443
FXUS63 KGRR 140704
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
304 AM EDT SUN SEP 14 2025
KEY MESSAGES
- DRY WEATHER MOST OF THIS WEEK
- CHANCE OF SHOWERS AND THUNDERSTORMS STARTING FRIDAY
DISCUSSION
ISSUED AT 304 AM EDT SUN SEP 14 2025
- DRY WEATHER MOST OF THIS WEEK
FLOW OVER THE EASTERN CONUS WILL RESEMBLE A REX BLOCK PATTERN (RIDGING
WITH THE POLAR JET AND TROUGHING WITH THE SUBTROPICAL JET) BEGINNING
EARLY THIS WORK WEEK. BEING A BLOCKY PATTERN, IT SHOULD PERSIST
FOR SEVERAL DAYS. AND, GIVEN RATHER SHARP RIDGING ALOFT IN OUR
VICINITY, WE CAN EXPECT DRY AND ABNORMALLY WARM MAXIMUM TEMPERATURES.
WE ARE NOW LOOKING AT UPPER 80S WEDNESDAY/THURSDAY, AND THIS
COULD EASILY BE EXCEEDED ON THURSDAY ESPECIALLY.
- CHANCE OF SHOWERS AND THUNDERSTORMS STARTING FRIDAY
MODEL GUIDANCE HAS BEEN FAIRLY CONSISTENT WITH BRINGING AN UPPER
SHORTWAVE TROUGH TO THE WESTERN GREAT LAKES, WHICH WILL BRING MORE
SEASONAL TEMPERATURES ALONG WITH A CHANCE FOR SHOWERS AND THUNDERSTORMS.
PREDICTABILITY IS LIMITED GIVEN WEAK AND POORLY PHASED FLOW ALOFT,
ESPECIALLY REGARDING PRECIPITATION CHANCES. QPF IS BROAD-BRUSHED
AREALLY AND TEMPORALLY (ACROSS MULTIPLE DAYS INCLUDING THE WEEKEND)
TO ILLUSTRATE THE UNCERTAINTY. BUT IN REALITY, PRECIPITATION MAY
BE QUITE EPISODIC AND SPOTTY WITH ANY ACCUMULATIONS NOT EXPECTED
TO MAKE MUCH OF A DENT IN OUR RECENT PRECIPITATION DEFICITS.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 138 AM EDT SUN SEP 14 2025
NO SUBSTANTIVE CHANGES FROM THE 00Z TAF ISSUANCE. NIGHTTIME GOES
MICROPHYSICS RGB PRODUCT SHOWS A PERSISTENT CLOUD DECK EXTENDING
NORTH THROUGH AZO/BTL AND TERMINATING WEST OF GRR. ASSOCIATED CEILINGS
RANGE FROM 5000-6000 FT AGL. THIS IS MARGINALLY CLOSE ENOUGH TO
THE GROUND TO HAMPER RADIATION FOG (DUE TO INTERRUPTED UPWELLING
OF LONGWAVE RADIATION THAT IS REQUIRED TO PRODUCE AND SUSTAIN
FOG). WILL CONTINUE MVFR VISIBILITY RESTRICTIONS AT AZO/BTL TO
ACCOUNT FOR THE POSSIBILITY OF THIS CLOUD DECK DISSIPATING OR
BEING LESS OF A FACTOR.
FARTHER EAST, UNDER CLEAR SKIES, WE ALREADY ARE SEEING FOG
REPORTED AT SITES IN THE VICINITY OF THE LAN AND JXN TERMINALS,
SO THE INHERITED TAFS FEATURING IFR VISIBILITY LOOK ON TRACK.
MARINE
ISSUED AT 304 AM EDT SUN SEP 14 2025
WINDS AND WAVES ARE EXPECTED TO REMAIN BELOW HAZARDOUS LEVELS. AS
NOTED PREVIOUSLY, THE LARGER SCALE FLOW WILL GENERALLY BE LIGHT
AND OFFSHORE. HOWEVER, LARGE DIURNAL TEMPERATURE SWINGS ARE
EXPECTED OVER LOWER MICHIGAN AND THIS WILL PROMOTE AN ACTIVE
LAKE/LAND BREEZE DIURNAL CYCLE.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...TJT
AVIATION...TJT
MARINE...TJT
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