096 FXUS63 KGRR 160102 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 902 PM EDT Sun Mar 15 2026 .KEY MESSAGES... - Rain and Thunder tonight with a low threat for Severe storms - Much Colder with Lake effect Snow on Monday into Tuesday && .UPDATE... Issued by National Weather Service Detroit/Pontiac MI Issued at 857 PM EDT Sun Mar 15 2026 Colder air has maintained itself over the northern CWA with sites reporting temps at or just below freezing. This has prevented a full changeover to liquid rain, instead falling mainly as freezing rain with some snow mixing in. As such, ice accumulations up to around a tenth of an inch are likely from Clare to Mason counties though some areas, particularly Mason, could be closer to 0.15-0.2". Evening update was to begin the Winter Weather Advisories for Newaygo, Oceana, Mason, and Lake this evening to account for icing before snow tomorrow as well as adding Osceola and Clare for tonight given their ice potential. A short fused upgrade to advisory for Mecosta could be needed tonight if obs begin to show freezing rain making inroads that far southeast. && .DISCUSSION... Issued at 303 PM EDT Sun Mar 15 2026 - Rain and Thunder tonight with a low threat for Severe storms We have hoisted a Winter Weather Advisory for the western two rows of counties and extended and expanded the Wind Advisory. Temperatures across Lower Michigan this afternoon range from 30 degrees at CAD to near 70 at the MI-IND border. Despite over 50 knots of deep layer shear, the severe weather threat is limited by a lack of instability as seen by forecast and observed soundings. A first batch of convection has weakened as it moved into a more stable environment this afternoon with dew points still in the 30s down to I-94. The dew points across the southern zones should recover to the lower 50s based on upstream obs, but the threat for severe appears to be limited to isolated wind gusts this evening across the far southern/southeast zones. Sfc low tracks through central Lower Michigan with cold advection beginning after midnight and synoptic winds expected to begin or continue gusting to 40 to 50 mph for all zones by daybreak. - Much Colder with Lake effect Snow on Monday into Tuesday Strong CAA continues all day Monday and temperatures will drop into the teens by evening. Model soundings show inversion heights around 8 kft and strong northwest flow with snow showers penetrating far inland. With temperatures well below freezing, blowing snow will reduce visibilities through Tuesday morning. The snow showers will diminish on Tuesday as the upper trough axis shifts east surface high pressure builds in. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY EVENING/... Issued at 739 PM EDT Sun Mar 15 2026 The warm front is expected to lift north of KGRR toward TAF issuance, driven northward by rapidly intensifying low pressure forecast to move from Illinois this evening to central Lower Mi by Monday morning. Warm sector mixing will support a few wind gusts over 35 knots at times. The exception may be KMKG which recent observations suggest may linger on the cool side of the front this evening. Inbound convection will track across the terminals in the 01Z to 04Z time frame. Although there may be some fluctuations in wind speeds within the broad region of showers overnight, the intensity of the wind fields will justify leaning on the strong end of guidance, with continued gusts over 30 knots. The associated cold front will rotate across SW MI between 08Z and 11Z, marked by a wind shift to the SW. Deepening mixing and continued strong wind fields will support wind gusts near 40 knots through the day Monday. Cold air will also ramp up the lake effect snow showers, some of which may be intense during the afternoon. && .MARINE... Issued at 303 PM EDT Sun Mar 15 2026 No changes to the Gale and Heavy Freezing Spray Warnings. After a line of showers and thunderstorms go through this evening the winds will go northwest on Monday with occasional gusts to 40 knots. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Winter Weather Advisory until 8 AM EDT Monday for MIZ037>040-043- 044. Wind Advisory until 11 PM EDT Monday for MIZ039-040-045-046-051- 052-058-059-064>067-071>074. Winter Weather Advisory from 8 AM Monday to 11 AM EDT Tuesday for MIZ050-056-057-064-065-071-072. MARINE...Gale Warning until 5 AM EDT Tuesday for LMZ844>849. Heavy Freezing Spray Warning from 8 AM Monday to noon EDT Tuesday for LMZ844>849. && $$ UPDATE...KDK DISCUSSION...Ostuno AVIATION...04 MARINE...Ostuno

NWS GRR Office Area Forecast Discussion