textproduct: Gaylord

KEY MESSAGES

-Showers and thunderstorms expected this evening into tonight. Potential for severe storms and heavy rain.

-Seasonably cool temperatures and breezy conditions continue though Wednesday. Showers linger Tuesday and into Wednesday.

-Overall quiet weather returns the rest of the week with little to no additional precipitation chances.

DISCUSSION

Issued at 407 PM EDT Mon Jul 20 2026

Pattern / Forecast Synopsis:

Northwest flow aloft remains in full swing as a robust shortwave passes through the Great Lakes region, with attendant occluding surface cyclone over northern Ontario. Associated occluded frontal boundary currently stretches from roughly the NW Lake Superior shore, passing NW of the Twin Cities (at the triple point) and a cold front runs toward Sioux Falls, SD... warm frontal boundary associated with the system running south from aforementioned triple point SSE through Saint Louis. Return flow will draw this front northward, but it is anticipated to stall out over western upper MI, south through WI and IL. Thus, most vigorous convection this evening to be suppressed SW of the CWA. That being said, good mid level support and diffluent 500mb and 300mb flow will still support deep convection over our neck of the woods, albeit, with a weakening trend, through later tonight. Following the passage of the occluded frontal boundary late tonight, lingering low level moisture should support additional diurnal convection through the day Tuesday and perhaps into Wednesday. Subtle ridging and subsidence should return by Thursday, aligned with surface high pressure passage, resulting in a drier day. Additional embedded 500mb height disturbances pass through over the weekend, perhaps supporting a returning rain / storm threat.

Details:

Severe Potential through Tonight: Current 1pm glance at radar and satellite shows the remains of some robust convection the initiated over western upper this morning making a run at eastern upper MI and the NW lower lakeshore. Anticipating this to continue weakening as it passes through the region, owing to a complete and utter lack of instability across the region... which may be an issue we fight through this event until better thermodynamics are forced into the region with the system's approach. As such, potential for a scattered shower or rumble of thunder anticipated to be confined to the aforementioned regions through the afternoon. Efficient mixing has led to surface dewpoints across our area to dip into the upper 50s and lower 60s... with the much more robust moisture holding over the western Corn Belt. This drier air will likely make high instability difficult to attain, but won't completely zero us out. As such, with the approach of the frontal boundary later this evening, anticipate upstream convection, while weakening, to maintain itself into at least the western half of the CWA, partially aided by a plume of developing elevated instability courtesy of an accelerating low level jet upwards of 50kt. Anticipated convective evolution entails a transition from discrete supercells over western / central upper MI to a linear mode by the time it reaches our doorstep this evening.

With the elevated nature of the storms, will see the threat of tornadoes diminish considerably, though SPC maintains a 2% risk over the region. The primary hazard will be damaging winds, which, despite the elevated instability profile, can still mix down with any gravity wave interactions to force those LLJ winds to the surface. As such, SPC has maintained the 15% risk for winds across the region. Severe hail, while possible (5% risk), is not anticipated to be overly widespread owing to the discrete mode not being able to be maintained. Current prognosis favors a window of roughly 7pm to 4am for the highest risk of severe weather across the region... and the general weakening trend is highlighted well with the SPC outlook... maintaining an Enhanced Risk (Level 3/5) over WI and western / central upper MI... a Slight Risk (2/5) eastward through most of our CWA, and a Marginal Risk (1/5) from the Lake Huron shores of Saginaw Bay north to the Alpena area.

Hydro Concerns Tonight: Not to be lost in all the noise of the severe potential, torrential rainfall will be possible with these storms as they make it through the region. PWATS progged to go north of 1.25 this evening / tonight. Some CAMs do support localized training convection, which could easily put some embedded 2.00"+ rainfall amounts down over any area that realizes this. Overall current SPC HREF guidance shows two concentrated highest probability areas of convection across the Great Lakes: one just to our SW across WI and leaking into IL and IA... and another that originates from western / central upper MI and carrying through the Straits region and eastern upper (should be noted probabilities for thunder exist CWA-wide, these are just the highest probability regions across the Great Lakes / Midwest). Considering recent rainfall trends (including all the way back to April), the Tip of the Mitt region southeast to APN, along with portions of eastern upper, and the Leelanau / Antrim / Otsego corridor remain highly sensitive to torrential rainfall rates. Toyed with the idea of a targeted Flood Watch for some of these areas, but thinking is that convection should remain transient enough to limit widespread issues. This too will need to be assessed with time through the evening.

Tuesday - Wednesday: Tight pressure gradient with this system will keep quite breezy conditions overhead as winds turn more NW (sustained 10-20mph, gusts 25-35mph) and cooler air begins to spill into the region. Lingering low level moisture supports additional diurnal shower and thunder development Tuesday , and with continued skinny CAPE profiles, may be heavy at times. Greatest instability favors NE lower, so while severe storms are not anticipated, that would be the area that serves most likely to see severe convection. Lesser shower coverage into the day Wednesday, but another trough passage will permit continued convection through the afternoon amid continued, but lesser breezy conditions (NW winds 10-15mph, gusts up to 25-30mph). Bigger story will be the seasonably cool weather... highs struggle to break 70 north and approach 80 south on Tuesday, and even cooler Wednesday with highs in the 60s to maybe mid 70s in the south.

Rest of the Period: High pressure returns drier weather Thursday. Return flow slowly materializes through the weekend, bringing back seasonable temperatures in the upper 70s to lower 80s. With subtle increases in humidity and the potential for additional 500mb height disturbances, there will be potential for more rain / thunder Friday through the weekend, but details are a bit murky this far out.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 135 PM EDT Mon Jul 20 2026

Decaying batch of showers will provide some light rain at CIU, PLN, and TVC early this afternoon - without much impact other that a brief visibility restriction. Smoke will still pose some minor visibility concerns for the balance of the day. The main weather maker is the developing line of thunderstorms over the western Upper Peninsula - which is expected to expand in coverage through the afternoon hours. Forecast timing has be adjusted to an earlier arrival given the current observed development. Otherwise, some MVFR clouds behind the front through the rest of the night as winds flip around to west-northwest. Clouds will lift Tuesday morning and the smoke is expected to be less of an issue.

APX WATCHES/WARNINGS/ADVISORIES

MI...Beach Hazards Statement through Tuesday morning for MIZ016-024- 025-031-095-096-098. MARINE...Small Craft Advisory until 11 PM EDT Wednesday for LHZ345>349. Small Craft Advisory until 11 PM EDT Wednesday for LMZ323-341- 342-344>346. Small Craft Advisory until 11 PM EDT Wednesday for LSZ321-322.