203 FXUS63 KGRR 021701 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 101 PM EDT Thu Jul 2 2026 .KEY MESSAGES... - Convective trends remain the main forecast concern - Heat continues into the holiday weekend && .DISCUSSION... Issued at 412 AM EDT Thu Jul 2 2026 - Convective trends remain the main forecast concern A quasi-stationary front drove convection upstream yesterday evening and into the overnight hours. This activity moved into far northern sections of the forecast area yesterday evening and into tonight. For our area we remain on the warm side of the boundary with around 2,000 j/kg of MUCAPE at 400am. Confidence in storm morphology remains on the lower side overall. A strong low level jet is in place overhead this morning which is usually a driver of additional storms. The SPC HREF does indicate a round of convection during the morning and into the midday hours between roughly 10am and 2pm. We are in a marginal to slight risk for severe weather today via the SPC and this is largely tied to the level of instability that will be in place. Some stronger winds in the profile will make damaging winds the main threat. Another round of storms is expected this evening. Heavy rain is also very possible today with high PWAT air in place and a boundary to focus the storms. We remain in a threat for severe weather both Friday and Saturday with the SPC having us in a marginal threat both days. Convection will be driven by a stationary front remaining in the area and mid level MCV`s floating through the region to enhance the threat. Again, confidence is on the lower side with regard to how storms evolve each day. Heavy rain will remain a threat on Friday and Saturday as the airmass will largely remain the same. - Heat continues into the holiday weekend GFS MOS numbers look more reasonable which keeps temperatures in the 90s today, Friday and Saturday (or at least near 90). We "cool" back into the 80s for highs on Sunday and into early next week. Will maintain the current Heat Warning as is, but we may need to extend it into Friday at least. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 100 PM EDT Thu Jul 2 2026 The next six hours will feature VFR conditions as daytime Cu develop in the 3-4kft range, with BKN cigs possible at JXN/BTL. After 00z, attention turns to convective potential however confidence is low in how convective development evolves and short range model guidance really struggles on coverage and placement so have maintained PROB30s for TSRA. There has been a bit of a later trend in thunderstorm timing with 02-10z as the favored window based on HRRR/RRFS/REFS/FV3 Guidance. MVFR and lower conditions and gusts in excess of 40 knots are possible in any convection that develops. Look for gusty winds to around 25 knots this afternoon diminishing tonight. && .MARINE... Issued at 412 AM EDT Thu Jul 2 2026 We were previously thinking that winds and waves would be near advisory criteria levels at this time, but that has not panned out early this morning. Winds are well below criteria at this point with many sites falling below 10 knots. Buoys at present are indicating 1 foot waves. So, no need to issue any headlines this morning given current conditions and what the rest of today and tonight look like. We may see conditions come up to a moderate swim risk today, otherwise we are heading into a lighter wind regime as we move into and through the holiday weekend. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Extreme Heat Warning until 8 PM EDT this evening for MIZ037>040- 043>046-050>052-056>059-064>067-071>074. Heat Advisory from 8 PM this evening to 8 PM EDT Friday for MIZ046-051-052-056>059-064>067-071>074. MARINE...None. && $$ DISCUSSION...Duke AVIATION...Thomas MARINE...Duke

NWS GRR Office Area Forecast Discussion