textproduct: Gaylord

KEY MESSAGES

- Rain/storm chances hang out in the region through at least Friday/Friday night...heavy rain and a stronger storm or two possible at times, especially today/tonight.

DISCUSSION

Issued at 353 AM EDT Thu Sep 3 2026

PATTERN SYNOPSIS/FORECAST:

SW flow aloft across the central US, feeding plume of very hot air (850mb temps up into the 25C range) and steep mid-level lapse rates from the SW US across the central and northern Plains attm. Broad troughing over the W US, including an upper low and attendant 100kt upper jet poking into the PacNW...and a PV max swirling almost due north through MT into Alberta. Broad troughing over eastern Canada with influences across the Lower Great Lakes and New England where the bulk of the convection has been ongoing as of 4z. Confluence and zonal flow over the Great Lakes between upper ridge over the SE and upper low near James Bay; a plume of deeper moisture (pwats at or above 1.5in) stretches along this confluence zone from the Plains eastward through the Upper MS Valley and into the Lower Great Lakes. Now that remnants of "Edouard" are tracking deeper into TX, starting to see better Gulf moisture transport north up the MS Valley. SW LLJ is a bit stronger tonight across the Plains as well...upwards of 40kts or better at 850mb, more or less orthogonal to aforementioned boundary from the Plains to Lower MI...but does turn to the SE across the Northern Plains up into Canada ahead of the occluded surface low in Alberta ahead of aforementioned PV maximum. Low-level col region and/or deformation axis over the Upper Midwest attm between upstream feature and last lobes of energy swirling around through Ontario on the backside of the James Bay area upper low. Slightly cooler and slightly less humid air around attm, with Tds across most of northern Lower in the upper 50s to lower 60s, vs the juicy upper 60s to lower 70s we had the day before...though that juicy air mass remains across S. MI south of aforementioned boundary.

PV over MT and a little wind of PV ahead of it track northward toward Canada today...resulting in the baroclinic zone buckling northward as upper low over James Bay slowly releases its grip on our weather...and will anticipate an increased threat for showers/storms tonight into Friday morning along said boundary, including into northern MI. Will need to keep an eye out for convection to ride the ridge axis into the Great Lakes Friday night into Saturday, which could lead to a damper start to the holiday weekend. It also appears high pressure will attempt to ooze back into northern MI from Ontario this weekend as the ridge axis strengthens just upstream; this will put a confluence zone likely well to our north across Canada, and may need to keep an eye out for any of this activity to try to drift down the thickness gradient into the Great Lakes. Signals point toward the ridge axis building into the Upper Midwest and even Great Lakes for Labor Day and perhaps beyond...with strengthening easterly flow across southern Canada and perhaps parts of the Upper Midwest...as energy ejects out of the western trough and drives pressure falls across the northern Plains. The overall pattern going into midweek next week suggests we will remain in a warm, moist, and potentially unsettled environment (barring any mid-level stability provided by the ridge)...though the evolution of the ejecting energy is unclear and will determine how strong a surface response is had in the Great Lakes next week. Increasing uncertainty in the pattern beyond the middle of next week, primarily in the evolution/strength/position of upstream troughing, which will impact how much of an influence the ridge axis will continue to exert on our area going into the second weekend of September.

FORECAST DETAILS...

Rain/storm chances today/tonight... Current expectation is for upstream convection (currently struggling to develop over IA as of 6z but finally taking shape around 7z over N. IA/S. MN) to eventually develop across MN/WI this morning as the deformation axis lifts northeastward. If this early morning batch does not hold together well, it may take till 12-15z to get going, which is when there is better synoptic-level support for ascent. Either way, will look for upstream convection to track generally eastward into Lower MI with time through the day. Think the greatest instability will remain to our south and west...but we will be on the instability gradient as a plume of steeper lapse rates aloft sneaks in this morning and the boundary (and juicier boundary layer) lifts back northward. Sticky wicket for spicier storms is mid-level warmth, as it would put something of a cap on deep moist convection potential this afternoon, particularly if we do not moisten/warm enough in the low levels to overcome this cap (and this may be harder to do as we may end up on the north and likely, stratiform- rain-with-embedded-thunder side of the boundary). Jet max moving through today (and redeveloping upstream this afternoon) should support sufficient deep-layer shear for storm organization for those storms that do get going...and could support upscale growth with time. Better shot at this would be to our south or to our west, the latter idea particularly this afternoon/tonight with LLJ-driven convection again (though progged thickness gradient orientation could trend it just to our southwest).

Think heavy rain will be a threat again today, given the deep warm layer, potential for skinnier CAPE, and relatively weak flow in the low-levels that could allow storms/rain to move slowly along this east-west(ish) boundary in the region...not to mention pwats at or above 1.5in again. If we end up with some sort of deformation axis forcing going this afternoon, we could be looking at a swath of rainfall in excess of 0.75-1in in 6hrs or less, perhaps near the M- 72/M-55 corridor...but any storms could certainly put down over an inch of rain (hi-res prob guidance suggests a non-zero threat of rainfall totals in excess of 2in, albeit a very small percentage). Current forecast does not reflect this higher-QPF idea attm, given lack of confidence in where the storms will focus...and certainly possible the heavier totals could end up just south of our area.

We remain close to the boundary Friday, and depending on what happens tonight, may be dealing with some leftovers from tonight Friday morning. It may not be out of the question tonight's activity could start further north along the edge of the 700mb cap over the Plains, which, if it occurs, could lead to some upstream convection sneaking in further north than expected...but we may not know till tonight if this idea will take place. It also appears we could remain under the deformation axis through much of Friday, which could keep the threat of better rainfall around into Friday as well. A similar ridge-riding pattern remains in place Friday night, and while it is more likely the action will stay to our west/south in WI and southern MI, it is worth keeping an eye on into at least the first half of Saturday. As mentioned in the pattern forecast above, it appears high pressure will try to ooze in from the northeast beyond Saturday, which should shunt the bulk of the action further to our west for the remainder of the weekend.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 1144 PM EDT Wed Sep 2 2026

Some fog expected at all sites but TVC overnight. MBL has already dipped down to MVFR briefly, then rebounded. CIU is the most likely to drop to IFR/LIFR. Some additional showers/storms could move in from WI on Thursday, best chance for that is at MBL and perhaps TVC. Mainly VFR from mid-morning Thursday onward. Light winds.

APX WATCHES/WARNINGS/ADVISORIES

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