723  
FXUS63 KIND 240240  
AFDIND  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE INDIANAPOLIS IN  
1040 PM EDT SAT JUN 23 2018  
   
UPDATE
 
 
THE AVIATION SECTION HAS BEEN UPDATED BELOW.  
 

 
   
SYNOPSIS
 
 
ISSUED AT 321 PM EDT SAT JUN 23 2018  
 
WEAK HIGH PRESSURE WILL BUILD INTO THE REGION AND PROVIDE MAINLY DRY  
WEATHER FOR CENTRAL INDIANA FOR THE REST OF THE WEEKEND ALONG WITH A  
LESS HUMID AIRMASS. THE APPROACH AND PASSAGE OF A WARM FRONT FOR  
EARLY WEEK WILL BRING AN INCREASE IN THUNDERSTORMS. THE  
DEVELOPMENT OF A STRONG UPPER LEVEL RIDGE BY LATE THIS UPCOMING  
WEEK SUPPORTS A RETURN TO HOT AND HUMID CONDITIONS WITH DAYTIME  
TEMPERATURES SOARING INTO THE 90S.  
 

 
   
NEAR TERM /TONIGHT/
 
 
ISSUED AT 321 PM EDT SAT JUN 23 2018  
 
MAINLY CLOUDY AND QUIET AFTERNOON ONGOING ACROSS CENTRAL INDIANA AS  
THE REGION RESIDES IN THE BACKWASH OF THE DEPARTING UPPER LOW OVER  
THE EASTERN GREAT LAKES. PLENTY OF LINGERING LOW LEVEL MOISTURE  
PRESENT MAINTAINING A BLANKET OF STRATOCU WITH A FEW LIGHT SHOWERS  
AS WELL. 19Z TEMPERATURES WERE GENERALLY IN THE 70S.  
 
OVERALL...NOT PARTICULARLY EXCITED ABOUT AN UPTICK IN RAINFALL AND  
CONVECTIVE COVERAGE THROUGH THE EVENING AS TOO MANY FACTORS ARE  
PRESENT TO MITIGATE MORE SUBSTANTIAL DEVELOPMENT. WEAK RIDGING ALOFT  
HAS DEVELOPED BEHIND THE UPPER LOW AND FORCING IS LARGELY NON-  
EXISTENT THROUGH THE BOUNDARY LAYER. DEEPER MOISTURE HAS SHIFTED  
EAST OF THE REGION AS WELL WITH PRECIP WATER VALUES NOW PROGGED  
BELOW 1.5 INCHES IN MOST AREAS. DIURNAL HEATING HAS BEEN LARGELY  
MITIGATED BY THE LOWER CLOUDS AND FURTHER ANALYSIS INDICATING STRONG  
CONVECTIVE INHIBITION ACROSS THE AREA AS WELL. HENCE THE REASON MUCH  
OF THE DAY SO FAR HAS SEEN LITTLE IN THE WAY OF RAIN AND LIKELY WILL  
CONTINUE TO DO SO THROUGH THE REST OF THE AFTERNOON.  
 
WHILE THE RAIN THREAT IS LOW...IT IS NON-ZERO THROUGH THE EVENING.  
SOUNDING ANALYSIS SUGGESTS THE CONVECTIVE INHIBITION WILL WEAKEN  
OVER THE NEXT FEW HOURS AND AT LEAST ALLOW FOR A MINIMAL AMOUNT OF  
INSTABILITY TO DEVELOP. THE APPROACH OF A BROAD...WEAK UPPER WAVE  
FROM THE WEST MAY PRESENT A NARROW WINDOW DURING THE LATE AFTERNOON  
AND EVENING WHERE WE SEE A SLIGHT INCREASE IN SHOWER COVERAGE...  
ENOUGH TO WARRANT A LOW CHANCE POP THROUGH THE EVENING. AVAILABLE  
INSTABILITY EVEN AT ITS PEAK WILL LIKELY NOT BE ENOUGH TO GENERATE A  
THUNDERSTORM LATER TODAY AND WILL CONTINUE WITH JUST SHOWERS  
MENTIONED. BEYOND THAT INTO THE OVERNIGHT HOWEVER...SUBTLE  
INSTABILITY IS LOST AND BETTER FORCING ALOFT ASSOCIATED WITH THE  
WAVE FOCUSES NORTH INTO THE GREAT LAKES. FEEL COMFORTABLE ROLLING  
WITH A DRY FORECAST AFTER MIDNIGHT.  
 
TEMPS...SLIGHTLY COOLER AIR WILL SPILL INTO THE REGION OVERNIGHT  
WITH LOWS LIKELY TO FALL INTO THE LOWER TO MIDDLE 60S FROM SOUTH TO  
NORTH. AN OVERALL MODEL BLEND HANDLED THIS WELL.  
 

 
   
SHORT TERM /SUNDAY THROUGH TUESDAY/
 
 
ISSUED AT 321 PM EDT SAT JUN 23 2018  
 
FORECAST CHALLENGES FOCUS ON PRECIP CHANCES...ESPECIALLY MONDAY AND  
TUESDAY AS A WARM FRONT FOLLOWED BY AN UPPER LOW IMPACT THE LOWER  
GREAT LAKES AND OHIO VALLEY.  
 
THE SECOND HALF OF THE WEEKEND WILL SEE A BRIEF BREAK FROM THE  
RECENT UNSETTLED REGIME AS RIDGING ALOFT AMPLIFIES AND SURFACE HIGH  
PRESSURE BUILDS IN FROM THE NORTH. LOW LEVEL FLOW WILL TRANSITION TO  
NORTHERLY FOR SUNDAY...ENSURING A DRIER SURGE OF AIR INTO THE REGION  
AND PROVIDING A BREAK FROM THE HIGHER HUMIDITY LEVELS OF LATE. MODEL  
SOUNDINGS SHOW LIMITED INSTABILITY ALOFT WITH A CAPPING INVERSION  
AND CONSIDERING THE LACK OF ANY AVAILABLE FORCING...EXPECT DRY  
WEATHER TO PERSIST INTO SUNDAY EVENING.  
 
A WARM FRONT LIFTING NORTH OUT OF THE OZARKS AND TENNESSEE VALLEY ON  
SUNDAY WILL BE A FOCUS FOR CONVECTIVE DEVELOPMENT DURING THE  
AFTERNOON AND EVENING AS IT LIFTS INTO THE LOWER OHIO VALLEY. COULD  
SEE THE NORTHERN EDGE OF THE CONVECTION CLIP THE LOWER WABASH VALLEY  
DURING THE EVENING...BUT OVERALL EXPECT THE EVENING TO REMAIN DRY.  
THE NORTHWARD PROGRESSION OF THE FRONT INTO THE AREA DURING THE  
PREDAWN HOURS MONDAY WILL WARRANT AN INTRODUCTION OF LOW CHANCE  
POPS IN SOUTHWEST COUNTIES BEFORE EXPANDING INTO THE FORECAST AREA  
ON MONDAY AS THE WARM FRONT PARKS FROM CENTRAL IOWA SOUTHEAST  
INTO SOUTHERN INDIANA AND NORTHERN KENTUCKY.  
 
STRONG HIGH PRESSURE OVER THE EASTERN GREAT LAKES WITH DEEP  
SUBSIDENCE WILL LIMIT THE FRONT FROM PUSHING FURTHER NORTH THROUGH  
MONDAY NIGHT. DEEPER MOISTURE AND INSTABILITY WILL BE CAPPED NEAR  
AND SOUTHWEST OF THE LOCATION OF THE FRONT...WITH CONVECTIVE  
POTENTIAL LARGELY CONFINED TO THE SOUTHWEST HALF OF THE FORECAST  
AREA. PRESENCE OF STRONGER BOUNDARY LAYER SHEAR AND HELICITY IN THE  
0-3KM LEVEL NEAR AND JUST SW OF THE FRONT SUPPORTS POTENTIAL FOR A  
FEW SEVERE STORMS MONDAY AFTERNOON AND EVENING AGAIN FOCUSED OVER  
THE SOUTHWEST HALF OF THE FORECAST AREA.  
 
SURFACE HIGH PRESSURE WILL SHIFT EAST TO THE NEW ENGLAND COAST ON  
TUESDAY WHICH WILL ENABLE THE WARM FRONT TO FINALLY PROGRESS NORTH  
THROUGH MOST IF NOT ALL OF THE FORECAST AREA. AN UPPER LOW WILL  
TRACK FROM THE NORTHERN PLAINS ON MONDAY INTO THE WESTERN GREAT  
LAKES TUESDAY WITH AN ATTENDANT SURFACE WAVE. FORCING ALOFT WILL  
INCREASE OVER THE REGION AS A RESULT...AIDED BY THE PRESENCE OF AN  
UPPER JETLET LIFTING NORTH AND OVERALL DIFFLUENT FLOW IN THE MID AND  
UPPER LEVELS. LOW LEVEL FLOW WILL INCREASE AS WELL FROM THE  
SOUTHWEST AND TRANSPORT RICH MOISTURE INTO THE REGION AS PRECIP  
WATER VALUES PEAK NEAR 2 INCHES AND DEWPOINTS LIKELY CLIMB TO 70  
DEGREES OR WARMER. ALL OF THESE FACTORS SUPPORT THE BEST POTENTIAL  
FOR WIDESPREAD CONVECTIVE IMPACTS FOR CENTRAL INDIANA ON TUESDAY AND  
WILL CARRY HIGH CHANCE POPS AS A RESULT. MODERATE INSTABILITY AND AN  
OVERALL INCREASE IN BOUNDARY LAYER SHEAR OVER THE REGION WILL ONCE  
AGAIN SUPPORT A POTENTIAL FOR SEVERE STORMS THROUGHOUT THE DAY.  
 
TEMPS...THE SHORT TERM WILL SERVE AS A REPRIEVE FROM THE HOTTER  
TEMPERATURES FROM THIS PAST WEEK AS MORE SUBSTANTIAL HEAT IS NOTED  
ON THE HORIZON FOR LATER THIS UPCOMING WEEK. LOW LEVEL THERMALS ARE  
SUPPORTIVE OF HIGH TEMPERATURES GENERALLY AT OR JUST ABOVE THE  
WARMEST GUIDANCE FROM THE MAV. EXPECT MID 80S SUNDAY FOLLOWED BY  
SLIGHTLY COOLER TEMPS MONDAY BEFORE WARMER AND MORE HUMID WEATHER  
RETURNS TUESDAY AS THE WARM FRONT LIFTS NORTH. LOWS WILL BE LARGELY  
IN THE 60S THROUGH THE PERIOD.  
 

 
   
LONG TERM /TUESDAY NIGHT TO SATURDAY/
 
 
ISSUED AT 321 PM EDT SAT JUN 23 2018  
 
THE EXTENDED TIMEFRAME BEGINS WITH AN UPPER LEVEL TROUGH PUSHING  
INTO THE GREAT LAKES REGION FROM THE WEST. CONTINUED WITH CHANCES  
FOR SHOWERS AND THUNDERSTORMS ACROSS THE FORECAST AREA AS THE  
UPPER TROUGH PRESSES EASTWARD...SENDING A WEAK FRONTAL BOUNDARY  
INTO THE AREA FROM THE NORTHWEST ON WEDNESDAY. SHOWER AND STORM  
CHANCES CLEAR WEDNESDAY EVENING AS THE WEAK FRONT PASSES THE AREA  
AND THE UPPER TROUGH CONTINUES ITS TREK TOWARD THE NEW ENGLAND  
STATES. AN UPPER LEVEL RIDGE THEN BUILDS NORTHEAST ACROSS THE OHIO  
RIVER VALLEY THURSDAY INTO FRIDAY. A WEAK UPPER WAVE PASSING  
THROUGH THE TOP OF THE RIDGE AS IT BUILDS NORTHEAST MAY PRODUCE  
SOME SHOWERS AND THUNDERSTORMS ON THURSDAY MORNING AND EARLY  
AFTERNOON. THEN THE HEAT IS ON. THERE LOOKS TO BE NO SHORTAGE OF  
90 DEGREE TEMPS STARTING THURSDAY AFTERNOON THROUGH THE REMAINDER  
OF THE PERIOD. FRIDAY AND SATURDAY APPEAR TO BE THE WARMEST DAYS  
OF THE EXTENDED AS THE UPPER RIDGE BUILDS FURTHER OVER THE  
FORECAST AREA...WITH LOW TO MID 90S ON FRIDAY AND DID INCREASE  
MAX TEMPS SLIGHTLY FROM THE REGIONAL INITIALIZATION BLEND TO LOWER  
90S ACROSS MUCH OF THE AREA ON SATURDAY. THOUGH UNDER THE UPPER  
RIDGING...CONVECTIVE TEMPS MAY BE REACHED IN SOME AREAS ON FRIDAY  
AND SATURDAY. CURRENT MODEL FORECASTED INSTABILITY IS QUITE HIGH.  
WILL BE INTERESTING TO KEEP AN EYE ON THIS AS WE HEAD INTO NEXT  
WEEK.  
 

 
   
AVIATION /DISCUSSION FOR THE 24/03Z TAF UPDATE/
 
 
ISSUED AT 1039 PM EDT SAT JUN 23 2018  
 
UPDATE...  
NO CHANGES.  
 
PREVIOUS DISCUSSION...  
VFR CONDITIONS WILL PREVAIL FOR THE DURATION OF THE TAF PERIOD AS  
WEAK HIGH PRESSURE MOVES INTO THE AREA. MEANWHILE, WINDS WILL  
GENERALLY BE LIGHT AND VARIABLE. A FEW RAIN SHOWERS WILL ALSO BE  
POSSIBLE THIS EVENING, BUT SHOULD HAVE NO IMPACT ON FLIGHT  
OPERATIONS.  
 

 
   
IND WATCHES/WARNINGS/ADVISORIES
 
NONE.  
 

 
 

 
 
SYNOPSIS...RYAN  
NEAR TERM...RYAN  
SHORT TERM...RYAN  
LONG TERM....MRD  
AVIATION...TDUD  
 
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