013  
FXUS63 KGRR 050830  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
330 AM EST FRI MAR 5 2021  
 
LATEST UPDATE...  
SYNOPSIS/DISCUSSION/MARINE  
   
SYNOPSIS
 
 
ISSUED AT 330 AM EST FRI MAR 5 2021  
 
- DRY WEATHER EXPECTED TO CONTINUE THROUGH EARLY NEXT WEEK  
 
- READINGS NEAR NORMAL THROUGH WEEKEND THEN WARMER NEXT WEEK  
 
- DETAILS A BIT FUZZY YET BUT EXPECTING RAIN MID NEXT WEEK  
 

 
   
DISCUSSION
 
(TODAY THROUGH NEXT THURSDAY)  
ISSUED AT 330 AM EST FRI MAR 5 2021  
 
-- DRY WEATHER EXPECTED TO CONTINUE THROUGH EARLY NEXT WEEK --  
 
RELATIVE HUMIDITY BUFKIT OVERVIEWS TELL THE STORY WELL OVER THE  
COURSE OF THE NEXT FEW DAYS WITH LIMITED MOISTURE TO WORK WITH. WE  
ARE MAINLY DRY FROM 5000FT ON UP THROUGH THE PROFILE, SO  
PRECIPITATION IS NOT A CONCERN TODAY OR THROUGH MONDAY FOR THAT  
MATTER. WE ARE HANGING ON TO AIR THAT IS JUST COLD ENOUGH FOR LAKE  
GENERATED STRATOCUMULUS AND THAT WILL BE A PLAYER IN THE SKY  
FORECAST BOTH TODAY AND SATURDAY. THE RELATIVE HUMIDITY PROGS IN  
THE 925-850MB LAYER SHOW A DIURNAL COMPONENT TO THE MOISTURE AS  
WELL, WITH MOISTURE INCREASING IN THAT LAYER EACH AFTERNOON. IT IS  
THE TIME OF YEAR WHERE WE START TO SEE THE CHANCE FOR DIURNAL  
CUMULUS DEVELOPMENT. SO, EACH AFTERNOON, TODAY AND TOMORROW COULD  
SEE PARTLY CLOUDY CONDITIONS AS LAKE STRATOCUMULUS DRIFTS IN ON  
NORTHERLY FLOW. DIURNAL CUMULUS SCHEME ALSO SUPPORTS SOME CLOUDS  
BOTH DAYS.  
 
DEEPER MOISTURE DOES NOT REALLY SHOW UP IN THE PROFILES UNTIL WE  
GET LATER INTO TUESDAY, SO HIGH CONFIDENCE IN DRY WEATHER THROUGH  
THAT TIME. SURFACE RIDGING WILL DOMINATE THROUGH THAT TIME.  
SOUTHERLY FLOW BEGINS TO TAKE HOLD AS WE HEAD THROUGH MONDAY AND  
TUESDAY.  
 
-- READINGS NEAR NORMAL THROUGH WEEKEND THEN WARMER NEXT WEEK --  
 
WE CONTINUE TO HANG ON TO 850MB TEMPERATURES IN THE -6C TO -8C  
RANGE TODAY THROUGH SATURDAY NIGHT. WARMING OF THE LOWER  
TROPOSPHERE REALLY STARTS ON SUNDAY AS WE WARM ABOVE 0C. SO  
THROUGH THE WEEKEND WE ARE EXPECTING TO REMAIN NEAR NORMAL IN  
TERMS OF HIGHS AND LOWS WITH LOWS IN THE TEENS AND 20S AND HIGHS  
UP AROUND 40.  
 
MODEL INDICATIONS, BOTH MOS AND ENSEMBLE OUTPUT, HAVE BEEN PRETTY  
CONSISTENT IN SHOWING AT LEAST SOUTHERN PORTIONS OF OUR AREA  
MAKING A RUN AT 60F ON TUESDAY AND WEDNESDAY OF NEXT WEEK. WE WILL  
LIKELY BE IN THE 50S ON MONDAY WITH TUESDAY POTENTIALLY BEING THE  
WARMEST DAY. THE OPERATIONAL ECWMF HAS 60+ READINGS OVER THE BULK  
OF OUR AREA TUESDAY, THE EXCEPTION BEING THE NORTHWEST CWA WITH A  
WIND OFF THE WATER UP THERE. EVEN ON WEDNESDAY AND THURSDAY WITH  
RAIN IT WILL FEEL WARM (50S) COMPARED TO WHERE WE WERE FOR THE  
BULK OF FEBRUARY.  
 
-- DETAILS A BIT FUZZY YET BUT EXPECTING RAIN MID NEXT WEEK--  
 
THE MODELS STILL HAVE A BIT OF SPREAD IN HOW THE PATTERN EVOLVES  
MID TO LATE NEXT WEEK IN TERMS OF SURFACE SYNOPTIC FEATURES. THE  
GFS STILL REMAINS A BIT QUICKER WITH A LOW AND FRONT MOVING  
THROUGH THE AREA, WITH THE ECMWF BEING SLOWER. THE GFS ALSO BRINGS  
THE FRONT BACK INTO THE AREA FOR ANOTHER SWATH OF RAIN INTO  
THURSDAY.  
 
THE BOTTOM LINE THOUGH IS WE WILL SEE DEEP SOUTHERLY FLOW IN PLACE  
WITH THE THREAT OF SOME HEAVIER RAIN. THE NEW GFS IS EVEN  
INDICATING THE POTENTIAL FOR 2+ INCHES OF RAIN IN SPOTS. PWAT  
VALUES INCREASE TO IN EXCESS OF AN INCH, 850MB DEW POINTS RISE TO  
AROUND +9C, 850MB LI'S DIP TO -1C IN A ZONE OF STRONG MOISTURE  
ADVECTION ON A LOW LEVEL JET THAT WILL BE NEAR 50 KNOTS. ALL THAT  
TO SAY THERE ARE SOLID INDICATIONS FOR A SOAKING HEAVIER RAIN,  
NOT TO MENTION THE THREAT OF SOME EMBEDDED THUNDERSTORMS GIVEN THE  
DEW POINT VALUES AND LIS.  
 
REGARDING HYDRO CONCERNS, THE SNOWPACK HAS LARGELY BEEN ERODED  
FROM I-96 TO THE SOUTH. SNOW REMAINS IN PLACE FOR AREAS ACROSS  
CENTRAL LOWER MICHIGAN. RIVER ICE IS LARGELY GONE WITH THE  
EXCEPTION OF AREAS BEHIND DAMS, WHICH IS NOT A CONCERN OBVIOUSLY  
IN REGARD TO ICE JAMS. THE SNOWPACK ACROSS CENTRAL LOWER WILL  
CONTINUE TO BE ERODED BY THE SUN AND WARM TEMPS IN NEXT WEEK. SO,  
WHILE THE THREAT EXISTS FOR SOME HEAVIER RAINS, WE HAVE AT LEAST  
CLEARED OUT OF THE WAY MOST OF THE RIVER ICE AND SNOW. SNOW MELT  
HAS RESULTED IN WITHIN BANK RISES SO IT IS NOT OUT OF THE  
QUESTION TO SEE SOME RIVERS NEXT WEEK EXCEED BANKFULL RESULTING IN  
SOME MINOR FLOODING. WE WILL CONTINUE TO MONITOR AND PROVIDE  
UPDATES AS WE HEAD THROUGH NEXT WEEK. AT THIS POINT THOUGH NOT  
EXPECTING MAJOR ISSUES.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)  
ISSUED AT 1212 AM EST FRI MAR 5 2021  
 
VFR WILL DOMINATE THE PATTERN THROUGH THE DAYTIME FRIDAY. GUSTY  
WINDS ARE EXPECTED THIS AFTERNOON, UPWARDS OF 25 KTS. WINDS WILL  
SUBSIDE AROUND 00Z.  
 

 
   
MARINE
 
 
ISSUED AT 330 AM EST FRI MAR 5 2021  
 
THE SURFACE RIDGE IS STILL JUST A BIT UPSTREAM OF THE GREAT LAKES  
WHICH IS ALLOWING SOME SLIGHTLY STRONGER NORTHERLY FLOW TO HANG  
ON. BUFKIT OVERVIEWS SHOW NORTH WINDS OF 10-20 KNOTS PREVAILING  
FROM TODAY THROUGH SATURDAY EVENING. THERE IS A TIME OF BRIEFLY  
HIGHER WINDS, 15-25 KNOTS WINDS, FROM OVERNIGHT TONIGHT INTO  
SATURDAY MORNING ACROSS NORTHERN/CENTRAL LAKE MICHIGAN. FOR THIS  
REASON, WE WILL BE ISSUING A SHORT DURATION SMALL CRAFT ADVISORY  
NORTH OF WHITEHALL FROM MIDNIGHT TONIGHT THROUGH MID MORNING ON  
SATURDAY. WAVES WILL PUSH INTO THE 3-5 FOOT RANGE ESPECIALLY NEAR  
THE POINTS AND MORE TOWARDS THE OUTER RANGES OF THE ZERO TO 5  
NAUTICAL MILE NEARSHORE ZONE.  
 
ICE UPDATE...SHORELINE ICE REMAINS IN PLACE FROM A BIT NORTH OF  
PIONEER PARK IN MUSKEGON COUNTY SOUTHWARD DOWN THE SHORELINE ALL  
THE WAY TO ST. JOSEPH. MOST OF THIS ICE THOUGH IS CONFINED PRETTY  
CLOSE TO SHORE. RIVER CHANNELS ARE A MIX OF OPEN WATER AND FRAZIL  
ICE. THE LARGEST CONCENTRATION OF ICE (LARGELY FLOATING) IS IN  
PLACE BETWEEN GRAND HAVEN AND SAUGATUCK. GIVEN THE WARMTH AND  
WIND THAT IS EXPECTED NEXT WEEK, NOT EXPECTING THE FLOATING ICE TO  
LAST MUCH LONGER. THAT WILL LEAVE THE SHORE FAST ICE THAT IS  
LOCATED FROM THE THIRD SANDBAR INWARD TOWARDS THE SHORELINE.  
BOTTOM LINE, LAKE ICE IS A BIT BELOW WHERE WE COULD BE THIS TIME  
OF YEAR AND IT IS GOING TO DWINDLE FURTHER AS WE HEAD THROUGH  
NEXT WEEK.  
 

 
   
GRR WATCHES/WARNINGS/ADVISORIES
 
 
MI...NONE.  
LM...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 10 AM EST SATURDAY  
FOR LMZ848-849.  
 

 
 

 
 
SYNOPSIS...DUKE  
DISCUSSION...DUKE  
AVIATION...CERU  
MARINE...DUKE  
 
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