textproduct: Gaylord

KEY MESSAGES

- Multiple rounds of showers and thunderstorms expected through Tuesday...a few of which could be strong to severe.

- Mostly dry weather expected after Tuesday.

- Above normal temperatures to kick off this week, with temperatures again cooling to below normal levels through the middle and end portions of the week. Frost/freeze concerns Wednesday night.

DISCUSSION

Issued at 202 PM EDT Sun May 17 2026

Large scale NOAM upper level amplification well underway early this afternoon...driven in large part by strong shortwave trough and 120+ knot upper jet core digging rapidly southeast into the Intermountain West. Secondary anti-cyclonic 120+ knot upper jet streak rotating east across northern Ontario also helping this amplification process...driving steadily increasing heights across the eastern Conus and Great Lakes. Strong moist/warm advection between these features rotating up through the central and northern Plains...with maturing surface boundary, weak low pressure, and MCV from overnight convection all helping ignite showers and storms within this increasing warm and moist axis. Southern lower Michigan stationary front showing signs of beginning its northward journey as a warm front as this return flow strengthens, with subsequent burgeoning isentropic upglide and moisture convergence (enhanced by MCV rotating northeast across southern Wisconsin) helping drive an area of showers and embedded thunderstorms into the western Great Lakes ...including now parts of our western footprint.

Per the northern Michigan warm season convective usual, plenty (emphasizing "plenty") of uncertainty in just how things unfold the next several days...with much of that uncertainty tied to how upstream convective trends unfold. Does appear their will be multiple opportunities to see some showers and storms across the Northwoods...first with current northward bowing warm front/approaching MCV...followed by sustained deep moisture advection and eventually cold frontal passage on Tuesday.

Primary Forecast Concerns:

Shower/storm evolution and severe potential through Tuesday.

Details:

Overall, a rather low confidence forecast through Tuesday. With that said, expect shower and thunderstorm threat to expand north with time the remainder of this afternoon and evening as moist advection increases north of northward bowing warm front and approaching MCV. Confidence remains low on overall deeper convective coverage, but definitely could see some locally heavier rain amounts with some hints of convective training along convectively congealed cold pools. Again, not entirely sure where (if) that sustained convergence will reside, but something to monitor with potential of one inch plus rain totals by sunrise Monday. Cannot rule out an isolated severe storm or two as well given northward expansion of enhanced mid level lapse rate plume/attendant core of elevated instability and respectable wind shear through the convective layer...with the latter enhanced by that approaching warm front. Main concern would be some marginally severe size hail, although cannot completely rule out an isolated wind threat or tornado, especially near and south of the warm front where surface based instability will reside.

Uncertainty remains high heading into Monday as well. Not overly confident on just how aggressive the northward push to the warm sector will be given potential for those overnight cold pools to slow its northward progress. Could see showers and storms continue to percolate along and to the north of this front, with additional afternoon shower/storm development within the warm sector as aggressive surface heating overcomes intial capping layer aloft. Could also see upstream dying convection make a run into the area (which could act to offset that aggressive heating and additional convective development). Definitely more questions than answers. Latest Storm Prediction Center Convective Outlook continues to place all areas south of the Mighty Mac in slight risk wording for severe storms...with all facets of severe attributes possible (to include 2 probs for tornadoes down near Saginaw Bay). Can definitely see this concern given the possibility for aggressive afternoon warming/attendant development of surface rooted instability within a still very favorable kinematic environment. Will simply have to see how things evolve tonight into tomorrow morning for better severe weather assessment Monday afternoon.

And...those convective uncertainties continue right into Monday night and Tuesday. Little doubt we will see additional rounds of shower and thunderstorms through this period with sustained deep moisture advection and eventually passage of the cold front on Tuesday, though exact timing/coverage/and intensity of those storms are far from certain. SPC continues to place the southeast half of our area under slight risk severe wording on Tuesday...with that risk tied to just how aggressive surface warming can become prior to frontal passage. Again, best course of action is to simply continue to monitor trends as we head through this period.

Cold frontal passage later Tuesday is a rather strong one, with rather aggressive drying and cold air advection kicking in Tuesday night into Wednesday...with highs on Wednesday likely not getting out of the 40s for at least parts of our area. Could very likely be looking at another night of frost/freeze concerns Wednesday night as high pressure looks to settle directly overhead. Pretty remarkable to already see the guidance consensus blend put low temperatures Wednesday night down into the lower and middle 30s (especially considering this blend is at least partially weighted toward normal values...which will be in the lower and middle 40s for Wednesday's date). Temperatures gradually moderate Thursday into the weekend under mostly quiet conditions.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 154 PM EDT Sun May 17 2026

VFR conditions to start, then CIGs decrease with scattered showers and thunderstorms later this afternoon and into the overnight hours. Expect MVFR and IFR possible within the most persistent rains. East winds continue as well, generally 5 to 15KTs, outside of any thunderstorms across KMBL which may produce gusty winds. Lower CIGs slowly lift northward through the night with KTVC and KMBL back to VFR after 06Z. Another round of showers and storms will be possible on Monday, favoring the afternoon and evening, although there is uncertainty in coverage during the morning hours. Low level wind shear is expected as well, with 30 to 40KTs possible ~06 to 14Z.

APX WATCHES/WARNINGS/ADVISORIES

MI...None. MARINE...Small Craft Advisory from 11 PM this evening to 8 PM EDT Monday for LMZ323-342-344>346. Small Craft Advisory from 8 PM this evening to 8 PM EDT Monday for LMZ341. Small Craft Advisory from 11 PM this evening to noon EDT Monday for LSZ321-322.