textproduct: Marquette

KEY MESSAGES

- Lake enhanced/effect rain showers spread back into the east today and continue through Thursday.

- Gusty north to northwest winds expected today and Thursday.

- Continued cool/unsettled into Thursday.

- Drier with a bit of a warming trend this weekend to early next week.

DISCUSSION

Issued at 241 AM EDT Wed Oct 22 2025

As the low's center spins over Upper Michigan early this morning and southeast into the rest of the Great Lakes region today, lake enhanced to lake effect rain showers continue over the north to northwest wind belts, with the precipitation spreading east with time the rest of today. Given the synoptic support of being in the northwest quadrant of the low, we could see some moderate rainfall rates at times today over the western half of the U.P.; some spots like the Michigamme Highlands west of Marquette or in the higher terrain of Gogebic and Ontonagon counties could see 0.50 to 1.00 inches of rainfall throughout the next 24 hours (chances depend on model run and where the heaviest rain bands set up; thinking it is around a 50 to 90% chance); with temperatures dropping into the 30s tonight in the interior areas, we could also see some snowflakes/graupel mix-in with the rainfall at times. As for the eastern half of the U.P., thinking rainfall amounts will be significantly lower due to the rain showers taking their time to get over that way today; the HREF currently only shows up to a 50% chance of receiving greater than half an inch or liquid today and tonight from Munising eastward, with areas away from Lake Superior only receiving a few hundreths between this afternoon and tonight. Outside of the rainfall today through tonight, winds will be fairly gusty today, with wind gusts up to 35 to 40 mph possible at times near the Lake Superior shoreline. Thankfully, it looks like winds will calm a little tonight as mixing between the surface and higher levels of the atmosphere weakens.

As troughing and cold air advection continue over the region, expect a continuation of lake-effect rain showers over mainly the northwest wind belts Thursday into Friday. While shortwave ridging pushing into the region will slowly eat away at the lake-effect precipitation with time, we may see up to an additional quarter inch or so of liquid fall over the northwest wind belts in the eastern U.P. between Thursday and Friday mornings. In addition, expect breezy northwest winds through Thursday too, with gusts up to 30 mph possible at times along the Lake Superior shoreline. With highs Thursday and Friday only getting into the 40s (for the most part) and lows ranging from the upper 20s to mid 30s, we may continue to see some snow/graupel mix-in at times in the lake-effect showers, particularly during the overnight hours over the higher terrain of the west half.

High pressure ridging eventually looks to put a stop to the lake- effect precipitation from west to east across the area Thursday night through Friday. As high pressure ridging moves over the Great Lakes region through this upcoming weekend, expect drier weather and a slight warm up, with highs getting into the 50s to potentially around 60F in a couple of spots. As a vertically-stacked low develops over the Northern Plains early next week, we may or may not receive rainfall from the low's warm front; it will depend on if a shortwave low develops over the Central Plains and digs into the Southeastern U.S. or not. If it does occur, then the rainfall should miss us to the west and south as remnant high pressure ridging keeps the area dry to end the forecast period. If this doesn't happen though, then we could see another wetting (0.25+ inch) rainfall event across Upper Michigan sometime early next week. Regardless, current guidance has us under a southerly surface flow pattern, which should keep high and low temperatures above normal for next week.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 727 AM EDT Wed Oct 22 2025

Remnant showers from low pressure over the eastern UP this morning will become lake effect SHRA throughout this TAF period, leaving all sites in MVFR and IFR today. Expect gusty N to NW winds in excess of 20 kt during the daytime hours, relaxing somewhat overnight. Improvement to VFR is not expected this TAF period, with the most likely site to see MVFR by tomorrow morning being IWD at around a 1 in 3 chance of VFR conditions.

MARINE

Issued at 305 AM EDT Wed Oct 22 2025

As the occluded surface low continues southeast into the rest of the Great Lakes region, the north to north-northeasterly gales up to 35 knots over the west-central lake this morning weaken to north to northwesterly winds of 20 to 30 knots across the waters over the next few hours as cold air advection continues to cycle through the region but the low departs the vicinity of the lake. The strong north-northwesterly winds continue through this evening into Thursday, backing more to the northwest slowly with time. While not expected, a rogue gale force gust or two up to 35 knots could be seen over the eastern open lake Thursday (up to a 10% chance according to the REFS). As ridging builds back into the Upper Great Lakes late this week, expect the winds to progressively dwindle over Lake Superior Thursday evening to Friday morning, eventually becoming 20 knots or less by early Friday morning. As high pressure ridging moves through the Great Lakes region this weekend, expect the lighter winds to remain until early next week at the earliest. If, however, remnant high pressure remains over our area early next week, expect the light winds to continue over Lake Superior.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... Gale Warning until 8 AM EDT this morning for LSZ242>245- 263>266.

Lake Michigan... None.