textproduct: Gaylord

KEY MESSAGES

- Freeze conditions over eastern upper and interior northern lower locations tonight, with frost potential elsewhere

- Frost potential for some spots Thursday night into Friday morning, with high fire danger potential Friday afternoon

- Gradual warming trend through the weekend, next rain chances arrive late Friday into early Saturday and will linger through Sunday

DISCUSSION

Issued at 136 PM EDT Wed May 20 2026

Current surface analysis show cooler air filtering in under generally northwest winds as a broad surface high seeps east over the northern plains towards the Great Lakes. Satellite depicts some lingering lower level moisture upstream (Ontario CAN and WI/MN) within this cooler airmass. In the upper levels, a quasi -PNA is seen with a few pockets of more concentrated energy moving through the larger flow over the northern Rockies and into southeastern CAN. This has somewhat flattened the upper ridging, resulting in mostly zonal flow over northern MI which will linger into tonight and early Friday.

With high confidence in the center of the surface high seeping over the U.P. of MI tonight, chances for temperatures to dip to near freezing or below do exist. However, where the coldest temperatures are for the longest duration will be up to cloud cover. Lingering lower level moisture will still exist tonight, with even some mid-high level clouds moving over northern lower early in the night as well. Without a dry column through much of the night, chances for longer duration freezing temperatures and/or widespread hard freeze conditions decrease. This isn't to say freezing temperatures won't be seen, in fact there is high confidence that temperatures will dip to freezing or just below over the typical interior cold spots for at least 2 to 4 hours. Where ideal conditions align (interior spots that have clear skies the whole night and larger areas of eastern upper), temperatures could dip into the high 20s. Frost conditions will be likely over the remainder of the area under this cooler airmass. Not only will cloud cover work to keep temperatures warmer, but northeast to east winds over areas along and south of M-55 will also remain elevated enough to keep the airmass mixed and temperatures remaining above freezing.

Skies will clear during the day on Thursday, allowing for temperatures to warm a few degrees. Winds will be diurnally driven, becoming breezy in the afternoon hours as mixing heights rise. Lake breezes will be seen in the afternoon/evening hours as well, which could shift directions around.

Friday, upper troughing over the western US will start to organize and become negatively tilted as it reaches the northern plains. Ahead of this, the locally amplified upper pattern will move an upper ridge over northern MI. Although winds aloft will be weaker, a strengthening lower level gradient will be seen as features organize in the plains. Initial vertical profiles over northern MI show ample dry air in the lower levels with east winds of 15 to 20 mph and possible frequent gusts up to 25 to 30 mph Friday afternoon ahead of this system. This would result in high fire danger concerns for Friday afternoon, especially after a couple days of drying. Uncertainty exists with how low RHs will go due to cooler air off of Lake Huron moving inland, and the duration and exact values of winds.

Early Saturday morning, deep gulf moisture will eventually work its way over northern MI from the south and west. Widespread rain chances return for the weekend, with storm chances late Saturday and/or Sunday. Widespread cloud cover Saturday and east winds could keep temperatures from warming a few more degrees, however temperatures will rise into the high 60s and 70s Sunday.

Moisture and warmer temperatures will linger into early next week, without clear signals of widespread showers and storms. An amplified upper ridge will reach northern MI near the end of the period, signaling a continuation to the warmth but a potential break in precipitation chances mid to late next week.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1251 PM EDT Wed May 20 2026

VFR likely to prevail through the TAF period. Occasional drops to MVFR cigs possible this afternoon for most sites, esp south of M-32. Winds largely NW/N this afternoon 10-15kts (though non-zero chance of lake breeze at MBL) gusting as high as 20-25kts, diminishing to 5- 10kts or less after dark, with land breezes possible overnight...as high pressure moves across the eastern UP/Tip of the Mitten region. Do wonder about fog development tonight, and have alluded to this at MBL/APN for now. Winds Thursday morning likely more NE to E with MVFR cigs possible.

APX WATCHES/WARNINGS/ADVISORIES

MI...Frost Advisory from 1 AM to 9 AM EDT Thursday for MIZ016>018- 020-021-024>026-030>036-041-042-088-099. Freeze Warning from 1 AM to 9 AM EDT Thursday for MIZ022-023- 027>029-086-087-095-096. MARINE...Small Craft Advisory until 2 PM EDT this afternoon for LHZ345>348. Small Craft Advisory until 2 PM EDT this afternoon for LSZ321- 322.