textproduct: Marquette

KEY MESSAGES

- Another round of showers with isolated thunderstorms is expected this afternoon and evening, mainly in the central UP. - Temperatures remain below normal this weekend into early next week.

UPDATE

Issued at 3xx AM EDT Sat Jun 20 2026

The going forecast remains mostly on track this morning as KMQT radar returns show scattered to isolated light rain showers over the central and western UP in response to a weak shortwave passing over the area. Precip should remain weak, and confidence is low (sub-20%) that whatever does fall early this morning will even be measurable (0.01"+). As noted in the previous discussion, CAMs do begin to bring more widespread PoPs back into the area after 14Z as diurnal heating and a steady supply of vorticity about a 500mb closed low over the Ontario/Manitoba line coincide with the left exit region of a ~100kt 250mb jet. High temperatures struggling to break into the 70s today thanks to cool northwesterly flow aloft will keep lapse rates tame and the HREF only shows isolated pockets where chances of 500+ J/kg of SBCAPE exceed 20%. Therefore, expect whatever showers do form to have some isolated thunder, but should remain sub-severe. Chances of precipitation fall below 15% after 00Z. Besides the NBM showing ~15% PoPs Sunday afternoon, a generally drier period is expected as high pressure builds south into the Great Lakes from the Canadian Prairie early next week. The next chances for widespread precip look to be late Tuesday into Wednesday as the GEFS shows a cluster of 1010-1015mb low pressures cutting from North Dakota to Wisconsin, but confidence is too low to deviate from the NBM much at this time.

DISCUSSION

Issued at 347 PM EDT Fri Jun 19 2026 Amended at 3xx AM EDT Sat Jun 20 2026

Cyclonic flow orbiting the persistent Hudson Bay/Nunavut low continues to dominate weather patterns in the UP. This afternoon will bring a similar story to yesterday, though with diurnally-driven PoPs rather than synoptic-driven PoPs in the western, central and southern UP. Again, CAMs show weak radar returns beginning in Ontonagon/Keweenaw Counties around 14Z and progressing southeastward toward Delta County into tonight. With a couple hundred j/kg of HREF MUCAPE present between Lake Superior and the WI border and similar QPF distributions to yesterday, be prepared again for passing thunderstorms and showers this afternoon and evening if you are in these areas. Sunday looks to be drier and still cool.

Looking ahead to next week, although the current perpetual troughing and steering jet streak deteriorate and move east beginning on Monday, another low forms nearly immediately in its wake over Ontario, though ensembles indicate that heights associated with this will be less anomalously low. That said, the cooler pattern continues. The ECMWF'S EFI within the WFO MQT domain shows anomalously cold (<-0.7) Tmax and Tmin for Days 1-7, except for Day 2, when values are simply slightly less negative (-0.67 for Tmax and negative 0.57 for Tmin). Additionally, days 4-7 for Tmax and days 5-7 for Tmin show a nonzero SoT, indicating possibility (albeit with low confidence) of more 'extreme' values for these fields. So, although a pattern disruption is expected early next week, surface temperatures are expected to remain roughly the same as they have been through this coming week.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 136 AM EDT Sat Jun 20 2026

Ongoing 0530Z conditions are VFR at all sites. With SHRA in the VC of IWD, cloud bases are trending lower and with higher coverage as chances of MVFR conditions exceed 50% by 07Z and chances of IFR exceed 45% by 10Z. Just as quickly as ceilings fall at IWD, they will rebound in the morning, with 80+% chances of VFR conditions by 17Z. SAW and CMX will remain VFR through the period, though each will have a period of 15-45% chances of precipitation today. As SAW will have around 15% chances of thunder with the SHRA this PM, will include CB mention in the PROB30 group, though confidence is low.

MARINE

Issued at 3xx AM EDT Sat Jun 20 2026

Weak pressure gradient this weekend followed by high pressure into the beginning of next week will keep wind gusts sub-20 kt in the forecast through this forecast period. The best chances for gusty conditions on the lake will be in the vicinity of thunderstorms, which are around 15-25% likely along the northwest shores of the lake this afternoon and then again along the southern shores late Tuesday through Wednesday in response to a low pressure passing south of the lake. In response to the low winds, waves will also be low, with the only 2+ ft waves forecast for late Monday in the east due to light, but long- duration, long-fetch northwesterly winds.

MQT WATCHES/WARNINGS/ADVISORIES

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