textproduct: Marquette

KEY MESSAGES

- Benign weather with cooler than normal temperatures expected for the rest of this week.

DISCUSSION

Issued at 223 PM EDT Tue May 5 2026

GOES-East Day Cloud Phase RGB imagery shows a broken stratocu deck with a few embedded deeper streaks of clouds where some overperforming light showers have been able to deliver some surprising bursts of snowfall, ice pellets, and rain. These showers are prevailing against increasing surface pressure and a trend of decreasing 500mb vorticity as the main cutoff low lifts into James Bay and the ridge over the western Canadian Rockies has been able to build surface high pressure in the lee of the Rockies, in addition to cold air advection at 850mb. The culprit seems to be a weak 500mb embedded shortwave coupled with a compact thermal trough evident on SPC mesoanalysis. The aforementioned cold air has also allowed for some lake enhancement as 850mb temps around -7 C are compared to the lake surface which is around 4 C.

For the rest of today, the aforementioned weak localized forcing amongst poor conditions on the synoptic scale will allow for weak off-again, on-again showers to continue, though impacts are not expected as chances of even 2 tenths of an inch of snow accumulation are only in excess of 10% for the Mount Arvon vicinity and the Painesdale area and chances for a tenth of an inch of total precip accumulation is only above 15% for the US-2 corridor in far-eastern Schoolcraft County. With the continued cold air advection, some elevated gusts aloft are being brought to the surface, with observed gusts still in excess of 30 mph are still ongoing for the Keweenaw and around 20-25 mph elsewhere especially along Lake Superior. The cooler air and increased cloud cover will keep RHs from falling too far, though some portions of Menominee County will be far enough away from Lake Superior to see enough breaks in the clouds to heat up to the mid 50s and drop RHs to near or below 30%. Expect lows tonight around freezing at the Great Lakes lakeshores and in the upper 20s in the interior.

A similar ripple in the 500mb flow will cause similar conditions tomorrow as today, with chances of measurable precip only rarely exceeding 10-20% for any given hour at a given point, but chances of at least some weak precip (aka sprinkles or flurries) are more consistently around 30-50%. Highs remain mostly in the 40s with winds decreasing somewhat to around 10-15 mph, perhaps a little higher for the Keweenaw.

For the end of the work week and beyond, the upper air pattern changes little, with the Hudson Bay trough refusing to budge except to wobble some and send periodic weak shortwaves and disturbances across the region. With the 500mb height in the bottom 5-10 percentile of climatology and sustained north to northwest flow aloft, cooler than normal temperatures prevail, though the NBM deterministic shows Saturday as the warmest day of the week, with highs around 60 for the interior and around 50 for the Lake Superior shores. Should the pattern hold much like today, fire weather concerns will be pretty much nil as cloud cover and the occasional light shower help temper RHs and the lack of nearby synoptic surface pressure features keeps wind gusts low, as well as the aforementioned cooler than normal temperatures. However, if a given day is more clear than another, RHs could fall to the 20s percent range in the interior west.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 720 PM EDT Tue May 5 2026

VFR conditions are expected overnight at all the TAF sites. Winds will diminish through the evening and remain west-northwest through Wednesday. Scattered rain showers are possible tomorrow during the afternoon, with the best chance at SAW. Any showers that form could bring brief MVFR conditions. Mentioned showers with a prob30 at SAW.

MARINE

Issued at 223 PM EDT Tue May 5 2026

Cold advection is pushing gusty west winds aloft to the surface, with west wind gusts around the Keweenaw Peninsula of 25-30 kt this afternoon and 20-25 kt elsewhere. However, as the low pressure in James Bay continues to weaken and depart, the gradient driving the wind decreases and gusts fall below 20 kt overnight. With the major surface pressure systems remaining away from the Upper Great Lakes, the chances of wind gusts exceeding 25 kt are less than 20% for the rest of the forecast period.

MQT WATCHES/WARNINGS/ADVISORIES

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