499  
FXUS63 KGRR 311927  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
327 PM EDT TUE MAY 31 2016  
 
LATEST UPDATE...  
SYNOPSIS/SHORT TERM/LONG TERM/MARINE  
   
SYNOPSIS
 
 
ISSUED AT 327 PM EDT TUE MAY 31 2016  
 
A FRONTAL SYSTEM MOVING TOWARD THE AREA WILL BEGIN TO INCREASE  
SHOWER AND STORM CHANCES TOWARD DAYBREAK WEDNESDAY ALONG THE  
LAKESHORE. SHOWERS AND STORMS WILL THEN MOVE THROUGH THE AREA  
WEDNESDAY AND WEDNESDAY EVENING. A FEW OF THE STORMS COULD BE  
LOCALLY STRONG WITH SOME LARGE HAIL AND GUSTY WINDS.  
 
RAIN WILL END BY THURSDAY MORNING, ALLOWING THE AREA TO DRY OUT.  
COOLER AND LESS HUMID AIR WILL ALSO FILTER INTO THE AREA. RAIN  
CHANCES WILL INCREASE AGAIN FOR THE WEEKEND AS AN UNSETTLED WEATHER  
PATTERN SETTLES IN ACROSS THE AREA.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH THURSDAY NIGHT)  
ISSUED AT 327 PM EDT TUE MAY 31 2016  
 
OUR MAIN FOCUS OF THE SHORT TERM IS CONVECTIVE POTENTIAL MAINLY FOR  
WED AND WED EVENING AS THE FRONTAL SYSTEM IS EXPECTED TO COME  
THROUGH AT THAT TIME.  
 
SHOWERS AND STORMS ARE NOT FAR FROM THE CWFA THIS AFTERNOON, AS  
CLOSE AS FAR NW INDIANA AND JUST WEST OF CHICAGO AND MILWAUKEE. THEY  
ARE MOVING MORE NORTH THAN EAST, AND ARE EXPECTED TO FOCUS BACK  
ACROSS WI FOR TONIGHT. THIS OCCURS SINCE THE LLJ CLOSEST TO MI WILL  
WEAKEN, AND WILL REFOCUS A LITTLE FURTHER N AND W WITH A LEAD SHORT  
WAVE STAYING NW OF THE AREA. WE WILL ALSO SEE SE WINDS STRENGTHEN A  
BIT AND HOLD THE DRY AIR IN A LITTLE LONGER.  
 
WE WILL SEE THE SHOWER AND STORM CHANCES INCREASE ON WED, WITH THE  
BEST CHANCES COMING FROM AFTERNOON INTO THE EARLY EVENING HOURS. WE  
WILL SEE WHAT IS LEFT OVER FROM THE LLJ TONIGHT SLIP ACROSS THE CWFA  
WED AFTERNOON. IT WILL BE WEAKENING AS IT DOES SO. THE FOCUS WILL  
THEN SHIFT TO A PRE-FRONTAL TROUGH THAT LOOKS TO ENTER THE AREA  
EARLY IN THE AFTERNOON AND EXIT BY 00Z THU.  
 
THE EASTERN AREAS HAVE THE BEST CHANCE OF SEEING SOME OF THE  
STRONGER STORMS ON WED. AREAS FURTHER WEST WILL SEE MORE CLOUDS AND  
SOME SHOWERS EARLY, LIMITING THE AMOUNT OF DIURNAL INSTABILITY THAT  
CAN BUILD. FURTHER EAST, SOME EARLY SUN LOOKS TO BUILD INSTABILITY  
FOR A LATER TROUGH PASSAGE. THE SEVERE SETUP IS NOT EXCITING AS DEEP  
LAYER SHEAR IS ONLY ON THE ORDER OF AROUND 25 TO 30 KNOTS. SOME  
THICKER CAPE WILL ALLOW FOR SOME DECENT UPDRAFTS THAT COULD PRODUCE  
SOME LARGER HAIL AND GUSTY WINDS.  
 
THE COLD FRONT WILL ARRIVE OVERNIGHT WED NIGHT AND SHOULD CLEAR THE  
CWFA BY 12Z THU. RIDGING WILL BUILD IN AND CLEAR THE AREA OUT  
THROUGH THU NIGHT. COOLER AND LESS HUMID AIR WILL FILTER IN WITH  
H850 TEMPS DROPPING TO AROUND 8-10C. THIS SHOULD YIELD HIGHS IN THE  
70S FOR THU AND FRI.  
   
LONG TERM
 
(FRIDAY THROUGH TUESDAY)  
ISSUED AT 327 PM EDT TUE MAY 31 2016  
 
THE LONG TERM BEGINS WITH HIGH PRESSURE SITUATED ACROSS THE GREAT  
LAKES REGION. DRY CONDITIONS ARE FORECAST ON FRIDAY WITH HIGHS WELL  
INTO THE 70S. SHOWERS CREEP IN FROM THE NORTHWEST FRIDAY NIGHT IN  
ADVANCE OF A LOW MOVING OUR DIRECTION FROM THE NORTHERN PLAINS.  
 
THE WEEKEND LOOKS LIKE IT WILL FEATURE A DECENT AMOUNT OF CLOUD  
COVER AND CHANCES FOR SHOWERS AND THUNDERSTORMS. THE THREAT FOR  
STORMS LOOKS TO EXIST FROM SATURDAY INTO SUNDAY AS AN UPPER TROUGH  
PIVOTS OUR DIRECTION FROM WISCONSIN. LATE IN THE WEEKEND AND INTO  
EARLY NEXT WEEK, THE UPPER TROUGH BECOMES MORE SITUATED OVERHEAD  
WHICH SHOULD RESULT IN COOLER WEATHER AND CHANCES FOR SHOWERS.  
 
SO, THE BOTTOM LINE WE ARE LOOKING AT A DRY FRIDAY WITH CHANCES FOR  
SHOWERS AND STORMS SATURDAY INTO SUNDAY. HIGHS WILL REMAIN IN THE  
70S THROUGH SATURDAY. SUNDAY NIGHT THROUGH TUESDAY LOOKS MORE  
SHOWERY WITH HIGHS COOLING BACK INTO THE 60S.  
 
MODELS ARE IN FAIRLY GOOD AGREEMENT ON THE MAIN FORECAST FEATURES SO  
CONFIDENCE IS ON THE HIGHER SIDE OF NORMAL.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)  
ISSUED AT 144 PM EDT TUE MAY 31 2016  
 
VFR CONDITIONS ARE FORECAST THROUGH THE 18Z TO 18Z PERIOD. SOME  
CIRRUS WITH BASES ABOVE 20000FT CAN BE EXPECTED THE REMAINDER OF  
TODAY, LOWERING TO AN ALTOCUMULUS CLOUD BASE AROUND 12000FT  
TONIGHT. WE WILL BE DRY THIS AFTERNOON AND TONIGHT.  
 
THE WEATHER BECOMES MORE ACTIVE INTO THE DAY ON WEDNESDAY WHEN A  
COLD FRONT PROGRESSING FROM WEST TO EAST TOUCHES OFF SOME SHOWERS  
AND THUNDERSTORMS. STILL EXPECTING VFR CONDITIONS FOR THE MOST  
PART THOUGH THROUGH 18Z ON WED. SHOWERS AND A FEW THUNDERSTORMS  
WILL BE PROGRESSING INTO WESTERN LOWER MICHIGAN WEDNESDAY MORNING,  
BUT COVERAGE IS PROBABLY STILL TOO SCATTERED TO HAVE ANYTHING MORE  
THAN VCSH AND VCTS THROUGH 18Z. COVERAGE OF SHOWERS AND STORMS  
WILL INCREASE AND PEAK DURING THE 18Z TO 00Z TIME FRAME TOMORROW  
AFTERNOON, JUST BEYOND THE TAF PERIOD.  
 

 
   
MARINE
 
 
ISSUED AT 327 PM EDT TUE MAY 31 2016  
 
WINDS WILL INCREASE A BIT TONIGHT AS THE FRONTAL SYSTEM MAKES A MOVE  
TOWARD THE AREA. FLOW LOOKS TO REMAIN OFFSHORE A BIT AND WARMER AIR  
OVER THE COOLER WATERS SHOULD LIMIT WINDS FROM COMING UP TOO MUCH.  
IT APPEARS THAT WINDS SHOULD REMAIN JUST BELOW SMALL CRAFT ADVISORY  
CRITERIA. WAVES SHOULD BE LIMITED ALSO WITH THE AFOREMENTIONED  
REASONS LISTED ABOVE. WINDS WILL REMAIN UP UNTIL THU NIGHT INTO FRI  
WHEN THEY ARE EXPECTED TO DROP OFF.  
 

 
   
HYDROLOGY
 
 
ISSUED AT 1203 PM EDT TUE MAY 31 2016  
 
RIVER LEVELS ARE STABLE OR SLOWLY FALLING AND NEAR NORMAL FOR THIS  
TIME OF YEAR. PARTS OF THE KALAMAZOO BASIN ARE EVEN SLIGHTLY BELOW  
NORMAL. WE EXPECT AROUND HALF AN INCH OR LESS OF RAIN WEDNESDAY  
INTO THURSDAY, WHICH SHOULD PRODUCE ONLY MINOR RISES. THIS PERIOD  
OF RAIN WILL BE FOLLOWED BY DRY WEATHER THROUGH THE END OF THE  
WORK WEEK. THIS SHOULD HELP TO LIMIT THE MAGNITUDE OF THE RISES.  
 

 
   
GRR WATCHES/WARNINGS/ADVISORIES
 
 
MI...NONE.  
LM...NONE.  

 
 

 
 
SYNOPSIS...NJJ  
SHORT TERM...NJJ  
LONG TERM...DUKE  
AVIATION...DUKE  
HYDROLOGY...TJT  
MARINE...NJJ  
 
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