746  
FXUS63 KGRR 242346  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
746 PM EDT THU MAY 24 2018  
 
LATEST UPDATE...  
AVIATION  
   
SYNOPSIS
 
 
ISSUED AT 300 PM EDT THU MAY 24 2018  
 
WARM WEATHER WILL REMAIN IN PLACE OVER THE AREA THROUGH THE NEXT  
WEEK. HIGH TEMPERATURES WILL GENERALLY BE IN THE 80S EVERYDAY.  
HUMIDITY LEVELS WILL INCREASE THIS WEEKEND, AND THEN DROP A BIT  
EARLY NEXT WEEK.  
 
RAIN CHANCES WILL BE RATHER LOW MUCH OF THE WEEKEND, HOWEVER THEY  
WILL NOT BE ZERO. FRIDAY WILL REMAIN DRY, WITH SHOWER/STORM CHANCES  
INCREASING A LITTLE ON SATURDAY. A MAJORITY OF THE TIME WILL REMAIN  
DRY, ESPECIALLY TOWARD THE LAKESHORE. THE CHANCE WILL BE BEST ALSO  
IN THE AFTERNOON AND EVENING HOURS. RAIN CHANCES WILL DROP BY NEXT  
TUESDAY AS A SLIGHTLY COOLER AIR MASS MOVES IN. THEY WILL RETURN BY  
THURSDAY OF NEXT WEEK.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH SATURDAY NIGHT)  
ISSUED AT 300 PM EDT THU MAY 24 2018  
 
NO IMPACTS EXPECTED THROUGH FRIDAY ACROSS THE AREA. SHOWER/STORM  
CHANCES WILL INCREASE BEGINNING FRIDAY NIGHT AND LINGER INTO  
SATURDAY EVENING.  
 
UPPER RIDGING SITUATED JUST WEST OF THE AREA TODAY, WILL SLOWLY  
TRAVERSE THE STATE THROUGH FRIDAY AFTERNOON. LIMITED MOISTURE RETURN  
THROUGH FRIDAY AND SUFFICIENT SUBSIDENCE WITH THE RIDGE WILL KEEP  
THE AREA DRY. A BIT MORE HUMIDITY WILL SNEAK IN ON FRIDAY, BUT WILL  
NOT BE ENOUGH TO CAUSE RAIN.  
 
A SHORT WAVE WILL APPROACH THE AREA FRIDAY NIGHT AND SATURDAY AS THE  
UPPER RIDGE SHIFTS EAST OF THE AREA. THE BETTER FORCING WITH THE  
SHORT WAVE WILL REMAIN JUST NORTH OF THE AREA. THE ASSOCIATED SFC  
FRONT WILL TRY AND DROP DOWN INTO THE AREA, BUT LIKELY GETS HUNG UP  
JUST NORTH WITH THE SHORT WAVE STAYING MOSTLY NORTH. THIS WILL KEEP  
THE BETTER CHANCES FOR SHOWERS/STORMS NORTH FRI NIGHT.  
 
THEN ON SATURDAY AS THE SFC WAVE MOVES BY, WRLY WINDS WILL LIKELY  
STABILIZE MUCH OF THE AREA WITH FLOW OFF OF THE LAKE. INLAND AREAS  
COULD SEE ML CAPES INCREASE TO 1500 J/KG BEFORE THE WEST WINDS KICK  
IN. DEEP LAYER SHEAR IS FAIRLY WEAK, SO WE DO NOT EXPECT ANYTHING  
ORGANIZED.  
   
LONG TERM
 
(SUNDAY THROUGH THURSDAY)  
ISSUED AT 300 PM EDT THU MAY 24 2018  
 
WE COULD SEE AN AFTERNOON OR EVENING SHOWER/STORM SUNDAY WITH TEMPS  
WELL INTO THE 80S ONCE AGAIN AND DEW POINTS AROUND 60. THE COVERAGE  
WILL ONCE AGAIN BE LIMITED AS THERE WILL NOT REALLY BE A GOOD FOCUS,  
OTHER THAN MAYBE SOMETHING ALONG THE LAKE BREEZE OR ANY OTHER  
BOUNDARY THAT COULD FORM ON THE SMALL SCALE.  
 
THE CHANCE FOR AFTERNOON SHOWERS/STORMS ON MON HAS GONE DOWN  
COMPARED TO PREVIOUS FORECASTS. THE MODELS INDICATE THAT A BACK DOOR  
COLD FRONT WILL DROP SOUTH THROUGH THE AREA MON MORNING. THIS WILL  
SHUNT INSTABILITY SOUTH OF THE AREA. HIGH PRESSURE WILL BUILD IN FOR  
TUE, ALONG WITH A NE WIND AROUND THE HIGH TO OUR NORTH.  
 
THE RIDGE WILL SLIP EAST OF THE AREA MID-WEEK NEXT WEEK, AND ALLOW  
WARM AND HUMID CONDITIONS TO RETURN TO THE AREA. EVENTUALLY ENOUGH  
INSTABILITY WILL RETURN TO BRING A CHANCE OF AN AFTERNOON/EVENING  
STORM TO THE AREA. A SHORT WAVE LOOKS TO COME THROUGH AROUND THE  
THURSDAY TIME FRAME, BRINGING A LITTLE BETTER CHANCE OF RAIN.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)  
ISSUED AT 745 PM EDT THU MAY 24 2018  
 
VFR WEATHER IS EXPECTED TONIGHT AND FRIDAY. SOME PATCHY SHALLOW  
GROUND FOG CANNOT BE RULED OUT 08Z-13Z FRIDAY, BUT THE FOG RISK  
IS LOWER THAN IT HAS BEEN PREVIOUS NIGHTS. SOUTHERLY SFC WINDS ARE  
EXPECTED TO BE 10 KNOTS OR LESS.  
 

 
   
MARINE
 
 
ISSUED AT 300 PM EDT THU MAY 24 2018  
 
NO HEADLINES EXPECTED THROUGH THE HOLIDAY WEEKEND, AND LIKELY  
THROUGH MUCH OF NEXT WEEK. WINDS WILL COME UP SOME BEGINNING  
TONIGHT, AND LINGERING INTO EARLY SATURDAY AHEAD OF A WEAK SYSTEM.  
THE STRONGEST WINDS WILL STAY FURTHER NORTH AND OFFSHORE. WINDS AND  
WAVES WILL TRY TO APPROACH ADVISORY CRITERIA, BUT ARE EXPECTED TO  
REMAIN SHORT OF IT AT THIS TIME.  
 
WINDS COMING UP SHOULD KEEP THE FOG CHANCES LIMITED OVER THE LAKE,  
EVEN AS DEW POINTS COME UP A BIT. CAN NOT RULE SOME FOG OUT, BUT IT  
SHOULD NOT BE SIGNIFICANT ENOUGH AT THIS TIME TO NEED ANOTHER  
ADVISORY.  
 

 
   
HYDROLOGY
 
 
ISSUED AT 300 PM EDT THU MAY 24 2018  
 
NO HYDROLOGY ISSUES EXPECTED OVER THE NEXT WEEK, AND LIKELY BEYOND.  
ANY RAINFALL EXPECTED OVER THE NEXT WEEK WILL BE SPOTTY AT BEST, AND  
THUS NOT CAUSE IMPACTS ON THE RIVERS AND STREAMS. THE HIGHER LEVELS  
CURRENTLY ON THE RIVERS AND STREAMS WILL ONLY FALL THROUGH NEXT  
WEEK.  
 

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

 
 

 
 
SYNOPSIS...NJJ  
SHORT TERM...NJJ  
LONG TERM...NJJ  
AVIATION...MEADE  
HYDROLOGY...NJJ  
MARINE...NJJ  
 
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