textproduct: Marquette

KEY MESSAGES

- Warmer than normal temperatures are favored through early next week.

- Low relative humidities paired with gusty winds and warm temperatures Friday and Saturday lead to elevated fire weather conditions. Red Flag Warnings are in effect for the far west on Friday where critical fire weather conditions are expected.

- Light rain showers tonight into Friday. Heavier rain showers as well as strong to potentially severe storms accompany a low pressure system early next week.

DISCUSSION

Issued at 353 PM EDT Thu May 14 2026

Afternoon GOES water vapor imagery and RAP analysis place the UP underneath an eastward shifting omega block pattern. Beneath it, high pressure ridging extending from James Bay over the western Great Lakes down toward the Lower Mississippi Valley also moves east. The trough upstream from the UP is moving out over the Canadian Prairie bringing a surface low with it. The high pressure overhead is yielding pleasant and dry weather with afternoon temps in the 60s for most of the UP; mid 40s to 50s by the lakeshores. A few spots may reach into the low 70s over the west yet this afternoon. Efficient mixing has already brought RHs down into the 20s to mid 30s percents with lowest values interior west. Thankfully winds are light with gusts ~15 mph where RH is lowest. That said, winds will continue to increase into tonight.

High pressure continues shifting east tonight, giving way for a shortwave, warm front and the associated round of light rain showers. Despite PWATs ~1 inch, QPF amounts will struggle to exceed 0.1 inches. This is due to the brevity of the event and the antecedent airmass in place. There's only a 25% chance for amounts up to 0.25 inches over the central UP and Keweenaw. Temps tonight settle into the 40s to mid 50s, warmest far west where downslope flow prevents efficient cooling. Once in the wake of round of showers Friday morning, mostly dry weather is expected. The warming pattern continues on Friday under increasing southwest flow. Highs are expected in the mid 70s to mid 80s west and mid 50s to upper 60s east where cooler onshore flow of Lake Michigan is occuring. A passing 40-45 kt LLJ yields gusty conditions throughout the day between 25-35 mph. These conditions and efficient mixing lowering RH down to 20-30% in the west lead to critical fire weather conditions. Elevated fire weather conditions are expected in the Keweenaw and central U.P. where minimum RH will not be as low or only briefly touch Red Flag Warning criteria. Given these conditions, opted to hoist a Red Flag Warning for Friday afternoon for Gogebic, Ontonagon, S Houghton, Baraga, and Iron counties from 1 to 9 pm EDT / 12 to 8 PM CDT. An additional SPS likely will be hoisted with the next forecast package to address elevated fire weather concerns outside that region. Friday night stays mild and mostly dry in the 50s.

Flow overhead becomes zonal on Saturday with an elongated mid level wave grazing the northern end of the CWA. Limited moisture and forcing mean dry weather likely persists (90% chance). Breezy west winds start the day off, gusting into the 20-25 mph range, but taper off in the afternoon as the gradient flow weakens and weak ridging begins building in from the Canadian Prairie. Highs will be in the 60s to low 80s, warmest south. Once again efficient mixing from dry air aloft presents another SPS day for elevated fire weather conditions. This high pressure influence persists through much of Sunday. Saturday night will be cooler in the upper 30s to 40s, warming up on Sunday into the upper 50s to low 70s; interior west reaches into the mid 70s. Sunday presents the last day for possibly elevated fire weather conditions interior west as winds pick up in the afternoon when RHs dip toward 30% or slightly lower. This will depend on how quick cloud cover ahead of the next precip arrives.

Attention then turns to a trough over the Rockies that sends shortwaves and possibly multiple surface lows over the region Sunday night through Tuesday. While model agreement in the pattern has improved somewhat in the last 24 hours, noteworthy changes in the overall narrative have occurred and still could given that this energy is still out over the Pacific...so confidence in exact details or timing is low. Overall expecting multiple rounds of showers and storms Sunday night through Tuesday. A warm airmass with a good Gulf connection ahead of these waves primes the region with ample moisture (PWATs between 1.25 and 1.75 inches) and instability. A warm front and primary shortwave likely bring the first wave Sunday night. Steep mid level lapse rates, sufficient bulk shear, and elevated instability around 1000 J/kg could yield some strong to severe storms. There is a 20-40% chance for up to 1 inch of rain over the far west with this round. Instability increases through Monday to between 1000-2500 J/kg alongside maintained steep lapse rates and shear, increasing strong to severe storm potential with trailing shortwaves/additional low pressure systems. Chances for greater than 1 inch of rain increase UP wide Monday/Monday night to 25-50%. Too many discrepancies remain in the upper pattern progression and surface tracks to nail down details, but will monitor severe potential with the coming forecast packages. The SPC Severe Weather Outlook has expanded the 15% chance across much of the UP now.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 141 PM EDT Thu May 14 2026

VFR conditions prevail under local ridging. Tonight through tomorrow morning, a deepening low pressure continues to lift from the High Plains NW into far northern Ontario. This will send an elevated front from west to east across the UP overnight through the early morning hours. Light precip looks to reach IWD by ~4z pressing east to SAW by ~11z. With a very dry airmass already in place, VFR cigs are largely expected though MVFR cigs may develop under heavier showers. Gusty S to SW winds between 20-30 kts will be common tonight through the rest of the TAF period.

MARINE

Issued at 353 PM EDT Thu May 14 2026

Relatively light winds (<20 kt) persist until this evening, then build out of south as a low passes eastward from the Canadian Prairies to Ontario. Starting late tonight until late Friday, southerly winds increase to around 20kt sustained, with gusts up to 30kt over the open lake and particularly in the east. There is a 30- 40% chance of gale-force gusts Friday throughout the day, so localized low-end gale gusts may occur. Despite model agreement that low-level jet wind speeds will reach at least up to 50 kts throughout early Friday morning, with the surface of Lake Superior around 36F (GLERL), the cold and stable surface layer will prohibit much of these higher wind speeds from mixing down. Significant wave heights are not expected to exceed 7 feet due to the passage of this first low.

Winds veer and diminish throughout day on Saturday, remaining calm until Sunday when a second low moves toward the Upper Great Lakes from the Plains. Timing, track, and strength of this system vary considerably, with some of the earliest models bringing the center of the low to the western edge of Lake Superior by as early as 06Z on Monday morning and as late as 18Z on Tuesday. At the time of this writing, though, NBM shows mostly 50-60% chance of gale-force gusts over western Lake Superior Sunday evening, similar probabilities over eastern Lake Superior early Monday morning, and 40-60% chance of widespread gales throughout much of the day on Tuesday. This system is also expected to be accompanied by thunderstorm potential.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Red Flag Warning from 1 PM EDT /noon CDT/ to 9 PM EDT /8 PM CDT/ Friday for MIZ002-004-009-010-084.

Lake Superior... None. Lake Michigan... None.