500  
FXUS63 KJKL 130320 AAA  
AFDJKL  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE JACKSON KY  
1120 PM EDT SUN JUL 12 2020  
   
UPDATE
 
 
ISSUED AT 1120 PM EDT SUN JUL 12 2020  
 
WITH THE STORM CLUSTERS WINDING DOWN ACROSS THE AREA HAVE UPDATED  
THE FORECAST TO FINE TUNE THE POPS/QPF/WX THROUGH THE REST OF THE  
NIGHT. WILL CARRY THUNDER IN THE FAR SOUTHEAST FOR A FEW MORE  
HOURS BEFORE DIMINISHING TO SHOWERS AND ENDING. HAVE ALSO ADDED IN  
THE LATEST OBS AND TRENDS FOR THE T/TD GRIDS. THESE UPDATES HAVE  
BEEN SENT TO THE NDFD AND WEB SERVERS. A FRESHENED SET OF ZONES  
AND HWO WILL BE ISSUED, AS WELL.  
 
UPDATE ISSUED AT 755 PM EDT SUN JUL 12 2020  
 
23Z SFC ANALYSIS SHOWS AN AREA OF LOW PRESSURE MOVING THROUGH  
EASTERN KENTUCKY WITH A COUPLE OF MESO FRONTS WASHING ACROSS THE  
CWA. THESE ARE SUPPORTING SOME STRONG TO SEVERE THUNDERSTORMS  
PASSING THROUGH - STARTING TO NARROW THEIR FOCUS TO THE SOUTHEAST  
PARTS OF THE JKL FORECAST AREA. WINDS ARE MAINLY LIGHT AND  
VARIABLE OUTSIDE OF ANY STORM OR WELL DEFINED GUST FRONT.  
MEANWHILE, TEMPERATURES ARE IN THE UPPER 70S AWAY FROM THE RAIN  
AND IN THE LOW 70S WITH THE STORMS AS DEWPOINTS REMAIN IN HE UPPER  
60S TO LOWER 70S. HAVE UPDATED THE FORECAST TO FINE TUNE THE POPS  
AND QPF THROUGH THE REST OF THE EVENING TIMING THE CONVECTION  
THROUGH. ALSO, ADDED IN THE LATEST OBS AND TRENDS FOR THE T/TD  
GRIDS. THESE UPDATES HAVE BEEN SENT TO THE NDFD AND WEB SERVERS.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH MONDAY NIGHT)  
ISSUED AT 348 PM EDT SUN JUL 12 2020  
 
THE AFTERNOON SURFACE ANALYSIS SHOWS A WEAK LOW PRESSURE TO OUR  
WEST, AND THIS FEATURE WILL PROGRESS EAST TONIGHT ALONG WITH A  
COLD FRONT. THE WATER VAPOR IMAGERY THIS AFTERNOON SHOWS A MID  
LEVEL SHORTWAVE PROGRESSING INTO THE OHIO VALLEY AND THAT FEATURE  
SEEMS TO BE DRIVING SOME CONVECTION THIS AFTERNOON. THE CAMS HAVE  
TRIED TO COME INTO BETTER ALIGNMENT THIS AFTERNOON WITH SOME  
SHOWERS AND THUNDERSTORMS DEVELOPING OR MOVING INTO MAINLY THE  
BLUEGRASS REGION. THIS ACTIVITY IS ANTICIPATED TO PROGRESS  
SOUTHWARD INTO THE AREA WITH THE PUSH OF THE MID LEVEL WAVE  
THROUGH THE EVENING. THE LATEST RADAR SCANS AT AROUND 19Z DID  
SHOW A FEW SHOWERS DEVELOPING IN FLEMING COUNTY. THE LATEST  
MESOANALYSIS FROM SPC SHOWS A DECENT 1000 TO 2000 J/KG OF MUCAPE  
HAS DEVELOPED IN PORTIONS OF CENTRAL AND EASTERN KENTUCKY, BUT  
SEEING SOME INDICATIONS OF LESSER EFFECTIVE SHEAR OF AROUND 30  
KNOTS AT BEST. THE BETTER INSTABILITY IS EXPECTED TO REMAIN IN  
THE BLUEGRASS WHERE MORE SUN HAS BEEN SEEN THIS AFTERNOON, AND  
THIS IS EVIDENT ON VISIBLE SATELLITE WHERE BETTER CUMULUS FIELD  
RESIDES NORTH OF A DIFFERENTIAL HEATING BOUNDARY. THIS AS DEBRIS  
CLOUDS HAVE KEPT THE CUMBERLAND VALLEY COOLER THROUGH THE MORNING  
AND AFTERNOON. THIS MEANS MAINLY ISOLATED SEVERE STORMS WOULD BE  
THE THREAT, WITH DAMAGING WINDS BEING THE MAIN THREAT. THE THREAT  
AREA SEEMS TO BE MOSTLY NORTH OF A DIFFERENTIAL HEATING BOUNDARY  
DISCUSSED EARLIER OR MAINLY ALONG AND NORTH OF THE MOUNTAIN  
PARKWAY, BUT AS THE MID LEVEL WAVE APPROACHES THE THREAT COULD  
SHIFT SOUTHEAST, HOWEVER, MORE UNCERTAINTY EXISTS IN THIS REGION.  
 
TONIGHT STORMS WILL RELENT THROUGH THE LATE EVENING, AS  
INSTABILITY DECREASES AND SHORTWAVE PUSHES EAST. THEN PERHAPS A  
LITTLE MORE FOG WILL BE POSSIBLE BEHIND THIS SYSTEM AND  
PARTICULARLY IN THE AREAS THAT SEE RAIN THIS AFTERNOON AND  
EVENING. OTHERWISE WEAK NORTHWEST FLOW AND BUILDING SURFACE HIGH  
PRESSURE WILL BE THE STORY TONIGHT. MONDAY THE WEATHER WILL  
FEATURE CLEARING SKIES AND WEAK NORTHERLY FLOW, AS SURFACE HIGH  
CRESTS AND MID LEVEL HEIGHTS RISE IN THE OHIO VALLEY. DID INCREASE  
TEMPERATURES SOME GIVEN THE CLEARING SKIES DESPITE THE WEAK  
NORTHERLY FLOW. THIS SURFACE HIGH BUILDS EVEN CLOSER TO EASTERN  
KENTUCKY BY MONDAY NIGHT AND HEIGHTS REMAIN ON THE RISE. GIVEN  
THIS ADDED MORE FOG TO THE VALLEYS AND HAVE TEMPERATURES A BIT  
LOWER IN THE VALLEYS. HOWEVER, WE COULD SEE A FEW UPPER 50S IN THE  
DEEPER VALLEYS GIVEN THE CLEAR AND CALM CONDITIONS, BUT THE FOG  
COULD ALSO KEEP TEMPERATURES AT BAY.  
   
LONG TERM
 
(TUESDAY THROUGH SUNDAY)  
ISSUED AT 439 PM EDT SUN JUL 12 2020  
 
THE HEAT RETURNS FROM TUESDAY RIGHT ON THROUGH THE WEEKEND AS A  
STRONG SUMMER-TIME RIDGE BUILDS EASTWARD ACROSS THE SOUTHEAST US.  
TEMPERATURES REBOUND IN THE UPPER 80S TO LOWER 90S ON TUESDAY  
AFTERNOON AND SURGE WELL INTO THE 90S ON WEDNESDAY. INCREASING  
HUMIDITY AND CLOUD COVER SHOULD TAMP HIGH TEMPERATURES DOWN TO  
NEAR 90 FROM THURSDAY THROUGH THE WEEKEND BUT HEAT INDICES WILL  
STILL SOAR INTO THE MID AND UPPER 90S EACH AFTERNOON, ECLIPSING  
THE CENTURY MARK AT THE HOTTEST LOCALES. DRY CONDITIONS ON TUESDAY  
AND WEDNESDAY YIELD TO A RENEWED SHOWER AND STORM THREAT AT TIMES  
FROM LATE WEDNESDAY NIGHT THROUGH SUNDAY.  
 
MODEL AGREEMENT REMAINS GOOD THROUGH WEDNESDAY BUT THE GFS AND  
EURO DIVERGE ON THE STRENGTH OF UPPER LEVEL RIDGING THEREAFTER.  
THE EXTENDED PERIOD BEGINS 12Z TUESDAY WITH UPPER LEVEL RIDGING  
BUILDING EASTWARD ACROSS THE SOUTHERN CONUS FROM AN UPPER LEVEL  
HIGH CENTERED OVER THE TRANS-PECOS REGION. TO THE NORTH, AN UPPER  
LEVEL TROUGH WILL BE TRAVERSING EASTWARD ACROSS THE NORTHERN  
PLAINS AND CANADIAN PRAIRIES. THE OVERALL STRENGTH OF THE RIDGE  
REMAINS THE PRIMARY QUESTION FROM THURSDAY ON THROUGH THE  
WEEKEND. THE OPERATIONAL GFS CONTINUES TO SHOW THE RIDGE  
PARTIALLY BREAKING DOWN OVER THE SE US AS MULTIPLE SHORTWAVE  
DISTURBANCES RIDE THROUGH THE FLOW BETWEEN THE SOUTHERN RIDGE AND  
NORTHERN TROUGHING. ON THE OTHER HAND, THE EURO AND GEFS FEATURE  
A STRONGER AND MORE RESILIENT RIDGE OVER THE SOUTHEAST US,  
ALTHOUGH SOME WEAKNESS IS EVIDENT WITH EACH PASSING SHORTWAVE.  
 
THE 12Z TUESDAY SURFACE ANALYSIS SHOWS SURFACE HIGH PRESSURE  
EXTENDING SOUTHWARD FROM THE GREAT LAKES KEEPING A DRY NE FLOW  
ACROSS THE AREA FOR TUESDAY. ADDITIONALLY, A STRONG SUBSIDENCE  
INVERSION NEAR 700 MB AND UNSEASONABLY LOW PWATS WELL UNDER 1  
INCH SHOULD RESULT IN MOSTLY SUNNY SKIES AND EFFICIENT SURFACE  
WARMING PROCESSES TUESDAY AFTERNOON. DEEP MIXING AND 850 TEMPS  
WARMING TO NEAR 19-21C SHOULD SUPPORT WARM HIGH TEMPS IN THE  
87-92 RANGE WHILE DEW POINTS REMAIN IN THE LOW-TO-MID 60S. THE  
CLEAR AND DRY ATMOSPHERE SHOULD SUPPORT STRONG RADIATIONAL COOLING  
TUESDAY NIGHT WITH TEMPERATURES FALLING BACK INTO THE LOW-TO-MID  
60S. AS PREVIOUSLY ADVERTISED, EVEN WARMER TEMPERATURES ARE  
EXPECTED FOR WEDNESDAY AS 850MB TEMPS NUDGE UPWARDS TO NEAR  
22-24C, WHICH COMBINED WITH DEEP MIXING TO 800 MB OR HIGHER,  
SHOULD SUPPORT AFTERNOON TEMPERATURES IN THE LOW TO MID 90S.  
FORTUNATELY, DEW POINTS REMAIN RELATIVELY LOW, WHICH SHOULD KEEP  
THE HEAT A LITTLE MORE TOLERABLE. THE CAPPING FINALLY STARTS TO  
ERODE WEDNESDAY AFTERNOON/NIGHT AS MOISTURE INCREASES AHEAD OF THE  
THE FIRST SHORTWAVE AND AN APPROACHING COLD FRONT. SOME MODELS  
ARE HINTING AT A DECAYING MCS, ASSOCIATED WITH THE SHORTWAVE,  
APPROACHING THE AREA WEDNESDAY NIGHT, PERHAPS BRINGING A SHOWER  
OR STORM TO THE BLUEGRASS LATE. THEREAFTER, THE LATEST MODELS  
WOULD SUGGEST THAT THE FRONT STALLS NORTH OF THE AREA THROUGH THE  
WEEKEND WHILE ADDITIONAL SHORTWAVE ENERGY PROVIDES SUFFICIENT  
FORCING FOR ADDITIONAL SHOWER STORM DEVELOPMENT AT TIMES. THE  
INCREASED HUMIDITY LEVELS AND CLOUD COVER SHOULD KEEP AFTERNOON  
TEMPERATURES WITHIN A COUPLE DEGREES OF 90 EACH AFTERNOON FROM  
THURSDAY ONWARD WHILE NIGHT LOWS RANGE FROM THE UPPER 60S TO LOWER  
70S. MEANWHILE, HEAT INDICES PEAK BETWEEN 95 AND 100 FOR MOST  
PLACES EACH AFTERNOON. VALLEY FOG FORMATION IS ALSO POSSIBLE EACH  
NIGHT IN THE TYPICAL LOCALES.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)  
ISSUED AT 825 PM EDT SUN JUL 12 2020  
 
STRONG TO SEVERE CONVECTION WILL CONTINUE ACROSS THE AREA THROUGH  
THE NEXT FEW HOURS LEADING TO MVFR OR LOWER CIGS AND IFR  
VISIBILITY FOR A SHORT TIME MAINLY BETWEEN NOW AND THE 03Z TIME  
FRAME. HAVE INCLUDED A TEMPO FOR THESE WORSENING CONDITIONS AT ALL  
TAF SITES AS THE STORMS WORK NORTHWEST TO SOUTHEAST. THE WINDS  
WILL MOSTLY REMAIN LIGHT OUT OF THE WEST AND THEN BECOME MORE  
NORTHWEST THROUGH THE NIGHT. HOWEVER, SOME STRONGER WIND GUSTS  
WOULD BE POSSIBLE UNDER ANY OF THE THUNDERSTORMS. ALSO GIVEN THE  
LIKELIHOOD OF FAIRLY WIDESPREAD SOAKING RAINS, EXPECT SOME POST  
FRONTAL FOG AND/OR LOW STRATUS FOR THE TAFS LATER TONIGHT INTO  
EARLY MONDAY MORNING.  
 

 
   
JKL WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
UPDATE...GREIF  
SHORT TERM...DJ  
LONG TERM...GEERTSON  
AVIATION...DJ/GREIF  
 
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