861  
FXUS63 KGRR 232332  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
632 PM EST SUN NOV 23 2014  
 
LATEST UPDATE...  
AVIATION  
   
SYNOPSIS
 
 
ISSUED AT 327 PM EST SUN NOV 23 2014  
 
LOW PRESSURE DEVELOPING OVER OKLAHOMA AND A CLIPPER MOVING ALONG THE  
NORTHERN TIER OF STATES WILL COMBINE OVER THE GREAT LAKES MONDAY.  
RAIN WILL MOVE ACROSS LOWER MICHIGAN TONIGHT AND MONDAY BEFORE  
COLDER AIR WORKS IN BEHIND THE SYSTEM AND TURNS THE RAIN TO SNOW. A  
FEW INCHES OF SNOW ARE POSSIBLE NORTHWEST OF A KALAMAZOO TO CLARE  
LINE MONDAY NIGHT AND TUESDAY.  
 
HIGH TEMPERATURES NEAR 50 MONDAY WILL GIVE WAY TO HIGHS AROUND 30  
ALONG WITH LAKE EFFECT SNOW SHOWERS FOR THE REST OF THE WEEK.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH TUESDAY NIGHT)  
ISSUED AT 327 PM EST SUN NOV 23 2014  
 
FORECAST CONCERNS DEAL WITH THE EVOLUTION OF THE DEEP LOW OVER THE  
GREAT LAKES MONDAY.  
 
A DEEP UPPER TROUGH WITH SEVERAL SHORT WAVES ARE MOVING TOWARD THE  
GREAT LAKES. SOUTH FLOW AHEAD OF A DEVELOPING LOW IN THE PLAINS IS  
SENDING QUITE A A BIT OF RAIN NORTH TOWARD LOWER MICHIGAN. TEMPS  
TONIGHT WILL REMAIN WELL ABOVE FREEZING SO SNOW OR ICE WON/T BE AN  
ISSUE. AM ALSO THINKING THAT ANY FLOODING WILL BE MINIMIZED BY THE  
UNFROZEN GROUND.  
 
THE LOW FROM THE SOUTHERN PLAINS WILL PHASE WITH A CLIPPER MOVING  
ACROSS THE NORTHERN TIER OF STATES. MODELS HAVE BEEN CONSISTENT IN  
SHOWING THIS PHASING OCCURRING OVER NORTHERN LOWER MICHIGAN. COLD  
AIR WILL BEGIN TO FUNNEL INTO THE CWA MONDAY AFTERNOON AND THE RAIN  
WILL CHANGE OVER TO SNOW. THAT SNOW THEN CONTINUES MONDAY NIGHT AND  
CHANGES OVER TO LAKE EFFECT. THE NAM IS THE COLDER OF THE MODELS AND  
YIELDS HIGHER SNOW RATIOS. CURRENT THINKING IS THAT WE COULD SEE 3  
TO 5 INCHES OF SYNOPTIC AND LAKE AFFECT SNOW NORTH WEST OF A  
KALAMAZOO TO CLARE LINE MONDAY NIGHT INTO TUESDAY. TRAVEL ISSUES  
COULD OCCUR MONDAY NIGHT/TUESDAY MORNING TOO AS HIGHER WINDS DEVELOP  
IN THE WAKE OF THE DEPARTING LOW. THE TRICKY PART ABOUT THE WINDS IS  
THAT A TROUGH REMAINS BEHIND THE LOW AND SO  
WE DON/T SEE A STRONG GRADIENT OVER THE CWA LIKE THERE IS ACROSS  
EASTERN LOWER MICHIGAN. WE HESITATED WITH A WIND ADVISORY BECAUSE OF  
THAT. SNOW SHOWERS WILL CONTINUE INTO TUESDAY NIGHT. THE HIGHER  
ACCUMS WILL OCCUR MONDAY NIGHT WHEN THERE IS BETTER LIFT WITHIN THE  
DGZ. BY TUESDAY...MUCH OF THE LIFT IS PROGD BENEATH THE DGZ  
RESULTING IN SMALLER FLAKE SIZE.  
   
LONG TERM
 
(WEDNESDAY THROUGH SUNDAY)  
ISSUED AT 327 PM EST SUN NOV 23 2014  
 
MODEL CONSENSUS CALLS FOR COLD AIR THROUGH THE LONG TERM WITH SNOW  
POSSIBLE FOR MUCH OF THE PERIOD. HOWEVER... THE TRACKS OF THE SHORT  
WAVES RESPONSIBLE FOR THE SNOW VARY... DEPENDENT ON MODEL AND  
FORECAST CYCLE. THIS LEADS TO LOW CONFIDENCE IN THE TIMING AND  
AMOUNTS OF SNOWFALL.  
 
A WEAK NORTHERN STREAM SYSTEM IS EXPECTED TO IMPACT THE AREA  
WEDNESDAY INTO THANKSGIVING DAY WITH LIGHT SNOW. THIS SHOULD BE  
FOLLOWED BY LIGHT LAKE EFFECT SNOW INTO THE NIGHT. A STRONGER SYSTEM  
WILL THEN MOVE THROUGH THE GREAT LAKES REGION FRIDAY INTO SATURDAY.  
THIS COULD BRING MEASURABLE SYSTEM SNOW AND POSSIBLY LAKE EFFECT IN  
ITS WAKE.  
 
TEMPERATURES ARE EXPECTED TO BE BELOW NORMAL THROUGH THE LONG TERM.  
NORMAL HIGHS ARE AROUND 40 DEGREES AND NORMAL LOWS ARE IN THE UPPER  
20S.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)  
ISSUED AT 623 PM EST SUN NOV 23 2014  
 
IMPACTS TO AVIATORS WILL CONTINUE. IFR OR LOWER TO PREVAIL INTO  
MONDAY AS A LOW PRESSURE SYSTEM TRACKS THROUGH. COLDER AIR WILL  
WRAP IN FROM THE WEST TO SOUTHWEST ON MONDAY CHANGING MUCH OF THE  
PRECIPITATION OVER TO SNOW. HOWEVER DOWN TOWARD KAZO...KBTL AND  
KJXN THERE IS AN INCREASED RISK FOR ICING GIVEN THE LIMITED  
MOISTURE DEPTH. ALSO THOSE SOUTHERN TAF SITES SHOULD SEE STRONGER  
WINDS DEVELOPING AS WE HEAD THROUGH THE AFTERNOON. SOME OF THE  
SNOW LATER MON AFTERNOON INTO THE EVENING COULD END UP PRODUCING  
LOWER THAN IFR...PRIMARILY FOR KGRR AND KMKG.  
 

 
   
MARINE
 
 
ISSUED AT 327 PM EST SUN NOV 23 2014  
 
LOW PRESSURE WILL MOVE OVER LOWER MICHIGAN MONDAY/MONDAY NIGHT. A  
TRAILING TROUGH IS PROGD TO SET UP ACROSS WESTERN LOWER MICHIGAN.  
THE MODELS ARE NOT CONSISTENT IN WHERE THIS TROUGH WILL END UP. AS  
SUCH PINNING DOWN WHERE THE GRADIENT OF HIGHEST WINDS WILL BE IS  
ALSO DIFFICULT. ULTIMATELY...WE ISSUED A GALE WARNING SOUTH OF GRAND  
HAVEN AND LEFT THE WATCH NORTH OF THERE.  
 

 
   
HYDROLOGY
 
 
ISSUED AT 327 PM EST SUN NOV 23 2014  
 
REGIONAL RADAR SHOWS RAIN SPREADING NORTHWARD FROM THE SOUTHERN US.  
QPF AROUND AN INCH IS POSSIBLE FROM LATER THIS AFTERNOON THROUGH  
MONDAY BEFORE THE PCPN CHANGES OVER TO SNOW. MUCH OF THE SNOW PACK  
IS GONE AND THE GROUND IS UNFROZEN...SW WE THINK THE POTENTIAL FOR  
WIDESPREAD FLOODING IS MINIMAL BUT WITHIN BANK RIVER RISES ARE  
EXPECTED.  
 

 
   
GRR WATCHES/WARNINGS/ADVISORIES
 
 
MI...NONE.  
LM...GALE WATCH FROM MONDAY MORNING THROUGH TUESDAY MORNING FOR  
LMZ847>849.  
 
SMALL CRAFT ADVISORY UNTIL 10 AM EST MONDAY FOR LMZ844>849.  
 
GALE WARNING FROM 10 AM MONDAY TO 7 AM EST TUESDAY FOR  
LMZ844>846.  
 

 
 

 
 
SYNOPSIS...93  
SHORT TERM...93  
LONG TERM...63  
AVIATION...MJS  
HYDROLOGY...93  
MARINE...93  
 
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