198
FXUS63 KGRR 081740
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
140 PM EDT SUN JUN 8 2025
KEY MESSAGES
- UPPER LOW BRINGS SOME RAIN NEXT COUPLE DAYS
- LOW CONFIDENCE IN RAIN/CONVECTION LATE WEEK
DISCUSSION
ISSUED AT 323 AM EDT SUN JUN 8 2025
- UPPER LOW BRINGS SOME RAIN NEXT COUPLE DAYS
LOW PRESSURE TRACKING ACROSS THE OHIO VALLEY WILL BRING LIGHT RAIN
TO THE FAR SOUTHERN ZONES TODAY, WHILE THE REST OF THE FORECAST
AREA SEES RAIN CHANCES INCREASE LATE THIS AFTERNOON. A LINE OF
SHOWERS AND A FEW THUNDERSTORMS CAN BE EXPECTED ALONG A COLD FRONT
IN ADVANCE OF A VIGOROUS UPPER LOW MOVING ACROSS THE GREAT LAKES
REGION.
THUNDER POTENTIAL IS LIMITED BY MARGINAL INSTABILITY BUT WIND
PROFILES SHOW 40 KNOTS OF DEEP LAYER SHEAR, SO THE NARROW NCFR
CURRENTLY SEEN ACROSS NORTHWEST WISCONSIN COULD HOLD TOGETHER AND
BE BUILDING SOUTH TODAY, THEN AND CROSSING THE LAKE INTO WESTERN
LOWER MICHIGAN BY LATE AFTERNOON OR EARLY EVENING AS SUGGESTED BY
THE HI-RES ARW AND HRRR.
THE CORE REGION OF THE UPPER LOW MOVES IN BY MONDAY AFTERNOON AND
COMBINES WITH DEEPER MOISTURE AND STEEPENING LAPSE RATES TO BRING
A DIURNAL ENHANCEMENT OF SHOWERS AND THUNDERSTORMS IN THE
AFTERNOON AND EVENING. THE LOW MOVES OUT LATE TUESDAY WITH FAIR
WEATHER RETURNING FOR WEDNESDAY.
- LOW CONFIDENCE IN RAIN/CONVECTION LATE WEEK
LONGER RANGE MODEL GUIDANCE SHOWS POTENTIAL FOR MCS DEVELOPMENT
THURSDAY INTO FRIDAY ALONG A BAROCLINIC ZONE/STALLED FRONT IN THE
VICINITY OF IOWA OR SOUTHERN MINNESOTA THAT PROPAGATES EAST AND
POTENTIALLY BRINGS RAIN AND CONVECTIVE STORMS INTO LOWER MICHIGAN.
THERE IS CONSIDERABLE SPREAD IN WHERE THIS FRONT SETS UP AND WHERE
THE MCS TRACKS, SO FORECAST CONFIDENCE IS LOW THE CURRENT NBM
POPS/TIMING APPEARS TO BE A GOOD COMPROMISE OF MODEL DIFFERENCES.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 140 PM EDT SUN JUN 8 2025
THE MAIN FOCUS OF THIS SET OF AVIATION FORECASTS IS ON THE LINE OF
SHOWERS AND EMBEDDED STORMS OVER WI AND IL THIS AFTERNOON THAT
WILL MOVE THROUGH THE TERMINALS THIS EVENING.
THE CLOUDS AND SHOWERS FROM LAST NIGHT HAVE MOVED OUT, AND ALLOWED
FOR SKIES TO CLEAR OUT. WE WILL SEE THESE CONDITIONS CONTINUE
UNTIL JUST PRIOR TO THE ARRIVAL OF THE FRONT AND BAND OF SHOWERS
AND STORMS. THE SHOWERS AND STORMS WILL MOVE IN AT KMKG AROUND 22Z
OR SO, AND MOVE EASTWARD THROUGH ABOUT 02-03Z AT KJXN BEFORE
MOVING OUT. SHOWERS ARE EXPECTED WITH SOME EMBEDDED THUNDER IN IT,
AND HAVE ELECTED TO USE PROB30 FOR THE THUNDER CHANCES. CONDITIONS
WILL BE MAINLY VFR, WITH SOME ISOLATED IFR UNDER THE HEAVIER
SHOWERS/STORMS.
THE THUNDER THREAT SHOULD BE GONE AFTER 2-3 HOURS, AND SHOWERS
LINGERING A FEW MORE HOURS. ONCE THE SHOWERS MOVE OUT, SKIES
SHOULD CLEAR OUT AGAIN BY DAYBREAK MONDAY MORNING. THESE
CONDITIONS ARE EXPECTED TO THEN HOLD THROUGH THE END OF THIS
FORECAST PERIOD AT 18Z MONDAY.
MARINE
ISSUED AT 128 AM EDT SUN JUN 8 2025
WINDS AND WAVES ARE EXPECTED TO BE RELATIVELY CALM THROUGH THE
MIDDLE OF NEXT WEEK WITH WINDS LESS THAN 20 KNOTS AND WAVES 3 FEET
OR LESS.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...OSTUNO
AVIATION...NJJ
MARINE...OSTUNO
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page