823
FXUS63 KGRR 090729
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
329 AM EDT MON JUN 9 2025
KEY MESSAGES
- UPPER LOW SPAWNS AFTERNOON SHOWERS
- INCREASING CONFIDENCE IN RAIN/CONVECTION LATE WEEK
DISCUSSION
ISSUED AT 328 AM EDT MON JUN 9 2025
- UPPER LOW SPAWNS AFTERNOON SHOWERS
THE CORE REGION OF THE UPPER LOW MOVES IN THIS AFTERNOON AND
STEEPENING LAPSE RATES COMBINE WITH DEEP MOISTURE TO BRING A
DIURNAL ENHANCEMENT OF SHOWERS AND THUNDERSTORMS FROM MID
AFTERNOON INTO THE EVENING. MODEL SOUNDINGS SHOW POTENTIAL FOR PEA
SIZED HAIL WITH PERSISTENT UPDRAFTS OVER 20 KFT. SHOWERS DIMINISH
AFTER SUNSET WITH A LESSER CHANCE OF DIURNAL ENHANCEMENT ON
TUESDAY AS THE UPPER LOW MOVES OUT.
- INCREASING CONFIDENCE IN RAIN/CONVECTION LATE WEEK
LONGER RANGE MODEL GUIDANCE IS COMING INTO BETTER AGREEMENT ON THE
POTENTIAL FOR CONVECTION AND POSSIBLE 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
STILL SOME SPREAD IN WHERE THIS FRONT SETS UP AND WHERE THE MCS
TRACKS, SO FORECAST CONFIDENCE IS MODERATE. THE CURRENT NBM
POPS/TIMING APPEARS TO BE A GOOD COMPROMISE OF MODEL DIFFERENCES.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 138 AM EDT MON JUN 9 2025
PATCHY IFR OVERNIGHT WITH LOW STRATUS AND SHALLOW GROUND FOG, BUT
THESE CONDITIONS WILL BE TRANSIENT AS WINDS PICK UP BEHIND A COLD
FRONT. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL FIRE UP
DURING THE AFTERNOON THEN DECREASE AT SUNSET. WEST WINDS WILL GUST
OVER 20 KNOTS AT TIMES TODAY.
MARINE
ISSUED AT 138 AM EDT MON JUN 9 2025
WINDS AND WAVES ARE EXPECTED TO BE RELATIVELY CALM THIS WEEK WITH
WINDS MOSTLY BELOW 20 KNOTS AND WAVES MOSTLY 3 FEET OR LESS.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...OSTUNO
AVIATION...OSTUNO
MARINE...OSTUNO
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