349  
FXUS63 KGRR 241806  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
106 PM EST TUE JAN 24 2017  
 
LATEST UPDATE...  
AVIATION  
   
SYNOPSIS
 
 
ISSUED AT 330 AM EST TUE JAN 24 2017  
 
RAIN WILL END THIS MORNING ACROSS CENTRAL AND EASTERN PORTIONS OF  
THE STATE WITH DRY WEATHER EXPECTED THIS AFTERNOON. OUR NEXT WEATHER  
MAKER WILL MOVE OUT OF COLORADO THIS MORNING, THROUGH THE PLAINS  
TODAY AND TONIGHT AND TAKE AIM ON OUR AREA FOR WEDNESDAY.  
PRECIPITATION WILL SPREAD INTO WESTERN LOWER MICHIGAN TONIGHT IN THE  
FORM OF A RAIN AND SNOW MIX. THE PRECIPITATION WILL BE THE MOST  
WIDESPREAD ON WEDNESDAY WITH A MIXTURE OF RAIN AND SNOW ACROSS  
CENTRAL LOWER MICHIGAN AND MAINLY RAIN ACROSS SOUTHERN LOWER  
MICHIGAN. COLDER AIR WILL FLOW IN BEHIND THE SYSTEM FOR THURSDAY AND  
FRIDAY ON NORTHWEST WINDS. LAKE EFFECT SNOW RETURNS TO THE FORECAST  
FOR THE END OF THE WEEK AND INTO THE WEEKEND.  
 

 
   
SHORT TERM
 
(TODAY THROUGH THURSDAY)  
ISSUED AT 330 AM EST TUE JAN 24 2017  
 
THE MAIN FORECAST CONCERNS REVOLVE AROUND PRECIPITATION TYPE AND  
DETERMINING WHETHER LIGHT ACCUMULATIONS OF SNOW ARE POSSIBLE IN THE  
LATE TONIGHT AND WEDNESDAY TIME FRAME.  
 
THE CURRENT LIGHT RAIN ACROSS EASTERN PORTIONS OF THE FORECAST AREA  
SHOULD WIND DOWN THROUGH THE COURSE OF THE MORNING HOURS AS THE  
CONVERGENCE IT IS ASSOCIATED WITH WANES. WE ARE EXPECTED A DRY  
AFTERNOON WITH PLENTY OF LOW CLOUDS.  
 
THE FOCUS SHIFTS TO THE INCOMING SYSTEM FOR TONIGHT AND WEDNESDAY.  
THE PRECIPITATION LOOKS DELAYED A BIT FROM LAST NIGHT'S MODEL RUNS  
BY 6 TO MAYBE 9 HOURS. MUCH OF THE EVENING HOURS MAY END UP BEING  
DRY. PRECIPITATION SPREAD IN OVERNIGHT WITH THE THREAT OF BOTH A  
COLD RAIN AND LIGHT SNOW. THE HEAVIER PRECIPITATION LOOKS TO REMAIN  
WEST SO NOT EXPECTING ANYTHING SIGNIFICANT IN TERMS ACCUMULATIONS.  
ANY ACCUMS TONIGHT WOULD BE LESS THAN A HALF INCH IT APPEARS.  
 
ON WEDNESDAY A MIX OF RAIN AND SNOW WILL CONTINUE ACROSS CENTRAL  
LOWER, WHILE TRENDING TO ALL RAIN IN THE SOUTHERN HALF OF THE  
FORECAST AREA. ACCUMULATIONS ACROSS THE HIGH GROUND OF CENTRAL LOWER  
MAY BE AROUND AN INCH ON WEDNESDAY.  
 
COLDER AIR GRADUALLY FILTERING FOR WEDNESDAY NIGHT AND THURSDAY  
SHOULD TURN THE PRECIPITATION OVER TO ALL SNOW. SOME LIGHT  
ADDITIONAL ACCUMULATIONS ARE POSSIBLE, ON THE ORDER OF A DUSTING TO  
AROUND AN INCH.  
   
LONG TERM
 
(THURSDAY NIGHT THROUGH MONDAY)  
ISSUED AT 330 AM EST TUE JAN 24 2017  
 
FORECAST CONCERNS DURING THE LONG TERM DEAL WITH LAKE EFFECT SNOW.  
 
WE'LL SEE A RETURN TO COLDER WEATHER DURING THE EXTENDED PERIOD. H8  
TEMPS THURSDAY NIGHT WILL BE AROUND -10C TO START AND THEN SLOWLY  
FALL TO AROUND -12C FRIDAY MORNING AS NORTHWEST FLOW ALOFT DRAWS  
DOWN COLDER AIR. BOTH THE GFS AND ECMWF SHOW A DEEP TROUGH ALOFT  
MOVING TOWARD THE LAKE BY 12Z FRIDAY. INVERSION HEIGHTS WILL RISE  
AND LAKE EFFECT SNOW WILL DEVELOP AS OVER-LAKE INSTABILITY WILL BE  
MORE THAN SUFFICIENT TO PRODUCE SNOW. WE BOOSTED POPS OVER GUIDANCE  
CONSIDERABLY FROM FRIDAY THROUGH SUNDAY.  
 
AS THE FRIDAY TROUGH MOVES EAST DURING THE AFTERNOON, THE ECMWF  
SHOWS ANOTHER QUICKLY MOVING SOUTHEAST ACROSS WISCONSIN. THAT SHOULD  
RESULT IN ANOTHER FLAREUP OF SNOW SHOWERS FRIDAY EVENING.  
 
ANOTHER DEEP TROUGH MOVES IN SATURDAY NIGHT AND SUNDAY RESULTING IN  
MORE SNOW.  
 
SEVERAL INCHES OF ACCUMULATION CERTAIN SEEMS POSSIBLE WITH THE  
ACTIVITY ALOFT AND H8 TEMPS REMAINING IN THE -12C TO -14C RANGE  
THROUGH THE WEEKEND. H8 TEMPS WILL WARM ABOVE -10C SUNDAY NIGHT AND  
MONDAY AS THE DEEP UPPER TROUGH MOVES EAST AND SOUTHWEST FLOW  
DEVELOPS.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)  
ISSUED AT 105 PM EST TUE JAN 24 2017  
 
IFR CONDITIONS SHOULD PREVAIL MUCH OF THE TIME WITH RAIN AND SNOW  
AT TIMES THIS EVENING THEN STEADIER RAIN WEDNESDAY MORNING. WINDS  
WILL BE NORTHWEST THIS AFTERNOON THEN GO SOUTHEAST OVERNIGHT AT OR  
BELOW 10 KNOTS.  
 

 
   
MARINE
 
 
ISSUED AT 330 AM EST TUE JAN 24 2017  
 
MAIN CONCERN ARE WINDS THAT WILL BE ON THE INCREASE IN THE WAKE OF A  
SURFACE LOW PASSING THROUGH THE AREA ON WEDNESDAY. SOUTHWEST WINDS  
WILL INCREASE WEDNESDAY AFTERNOON, WITH STRONGER NORTHWEST WINDS  
INCREASE WEDNESDAY NIGHT. IT APPEARS WILL WE NEED SMALL CRAFT  
ADVISORIES WEDNESDAY AFTERNOON INTO THURSDAY, BUT WILL HOLD OFF FOR  
NOW GIVEN ITS LATE THIRD AND INTO THE FOURTH FORECAST PERIOD. WAVES  
WILL LIKELY BE BUILDING INTO THE 4 TO 7 FOOT RANGE INTO THURSDAY  
MORNING.  
 

 
   
HYDROLOGY
 
 
ISSUED AT 1151 AM EST TUE JAN 24 2017  
 
THE AREA SAW ANYWHERE FROM NO RAIN FOR THE LAKESHORE COUNTIES, TO  
A THIRD OF AN INCH FOR SOME LOCALES ALONG THE U.S.-127 CORRIDOR  
LAST NIGHT THROUGH THIS MORNING. THIS IS FORECAST TO BRING STABLE  
RIVER LEVELS OR EVEN SOME MINOR RISES IN THE NEXT DAY OR TWO.  
ADDITIONAL PCPN COMING LATE TONIGHT THROUGH WED WILL BRING BETWEEN  
0.10 TO 0.50 INCHES, HIGHEST AMOUNTS TO THE NW. THE HIGHEST  
AMOUNTS WILL BE LOCATIONS THAT DID NOT SEE MUCH, SO NO SIGNIFICANT  
IMPACTS ON THE RIVERS ARE EXPECTED. ALSO, WITH SOME/MOST OF THE  
PCPN UP NORTH COMING AS SNOW, THIS WILL NOT RUN OFF INTO THE  
RIVERS.  
 
COOLER AIR MOVING IN LATER THIS WEEK WILL LIMIT RUN OFF ALSO, AS  
PCPN WILL FALL MOSTLY AS SNOW AND LITTLE WILL MELT.  
 

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

 
 

 
 
SYNOPSIS...DUKE  
SHORT TERM...DUKE  
LONG TERM...04  
AVIATION...OSTUNO  
HYDROLOGY...NJJ  
MARINE...DUKE  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab MI Page
The Nexlab IN Page Main Text Page