941  
FXUS61 KILN 201955  
AFDILN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE WILMINGTON OH  
355 PM EDT THU JUL 20 2017  
   
SYNOPSIS
 
 
A FRONTAL BOUNDARY WILL SLOWLY SAG SOUTH ACROSS THE REGION  
THROUGH THE WEEKEND. THIS WILL COMBINE WITH A WARM AND HUMID  
AIRMASS TO PRODUCE OCCASIONAL THUNDERSTORMS THROUGH THE REST OF  
THE WEEK AND INTO THE WEEKEND.  
 

 
   
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
 
 
REMNANTS OF A MCS WERE MOVING ACROSS THE CWA EARLY THIS  
AFTERNOON. WE HAVE ALSO SEEN SEPARATE SCATTERED CONVECTIVE  
DEVELOPMENT ACROSS PORTIONS OF EASTERN OH.  
 
MCS WILL LIKELY CONTINUE TO WEAKEN AND THEN DISSIPATE AS IT  
MOVES ACROSS SOUTHERN OH THROUGH MID AFTERNOON. EXPECT A  
RELATIVE LULL IN CONVECTIVE ACTIVITY AFTER THAT DUE TO SOME  
SUBSIDENCE AND LINGERING CLOUDS BEHIND THIS SYSTEM.  
 
MOST HIGH RESOLUTION MODELS THEN SUGGEST THAT AFTER THIS LULL  
THERE WILL BE RENEWED CONVECTION ACROSS THE CWA SOMETIME THIS  
EVENING, LIKELY AIDED BY SUFFICIENT INSTABILITY (CAPE) AND  
ALSO AN INCREASE IN SHEAR PARTICULARLY ACROSS THE NORTHERN  
PORTION OF THE CWA. THERE IS STILL UNCERTAINTY WITH THE EXACT  
LOCATION/COVERAGE OF CONVECTION, AND THEREFORE HAVE KEPT POPS  
IN THE LOW CHANCE CATEGORY. SOME OF GUIDANCE ALSO INDICATES  
CONVECTION MAKING IT PRETTY FAR SOUTH TOWARD THE OHIO RIVER LATE  
AT NIGHT. CAN'T COMPLETELY RULE OUT THIS SOLUTION, BUT FAVORED  
HIGHEST POPS NEAR/NORTH OF INTERSTATE 70 WHERE IT LOOKED MORE  
FAVORABLE FOR CONVECTION INTO THE NIGHT. ANY STORMS WILL BE  
CAPABLE OF PRODUCING LOCALLY STRONG/DAMAGING WIND GUSTS AND ALSO  
HEAVY RAINFALL THAT COULD LEAD TO LOCALIZED FLASH FLOODING.  
 

 
   
SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/
 
 
A HOT AND HUMID AIR MASS WILL CONTINUE TO RESIDE OVER THE CWA ON  
FRIDAY. THERE IS GENERAL AGREEMENT THAT THE MORNING WILL BE DRY.  
THERE MAY BE SOME CLOUDS TO START TO DAY, BUT WITH SUFFICIENT  
INSOLATION MAXIMA HAVE THE POTENTIAL TO BE JUST AS WARM IF NOT  
1-2F HIGHER THAN THURSDAY. COMBINING THIS WITH LOWER TO MID 70S  
DEWPOINTS BRINGS HEAT INDEX VALUES INTO HEAT ADVISORY CRITERIA  
(100-104F) FOR A FEW HOURS FRIDAY AFTERNOON ACROSS PORTIONS OF  
SOUTHEAST IN, SOUTHERN OH AND NORTHERN KENTUCKY. AS SUCH, A  
HEAT ADVISORY HAS BEEN ISSUED FOR THESE AREAS. UPPER 90S HEAT  
INDEX VALUES ARE FORECAST FURTHER NORTH.  
 
UNCERTAINTY CONTINUES REGARDING CONVECTION FRIDAY AFTERNOON INTO  
FRIDAY NIGHT. A COLD FRONT WILL LIKELY SAG DOWN INTO CENTRAL  
IN/OH WHICH CAN SERVE AS ONE FOCUS FOR CONVECTION, BUT THINK  
THAT MESOSCALE INFLUENCES MAY BE MORE IMPORTANT AND THOSE  
DETAILS ARE NOT WELL KNOWN AT THIS TIME. FOLLOWED CONTINUITY  
WITH CHANCE OF CONVECTION INCREASING IN THE AFTERNOON/EVENING,  
AND KEPT CHANCE POPS INTO THE NIGHT ESPECIALLY ACROSS THE  
NORTHERN CWA GIVEN THE BOUNDARY IN PLACE AND ALSO POTENTIAL FOR  
A NEW MCS TO APPROACH LATE AT NIGHT.  
 

 
   
LONG TERM /SATURDAY THROUGH THURSDAY/
 
 
ACTIVE WEATHER PATTERN WILL CONTINUE INTO SATURDAY. FRONTAL BOUNDARY  
MAY MOVE SLIGHTLY NORTHEAST AS A WARM FRONT, BUT ITS EFFECTIVE PUSH  
WILL BE DEPENDENT ON WHERE EXACTLY ANOTHER POTENTIAL MCS MOVES. FOR  
NOW, AN EMBEDDED DISTURBANCE IN THE NORTHWEST FLOW ALOFT TO PRODUCE  
SUCH AN MCS IS FORECAST TO AFFECT OUR NORTHERN ZONES WHERE THE  
HIGHEST POPS HAVE BEEN PLACED. CHANCES FOR SHOWERS AND THUNDERSTORMS  
THEN DECREASE AS ONE HEADS TOWARD THE TRI-STATE. POTENTIAL FOR  
SEVERE STORMS WILL BE THERE DUE TO ADEQUATE4 INSTABILITY AND DEEP  
LAYERED SHEAR. HEAVY RAIN DUE TO HIGH PWATS AND POTENTIAL FLASH  
FLOODING WILL ALSO EXIST. AGAIN, TEMPERATURES WILL BE DEPENDENT ON  
CONVECTION AND CONVECTIVE DEBRIS CLOUDS BUT SHOULD MAKE THE  
MID/UPPER 80S FAR NORTH TO THE LOWER 90S SOUTH. SOME HEAT INDICES  
MAY TOUCH 100 BRIEFLY IN THE SOUTH ON SATURDAY AFTERNOON.  
 
FOR SATURDAY NIGHT, LOOKS LIKE ANOTHER DISTURBANCE AND PERHAPS A LOW  
LEVEL JET WILL GENERATE ANOTHER ROUND OF SHOWERS/STORMS WITH THE  
NORTHERN ZONES AGAIN HAVING THE HIGHEST THREAT.  
 
ON SUNDAY, MODELS SUGGEST THAT A WEAK BOUNDARY/TROUGH AXIS MAY MOVE  
EAST OF THE REGION BY AFTERNOON. AS SUCH, HIGHEST CHANCES OF  
SHOWERS/STORMS WILL BE IN OUR SOUTHEAST WITH THE LOWEST IN THE WEST.  
 
FOR SUNDAY NIGHT INTO MONDAY NIGHT, MID LEVEL TROUGH AXIS WILL  
TRAVERSE THE GREAT LAKES AND OHIO VALLEY. THIS WILL BE ASSOCIATED  
WITH A COLD FRONT THAT WILL MOVE SLOWLY SOUTHEAST THROUGH THE  
REGION. WILL CONTINUE WITH A CHANCE OF SHOWERS/STORMS SUNDAY NIGHT,  
WITH DECREASING CHANCES OF PRECIPITATION OCCURRING AS THE FRONT  
PASSES THROUGH. WE SHOULD BE DRY FOR THE MOST PART BY MONDAY NIGHT.  
 
UNDER NORTHWEST FLOW IN THE WAKE OF THE MID LEVEL TROUGH, SURFACE  
HIGH PRESSURE WILL BUILD INTO THE REGION TUESDAY. THE HIGH WILL  
CONTINUE TO EXTEND AND INFLUENCE OUR WEATHER INTO WEDNESDAY. DRY  
WEATHER AND HIGHS IN THE LOWER TO MID 80S ARE EXPECTED.  
 
THE NEXT WEATHER SYSTEM MAY BEGIN TO AFFECT THE AREA BY THURSDAY AS  
RETURN FLOW BETWEEN DEPARTING HIGH AND AN APPROACHING COLD FRONT  
BRING THE NEXT THREAT FOR SHOWERS AND THUNDERSTORMS.  
 

 
   
AVIATION /19Z THURSDAY THROUGH TUESDAY/
 
 
THE REMNANTS OF A MCS WILL CROSS THE DAYTON/CINCINNATI TAF  
SITES THROUGH 19Z AS THE MCS CONTINUES TO WEAKEN. MAY HAVE AN  
ISOLATED POP UP THUNDERSTORM NEAR KCMH/KLCK THIS AFTERNOON AS  
WELL, OTHERWISE IN THE WAKE OF THE MCS THERE SHOULD BE A LULL IN  
CONVECTION FOR THE BULK OF THE AFTERNOON. HOWEVER, MODELS  
CONTINUE TO SUGGEST POTENTIAL FOR NEW CONVECTION THIS EVENING  
TO THE SOUTH OF A COLD FRONT DROPPING DOWN FROM NORTHERN OHIO.  
THERE IS STILL UNCERTAINTY WITH THE DETAILS, INCLUDING LOCATION,  
COVERAGE AND TIMING, SO JUST HAVE VCTS/VCSH IN TAFS AT THIS  
TIME.  
 
SOME GUIDANCE ALSO SUGGESTS THAT BEHIND THE BOUNDARY ACROSS  
KCMH/KLCK THERE MAY BE LOW CLOUDS DEVELOPING LATE TONIGHT/EARLY  
FRIDAY MORNING. CONFIDENCE IS LOW AND HAVE KEPT VFR CIGS AT THIS  
TIME. THE ONLY RESTRICTIONS OUTSIDE OF CONVECTION IS AT KLUK  
WITH LATE NIGHT FOG.  
 
THUNDERSTORMS WILL BE POSSIBLE AGAIN FRIDAY AFTERNOON.  
 
OUTLOOK...THUNDERSTORMS WILL BE POSSIBLE AT TIMES BETWEEN  
FRIDAY THOUGH MONDAY.  
 

 
   
ILN WATCHES/WARNINGS/ADVISORIES
 
 
OH...HEAT ADVISORY FROM NOON TO 7 PM EDT FRIDAY FOR OHZ077>082-088.  
KY...HEAT ADVISORY FROM NOON TO 7 PM EDT FRIDAY FOR KYZ089>100.  
IN...HEAT ADVISORY FROM NOON TO 7 PM EDT FRIDAY FOR INZ073>075-080.  
 

 
 

 
SYNOPSIS...BPP  
NEAR TERM...BPP  
SHORT TERM...BPP  
LONG TERM...HICKMAN  
AVIATION...BPP  
 
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