textproduct: Gaylord

KEY MESSAGES

- Shower and storm chances build into eastern upper by Sunday morning, spreading across the rest of the region through the afternoon into Sunday evening. Localized downpours possible.

- Dry start to next week with rain chances returning by Tuesday.

- Trending cooler after midweek with highs in the low to mid 70s.

DISCUSSION

Issued at 255 PM EDT Sat Aug 15 2026

Pattern / Forecast Synopsis:

Ridging overhead in the process of being dispatched stage right into northeastern NOAM. Double barrel shortwave setup to traverse the region later tonight into Sunday: a primary wave over Manitoba that will pass to the north of Lake Superior, and a convectively charged wave associated with a stationary front (the one that has been causing high end hydro issues across Illinois, Indiana, and Ohio the last week) that will lift north into southern Michigan Sunday. Anticipation is that the stationary front will remain well to the south, suppressing deeper moisture (surface dewpoints into the mid 70s) south of the area, but nonetheless anticipation is we see dewpoints spike into the upper 60s to lower 70s (so it's still gonna be a bit humid here), especially the farther south and east one goes in the CWA. Passage of the primary shortwave will force a cold front through the region. Coupled with decreasing 500mb heights and diffluence aloft, instability should be readily available with modest synoptic forcing to generate a convective response across the region. Associated convection / thunderstorm activity will carry on Sunday afternoon before the cold front passes and high pressure returns for a short period on Monday. Progressive flow regime makes a comeback next week, reinforced by digging longwave troughing over Hudson Bay. Initial likely convectively charged wave passages anticipated around midweek before aforementioned longwave troughing digs farther south and settles into northeastern NOAM, with the Great Lakes right on the western periphery of the feature.

Details:

Wedge of drier air to play heck on rain chances today, as the primary deeper moisture axis suppresses northward advancement of moisture to downstate... as evidenced by visible satellite, which showcases a mid level cloud deck sharply cutting off right near the M-55 corridor. Current thinking is that this plume of cloud cover eventually does advance northward through tonight, and perhaps a shower materializes across the far southern reaches of the CWA. Additional support from the northern stream wave should drive shower and perhaps thunder activity in eastern upper later tonight as the core of forcing and moisture approaches. Sunday looks to be the day for transient downpours as PWATs surge to the 1.50-1.75 range, complete with skinny CAPE profiles (essentially screaming that the atmosphere is juiced and probably gonna turn loose). Best overlap of forcing, instability, and moisture will come in two phases... the morning hours over eastern upper should see help from elevated convection owing to LLJ processes. Transient downpours could easily drop a quick localized 1.00"+, but overall, there should be enough storm motion to eschew hydro issues for our friends north of the Big Bridge. Should be noted... there is potential for some places in eastern upper to get skipped by rain.

Storm coverage over far northern and northwest lower to remain much more isolated through the morning into the afternoon. Front to pass through during peak heating the farther south and east one goes, coupled with subtle Lake Huron generated boundaries amid S to SSE flow. Result should be a pronounced uptick in convection across far northeast lower amid an increasingly moist profile. As such, while much of northern lower sees isolated downpours, the area generally along and east of a Cheboygan to Tawas line poses the greatest risk for repeated downpours, and, while not specifically outlooked by SPC, wouldn't be surprising to see a locally stronger to marginally severe storm (primary concerns wind and hail) considering some guidance throwing instability values in excess of 1500 J/kg right during the frontal passage and peak shear. As far as rainfall and amounts go... anticipate some places west of I-75 (in particular the farther south one goes) to hold dry through Sunday, with isolated downpours producing localized totals of 0.50-1.00"+. In northeast lower, storm coverage will be greater, so there will be less "rain gaps", indicating more spatial coverage of at least 0.10-0.25" of rainfall than the rest of northern lower. In the aforementioned highlighted area of northeast lower, potential for repeated downpours does pose a risk for localized 2.00"+ rainfalls over a short duration of time, but here too, anticipation is that downpours will be transient enough to dissuade hydro concerns on much more than a marginal, localized level.

Looking ahead, high pressure returns by Monday ushering in drier and seasonable weather. Next system quick to return by Tuesday delivering another round of showers and thunderstorms to the region. Deeper longwave troughing to build into the region thereafter, which will induce seasonably cool temperatures in the low to mid 70s, perhaps moderating to the upper 70s lower 80s by the weekend.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 1135 PM EDT Sat Aug 15 2026

VFR conditions are expected into early tonight. Winds will become generally light tonight from the southeast, increasing and turning northwest by Sunday afternoon with gusts around 20 kts. A few light showers are noticed on radar as low to mid clouds increase ahead of showers/ thunderstorms expected early Sunday morning lasting through the evening... Within any stronger storms, heavy rain could impact visibilities. MVFR/IFR conditions look to begin to improve ~18z, especially for TVC/ MBL as shower/ thunderstorm chances increase across APN.

APX WATCHES/WARNINGS/ADVISORIES

MI...None. MARINE...None.