714  
FXUS63 KLMK 201907  
AFDLMK  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LOUISVILLE KY  
307 PM EDT THU JUL 20 2017  
   
SHORT TERM
 
(THIS EVENING THROUGH FRIDAY NIGHT)  
ISSUED AT 255 PM EDT THU JUL 20 2017  
   
..VERY HOT AND HUMID THROUGH SATURDAY
 
 
THE MAIN FOCUS IN THE SHORT TERM IS ON THE HIGH HEAT AND HUMIDITY  
ACROSS SOUTHERN INDIANA AND CENTRAL KENTUCKY.  
 
AS OF MID AFTERNOON, A SURFACE ANALYSIS SHOWS HIGH PRESSURE CENTERED  
OVER TENNESSEE WITH A SURFACE BOUNDARY WELL NORTH ACROSS THE LOWER  
GREAT LAKES. SATELLITE IMAGERY SHOWS THE REMNANTS OF A MORNING MCS  
SPREADING HIGH LEVEL CLOUDS ACROSS PORTIONS OF THE AREA, THOUGH THIS  
HASN'T HAD TOO MUCH OF AN EFFECT ON TEMPERATURES AS READINGS HAVE  
EASILY CLIMBED INTO THE LOWER TO MIDDLE 90S. COMPARED TO YESTERDAY,  
DEWPOINTS HAVEN'T MIXED OUT AND ARE IN THE LOWER TO MIDDLE 70S. THIS  
IS CREATING HIGH HEAT INDICES IN THE 100 TO 103 RANGE, ESPECIALLY  
FOR AREAS ALONG AND WEST OF I-65.  
 
THE REMAINDER OF THE EVENING WILL BE HOT AND HUMID WITH TEMPERATURES  
VERY SLOW TO FALL. EVENING HEAT INDICES WILL REMAIN IN THE UPPER 90S  
TO AROUND 100. OVERNIGHT TEMPERATURES WILL BE VERY WARM, ONLY  
FALLING INTO THE MID TO UPPER 70S. LOUISVILLE METRO MAY ONLY BRIEFLY  
DROP BELOW 80 FOR A COUPLE OF HOURS.  
 
ONE OF THE HOTTEST AND MOST HUMID DAYS OF THE SUMMER SO FAR IS  
EXPECTED TOMORROW AND AGAIN ON SATURDAY. OVERALL, NO LARGE CHANGES  
IN THE FORECAST MESSAGE AS TEMPERATURES CLIMB INTO THE LOW TO MID  
90S. IF DEWPOINTS REMAIN IN THE MID 70S, THIS WILL PUT THE HIGHEST  
AFTERNOON HEAT INDICES IN THE 105 TO 108 RANGE FOR AREAS MAINLY  
ALONG AND WEST OF THE I-65 CORRIDOR. IN COORDINATION WITH  
SURROUNDING OFFICES, WILL ADD A FEW COUNTIES IN SOUTHERN INDIANA AND  
NORTHERN KENTUCKY TO THE HEAT ADVISORY WHERE MAX HEAT INDICES WILL  
TOP OUT IN THE 105 TO 108 RANGE. ALSO, HAVE DECIDED TO GO AHEAD AND  
EXTEND THE ADVISORY THROUGH SATURDAY EVENING (8 PM EDT) AS  
CONDITIONS ARE EXPECTED TO REMAIN JUST AS HOT/HUMID SATURDAY.  
 
ADDITIONALLY, SOME RELIEF FROM THE HEAT AND HUMIDITY FRIDAY MAY  
COME WITH POP-UP SHOWERS OR THUNDERSTORMS. HI-RES AND OTHER MESO  
MODELS SHOW DIURNALLY DRIVEN CONVECTION BY MID AFTERNOON MAINLY  
ACROSS SOUTHERN INDIANA AND NORTH CENTRAL KENTUCKY WHERE THE RIDGE  
IS SLIGHTLY WEAKER AND THERE IS A WEAKER CAP. WILL MAINTAIN THE  
20 TO 30 PERCENT CHANCES ACROSS THE AREA. GIVEN THE VERY STRONG  
AFTERNOON DESTABILIZATION, SOME LOCALLY STRONG STORMS MAY BE  
POSSIBLE ACROSS PORTIONS OF SOUTHERN INDIANA AND NORTH CENTRAL  
KENTUCKY INCLUDING THE BLUEGRASS REGION. THIS IS WHERE THE DEEP  
LAYER SHEAR IS SLIGHTLY HIGHER. GUSTY WINDS WOULD BE THE MAIN  
THREAT.  
 

 
   
LONG TERM
 
(SATURDAY THROUGH THURSDAY)  
ISSUED AT 255 PM EDT THU JUL 20 2017  
 
TOWARD THE END OF THE WEEKEND AND INTO EARLY NEXT WEEK, THE UPPER  
RIDGE IS EXPECTED TO BREAK DOWN AND SHIFT ITS CENTER BACK TO THE  
WEST. THIS SHOULD LOWER THICKNESS AND 850 MB TEMPERATURES AND ALLOW  
UPPER TROUGHING TO SPREAD ACROSS THE LOWER GREAT LAKES AND LOWER  
OHIO VALLEY.  
 
A COLD FRONT WILL PASS THROUGH THE AREA SUNDAY INTO MONDAY BRINGING  
SCATTERED TO PERHAPS NUMEROUS SHOWERS AND THUNDERSTORMS TO THE AREA.  
COULDN'T RULE OUT ISOLATED STRONGER STORMS ON SUNDAY, PARTICULARLY  
OVER SOUTHERN INDIANA AND FAR NORTHERN KENTUCKY WHERE THERE IS  
SLIGHTLY BETTER DEEP LAYER SHEAR (30 KTS). OTHERWISE, STORM  
ORGANIZATION SHOULD BE WEAK ACROSS SOUTH-CENTRAL KENTUCKY.  
 
SLIGHTLY COOLER BUT MUCH DRIER CANADIAN HIGH PRESSURE IS THEN  
EXPECTED TO BUILD INTO THE REGION TUESDAY AND WEDNESDAY PROVIDING A  
COUPLE OF DRIER AND LESS HUMID DAYS.  
 

 
   
AVIATION
 
(18Z TAF ISSUANCE)  
ISSUED AT 1223 PM EDT THU JUL 20 2017  
 
QUIET AVIATION WEATHER TODAY, PREDOMINANTLY VFR WITH SCATTERED-  
BROKEN HIGH CLOUDS. EXPECT CLOUDS TO DECREASE THIS EVENING WITH  
PERHAPS A SMALL CHANCE AT LIGHT, BRIEF BR AT BWG/LEX TOMORROW  
MORNING. WESTERLY WINDS WILL REMAIN UNDER 7 KTS TODAY BACKING TO THE  
SSW LATE TONIGHT INTO TOMORROW. A CHANCE FOR ISLD CONVECTION MAY  
RETURN TO LEX/SDF TOMORROW AFTERNOON.  
 

 
   
LMK WATCHES/WARNINGS/ADVISORIES
 
 
IN...HEAT ADVISORY FROM NOON EDT /11 AM CDT/ FRIDAY TO 8 PM EDT /7 PM  
CDT/ SATURDAY FOR INZ076>079-083-084-089>092.  
 
KY...HEAT ADVISORY FROM NOON EDT /11 AM CDT/ FRIDAY TO 8 PM EDT /7 PM  
CDT/ SATURDAY FOR KYZ023>034-038-045-053-061>063-070>074.  
 

 
 

 
 
SHORT TERM...ZT  
LONG TERM...ZT  
AVIATION...AMS  
 
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