textproduct: Gaylord

KEY MESSAGES

- Showers and thunderstorms through tonight with strong/severe thunderstorm potential along with a heavy rain threat.

- A little cooler and a little breezy Tuesday with an increasing Great Lakes swim risk.

- Maybe more unsettled weather for next weekend.

DISCUSSION

Issued at 318 AM EDT Mon Jul 27 2026

Pattern Synopsis/Forecast: Broad upper ridge encompasses the southwest/southern Plains and the lower Mississippi Valley...with a split trough long wave trough across eastern North America. Closed low in the northern branch of the split trough is part of a high- latitude block from Hudson Bay eastward across the North Atlantic. Long wave trough off the west coast is firing pieces of energy over the top of the western ridge...one such wave was moving into northern Manitoba with a second over southern Saskatchewan. Elongated latent PV anomaly around the fringes of the upper ridge associated with the cyclonic shear side of an anticyclonically curved jet extending from off the California coast...up and around the periphery of the ridge and diving across the Great Lakes/mid Atlantic. Steep mid level lapse rates/elevated mixed layer spreading into the Great Lakes from the northwest...700mb temperatures at or above +12C knocking on Michigan's doorstep. Sunday evening surface analysis shows the usual summer mesoscale chaos: 1002mb surface low along the North Dakota/Minnesota border with a wavy frontal boundary extending to a 1005mb frontal wave over Lake Superior. A second warm front extends southeast across Minnesota/Wisconsin/Illinois and into the Ohio Valley...with 70s- lower 80s dew points pooled along and on the warm side of this front. Michigan is in a narrow wedge between these two boundaries.

Northern Manitoba short wave trough digs southeast across the Great Lakes today...reinforcing the southern branch of the split long wave trough downstream. Overall pattern configuration doesn't look to change much through midweek; forecast trends continue to show a more blocky pattern across the Atlantic basin...with more agreement on a closed low developing in the southern branch over the mid Atlantic/ southern New England...as well as more agreement that height rises will push into the Great Lakes for midweek. For the latter half of the week...energy undercutting the ridge may allow for some height falls across the eastern CONUS and some overall retrogression of the pattern as the ridge amplitude sharpens across the Rockies in response to a strong upper low moving into the Pacific Northwest/ British Columbia next weekend (an impressive 600dam 500mb high centered in the vicinity of the Four Corners next weekend).

Low pressure moving across the Great Lakes later tonight will become better organized as it moves into the lower Lakes tonight...with a stronger pressure gradient setting up across Michigan for Tuesday as a result. High pressure nudges into the upper Lakes Wednesday/ Thursday along with rising heights as the downstream pattern gets backed up. Looking at some height falls and possibly a frontal passage for Friday/Saturday.

Primary Forecast Concerns:

Showers and thunderstorms through tonight with strong/severe thunderstorm potential along with a heavy rain threat: As of this writing (0630Z)...a narrow northwest-southeast line of convection is developing from southern Lake Winnipeg to northeast Wisconsin. A smaller cluster of thunderstorms is dropping southeast across eastern Upper Michigan....also getting some radar returns east of I- 75 in northern Lower. All of this is developing along an elevated instability gradient... which will be shifting across the upper Lakes today. Current thinking is that upstream convection will propagate east during the overnight hours (mid level winds are backing more west)...and eventually spread into northern Michigan this morning. It is quite possible that with surface low approaching this afternoon...along with larger scale forcing with digging short wave trough/left front quadrant jet forcing...there may be several clusters of storms impacting northern Michigan throughout the day into tonight. Severe threat will certainly be in play today given magnitude of the instability and deep layer shear...have already popped off a few SVRs across eastern Upper this morning. Other concern is heavy rain potential...especially the way upstream convection is lining up. As a result not going to get too cute with PoPs and timing...if there is a larger break in the precipitation then so be it...otherwise one is just asking for trouble. Plan to have an explicit mention of heavy rain in the forecast through this evening.

A little cooler and a little breezy Tuesday with an increasing Great Lakes swim risk: Tighter pressure gradient and some momentum to mix down expected to result in gusty winds Tuesday from the north/ northwest...on the order of 20-30mph. Higher waves in a more limited northerly fetch would be south of Grand Traverse Light on Lake Michigan (high swim risk for Manistee County...moderate for rest of northwest Lower shoreline counties)...and south of Thunder Bay Island on Lake Huron (moderate swim risk for northeast Lower shoreline counties). Cold water upwelling also a concern on the Lake Michigan side. Highs Tuesday should be mostly in the 70s.

Maybe more unsettled weather for next weekend: After tonight next threat for rain arrives on Friday as short wave energy cuts underneath the western ridge and dives across the Great Lakes/Ohio Valley.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 618 AM EDT Mon Jul 27 2026

Multiple rounds of storms will be possible across northern Michigan today ranging from this morning into this evening, making it difficult to pin-point precise timing at specific locations in the TAFs. That said, highest confidence in best storm coverage across the area comes later this afternoon and early evening. Otherwise, patchy FG/BR across parts of the area is expected to burn off shortly after sunrise. Southwest to west winds around 5-10 kts are anticipated for most areas today with lake breeze formation likely pushing inland from Lake Huron this afternoon. Drops to MVFR/IFR CIGs will be possible with any storms later today and may linger into tonight with low-level moisture hanging around after a cold front swings through this evening.

APX WATCHES/WARNINGS/ADVISORIES

MI...Beach Hazards Statement from Tuesday morning through Tuesday evening for MIZ031. MARINE...None.