181
FXUS63 KGRR 130532
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
132 AM EDT SUN JUL 13 2025
KEY MESSAGES
- CHANCE FOR RAIN WED/THU
DISCUSSION
ISSUED AT 132 AM EDT SUN JUL 13 2025
- CHANCE FOR RAIN WED/THU
ZONAL FLOW WITH WEAK SFC RIDGING BRINGS FAIR WEATHER THROUGH
TUESDAY THEN RAIN CHANCES RETURN FOR MID-WEEK WITH THE APPROACH
OF A WEAK SHORTWAVE TROUGH. SHOWERS AND STORMS ARRIVE TUESDAY
NIGHT INTO WEDNESDAY AND PERSIST INTO THURSDAY AS A COLD FRONT
MOVES THROUGH. SEVERE WEATHER THREAT ALSO INCREASES AS FORECAST
DEEP LAYER SHEAR IS PROGGED TO BE 25 TO 30 KNOTS ALONG WITH
SUFFICIENT INSTABILITY FOR ORGANIZED STORMS ON WEDNESDAY
AFTERNOON AND PERHAPS INTO THURSDAY.
THE END OF THE WEEK FEATURES LOW CONFIDENCE FORECAST FOR DETAILS
ON WHERE THE FRONT STALLS AND IF SFC HIGH PRESSURE BUILDS IN.
SHOWERS AND A FEW STORMS COULD PERSIST ACROSS THE SOUTHERN ZONES
FROM THURSDAY INTO FRIDAY. LATER IN THE WEEKEND AND EARLY NEXT
WEEK IS ALSO UNCERTAIN AS THERE ARE INDICATIONS OF AN ACTIVE AREA
OF MCS GENERATION ON THE NORTHERN PERIPHERY OF AN UPPER HIGH
ACROSS THE SE CONUS. SOME OF THIS CONVECTION COULD MAKE IT INTO
LOWER MICHIGAN.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 132 AM EDT SUN JUL 13 2025
VFR CONDITIONS WILL PREVAIL THROUGH TONIGHT WITH GENERALLY WEST
WINDS LESS THAN 10 KNOTS.
MARINE
ISSUED AT 132 AM EDT SUN JUL 13 2025
WINDS AND WAVES WILL BE RELATIVELY LIGHT THROUGH TUESDAY WITH
SLOWLY INCREASING SOUTHWEST AND SOUTH FLOW. THUNDERSTORMS ARE
POSSIBLE FROM TUESDAY NIGHT INTO THURSDAY AND NORTH WINDS COULD
RAMP UP BEHIND A COLD FRONT LATER THURSDAY.
GRR WATCHES/WARNINGS/ADVISORIES
MI...AIR QUALITY ALERT UNTIL NOON EDT MONDAY FOR MIZ037>040-043>046-
050>052-056>059-064>067-071>074.
MARINE...NONE.
DISCUSSION...OSTUNO
AVIATION...OSTUNO
MARINE...OSTUNO
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