757 FXUS63 KGRR 231056 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 656 AM EDT Thu Apr 23 2026 .KEY MESSAGES... - Very small chances for a shower or storm today - Showers and storms likely on Friday - Another round of showers and storms expected on Monday && .DISCUSSION... Issued at 400 AM EDT Thu Apr 23 2026 - Very small chances for a shower or storm today A warm front will be lifting north and northeast today through the region ushering in higher dew point from the southwest. Dew points in the HRRR are forecast to reach around the 60F mark. It is not often that a decent surge of moisture in the lower troposphere does not result in some precipitation and today is no exception. High resolution models are indicating small chances (20pct) for some isolated showers and storms in the midday and afternoon hours across the forecast area, but especially from near GRR to the east and south. Deep layer shear is very weak, less than 10 knots, so we are not expecting any strong storms. The surface moisture is respectable though which will produce Most Unstable CAPE values near 1,500 j/kg around 16Z/17Z. Expecting isolated showers and storms today. Otherwise, skies will be partly sunny for the most part with scattered to broken cumulus clouds. - Showers and storms likely on Friday A much better chance for showers and storms will come late tonight, but especially on Friday. An upper shortwave will move into Wisconsin tonight and into Lower Michigan on Friday. The upper shortwave will aid in pushing a cold front through the area on Friday. Latest 4hr Max Reflectivity supports the prior forecaster`s thinking in that a round of weakening showers and storms will move in from the west late tonight and Friday morning. Another round of showers and storms should develop in the afternoon. The morning round of precipitation could modulate the afternoon showers/storms. We are likely looking at 0.20 to 0.60 inches of rain across the area based on the HREF probability matched mean QPF. Regarding severe weather on Friday, chances are once again low given the morning clouds and rain. Deep layer shear is weak and Most Unstable CAPE values look to be even less than tonight. Agree with the general thunder forecast from SPC for both today and Friday. - Another round of showers and storms expected on Monday A much stronger system remains in tonight`s model runs for Monday. Deep southwest flow and a strong upper will be moving through the Great Lakes. Upper 50s to around 60F surface dew points will aid in shower/storm development. PWAT values will increase to in excess of 1 inch. Rainfall of 0.50 to 1.00 inches looks likely. A bit too early to dial in chances for severe, but they look lower overall once again as the Most Unstable CAPE values only make it into the 500 to 1,000 j/kg range and this will likely hold off until into Monday evening/night. && .AVIATION /12Z TAFS THROUGH 12Z FRIDAY/... Issued at 656 AM EDT Thu Apr 23 2026 Two areas of concern with the 12Z set of TAFs are low clouds/fog this morning and the chance of isolated showers/storms midday into the afternoon. Regarding the fog, it is largely radiational and shallow so it should lift quickly overall. There is a batch of more formidable clouds/fog near BTL and that may take a bit longer to burn off. Guidance shows all of it lifting pretty quick though. Scattered to broken cumulus clouds will develop through the course of the morning aided by a warm front lifting northward. The warm front may be a focus for some isolated showers/storms in the midday through afternoon hours (16Z-22Z). Overall feel this threat is quite isolated and will likely not impact the TAF sites too much given very low coverage. VFR ceilings will begin to push in from the west overnight tonight but expecting no appreciable impact to the TAF sites through 12z. Winds today will be from the south at 10-15 knots with some gusts towards 20 knots at times. && .MARINE... Issued at 400 AM EDT Thu Apr 23 2026 Winds and waves will remain below advisory thresholds both today and tonight. Today southerly winds will reach the 10-20 knot range at times today. The winds today will be driven by a fairly deep low for this time of year (sub 990mb) moving across Southern Manitoba. The low fills and moves northward tonight away from our area, although a cold front will press in from the west. Winds in the mixed layer (shallow as it is) will reach the 10-20 knot range once again from the south. Friday the winds pick up to 15-25 knots which will push waves north of Holland to 2 to 4 feet. It is possible we could need a Small Craft Advisory north of Holland or Grand Haven on Friday, but will hold off for now. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...Duke AVIATION...Duke MARINE...Duke

NWS GRR Office Area Forecast Discussion