textproduct: Marquette

KEY MESSAGES

- The threat for flooding continues due to snowmelt. A Flood Watch is in effect for everywhere except the far western UP through Saturday morning.

- Southerly gales up to 40 knots are expected over east-central Lake Superior this afternoon into this evening.

- Showers and thunderstorms are expected with a cold front late this afternoon into this evening. Widespread totals of 0.25 to 0.75 inches are expected.

- Some stronger storms capable of producing hail and strong wind gusts are possible late this afternoon into early this evening over the west half of the U.P.; while the chance is very low (less than 5%), a spin-up tornado also cannot be ruled out.

- Becoming much cooler this weekend, which will slow snowmelt.

- West to northwest gales up to 35 knots are possible late tonight through Saturday. A Gale Watch is in effect for most of the lake save for the far west.

DISCUSSION

Issued at 222 AM EDT Fri Apr 17 2026

While satellite imagery early this morning is showing mostly clear skies across the area, there is an area of marine fog along Green Bay that is bringing locally dense for along the shoreline from Escanaba through Rapid River (as evidenced by webcam imagery). While this isn't quite necessitating a Dense Fog Advisory yet for Delta County, will continue to monitor the situation as marine fog is expected to expand across Green Bay through the rest of the pre-dawn hours; the shoreline along Menominee County and southern Schoolcraft County may need to be monitored too depending on how great the expansion is of the marine fog. Otherwise, having cooled from the warm, Spring-like temperatures we saw yesterday, we may see a patch or two of fog form in the low-lying cold spots as some isolated spots have fallen into the 30s early this morning. However, with widespread fog not being expected across the area during the pre- dawn hours, no Fog Advisory (save for maybe near Lake Michigan and Green Bay) is expected for the U.P. early this morning. Overall, expect to see the U.P. cool into the 30s and 40s this morning, with the far west potentially remaining in the lower 50s as they've lost all of their snowpack and southerly winds continue to increase.

After dawn this morning, expect temperatures to rise as southerly winds pick up across the area as very warm air from the Gulf is pulled into the region. With partly cloudy skies and strong warm air advection moving in to the area today, expect temperatures to soar once again into the 70s over the western U.P.; as for the east half, thinking the increasing southerly winds may help to push the marine layer from Lake Michigan across this portion of the U.P., thus limiting temperatures to the 50s and 60s. While a robust 50-60mph LLJ at 850mb looks to move over the area this afternoon, with an inversion setting up shop at 925mb expect the mixing into the LLJ to be somewhat limited. Thus, while we may see a few southerly wind gusts up to 35 to potentially even 40 mph late this afternoon ahead of the cold front moving in late this afternoon/this evening (up to around a 100% chance according to the REFS and HREF, but only up to a 40% chance in the NBM), expect the stronger wind gusts to be relegated to the south-wind downslope areas near Lake Superior. As of right now, there is no plan to issue a Wind Advisory for the south-wind downslope areas near Lake Superior as confidence/chances for maintaining 45+ mph wind gusts through today are too low.

Expect the strong cold front to push through the U.P. beginning late this afternoon over the far west. With guidance suggesting the front coming in a couple of hours sooner than previously expected, this may increase the severe weather threat for the western half of the U.P. late this afternoon into early this evening as convection may be more sfc based. Indeed, if the convection is more sfc-based over the west half (and the trend seems to suggest this), then all of the severe weather threats could be on the table: severe hail and winds as well as a low-end chance for a spin-up tornado. That being said, the better dynamics for severe weather do look to be south of us in Wisconsin and further south. Therefore, while strong to severe storms are possible late this afternoon into this evening over the western half of the U.P., the chances of having hail of one inch in diameter or greater and for damaging winds of 60 mph or greater is around 5-10%, and the chance for a tornado is around 5% or less. In addition to the severe threat, some downpours of rain could bring a quick quarter to three-quarters of an inch of rainfall to areas where convection occurs; while not expected to be widespread, there could be a few spots that see over an inch of rainfall, with the latest HREF showing up to a 40% chance of this occurring. Therefore, while it won't be as impactful as the rainfall that occurred this past Monday, the rainfall in addition to the areas with remaining snowpack melting today could bring river rises and create/enhance ponding in the low-lying and poor drainage areas of the central and east this evening; with the far west being snowpack-free for the past couple of days, the flooding threat looks to be low (less than 5%). However, with the soils remaining saturated and several inches of SWE left in portions of the remaining snowpack in the central and east (most of the snowpack left is in the higher terrain of the north central and Keweenaw), the flooding threat is a little higher (5% or greater).

Once the cold front passes through this evening, we may see a quick changeover to light freezing rain/sleet/snow at the end of precipitation associated with the cold front tonight as temperatures rapidly drop. However, with the moisture being relegated to the lower-levels as the last of the frontal precipitation moves through, thinking any wintry precipitation that does fall tonight to bring no more than a trace of ice/snow at most to the area. As cold air advection works into the area late tonight through Saturday, expect the strong northwest winds over Lake Superior and delta-Ts increasing into the mid-teens to potentially bring light lake effect snowfall over the northwest and west wind snow belts Saturday into Sunday. However, with sfc high pressure building in, accumulations would be limited to just up to a dusting if the lake effect occurs; if the dry air from the incoming high pressure wins-out, then expect nothing more than some lake effect cloud cover across the area and potentially a few flurries. While the confidence in lake effect snow showers is low to medium at this point, there is high confidence that temperatures will be well below normal this weekend; expect it to feel more like winter once again this weekend as highs across the area struggle to get above freezing, especially in the northwest wind snow belts. That being said, the areas outside of the northwest wind snow belts and the lake effect cloud cover could get into the 40s thanks to some sunshine.

As we head into the rest of next week, expect a gradual warming trend as generally dry conditions remain across the area until near the end of the forecast period. Thankfully, the cooler temperatures this weekend and drier conditions through the rest of the forecast period look to decrease flooding potential across much of the area.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 736 AM EDT Fri Apr 17 2026

Main aviation concerns are: 1) lingering morning fog at SAW, 2) low- level wind shear through this morning, 3) southerly winds gusting to near 30 kt today, and 4) potential for thunderstorms after ~20Z today.

1). Fair SSE flow off of Lake Michigan is advecting low level moisture across much of the SE half of the UP, nosing into SAW within the last hour. As has been the case the last few nights, thinking that fog should lift through the next few hours, becoming VFR through the rest of the late morning and early afternoon.

2). LLWS and gusty winds: Strong low-level jet should bring LLWS conditions to all terminals for a time for the remainder of the this morning before diurnal mixing brings stronger winds to the surface late morning into the afternoon. Expect wind gusts to be near 25-30 kt for much of the day today, strongest at IWD.

3.) TS potential: An approaching cold front will bring a band of showers and embedded thunderstorms to the western UP mainly after ~19-20z, continuing eastward across the rest of the UP through ~06- 09z. A stronger storm containing large hail and gusty westerly winds cannot be ruled out at IWD. Have opted to include prob30s for TSRA with this TAF cycle at all sites.

MARINE

Issued at 244 AM EDT Fri Apr 17 2026

As a robust cold front approaches from the west today, expect the winds to increase from the southeast to south ahead of it across Lake Superior, with gales up to 35 to 40 knots expected over the east-central lake by the afternoon hours as a few of the strong winds from a LLJ at 850mb reaches the sfc. Because of this, a Gale Warning has been issued for the east-central lake from 3 PM EDT to around midnight EDT tonight.

As the front begins to push convection over the far western lake this afternoon, a few strong to severe thunderstorms may be seen; while the chance is low due to the cold waters hampering the sfc- based convection, there is a non-zero chance for damaging hail and winds as well as waterspouts. As the front continues to push through the rest of Lake Superior this afternoon through this evening, expect the severe weather threat to diminish, eventually going away late tonight. Nevertheless, some erratic gale force winds from the convection could make it to the sfc over the eastern half of the lake this evening/tonight as the cold front pushes through the region.

Behind the cold front, expect strong cold air advection to bring west to northwest winds of around 30 knots across the entire lake late tonight into Saturday. As of the time of this writing, the REFS and NBM bring a 50 to around a 100% chance of low-end gales to the lake from before dawn Saturday morning through the day. Therefore, a Gale Watch has been issued for all but the far western lake 2 AM EDT to 11 PM EDT Saturday; it is worth noting that a Gale Warning is in effect for the katabatic winds along the North Shore tonight through Saturday as the chances for gales are higher over there.

As high pressure moves into the area early next week, expect the winds to progressively die down Saturday night through Sunday; expect the winds to lighten up to 20 knots or less by Sunday night. While calmer waters are expected for early Monday, a dry cold front dropping down from northern Ontario has over a 40% chance to bring south to southwest gales up to 34 knots over at least the eastern open lake Monday night into Tuesday morning.

HYDROLOGY

Issued at 253 AM EDT Fri Apr 17 2026

NOHRSC analysis showed snowpack remained over the northern half of the U.P. were several inches to over a foot of SWE remained, greatest in the higher terrain. Snowmelt will continue through today as the warm, moist airmass from the Gulf advects over the U.P. An area of showers and thunderstorms will move through late this afternoon through this evening with generally 0.25-0.75 inches of rainfall expected across most of the area, although there is up to a 40% chance for greater than 1 inch possible in some of the thunderstorms. Colder weather is expected for late tonight through Sunday, which should slow the melt of any remaining snowpack.

Waters remain high in the southern U.P. where recent heavy rains and snowmelt contributed to flooding of low-lying areas and some rivers. Rivers will continue to rise in portions of the northern U.P. due to continued snowmelt and additional rainfall. A Flood Watch remains in effect over the central and eastern U.P. today through tonight. Once drier and cooler air moves overhead for this weekend through next week, expect the flood risk to decrease. Therefore, expect the Flood Watch to expire by Saturday morning.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Flood Watch through Saturday morning for MIZ001-003>007- 010>014-084-085.

Dense Fog Advisory until 9 AM EDT /8 AM CDT/ Sunday for MIZ006- 011>014-085.

Lake Superior... Gale Watch from late tonight through Saturday evening for LSZ241>250-263>266.

Gale Warning from 3 PM this afternoon to 11 PM EDT this evening for LSZ244-245-264-265.

Gale Watch from late tonight through Saturday evening for LSZ251-267.

Gale Warning from 3 PM this afternoon to midnight EDT tonight for LSZ266.

Lake Michigan... Dense Fog Advisory until 11 AM EDT this morning for LMZ221-248- 250.