textproduct: Marquette

KEY MESSAGES

- Lake effect snow today and tonight could yield impactful travel conditions in western and eastern Upper Michigan. Winter Storm Warnings now in effect for Ontonagon and N Houghton. Multiple Winter Weather Advisories for western and eastern Upper Michigan as well.

- Light lake effect snow lingers in the NW wind belts Tuesday into early Wednesday.

- Additional rounds of system snow and lake effect snow are expected Thursday through the weekend.

- Low temperatures around 0 degrees with wind chills in the negative double digits for the interior west Monday through Wednesday mornings.

- Pattern into late January favors cooler than normal temperatures and active weather.

SHORT TERM /THROUGH TONIGHT/

Issued at 325 AM EST Mon Jan 13 2025

Secondary shortwave associated with yesterday's clipper continued to support light snow across the central and eastern portions of the forecast area overnight, with lake effect developing over western Lake Superior and pressing into the western counties. Tough to tell from webcams, but accumulations from this secondary shortwave appear to be light but are still resulting in some snow covered roadways. Aloft, a closed upper level low is currently pressing south near Lake Winnipeg while another shortwave is moving eastward through the Arrowhead. So far temperatures have been in the teens west and 20s east.

For the remainder of the night and through tonight, the upper level low will continue pressing south, which will help push east the shortwave over the region now, bringing an end to the snow this morning. Lake effect will continue in the west though under a cooling airmass aloft with northwest flow, gradually becoming west- northwesterly as the pressure gradient sharpens over the region. The results of this will be increased gustiness over the forecast area and lake effect showers continuing in the west through the day and developing and pressing into the eastern U.P. late this morning or afternoon. Expecting fluffy snow enhanced by terrain in the west yielding another 2 to 7 inches during daylight hours of the west to west-northwest wind snow belts. In the east, shoreline convergence in these bands may result in an additional 1 to 3 inches into eastern Alger and northern Luce. There is the potential for a stronger band to press into eastern Luce this afternoon, which could yield an area of 5-8 inches of snow in 6 hours. Current guidance suggests this should press into the county south of Grand Marais.

Last night, guidance has suggested strong clusters of showers developing along the surface trough over Lake Superior today, then dropping into Upper Michigan tonight. Snowfall rates in this band could increase to 0.5-1 inches per hour, mainly in Alger/Luce county. Through tonight, an additional 2 to 6 inches will be possible in the west and eastern snow belts with isolated higher amounts being possible along the Spine and in eastern Luce. Given this uptick in snow amounts and the higher amounts are along key routes from Houghton to Mass City, opted to upgrade the inherited Winter Weather Advisory in Ontonagon/N Houghton to Winter Storm Warnings, add in Weather Winter Advisories for S Houghton, Baraga, Alger, N Schoolcraft and Luce counties. Opted to wait for adding Marquette County to monitor today's CAM guidance for trends in the southward descending snow band.

LONG TERM /TUESDAY THROUGH SUNDAY/

Issued at 333 AM EST Mon Jan 13 2025

By Tuesday morning, the surface trough will be dropping southward through the UP while the midlevel rough slides over the Lower Great Lakes , with westerly winds veering northwesterly in response. With 850mb temperatures at around -16 to -18C and a saturated DGZ, lake effect snow should continue across the NW wind snow belts in the western and eastern UP. However, lowering inversion heights and drier air moving in should cut back on snowfall rates, with only a couple more inches of snow expected Tuesday through Tuesday night. Breezy conditions continue, with NW wind gusts up to around 20-25mph especially across the Keweenaw and eastern UP. Winds fall back into the night, while temperatures in the teens to lower 20s Tuesday afternoon fall back to overnight lows in the single digits above and below zero across most of the UP. The eastern UP may be able to stay slightly warmer overnight, generally around 10F.

The remainder of the forecast period remains fairly active, but relatively low-impact. High pressure approaching the area will decrease confidence in lake effect continuing through Wednesday, especially as surface winds become more southwesterly, helping to push lake effect bands offshore. Beyond then, ensembles have coalesced around a solution that brings a low pressure system through far northern Ontario late Wednesday night into Thursday, though a cold front draped from it will bring at least some snow to the UP. Snowfall rates are generally expected to be less than an inch per 6 hours with this system. Warm advection with the southwesterly flow ahead of the system will bring some above freezing temperatures to some portions of the UP, especially for Delta and Schoolcraft counties upstream of Lake Michigan. This could (~15% chance) introduce a brief period of rainfall Thursday. Guidance continues to favor another clipper passing through the region sometime Friday into the weekend, though differences in the particulars on timing and rack persist. This will bring our next window for some "system" snow beginning Friday, with lingering lake effect into the weekend. Strong Alaskan ridging beginning late next weekend into the following week looks to support cold arctic Canadian air spilling into the Upper Great Lakes region, with NBM highs in the low single digits and NBM lows into the negative double digits for the interior west by Sunday night.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 635 AM EST Mon Jan 13 2025

Lake effect snow showers today with gusty winds of 20 to 30kts will produce prevailing IFR/MVFR conditions at KIWD and KCMX today. This afternoon, expect ongoing MVFR conditions to fall to IFR as lake effect ramps up. Expect these conditions to continue overnight as winds shift to NW to NNW. At KSAW, conditions will improve to VFR conditions today. This evening and overnight though, guidance suggests a stronger band will move south through Lake Superior. Its possible this may result in quickly deteriorating conditions

MARINE

Issued at 333 AM EST Mon Jan 13 2025

Active weather pattern to provide multiple chances for gale force conditions through the next week. First, a low pressure passing directly over Lake Superior today is causing wind gusts of 25-30 kt out of the northwest over the west end of Lake Superior with isolated gale force gusts within 5 miles of the Minnesota shores. Over the east, winds turning more northwesterly are increasing to gales to 35-40 kt. Widespread gales fall off tonight, but a few gale force gusts may linger across the eastern half of the lake through Tuesday morning (~20% chance). A passing high pressure will gradually ramp down winds to below 20 kt by Tuesday night. Chances of gales increase sharply by Wednesday evening with a cold front moving through the region, with southwesterly wind gusts up to 40 kt possible (60-70% chance) over the west half of the lake potentially giving way to northwest gales to 35-40kts (30-50% chance). Another low pressure system moving through the region will bring a gale potential into next weekend, but confidence is low on the track and timing of this next system. Moderate to isolated heavy freezing spray is possible during gale force conditions, with wave heights of 8-10ft (locally up to 12 ft in areas of higher fetch) possible during the later periods of the gales.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Winter Weather Advisory until 7 AM EST /6 AM CST/ Tuesday for MIZ001-009.

Winter Storm Warning until 7 AM EST Tuesday for MIZ002-003.

Winter Weather Advisory until 7 AM EST Tuesday for MIZ004-084.

Winter Weather Advisory from 1 PM this afternoon to 7 AM EST Tuesday for MIZ006-007-085.

Lake Superior... Gale Warning until 9 AM EST this morning for LSZ244-245-248- 264-265.

Gale Warning until 10 PM EST this evening for LSZ266.

Gale Warning until 10 PM EST this evening for LSZ267.

Lake Michigan... None.