textproduct: Gaylord

KEY MESSAGES

-Shower and storm chances this afternoon / evening across eastern upper and portions of northeast lower.

-Additional shower and thunder chances Friday, again favoring northeast lower and eastern upper. Rain chances continue into Saturday. Limited footprint of appreciable rainfall suggests that rainfall amounts in excess of 1-2" will remain highly localized through the weekend.

-Drier and cooler to start next week, with warmer weather and rain chances building by next Tuesday.

DISCUSSION

Issued at 235 PM EDT Thu Jul 30 2026

Pattern / Forecast Synopsis:

Convoluted weather pattern locally courtesy of a pair of disturbances riding a weak point in jet stream flow. Northern wave, much more robust with attendant 998mb surface low, will continue a south and east progression over Hudson Bay into the weekend. Southern wave set to manifest as a convectively charged wave over South Dakota and Nebraska later today, riding a regime of NW flow into Iowa and illinois by the weekend. Cold frontal boundary from the northern wave will slowly progress south and east Friday into Saturday as the southern wave passes to our south and west. Nose of deeper moisture along the front will be drawn southward from the frontal boundary into northern lower, resulting in budding instability development in an environment that will essentially become the neutral point of the trough from Friday into Saturday. Weak synoptic flow may lead to lake breeze processes becoming the lifting mechanism in northeast lower Friday afternoon, with outflow driven convection spreading westward across the region. Meanwhile, the approach of the cold (and soon to be stationary) front will provide enough forcing to generate convection across eastern upper. Eventually, this front will slowly drift southward into Saturday, and should exit by Sunday, with rising (but still low) 500mb heights supporting a period of drier and cooler weather into early next week before the next wave passage is progged to transpire across the Great Lakes.

Details:

Today - Tonight: Subtle pre-frontal trough currently analyzed from roughly Thunder Bay to Escanaba will provide just enough forcing to continue shower and thunder development through the evening across those regions, perhaps sending a few showers into NW lower overnight, but realistically the better shot of rain by the evening into the overnight will first be driven by lake breeze convergence processes over eastern upper, and to a lesser extent, northeast lower. Surface dewpoints in the low to mid 60s should provide just enough to force some diurnal instability. Storm coverage may increase in eastern upper later tonight as the stationary front increases.

Friday-Saturday: Influx of deeper moisture (dewpoints anywhere from 64 to 70) makes its presence known by Friday as the double barreled systems move closer. Weak westerly flow coupled with ample daytime heating should be enough to drum up a Lake Huron lake breeze. As instability builds through the day, could see a very outflow dominant batch of convection, likely very pulsey in nature, manifest through late morning into the afternoon. With the stationary front drawing closer to eastern upper, greatly instability potential supports a better shot at rain up there through the day Friday. Resultant stratiform rain with embedded downpours to sag southward into northern lower with the advance of the front Friday night into Saturday... which may trend a bit more showery through the day (especially areas south of the front, looking at M-55 in particular) before activity wanes into the overnight hours. Will need to watch how any embedded downpours behave over this timeframe.

Aforementioned deeper moisture plume will balloon PWATS potentially as high as 1.75 at the zenith of moisture concentration, which suggests very efficient rainfall potential. As such, looking at probabilistic guidance, most areas have a 48hr (through 00z Sunday) 50th percentile value of 0.40-0.75" of QPF, with the highest values favoring aforementioned M-55 corridor, up the Lake Huron coast and into eastern upper. 48hr (thru 00z Sunday) 90th percentile (i.e, only a 10% chance this much rain or more falls over that period) tops out at 1 to 2.50" area wide, with highest amounts focused on northeast lower and eastern upper, which to me, suggests that Friday's convective potential may drive robust rainfall in the event the environment supports repeated convection. In addition, the lack of forcing conveys that not everyone is set to see high rainfall rates. These patters are extremely fickle, and area-wide, it would be unsurprising to see some areas see less than 0.05" of rain, while some localized area sees rainfall in excess of 2.50" over 48 hours. At this juncture, severe potential looks limited to storm core collapse processes on Friday when the most robust convection is anticipated, and a widespread organized severe threat seems unlikely.

Rest of the period: Cooler Canadian air filters in behind the front by Sunday, with cooler and drier weather to kick off next week. Seasonable to perhaps above normal temps return Tuesday-Wednesday as the next wave approaches, bringing with it, the next rain chances after this weekend.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 114 PM EDT Thu Jul 30 2026

VFR expected thru the period, though any SHRA or TSRA could bring MVFR or lower visbys into play. Still a lot of uncertainty in how things play out given upstream storms over W. Lake Superior, but think there is a shot at some shower/storm development here late afternoon into this evening, esp on the Lake Huron lake breeze near APN and CIU, though we more likely stay dry. Better shot for SHRA/TSRA may be tonight into Fri AM, but with low confidence in how this plays out, too. Lake breezes and light flow today; light flow hangs on tonight but could turn more W by morning as a front starts to drape in.

APX WATCHES/WARNINGS/ADVISORIES

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