591
FXUS63 KGRR 220541
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
141 AM EDT WED JUL 22 2026
KEY MESSAGES
- COOLER MIDWEEK THEN WARMING UP INTO THE WEEKEND
- CHANCE OF THUNDERSTORMS SUNDAY-MONDAY
DISCUSSION
ISSUED AT 309 PM EDT TUE JUL 21 2026
- COOLER MIDWEEK THEN WARMING UP INTO THE WEEKEND
SCATTERED SHOWERS AND ISOLATED THUNDERSTORM CELLS WILL PERSIST
INTO THE EVENING AMID BREEZY NORTHWEST WINDS AND COLD AIR
ADVECTION. ON WEDNESDAY, 850 MB TEMPERATURES AROUND 8 C WILL KEEP
HIGHS NO WARMER THAN THE MID 70S EVEN UNDER MOSTLY SUNNY SKIES,
OUR COOLEST DAY SINCE JUNE 26.
THE LARGE-SCALE WAVE PATTERN REMAINS RATHER STEADY-STATE FOR THE
REST OF THE MONTH, WITH AN UPPER-LEVEL HIGH OVER COLORADO AND THE
SOUTHWEST, AND TROUGHING OVER THE EASTERN GREAT LAKES. SHORTWAVES
WILL OCCASIONALLY TRAVERSE THIS FLOW REGIME. HEAT IS EXPECTED TO
BUILD OUT WEST AND THEN WASH OVER MICHIGAN THIS WEEKEND. ENSEMBLES
ARE NEARLY UNANIMOUS ON THE WARMING TREND THURSDAY INTO SUNDAY,
THEN DIVERGE FROM MONDAY ONWARD. TEMPERATURES ARE FAVORED TO CLIMB
TO AROUND 90 ON SUNDAY WITH THE HIGHER AND MORE UNCOMFORTABLE DEW
POINTS ALSO ARRIVING ON THAT DAY.
- CHANCE OF THUNDERSTORMS SUNDAY-MONDAY
ALONG WITH THE ARRIVAL OF WARMER AND MORE HUMID AIR ON SUNDAY,
STEEPER MIDLEVEL LAPSE RATES ADVECTING OVER THE REGION WILL ALSO
SERVE TO INCREASE INSTABILITY. ANOTHER FAIRLY ROBUST SHORTWAVE
TROUGH AND ASSOCIATED SURFACE LOW MOVING ACROSS THE NORTHERN GREAT
LAKES WILL PROVIDE THE NEXT CHANCE OF THUNDERSTORMS BETWEEN
SUNDAY AND MONDAY. MEANINGFUL DIFFERENCES DO EXIST ON THE EXACT
TRACK AND ARRIVAL TIME OF THE LOW, AND THAT MEANS CONFIDENCE IN
THE THREAT HEAVY RAIN OR SEVERE WEATHER IS RELATIVELY LOW FOR OUR
AREA AT THIS TIME.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 141 AM EDT WED JUL 22 2026
SKIES HAVE CLEARED UP A BIT AS MUCH DRIER AIR MOVES IN FROM
CANADA. THERE ARE STILL A FEW POCKETS OF MAINLY VFR CLOUDS. WE
SHOULD CONTINUE TO SEE A CLEARING TREND TONIGHT, WINDS WILL REMAIN
FROM THE NNW UNDER 10 KNOTS.
WE WILL SEE SOME DIURNAL CUMULUS CLOUD COVER DEVELOP, IN THE FORM
OF HIGH BASED CUMULUS BASED AROUND 6-7K FT. IN ADDITION TO THE
CLOUD COVER, WINDS WILL BECOME A LITTLE GUSTY WITH GUSTS OF 20-25
KNOTS DURING THE AFTERNOON. THESE WINDS AND DIURNAL CUMULUS WILL
TEND TO DISSIPATE TOWARD 00Z TONIGHT.
MARINE
ISSUED AT 309 PM EDT TUE JUL 21 2026
MODERATE TO HIGH SWIM RISK IS ONGOING WITH 2-4 OR 3-5 FT WAVES AT
WEST MICHIGAN BEACHES. WAVES ARE EXPECTED TO INCREASE LATER THIS
AFTERNOON THROUGH EVENING AS 20-30 KNOT WINDS FROM THE NORTH ARE
CHANNELED DOWN THE LENGTH OF LAKE MICHIGAN. THERE COULD BE SOME
GALE FORCE GUSTS TO 35 KNOTS NEAR THE SABLE POINTS THIS EVENING.
WAVES PEAK TONIGHT AT 5-10 FEET THEN SLOWLY SUBSIDE ON WEDNESDAY,
BUT WILL REMAIN HAZARDOUS TO SMALL CRAFT AND SWIMMERS ALL DAY.
UPWELLING OF COLDER WATER ALONG PORTIONS OF THE WEST MICHIGAN THE
SHORELINE IS LIKELY.
GRR WATCHES/WARNINGS/ADVISORIES
MI...BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR MIZ037-043-050-
056-064-071.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LMZ844>849.
DISCUSSION...CAS
AVIATION...NJJ
MARINE...CAS
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