938  
FXUS63 KGRR 242318  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
718 PM EDT SAT OCT 24 2020  
 
LATEST UPDATE...  
AVIATION  
   
SYNOPSIS
 
 
ISSUED AT 323 PM EDT SAT OCT 24 2020  
 
-COOL WEEK AHEAD; BENIGN PATTERN  
 
-CHANCE OF LIGHT PRECIPITATION LATE SUNDAY INTO MONDAY NIGHT  
 
-LATE WEEK SOUTHERN STREAM STORM NEEDS WATCHED  
 

 
   
DISCUSSION
 
(THIS EVENING THROUGH NEXT SATURDAY)  
ISSUED AT 323 PM EDT SAT OCT 24 2020  
 
-- COOL WEEK AHEAD; BENIGN PATTERN --  
 
SURFACE RIDGING GENERALLY PREVAILS FOR THE NEXT SEVERAL DAYS WHICH  
KEEPS THE LOW LEVELS COOL AND DRY. NO BIG STORMS AND NO BIG PUSHES  
OF REALLY COLD OR WARM AIR EXPECTED. THE NICEST DAY OF THE  
UPCOMING WEEK CURRENTLY LOOKS TO BE WEDNESDAY WHEN PLENTY OF  
SUNSHINE IS EXPECTED ALONG WITH TEMPS REACHING OR EXCEEDING 50.  
 
-- CHANCE OF LIGHT PRECIP LATE SUNDAY INTO MON NIGHT --  
 
POSITIVELY TILTED UPPER LEVEL TROUGH, WITH THE AXIS OVER THE NRN  
PLAINS AND ROCKIES, SENDS SEVERAL WEAK VORTICITY MAXIMA THROUGH  
THE REGION SUNDAY INTO MONDAY NIGHT ALONG THE MID LEVEL  
BAROCLINIC ZONE. THIS WILL RESULT IN CONSIDERABLE MID AND HIGH  
LEVEL CLOUDINESS ALONG WITH OCCASIONAL LIGHT PRECIP OR VIRGA.  
 
THE LOW LEVELS REMAIN RELATIVELY DRY AND TOTAL QPF AMOUNTS DURING  
THIS TIME SHOULD BE MOSTLY UNDER A TENTH OF AN INCH. CAN'T RULE  
OUT A FEW SNOWFLAKES AT NIGHT AND EARLY IN THE MORNING WHEN WET  
BULB ZERO HEIGHTS LOWER BELOW 1500 FT. WORST CASE SCENARIO WOULD  
BE A COATING OF SNOW ON THE GRASS.  
 
-- LATE WEEK SOUTHERN STREAM STORM NEEDS WATCHED --  
 
LATER IN THE WEEK A SRN STREAM SYSTEM/CLOSED UPR LOW, WHICH TAPS  
MOISTURE FROM THE TROPICAL SYSTEM IN THE GULF, TRACKS EAST-  
NORTHEAST FROM TEXAS. MOST MEDIUM RANGE DETERMINISTIC GUIDANCE  
HAS BEEN INDICATING THAT THIS SYSTEM STAYS SOUTH OF US, BUT SOME  
ENSEMBLE MEMBERS SUGGEST THAT HEAVIER PRECIP ASSOCIATED WITH THE  
DEFORMATION ZONE MAY IMPACT SRN LWR MI.  
 
OVER HALF OF THE ECMWF ENSEMBLE MEMBERS ARE SHOWING RAIN AT AZO  
ON THURSDAY, AND ABOUT A THIRD OF THE MEMBERS PRODUCE OVER AN INCH  
OF RAIN. SOME OF THEM EVEN HAVE OVER TWO INCHES OF RAIN, AND THAT  
IS TRUE AT GRR AS WELL. THIS WOULD BE A COLD RAIN IF IT HAPPENED  
WITH A SFC HIGH SITUATED TO OUR NORTH AND A NORTHEAST SFC WIND.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)  
ISSUED AT 718 PM EDT SAT OCT 24 2020  
 
VFR CONDITIONS WILL CONTINUE THROUGH SUNDAY AFTERNOON AND  
NORTHEAST WINDS WILL BE LESS THAN 10 KNOTS.  
 

 
   
MARINE
 
 
ISSUED AT 323 PM EDT SAT OCT 24 2020  
 
WE'RE ACTUALLY LOOKING AT RELATIVELY TRANQUIL CONDITIONS ON LAKE  
MICHIGAN THE NEXT COUPLE DAYS WITH HIGH PRESSURE AND OFFSHORE  
FLOW. THE NEXT PERIOD OF CONCERN FOR CONDITIONS POSSIBLY REACHING  
SMALL CRAFT ADVISORY CRITERIA APPEARS TO BE TUESDAY NIGHT INTO  
WEDNESDAY AS WINDS INCREASE OUT OF THE SOUTHWEST.  
 

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

 
 

 
 
SYNOPSIS...MEADE  
DISCUSSION...MEADE  
AVIATION...OSTUNO  
MARINE...MEADE  
 
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