087
FXUS63 KGRR 011741
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
141 PM EDT TUE SEP 1 2026
KEY MESSAGES
- SMALL CHANCES FOR SHOWERS AND STORMS TODAY
- ADDITIONAL SHOWER AND STORM CHANCES WEDNESDAY THROUGH FRIDAY
- ABOVE NORMAL TEMPERATURES THROUGH THE 7 DAY FORECAST
DISCUSSION
ISSUED AT 354 AM EDT TUE SEP 1 2026
- SMALL CHANCES FOR SHOWERS AND STORMS TODAY
LIGHT SOUTHWEST FLOW IS IN PLACE THIS MORNING ALONG WITH DEW
POINTS AROUND 70F. UPSTREAM A COLD FRONT IS SITUATED FROM THE U.P.
SOUTHWEST ACROSS WISCONSIN AND INTO IOWA. WE REMAIN IN THE WARM
SECTOR TODAY WITH BUILDING INSTABILITY. MUCAPE VALUES EVEN AT THIS
EARLY HOUR RANGE FROM 2,000 J/KG IN SOUTHWEST LOWER MICHIGAN TO
AROUND 4,000 J/KG IN IOWA. THE FRONT REMAINS UPSTREAM TODAY AND
ONLY SLOWLY SAGS INTO THE AREA TONIGHT WHILE LOSING DEFINITION.
ALOFT, IT IS DIFFICULT TO PICK OUT MUCH OF ANY SHORTWAVE ACTIVITY
UPSTREAM EARLY THIS MORNING AND MODEL DATA MOVING THROUGH THE DAY
SHOWS LITTLE ENERGY ALOFT EITHER. THE BOTTOM LINE IS A THREAT FOR
SOME ISOLATED SHOWERS AND STORMS IS CERTAINLY THERE TODAY/TONIGHT,
BUT THERE IS LITTLE TO TRULY PINPOINT TIMING OR AREAS. CONFIDENCE
IN MORPHOLOGY OF STORMS TODAY IS LOW AS IS THE THREAT FOR STORMS
AT ALL. WOULD NOT BE SURPRISED TO SEE SOME ISOLATED ACTIVITY
DURING THE HEAT OF THE DAY TODAY, BUT HAVE KEPT THE FORECAST DRY.
WE DO HAVE SOME SMALL POPS AROUND 20 PERCENT THIS EVENING BASED ON
A CONSENSUS OF SHORT TERM MODELS AND BLENDS. SPC HAS THE AREA IN
A MARGINAL RISK TODAY, WHICH IS RELATED TO AN INCREASE IN WIND
FIELDS AT 850MB AND 500MB AFTER 00Z. AGAIN, WE WILL NEED A
KICKER/LIFTING MECHANISM AND AT THIS POINT THAT COMPONENT IS
NEBULOUS.
HAVE HELD OFF ON ANY HEAT HEADLINE TODAY AS INDEX VALUES ARE
MARGINAL ONLY IN THE FAR SOUTH. WE COULD SEE HEAT INDEX VALUES
APPROACH 100 FROM AZO OVER TO JXN THIS AFTERNOON, BUT MOST AREAS
SHOULD HOLD IN THE 90S FOR MAXIMUM APPARENT TEMPERATURES TODAY.
- ADDITIONAL SHOWER AND STORM CHANCES WEDNESDAY THROUGH FRIDAY
THE SURFACE FRONT WILL REMAIN IN THE AREA ON WEDNESDAY WHICH MAY
PROVIDE A FOCUS FOR SHOWERS AND THUNDERSTORMS. MULTIPLE SHORTWAVE'S
ARE FORECAST TO BE MOVING THROUGH THE GENERALLY ZONAL FLOW ALOFT
ON WEDNESDAY AS WELL. STRONG INSTABILITY WILL REMAIN IN PLACE ON
WEDNESDAY MAKING FOR BETTER CHANCES FOR SHOWERS AND STORMS. SPC
HAS SOME OF OUR FAR EASTERN AREAS TOWARDS THE U.S. 27/127 CORRIDOR
IN A SLIGHT RISK FOR SEVERE WEATHER. CANNOT RULE THIS OUT GIVEN
STRONG WINDS ALOFT REMAINING IN PLACE.
ADDITIONAL SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED ON
THURSDAY AND FRIDAY AS WELL BEFORE HIGH PRESSURE BUILDS IN FOR THE
WEEKEND. THAT SAID, QUITE A FEW ENSEMBLE MEMBERS OF BOTH THE GFS
AND THE ECMWF INDICATE PRECIPITATION POTENTIAL INTO THE WEEKEND AS
WELL. SUFFICE IT TO SAY, FORECAST CONFIDENCE IN PRECIPITATION IN
THE COMING DAYS IS NOT HIGH OWING TO TRANSIENT WEAKER SHORTWAVES
ALOFT AND A WEAK SURFACE PATTERN MOST DAYS.
- ABOVE NORMAL TEMPERATURES THROUGH THE 7 DAY FORECAST
WE ARE EXPECTING ABOVE NORMAL TEMPERATURES THROUGH MUCH OF THE
PERIOD WITH THE WARMEST DAYS BEING TODAY AND WEDNESDAY. A SLOW
COOLING TREND IS NOTED INTO EARLY NEXT WEEK. IT WILL TAKE UNTIL
NEXT MONDAY BEFORE WE SEE TEMPERATURES APPROACHING NORMALS FOR
THIS TIME OF YEAR.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 135 PM EDT TUE SEP 1 2026
RADAR SHOWS A BAND OF SHOWERS/STORMS MOVING ESE ACROSS SOUTHERN
LAKE MI AND FAR SOUTHWEST LOWER MI. THIS PRECIPITATION IS CLOSE
ENOUGH TO AZO AND BTL TO INCLUDE IN THE TAFS.
THERE IS SOME CONCERN FOR STRONG STORMS DEVELOPING MID LAKE NEAR
MKG AROUND MIDNIGHT AND MOVING ESE ACROSS LAN/JXN DURING THE
OVERNIGHT HOURS. A FEW MODELS SHOW THIS, BUT NOT ALL. WE INCLUDED
A PROB30 FOR THIS POTENTIAL EXCEPT AT AZO/BTL WHICH SHOULD BE FAR
ENOUGH SOUTH TO PRECLUDE MENTION.
GIVEN HIGH DEWPOINTS AND RESIDUAL MOISTURE FROM RECENT RAINS, SOME
FOG/HAZE IS POSSIBLE WEDNESDAY MORNING.
MARINE
ISSUED AT 354 AM EDT TUE SEP 1 2026
AS FORECAST, WAVES SUBSIDED BELOW ADVISORY LEVELS YESTERDAY
EVENING. SUB ADVISORY CONDITIONS ARE NOW EXPECTED THE NEXT COUPLE
OF DAYS AT LEAST. THE PRESSURE GRADIENT WILL BE FAIRLY SLACK IT
APPEARS AS A WEAK BOUNDARY SAGS INTO THE AREA TODAY AND REMAINS
NEAR THROUGH THE END OF THE WORK WEEK. WITHOUT A LOW OF SOME
DEPTH AND/OR A BUILDING HIGH WINDS WILL REMAIN ON THE LIGHTER
SIDE. WAVES LOOK TO BE 2 FEET OR LESS THE NEXT FEW DAYS. THE
CAVEAT HOWEVER AS ALWAYS IS THUNDERSTORMS. WE ARE EXPECTING AT
LEAST SOME PERIODIC THUNDERSTORM ACTIVITY THROUGH FRIDAY WHICH
WILL BRING A LOCAL UPTICK IN WAVE ACTION AS THE STORMS AND
ASSOCIATED LOCALIZED WIND MOVE THROUGH.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...04
AVIATION...DUKE
MARINE...DUKE
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