498  
FXUS63 KGRR 251103  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
703 AM EDT MON JUL 25 2016  
 
LATEST UPDATE...  
AVIATION  
   
SYNOPSIS
 
 
ISSUED AT 214 AM EDT MON JUL 25 2016  
 
A HIGH PRESSURE SYSTEM CENTERED IN IOWA WILL BUILD SLOWLY EAST  
TODAY AND INTO MICHIGAN ON TUESDAY. THIS FAIR WEATHER SYSTEM WILL  
ACT TO DRY OUT THE REGION AND LOWER TEMPERATURES CLOSER TO  
SEASONABLE VALUES. A LOW PRESSURE SYSTEM WILL APPROACH THE GREAT  
LAKES REGION WEDNESDAY INTO THURSDAY BRINGING WITH IT AN INCREASED  
POTENTIAL FOR SHOWERS.  
 

 
   
UPDATE
 
 
ISSUED AT 523 AM EDT MON JUL 25 2016  
 
THE SOUTH HAVEN BUOY WAS UP CLOSE TO 5 FEET AS OF 5 AM. THUS A  
HEADLINE WAS NEEDED FOR PARTS OF THE NEARSHORE WATERS. THE UPDATE  
HAS BEEN SENT.  
 

 
   
SHORT TERM
 
(TODAY THROUGH WEDNESDAY)  
ISSUED AT 214 AM EDT MON JUL 25 2016  
 
THE MAIN CHALLENGE DEALS WITH THE PRECIPITATION CHANCES THIS  
MORNING. I DID RAISE POPS FOR SOUTHEAST PARTS OF THE CWA TO START  
THE MORNING.  
 
THERE HAVE BEEN A FEW STRONGER THUNDERSTORMS IN SOUTHERN JACKSON  
COUNTY EARLY THIS MORNING. THE AXIS OF STRONGER INSTABILITY  
ASSOCIATED WITH THESE STORMS WILL PIVOT EAST OVER THE NEXT COUPLE  
OF HOURS. THUS THE RISK FOR THUNDERSTORMS WILL DECREASE THROUGH  
DAYBREAK. HOWEVER...THE MID LEVEL WAVE IS STILL HANGING BACK. THE  
RADAR DOES SHOW RETURNS OVER LAKE MI...IN AN AREA WHERE THE DGZ IS  
FORECASTED TO BE MOIST. BUFKIT PROFILES SHOW A DRY LAYER BELOW THE  
MOIST DGZ...SO IT IS NOT CERTAIN THAT WHAT IS OVER THE LAKE IS  
REACHING THE GROUND. MY THOUGH IS THAT WITH A STILL VERY MOIST LOW  
LEVEL AIRMASS OVER SOUTHEAST PARTS OF THE CWA...THAT I SHOULD  
INCREASE POPS FOR A FEW HOURS TO START THE DAY UNTIL THE MID LEVEL  
WAVE TRACKS THOUGH.  
 
WITH SKIES CLEARING OUT AND DIMINISHING WINDS TONIGHT...THERE  
SHOULD BE SOME PATCHY FOG DEVELOPING ESPECIALLY UP OVER NORTHERN  
PARTS OF THE CWA. A SIMILAR SETUP FOR TUESDAY NIGHT AS WELL.  
 
I DO SEE A SMALL RISK FOR A THUNDERSTORM ARRIVING...MAINLY TUESDAY  
NIGHT FOR NORTHWEST PARTS OF THE CWA. THIS WOULD INCLUDE  
LUDINGTON. MID LEVEL COOLING DEVELOPS WHILE WARM AND MOIST AIR  
ADVECTION DEVELOPS IN THE LOW LEVELS. THIS WILL ACT TO DESTABILIZE  
THE ATMOSPHERE SOMEWHAT...POSSIBLY LEADING TO A STORM OR TWO. A  
BETTER CHANCE FOR THUNDERSTORMS IS ON WEDNESDAY. THE MID LEVEL  
COOLING CONTINUES. THUS WE MAY SEE A COUPLE OF STORMS DEVELOPING.  
   
LONG TERM
 
(WEDNESDAY NIGHT THROUGH SUNDAY)  
ISSUED AT 214 AM EDT MON JUL 25 2016  
 
THE EXTENDED PORTION OF THE FORECAST FEATURES A RETURN TO MORE  
SEASONABLE TEMPERATURES AND MULTIPLE CHANCES FOR SHOWERS AND  
THUNDERSTORMS. A SERIES OF A COUPLE SHORTWAVES WILL DIG OUT AN UPPER  
LEVEL TROUGH OVER THE MIDWEST AND GREAT LAKES THURSDAY INTO FRIDAY.  
DURING THIS TIME, AN UPPER LEVEL RIDGE THAT WAS PREVIOUSLY OVER THE  
SOUTHERN CONUS WILL AMPLIFY OVER THE WESTERN COAST OF NORTH AMERICA.  
 
IN GENERAL, EXPECT A FAIR AMOUNT OF CLOUDINESS LATE IN THE WORK WEEK  
INTO THE EARLY PART OF THE WEEKEND. SHOWERS ARE EXPECTED AT TIMES,  
BUT MODELS ARE NOT CONSISTENT ON THE HANDLING OF ANY SINGLE,  
SIGNIFICANT LOW-LEVEL FEATURE. AFTER HIGHS IN THE LOW TO MID 80S  
THURSDAY, TEMPS WILL HOLD IN THE LOWER 80S FRIDAY THROUGH THE  
WEEKEND. LOWS WILL BE IN THE UPPER 50S AND 60S.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)  
ISSUED AT 658 AM EDT MON JUL 25 2016  
 
THE RAIN IS PULLING AWAY FROM THE TAF SITES...TAKING ANY LOWER  
CLOUDS AND VISIBILITIES WITH IT. SKIES WILL BE CLEARING OUT.  
TONIGHT WITH GOOD RADIATIONAL COOLING WE SHOULD SEE AREAS OF FOG  
FORMING. WILL NEED TO MONITOR THE RISK FOR IFR...FOR NOW WENT WITH  
MVFR.  
 

 
   
MARINE
 
 
ISSUED AT 214 AM EDT MON JUL 25 2016  
 
THE WIND AND WAVES WILL CONTINUE TO DIMINISH TODAY AND TUESDAY AS  
THE PRESSURE GRADIENT WEAKENS. WAVES WILL INITIALLY START OUT  
TODAY IN THE 2 TO 3 FOOT RANGE.  
 

 
   
HYDROLOGY
 
 
ISSUED AT 1250 PM EDT SUN JUL 24 2016  
 
NO RIVER FLOODING IS EXPECTED THROUGH NEXT WEEK. AREA WIDE RAIN OF  
AROUND AN INCH WITH LOCALLY UP TO 3 INCHES (MAINLY NEAR LAKE  
MICHIGAN) HAS FALLEN SINCE SATURDAY EVENING. ANOTHER WAVE OF SHOWERS  
AND STORMS ARE POSSIBLE TONIGHT. A SMALL CHANCE OF RAIN IS ALSO IN  
THE FORECAST WEDNESDAY THROUGH FRIDAY. RIVER LEVELS ARE AT OR BELOW  
NORMAL FOR THIS TIME OF YEAR, SO THIS RAIN SHOULD NOT BRING ANY  
RIVERS TO FLOOD.  
 
STRONG THUNDERSTORMS COULD PRODUCE LOCALIZED RAINFALL TOTALS OVER AN  
INCH AND LEAD TO LOCALIZED PONDING OF WATER. RAINFALL TOTALS WILL  
PROBABLY VARY SUBSTANTIALLY OVER SHORT DISTANCES.  
 

 
   
GRR WATCHES/WARNINGS/ADVISORIES
 
 
MI...BEACH HAZARDS STATEMENT UNTIL NOON EDT TODAY FOR MIZ056-064-071.  
 
LM...SMALL CRAFT ADVISORY UNTIL NOON EDT TODAY FOR LMZ844>846.  
 

 
 

 
 
UPDATE...MJS  
SYNOPSIS...MJS  
SHORT TERM...MJS  
LONG TERM...EBW  
AVIATION...MJS  
HYDROLOGY...63  
MARINE...MJS  
 
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