575  
FXUS61 KCLE 220006  
AFDCLE  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CLEVELAND OH  
806 PM EDT MON AUG 21 2017  
   
SYNOPSIS
 
 
HIGH PRESSURE OVER THE REGION WILL CONTINUE TO MOVE EAST OF THE  
AREA TONIGHT. LOW PRESSURE WILL MOVE NORTHEAST ACROSS THE GREAT  
LAKES TUESDAY, FORCING A COLD FRONT THROUGH THE REGION BY  
TUESDAY NIGHT. HIGH PRESSURE WILL BUILD EAST ACROSS THE REGION  
WEDNESDAY THROUGH THE FIRST HALF OF THE WEEKEND.  
 

 
   
NEAR TERM /THROUGH TUESDAY NIGHT/
 
 
AFTER A FLARE UP IN CONVECTION THIS AFTERNOON, THUNDERSTORM  
ACTIVITY HAS DROPPED OFF WITH JUST A COUPLE ISOLATED STORMS  
REMAINING. ADJUSTED THE GRIDS TO REFLECT A DECREASE IN CLOUD  
COVER BEHIND THE CONVECTION THIS EVENING, FOLLOWED BY INCREASING  
CLOUDS FOR THE OVERNIGHT HOURS. MONITORING SCATTERED  
THUNDERSTORMS IN WESTERN INDIANA BUT EXPECTING THIS ACTIVITY TO  
MOVE NE INTO MICHIGAN IF IT HOLDS TOGETHER OVERNIGHT. POPS STILL  
RAMP UP TOWARDS DAWN AS THE TROUGH APPROACHES WITH INCREASING  
MOISTURE ADVECTION.  
 
PREVIOUS DISCUSSION...  
SCATTERED CONVECTION HAS DEVELOPED ACROSS WESTERN OHIO. MODELS  
CONTINUE TO INDICATE AN EASTWARD EXPANSION OF THIS ACTIVITY THROUGH  
THE AFTERNOON/EARLY EVENING. SPC HAS MAINTAINED A MARGINAL RISK,  
MAINLY FOR WIND DAMAGE, AND WITH UP TO 2000-3000 J/KG SBCAPE, 1000-  
1200 J/KG DCAPE AND ~30 KTS OF 0-6KM BULK SHEAR, AGREE THAT A FEW  
MORE ORGANIZED CLUSTERS OF STORMS COULD PRODUCE DAMAGING WINDS AND  
POSSIBLY HAIL. EXPECTING THE BULK OF THIS ACTIVITY TO WIND DOWN  
TOWARDS 00Z. MUCH OF THE OVERNIGHT WILL REMAIN DRY FOR THE  
FORECAST AREA.  
 
MOST OF THE MODELS ARE INDICATING SOME TYPE OF PREFRONTAL  
TROUGH/SCATTERED CONVECTION MOVING INTO THE AREA LATE IN THE  
OVERNIGHT INTO TOMORROW MORNING. THIS MAY HAMPER THE SEVERE RISK  
ACROSS THE AREA A BIT, DEPENDING ON THE AMOUNT OF CLOUD COVER AND  
ONGOING CONVECTION. MAIN SYNOPTIC FRONT WILL NOT PUSH INTO THE AREA  
UNTIL LATE TUESDAY AFTERNOON THROUGH TUESDAY EVENING. IT IS POSSIBLE  
THAT THE PREFRONTAL TROUGH WILL BECOME THE DOMINANT SEVERE THREAT,  
PUSHING THE BULK OF THE ACTIVITY SOUTHEAST OF THE FORECAST AREA.  
ADDITIONAL REDEVELOPMENT IS POSSIBLE ALONG AND JUST AHEAD OF THE  
MAIN SYNOPTIC FRONT, BUT THE SEVERE THREAT WOULD BE CONSIDERABLY  
DIMINISHED. TIMED POPS TOMORROW TO REFLECT THIS SCENARIO, WITH THE  
HIGHEST POPS EAST OF THE I-71 CORRIDOR DURING THE AFTERNOON.  
 
NO MAJOR CHANGES TO THE TEMPERATURES THROUGH TUESDAY, WITH A DEGREE  
OR TWO DROP FOR LOWS TUESDAY NIGHT AS COLD FRONT MOVES THROUGH THE  
AREA.  
 

 
   
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
 
 
THE SHORT TERM BEGINS WEDNESDAY WITH MODELS SHOWING AN UPPER  
LOW OVER ONTARIO AND CYCLONIC FLOW ACROSS THE GREAT LAKES. A  
SHORT WAVE WITH SOME LIMITED MOISTURE WILL BE DROPPING SOUTHEAST  
ACROSS THE LAKES AND WILL MOVE INTO THE REGION DURING THE  
AFTERNOON WEDNESDAY. LOOKED AT FORECAST SOUNDING FOR KERI AND IS  
SHOWS LOW LEVEL LAKE CAPE AND MOISTURE BELOW 700 MB IN THE  
AFTERNOON AND EVENING. FOR THIS WILL HAVE A BAND OF CHANCE POPS  
FOR SHOWERS FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY NIGHT.  
THURSDAY A RATHER SHARP SHORT WAVE ROTATES THROUGH THE GREAT  
LAKES SO WILL CONTINUE CHANCE POPS MOST PLACES. THURSDAY NIGHT  
AND FRIDAY HIGH PRESSURE BUILDS IN SO WILL KEEP FORECAST DRY.  
TEMPS BELOW NORMAL THROUGH THE PERIOD.  
 

 
   
LONG TERM /FRIDAY THROUGH MONDAY/
 
 
BY SATURDAY LARGE AREA OF CANADIAN HIGH PRESSURE WILL EXTEND  
FROM JAMES BAY SOUTH ACROSS ALL OF THE GREAT LAKES. MODELS  
CONTINUE TO TRACK THE HIGH SLOWLY EAST ACROSS THE LAKES. EXPECT  
DRY CONDITIONS WITH MOSTLY SUNNY SKIES AND MILD TEMPERATURES  
THROUGH THE WEEKEND. MODELS BEGIN TO DIVERGE LATE IN THE PERIOD.  
MODELS A LITTLE SLOWER THAN YDY. ECMWF MOVES NEXT SYSTEM  
THROUGH LATE MONDAY INTO MONDAY NIGHT WHILE GFS CONTINUES STRONG  
RIDGE OVER THE EASTERN LAKES. FOR NOW WILL CONTINUE WITH THE  
ECMWF SOLUTION AND KEEP LOW CHANCE POPS GOING FOR NEXT MONDAY.  
 

 
   
AVIATION /00Z TUESDAY THROUGH SATURDAY/
 
 
AN ISOLATED SHOWER/THUNDERSTORM STILL NEAR YNG WITH  
THUNDERSTORM ACTIVITY DECREASING QUICKLY THIS EVENING. VFR  
CONDITIONS EXPECTED FOR THE OVERNIGHT WITH HIGH CLOUDS  
THICKENING AND STARTING TO LOWER. CONTINUED WITH A MENTION OF  
LLWS AT TOL/FDY AS A LOW LEVEL JET CLIPS NW OHIO WHILE MOVING  
FROM INDIANA INTO MICHIGAN. CHANCES FOR SHOWERS WILL INCREASE  
TOWARDS 10-12Z IN NW OHIO AS A TROUGH APPROACHES FROM THE WEST  
AND MOISTURE ADVECTION INCREASES. SCATTERED SHOWERS ARE POSSIBLE  
THROUGH MIDDAY WITH COVERAGE OF THUNDERSTORMS INCREASING DURING  
THE AFTERNOON AS INSTABILITY DEVELOPS AHEAD OF A COLD FRONT.  
SOME THUNDERSTORMS ON TUESDAY AFTERNOON COULD BE STRONG TO  
SEVERE. SOUTHWEST WINDS WILL BE BREEZY ON TUESDAY WITH GUSTS TO  
20-25 KNOTS ALL SITES. WINDS WILL SHIFT TO THE WEST AND  
EVENTUALLY NW BEHIND THE COLD FRONT.  
 
OUTLOOK...NON-VFR LIKELY IN SCATTERED SHOWERS AND THUNDERSTORMS  
TUESDAY NIGHT ACROSS EASTERN SITES. PATCHY MORNING BR POSSIBLE  
AROUND SUNRISE, THURSDAY-SATURDAY.  
 

 
   
MARINE
 
 
HIGH PRESSURE NOW OFF THE EAST COAST AS LOW PRESSURE DEVELOPS FROM  
NEBRASKA AND IOWA TO WISCONSIN. THIS LOW WILL STRENGTHEN OVERNIGHT  
AS IT MOVES NORTHEAST ACROSS THE CENTRAL GREAT LAKES. THE LOW WILL  
REACH SOUTHEAST ONTARIO BY TUESDAY MORNING. A TRAILING COLD FRONT  
WILL CROSS THE LAKE TUESDAY AFTERNOON AND EVENING. EXPECTING  
SOUTHWEST WINDS TO INCREASE ON TUESDAY TO 15 TO 25 KNOTS AHEAD OF  
THE FRONT WITH WINDS DROPPING TO 15 TO 20 KNOTS TUESDAY NIGHT AS  
THEY TURN NORTHWEST BEHIND THE FRONT. WILL ISSUE A SMALL CRAFT  
ADVISORY FOR LAKE ERIE STARTING AT 10AM TUESDAY LASTING THROUGH  
10AM WEDNESDAY. WINDS WILL REMAIN NORTHWEST ON WEDNESDAY AT 15 KNOTS  
OR SO SO THERE IS A CHANCE THE SMALL CRAFT ADVISORY MAY NEED TO BE  
EXTENDED EAST THIRD. EITHER WAY THE LAKE SHOULD CONTINUE ROUGH  
THROUGH THE DAY. WEDNESDAY AND WEDNESDAY NIGHT THROUGH SATURDAY  
HIGH PRESSURE WILL BUILD ACROSS THE LAKES FROM CENTRAL CANADA. NORTH  
WINDS THURSDAY SHOULD TURN MORE NORTHEAST FRIDAY AND SATURDAY. AGAIN  
WOULD EXPECT CHOPPY CONDITIONS BUT AT 5 TO 15 KNOTS EXPECT WAVES  
WILL BE WELL UNDER ADVISORY LEVELS.  
 

 
   
CLE WATCHES/WARNINGS/ADVISORIES
 
 
OH...BEACH HAZARDS STATEMENT FROM TUESDAY MORNING THROUGH TUESDAY  
EVENING FOR OHZ010>012-089.  
PA...BEACH HAZARDS STATEMENT FROM TUESDAY MORNING THROUGH TUESDAY  
EVENING FOR PAZ001.  
MARINE...SMALL CRAFT ADVISORY FROM 10 AM TUESDAY TO 10 AM EDT WEDNESDAY  
FOR LEZ146>149.  
SMALL CRAFT ADVISORY FROM 10 AM TUESDAY TO 4 AM EDT WEDNESDAY  
FOR LEZ142>145.  
 

 
 

 
SYNOPSIS...GREENAWALT  
NEAR TERM...KEC/GREENAWALT  
SHORT TERM...TK  
LONG TERM...DJB  
AVIATION...KEC  
MARINE...TK  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab OH Page
The Nexlab PA Page Main Text Page