...SOME RIDGE VALLEY SPLIT WILL STILL DEVELOP TONIGHT. THE DRY AIR THIS EVENING AND GUSTY WINDS WITH THE COLD FRONT WILL ALLOW FOR SOME HAZARDOUS FIRE WEATHER CONDITIONS AND WILL KEEP THIS IN THE HWO. HEADING INTO THE DAY ON WEDNESDAY...MID LEVEL RIDGING WILL BE MOVING INTO THE AREA WITH SURFACE HIGH PRESSURE CENTERED OVER THE OH VALLEY. WINDS WILL BE LIGHT DURING THIS TIME AND WITH THE HIGHER SUN ANGLE...TEMPERATURES WILL REBOUND INTO THE MID 60S DESPITE THE COLD FRONT PASSING THROUGH ON TUESDAY EVENING. STILL A DRY AIR MASS WILL BE IN PLACE WITH AFTERNOON RELATIVE HUMIDITIES DROPPING INTO THE LOWER 30 PERCENT RANGE. FOR WEDNESDAY NIGHT... A STRONG SHORT WAVE MOVES INTO THE MS RIVER VALLEY AS SOUTHERLY FLOW INCREASES INTO THE TN AND OH VALLEY. A WEAK DISTURBANCE MOVES NORTHEAST OUT OF THE GULF AND INTO KY BRINGING A CHANCE FOR SHOWERS INTO EASTERN KENTUCKY BY DAWN ON THURSDAY. BY DAWN ON THURSDAY...A STRONG COLD FRONT DEVELOPS AS THIS WAVES MOVES INTO THE MIDWEST. FORCING AND INSTABILITY LOOKS TO BE STRONG ENOUGH THAT A FEW THUNDERSTORMS MAY MOVE INTO THE AREA BY DAWN ON THURSDAY. FOR NOW WILL STAY WITH CHANCE SHOWERS AS THERE WILL BE SOME DRY AIR TO OVERCOME AS WELL. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 357 PM EDT TUE MAR 31 2015 THE OHIO RIVER VALLEY WILL FIND ITSELF IN TRANSITION DURING THE DAY THURSDAY...AS UPPER LEVEL RIDGING BEGINS TO EXIT...AND A SUBTLE LONGWAVE TROUGH OVER THE WESTERN HALF OF THE CONUS BEGINS TO SHIFT EASTWARD. EXPECT THIS LONGWAVE TROUGH TO MAKE IT INTO THE MISSISSIPPI RIVER VALLEY...AND THEN THEN OHIO RIVER VALLEY BY FRIDAY EVENING. MEANWHILE...A STRONG SHORTWAVE WILL TRAVERSE SOUTHERN CANADA JUST AHEAD OF THIS LONGWAVE TROUGH. MODELS ARE IN SURPRISINGLY GOOD AGREEMENT WITH THESE FEATURES...OTHER THAN A FEW SLIGHT TIMING DIFFERENCES...AND CONTINUE TO BE SO THROUGHOUT THE WEEKEND AS THE TROUGH AXIS EXITS. ZONAL FLOW AND GENERAL RIDGING WILL THEN TAKE HOLD SUNDAY NIGHT THROUGH THE REMAINDER OF THE FORECAST PERIOD. TWO SURFACE LOW PRESSURE SYSTEMS WILL SET UP ALONG THE LONGWAVE TROUGH AND SHORTWAVE AS WE HEAD INTO THE EXTENDED. BY 12Z THU...EXPECT THESE SURFACE LOW PRESSURE SYSTEMS TO BE LOCATED...ONE...JUST NORTH OF LAKE SUPERIOR...AND 2...ALONG THE SOUTHERN PLAINS. AN EXTENSIVE COLD FRONT WILL LINK THESE TWO SYSTEMS...QUICKLY SWEEPING EASTWARD WITH THE LONGWAVE TROUGH MOVEMENT. WITH SOUTHERLY FLOW ALREADY IN PLACE...AND A GOOD PULL OF WARM MOIST AIR COMING OFF THE GULF OF MEXICO...EXPECT CONVECTION TO BEGIN DEVELOPING DURING THE DAY ACROSS KY...WELL AHEAD OF THE COLD FRONT. COVERAGE AND INSTABILITY WILL INCREASE AS THE COLD FRONT NEARS THURSDAY NIGHT. BY FRIDAY MORNING...THE SOUTHERN-MOST LOW PRESSURE SYSTEM WILL BE IN MI/AR...AND THE NORTHERN ONE WILL HAVE RACED FARTHER AHEAD AND NORTHWARD INTO FAR NE CANADA. THE COLD FRONT WILL BE LOCATED ALONG THE OHIO RIVER AND BECOME NEARLY STATIONARY AS IT BECOMES FURTHER ELONGATED FROM WEST TO EAST. THIS LARGE AREA OF FRONTOGENESIS/INSTABILITY WILL INCREASE CONVECTIVE ACTIVITY THURSDAY NIGHT AND INTO FRIDAY...WITH 6 HOUR PWAT VALUES WELL OVER 1 INCH THURSDAY AFTERNOON THROUGH FRIDAY MORNING...INCREASING TO OVER 1.25 INCHES DURING THE DAY FRIDAY. AS SUCH...EXPECT FLASH FLOODING TO BE A CONCERN AS WE HEAD INTO THE DAY FRIDAY...ESPECIALLY UNDER SOME OF THE LARGER SHOWERS AND THUNDERSTORMS. FRIDAY EVENING...THE FRONT WILL FINALLY MAKE A VERY QUICK SHIFT ACROSS KY FRIDAY EVENING...PULLING IN MUCH DRIER AND SOMEWHAT COOLER NW FLOW. THIS WILL ALSO KICK IN A SUBSIDENCE INVERSION...PREVENTING ANY FURTHER THUNDERSTORM DEVELOPMENT...AND QUICKLY CUTTING OFF BEST QPF. EXPECT SHOWERS AND ANY LINGERING THUNDER TO TAPER OFF OVERNIGHT. ECMWF TRIES TO HOLD ONTO SOME UPSLOPE FLOW THROUGH THE FIRST HALF OF THE DAY SATURDAY...WHILE THE GFS PULLS THE FRONT FAR ENOUGH SE THAT THERE IS NO LINGERING MOISTURE INFLUENCE. EXPECT IT WILL LIKELY BE A COMBINATION OF THESE TWO SOLUTIONS...SO WILL KEEP WITH A MODEL BLEND OF PRECIP THROUGH THE DAY SATURDAY. ANY ADDITIONAL ACCUMULATIONS WILL BE VERY LIGHT WITH VERY LITTLE MOISTURE LEFT IN THE SOUNDINGS. MORE ZONAL UPPER LEVEL FLOW WILL TAKE HOLD THROUGH THE REMAINDER OF THE WEEKEND. AFTER A DROP IN TEMPS FROM THE COLD FRONTAL PASSAGE ON SATURDAY...EXPECT THEM TO SLOWLY MODERATE TO NEAR OR ABOVE NORMAL. HOWEVER...BOTH THE ECMWF AND GFS ARE TRYING TO DEVELOP A WEAK FRONTAL BOUNDARY ALONG THIS ZONAL FLOW AS WE HEAD FROM MONDAY INTO TUESDAY...WITH STRONG SOUTHERLY FLOW AND ABUNDANT MOISTURE FLOWING INTO THE OHIO RIVER VALLEY OFF OF THE GULF OF MEXICO. IF THIS CONTINUES TO ORGANIZE...COULD BE LOOKING AT ANOTHER CHANCE FOR RAIN AND THUNDERSTORMS...THOUGH THERE IS STILL QUITE A BIT OF DISAGREEMENT ON INTENSITY AND COVERAGE. && .AVIATION...
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(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 825 PM EDT TUE MAR 31 2015 VFR CONDITIONS WILL CONTINUE THROUGH THE PERIOD. A COLD FRONT IS MOVING THROUGH THE AREA THIS EVENING WITH WEST TO NORTHWEST WINDS GUSTING TO BETWEEN 20-25 KTS. THESE WINDS WILL SUBSIDE OVER THE NEXT COUPLE OF HOURS WITH NO AVN CONCERNS THROUGH THE REMAINDER OF THE PERIOD AS SKIES REMAIN MAINLY CLEAR AND THE WINDS STAY LIGHT INTO THE DAY WEDNESDAY.
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&& .JKL WATCHES/WARNINGS/ADVISORIES...
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NONE.
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&& $$ UPDATE...GREIF SHORT TERM...SHALLENBERGER LONG TERM...JMW AVIATION...GREIF

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