875  
FXUS63 KGRR 181930  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
330 PM EDT THU JUL 18 2019  
 
LATEST UPDATE...  
SYNOPSIS/DISCUSSION/MARINE  
   
SYNOPSIS
 
 
ISSUED AT 330 PM EDT THU JUL 18 2019  
 
- HEAVY RAIN POTENTIAL LATE TONIGHT  
 
- HIGH HUMIDITY AND HEAT THROUGH SATURDAY  
 
- MUCH COOLER AND LESS HUMID NEXT WEEK  
 

 
   
DISCUSSION
 
(THIS EVENING THROUGH NEXT THURSDAY)  
ISSUED AT 330 PM EDT THU JUL 18 2019  
 
MCS FINALLY MOVING OUT OF THE FORECAST AREA WITH CLEARING ON THE  
BACK SIDE WHICH WILL ALLOW TEMPERATURES TO REACH THE 80S BY  
SUNDOWN ACROSS MOST PLACES. WE STILL SHOULD FALL WELL SHORT OF  
HEAT WARNING CRITERIA, BUT THE HEADLINE WAS LEFT IN EFFECT GIVEN  
THE CUMULATIVE EFFECT OF A LONG PERIOD OF 70 PLUS DEW POINTS.  
 
SYNOPTIC SCALE ANALYSIS SHOWS UPPER RIDGE WILL REMAIN ANCHORED  
SOUTH OF LOWER MICHIGAN THROUGH SATURDAY AND THE BIG QUESTION MARK  
CONTINUES TO BE THE EXTENT OF FUTURE MCS ACTIVITY THE NEXT COUPLE  
DAYS. BEST GUESS IS THAT WE WILL SEE ANOTHER AREA OF CONVECTION  
FORM ACROSS CENTRAL WISCONSIN OVERNIGHT AND TRACK EAST INTO THE  
NORTHERN FORECAST AREA LATE TONIGHT INTO FRIDAY MORNING AS SHOWN  
BY MOST MODEL GUIDANCE. THIS MAKES PHYSICAL SENSE WITH EXPECTED  
DIURNAL ENHANCEMENT OF LOW LEVEL JET IN THAT AREA AND WITH ZONAL  
FLOW GIVEN THE FLAT RIDGING. MBE VECTORS SHOW POTENTIAL FOR  
BACKBUILDING AND TRAINING OF STORMS WHICH MEAN THE FLOOD POTENTIAL  
IS HIGH GIVEN PWATS OVER 2 INCHES AND EFFICIENT WARM RAIN  
PROCESSES EXPECTED.  
 
THE MCS MAY TURN SOUTHEAST FRIDAY MORNING AS SOME EXPANSION OF THE  
COLD POOL IS EXPECTED GIVEN THERMODYNAMIC PROCESSES AS DRY WEDGE  
EXISTS AT MID-LEVELS. THIS HAS THE POTENTIAL TO AGAIN PUT A DAMPER  
ON THE HIGH TEMPERATURES ACROSS THE CENTRAL AND SOUTHERN FORECAST  
AREA ON FRIDAY AFTERNOON.  
 
HOT WEATHER LOOKS MORE LIKELY SATURDAY ACROSS THE SOUTHERN HALF OF  
THE FORECAST AREA AS THE UPPER RIDGE BUILDS INTO THIS AREA AND 850  
AND 925 MB TEMPERATURES PEAK. THEN THE COLD FRONT SLIDES SOUTH  
DURING THE EVENING WITH STRONG STORMS AND HEAVY RAIN POTENTIAL.  
RAIN CONTINUES INTO SUNDAY AS SFC WAVE MOVES THROUGH WITH MUCH  
COOLER AND DRIER WEATHER NEXT WEEK UNDER CANADIAN SURFACE HIGH  
PRESSURE.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)  
ISSUED AT 143 PM EDT THU JUL 18 2019  
 
STRONG WINDS IN THE WAKE OF THE AREA OF SHOWERS AND THUNDERSTORMS  
ACROSS SOUTHERN LOWER MICHIGAN WILL CONTINUE TO BRING STRONG  
SOUTHWEST WINDS WITH GUSTS ABOVE 25 KNOTS FROM MKG EASTWARD TO  
NEAR GRR AND LAN THIS AFTERNOON. FURTHER SOUTH GUSTS WILL NOT BE  
AS STRONG BUT WILL BE ABOVE 20 KNOTS AT TIMES. SHOWERS AND  
THUNDERSTORMS WILL MOVE EAST THIS AFTERNOON BUT THEN REDEVELOP  
TONIGHT WITH LOCAL AREAS OF IFR AT TIMES IN THE HEAVIER STORMS.  
 

 
   
MARINE
 
 
ISSUED AT 330 PM EDT THU JUL 18 2019  
 
SMALL CRAFT ADVISORY IS UNCHANGED. THERE COULD BE AREAS OF MARINE  
FOG FRIDAY NIGHT AND SATURDAY MORNING AS WINDS DECREASE.  
 

 
   
GRR WATCHES/WARNINGS/ADVISORIES
 
 
MI...EXCESSIVE HEAT WARNING UNTIL 8 PM EDT SATURDAY FOR MIZ056>059-  
064>067-071>074.  
 
BEACH HAZARDS STATEMENT THROUGH FRIDAY EVENING FOR MIZ037-043-  
050-056.  
 
HEAT ADVISORY UNTIL 8 PM EDT SATURDAY FOR MIZ037>040-043>046-  
050>052.  
 
LM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT FRIDAY FOR LMZ846>849.  
 

 
 

 
 
SYNOPSIS...OSTUNO  
DISCUSSION...OSTUNO  
AVIATION...OSTUNO  
MARINE...OSTUNO  
 
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