386  
FXUS63 KGRR 202025  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
325 PM EST MON NOV 20 2017  
 
LATEST UPDATE...  
SYNOPSIS/SHORT TERM/LONG TERM/MARINE  
   
SYNOPSIS
 
 
ISSUED AT 325 PM EST MON NOV 20 2017  
 
A PREDOMINATELY DRY AND BENIGN WEATHER PATTERN WILL PREVAIL THIS  
WEEK, INCLUDING THE THANKSGIVING TRAVEL PERIOD. A COLD FRONT WILL  
PASS THROUGH ON TUESDAY BUT WILL HAVE LITTLE PRECIPITATION  
ASSOCIATED WITH IT. ANOTHER COLD FRONT OVER THE WEEKEND WILL BRING  
SOME RAIN AND SNOW SHOWERS, ALTHOUGH MINIMAL TRAVEL IMPACTS  
ARE EXPECTED AT THIS TIME.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH WEDNESDAY NIGHT)  
ISSUED AT 325 PM EST MON NOV 20 2017  
 
STRONG SOUTHWEST FLOW OFF LAKE MI WILL LEAD TO A TEMPERATURE  
CONTRAST ACROSS THE AREA TONIGHT, WITH OVERNIGHT MIN TEMPS  
RANGING FORM THE MID 30S INLAND WHERE BOUNDARY DECOUPLING OCCURS  
TO THE MID 40S ALONG THE LAKESHORE.  
 
THE PESKY AREA OF STRATOCUMULUS CLOUDS WHICH WAS NORTH AND WEST OF  
A HOLLAND TO HARRISON EARLY TODAY HAS MIXED OUT, BUT MAY RETURN  
AGAIN LATE TONIGHT DUE TO LK MI EFFECTS.  
 
THE COLD FRONT ON TUESDAY IS MOISTURE STARVED AS IT COMES THROUGH  
MICHIGAN BUT MODELS DO SUGGEST A BAND OF RAIN SHOWERS DEVELOPING  
ALONG THE FRONT ABOUT THE TIME IT'S EXITING THE STATE LATE IN THE  
DAY. BEST POPS TOMORROW THEREFORE, ALTHOUGH STILL JUST CHANCE,  
WILL BE AROUND JXN IN THE AFTERNOON.  
 
THE AIR BEHIND THE COLD FRONT LATE TUESDAY AND TUESDAY NIGHT IS  
PLENTY COLD ENOUGH FOR LAKE EFFECT, BUT AS WITH THE LAST FEW  
PUSHES OF COLD AIR THE MOISTURE IS QUITE SHALLOW. SO WHILE WE WILL  
HAVE SOME LAKE EFFECT SNOW SHOWERS ON TUESDAY EVENING, THEY WILL  
BE MOSTLY LIGHT WITH LITTLE OR NO ACCUMULATION EXPECTED.  
 
SURFACE RIDGING RETURNS ON WEDNESDAY, ALTHOUGH WITH THE CENTER OF  
THE HIGH BEING SOUTH OF MICHIGAN AND OUR LOW LEVEL FLOW REMAINING  
WESTERLY, SOME LAKE EFFECT CLOUDINESS MAY LINGER.  
 
   
LONG TERM
 
(THURSDAY THROUGH MONDAY)  
ISSUED AT 325 PM EST MON NOV 20 2017  
 
THE ONLY WEATHER IN THE EXTENDED PERIOD IS A CLIPPER MOVING ACROSS  
SOUTHERN CANADA WHICH BRINGS A TRAILING COLD FRONT THROUGH MICHIGAN  
FRIDAY NIGHT.  
 
WARM ADVECTION AHEAD OF THE FRONT SHOULD BRING MAX TEMPS TO NEAR 50  
ON FRIDAY THEN STRONG COLD ADVECTION KICKS IN FOR SATURDAY WITH A  
REINFORCING COLD SHOT BEHIND AN ARCTIC FRONT COMING THROUGH SATURDAY  
NIGHT. LOWERED MODEL BLEND TEMPERATURES FOR SATURDAY THROUGH SUNDAY  
AS 850 MB TEMPS TUMBLE TO ABOUT MINUS 15C SUNDAY AFTERNOON. MAXES  
SHOULD REMAIN BELOW FREEZING SUNDAY AFTERNOON. ALSO BUMPED UP POPS  
AS LIGHT LAKE EFFECT SNOW SHOWERS IN NORTHWEST FLOW WILL CONTINUE  
INTO SUNDAY EVENING BEFORE SFC RIDGING BUILDS IN AND INVERSION  
HEIGHTS LOWER.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)  
ISSUED AT 1230 PM EST MON NOV 20 2017  
 
VFR CONDITIONS WILL CONTINUE THROUGH TUESDAY AFTERNOON. SOUTHWEST  
WINDS WILL GUST OVER 20 KNOTS TODAY AND TUESDAY WITH SOME GUSTS  
TO 30 KNOTS POSSIBLE THIS EVENING.  
 

 
   
MARINE
 
 
ISSUED AT 325 PM EST MON NOV 20 2017  
 
WIND SPEEDS HAVE NOT REACHED GALE FORCE YET, BUT THE WINDS ARE  
FORECAST TO FURTHER INCREASE LATE THIS AFTERNOON AND EVENING. WILL  
NOT BE MAKING ANY CHANGES TO THE ONGOING GALE WARNING. WINDS AND  
WAVES WILL SUBSIDE BELOW GALES ON TUESDAY AFTERNOON BUT WILL  
REMAIN STRONG ENOUGH TO WARRANT SMALL CRAFT ADVISORIES AFTER THE  
GALE WARNING EXPIRES.  
 

 
   
HYDROLOGY
 
 
ISSUED AT 1145 AM EST MON NOV 20 2017  
 
FEW RIVERS CONTINUE TO RISE, BUT RISES HAVE SLOWED, WHILE OTHERS  
ARE SHOWING SIGNS OF STABILIZING. THERE ARE SMALL CHANCES FOR  
PRECIPITATION TUESDAY AFTERNOON AND WEDNESDAY. AMOUNTS, IF  
MEASURABLE, SHOULD NOT HAVE ANY IMPACT ON RIVERS. BEYOND  
WEDNESDAY, WEATHER LOOKS RELATIVELY QUIET.  
 
DESPITE ELEVATED RIVER LEVELS, ADDITIONAL RIVER FLOODING IS OF LOW  
CONCERN. RIVERS ARE LIKELY TO RECEDE THROUGH THE COURSE OF THE  
UPCOMING WEEK.  
 

 
   
GRR WATCHES/WARNINGS/ADVISORIES
 
 
MI...NONE.  
LM...GALE WARNING UNTIL 10 AM EST TUESDAY FOR LMZ844>849.  
 

 
 

 
 
SYNOPSIS...MEADE  
SHORT TERM...MEADE  
LONG TERM...OSTUNO  
AVIATION...OSTUNO  
HYDROLOGY...JAM  
MARINE...MEADE  
 
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