670  
FXUS63 KGRR 200415  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
1215 AM EDT MON OCT 20 2014  
 
LATEST UPDATE...  
AVIATION  
   
SYNOPSIS
 
 
ISSUED AT 310 PM EDT SUN OCT 19 2014  
 
A CLIPPER SYSTEM MOVING SOUTHEAST FROM CENTRAL CANADA WILL GIVE US A  
CHANCE OF SHOWERS TONIGHT AND MONDAY. MUCH OF THE REST OF THE WEEK  
WILL BE DRY. TUESDAY AND WEDNESDAY WILL BE THE COOLEST DAYS WITH  
HIGHS IN THE LOWER TO MID 50S...AFTER WHICH A SLOW WARM UP INTO THE  
LOWER 60S IS EXPECTED.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH TUESDAY NIGHT)  
ISSUED AT 310 PM EDT SUN OCT 19 2014  
 
FORECAST CONCERNS ARE MINIMAL TODAY AND FOCUS ON THE CLIPPER MOVING  
SOUTHEAST TOWARD MICHIGAN.  
 
REGIONAL RADAR SHOWS LIGHT SHOWERS MOVING ACROSS NORTHERN WISCONSIN.  
HOWEVER A QUICK CHECK OF THE OBS SHOWS MOST OF IT AS VIRGA. THE PCPN  
IS IN THE WARM ADVECTION PATTERN AHEAD OF THE LOW THAT IS STILL IN  
SOUTHERN CANADA. MODELS SHOW CONDENSATION PRESSURE DEFICITS FALLING  
THE MOST OVER THE NORTHERN CWA TONIGHT AND FAR EASTERN CWA MONDAY.  
HOWEVER THE WARM ADVECTION ISN/T ALL THAT IMPRESSIVE THE VALUE OF  
THOSE DEFICITS ARE NOT ENOUGH TO SUGGEST MUCH RAINFALL. QPF IS LIGHT  
AND POPS WERE HELD IN THE CHANCE CATEGORY. THE TRAILING UPPER LOW IS  
PRETTY SHARP AND WELL VISIBLE IN WATER VAPOR IMAGERY AND THE LIFT  
AHEAD OF IT WILL PROVIDE THE BEST CHANCE FOR SHOWERS EAST OF US-127  
MONDAY.  
 
H8 TEMPS FALL TO AROUND 1C BEHIND THE SYSTEM TUESDAY RESULTING IN  
HIGHS IN THE LOWER 50S TUE.  
   
LONG TERM
 
(WEDNESDAY THROUGH SUNDAY)  
ISSUED AT 310 PM EDT SUN OCT 19 2014  
 
MODELS ARE IN DECENT AGREEMENT IN SHOWING A CLOSED UPPER LOW OFF THE  
NEW ENGLAND COAST THROUGH FRIDAY. THIS WILL IMPACT OUR AREA BY  
ALLOWING FOR AN UPPER RIDGE TO DOMINATE OUR WEATHER HERE IN MICHIGAN.  
A WEAK MID LEVEL SHORTWAVE DOES PUSH IN FOR THU NIGHT...BUT THIS  
SYSTEM WILL BE WEAKENING...SO NO PRECIPITATION IS EXPECTED AT THIS  
TIME.  
 
THURSDAY INTO SATURDAY...TEMPERATURES WILL WARM UP. A PERSISTENT  
SOUTHWESTERLY FLOW WILL ADVECT IN A RELATIVELY MILD AIRMASS. AT  
THIS POINT THE 850 MB THERMAL RIDGE PUSHES THROUGH ON SATURDAY.  
THIS WOULD BE OUR WARMEST DAY. A COLD FRONT ARRIVES LATER SATURDAY  
OR SATURDAY NIGHT...WHICH LOOKS DRY AT THIS POINT.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z TUESDAY)  
ISSUED AT 1215 AM EDT MON OCT 20 2014  
 
VFR CONDITIONS ARE LIKELY TO CONTINUE OVERNIGHT ALTHOUGH CONDITIONS  
MAY BEGIN TO DETERIORATE TO MVFR AROUND TO AFTER DAYBREAK AS SHOWERS  
BECOME MORE PREVALENT ACROSS SOUTHERN MICHIGAN. MVFR CONDITIONS ARE  
THEN LIKELY FOR MOST OF MONDAY DUE TO LOW CLOUDS AND SCATTERED  
SHOWERS.  
 
CONDITIONS SHOULD GRADUALLY IMPROVE TO VFR LATE MONDAY AND MONDAY  
EVENING. SOUTHWEST WINDS OF AROUND 10 KTS OVERNIGHT WILL SHIFT TO  
THE NORTHWEST BEHIND THE COLD FRONT ON MONDAY. SOME  
GUSTS TO AROUND 20KTS ARE LIKELY ALONG THE LK MI SHORELINE INCLUDING  
KMKG BOTH TONIGHT AND MONDAY.  
 

 
   
MARINE
 
 
ISSUED AT 310 PM EDT SUN OCT 19 2014  
 
THE SCA CONTINUES THROUGH TUESDAY NIGHT.  
 

 
   
HYDROLOGY
 
 
ISSUED AT 310 PM EDT SUN OCT 19 2014  
 
NO HYDRO ISSUES. LIGHT RAIN SHOWERS TONIGHT/TUESDAY WILL HAVE A  
NEGLIGIBLE AFFECT ON LOCAL STREAMS.  
 

 
   
GRR WATCHES/WARNINGS/ADVISORIES
 
 
MI...NONE.  
LM...SMALL CRAFT ADVISORY UNTIL 8 AM EDT WEDNESDAY FOR LMZ844>849.  
 

 
 

 
 
SYNOPSIS...93  
SHORT TERM...93  
LONG TERM...MJS  
AVIATION...LAURENS  
HYDROLOGY...93  
MARINE...93  
 
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