textproduct: Marquette

KEY MESSAGES

- The combination of warm, moist air contributing to snowmelt and moderate to locally heavy rain tonight into Friday will result in renewed flooding concerns for low-lying areas, streams, and rivers over the western half of the UP. A Flood Watch remains in effect.

- Unseasonably warm temperatures today settle back to near to slightly above normal Friday into the weekend. The next period of widespread precipitation is expected Monday into Monday night.

- A Gale Warning is in effect for central and eastern parts of Lake Superior near the international border this evening through Friday morning.

DISCUSSION

Issued at 331 PM EDT Thu Apr 23 2026

GOES visible satellite shows mostly sunny skies across Upper Michigan this afternoon, with warm and moist southerly flow helping temperatures to climb well into the 70s across the western half of the U.P. and generally into the 60s in the east. Higher dewpoints in the 50s are also helping to keep humidity values mostly in the 40% range and limiting any minor fire weather concerns from yesterday. Meanwhile, water vapor imagery depicts broad upper level troughing centered over Alberta and Saskatchewan, with an embedded shortwave trough lifting into the Dakotas. An occluding surface low is analyzed over southern Manitoba, with a cold front and associated precipitation extending down through the Upper Mississippi River Valley. This precipitation will move into the western U.P. later this evening as the surface cold front approaches the region, with some embedded thunderstorm activity also remaining possible. Most of the CAMs bring this activity into the western U.P. between about 7 and 9 PM EDT this evening. Guidance continues to suggest a brief window of marginally severe thunderstorms will be possible as MUCAPE values climb to around 1000 J/kg before the loss of daytime heating. Rather weak shear around 20-25 kt will limit this potential, but guidance continues to highlight around a 15% chance for severe wind gusts in the west through around sunset. Any severe threat will quickly subside as instability wanes with the loss of daytime heating, however elevated instability will maintain a general thunder threat as rain spread east across the U.P. tonight.

Attention then shifts to renewed flood concerns tonight into Friday as another round of rain looks to compound the issues with ongoing snowmelt. Model QPF values are more or less in line with previous thinking, with most of the U.P expected to see around a half inch of rain through Friday. Still, the potential is there for locally higher rainfall amounts given convective potential and PWAT values climbing to 1.00-1.25" across the U.P. tonight. Fortunately, latest HREF guidance depicts the highest probabilities to exceed one inch of rain (~40%) in the far west across Ontonogan and Gogebic counties where snowpack is already gone for the most part. HREF retains around a 15-25% to exceed an inch of rain across central parts of the U.P. including river basins where most of the ongoing flood concerns reside. Will continue to keep a close eye on how these basins respond through Friday and into the weekend. Refer to the Hydrology section below for further details on ongoing flood concerns.

Any lingering rain should depart the eastern U.P. by early Saturday. High pressure building back into the region should make for a pleasant and dry weekend with temperatures falling back closer to seasonal norms in the 50s and perhaps the 60s closer to the WI border. The next system looks to arrive early next week, with rain spreading back into the area Monday night into Tuesday. Will obviously need to monitor how this next round of precipitation will impact ongoing flood concerns as a relatively warm and moist airmass continues to contribute to accelerated snowmelt.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 121 PM EDT Thu Apr 23 2026

VFR conditions at all sites to begin this TAF period as relatively quiet weather persists ahead of a cold front. As that cold front arrives this evening into tonight, it will bring thunderstorms (~15% chance of a severe wind gust in the vicinity of IWD this evening) and rain showers to the TAF sites from west to east. While this will bring lowering ceilings, chances of MVFR conditions don't exceed 50% until 4Z at IWD, 10Z at CMX, and 11Z at SAW. Will begin MVFR ceilings a little earlier than the 50% probabilities to err on the safe side. Chances of MVFR vis are around 30% at all sites and will likely be dependent on whether a stronger cell goes directly over the terminal or not. Chances for thunder wrap up into early Friday morning, but showers are expected to linger into the end of the forecast period. Ceilings lower further to IFR at CMX and SAW closer to 12Z Friday.

MARINE

Issued at 331 PM EDT Thu Apr 23 2026

Winds will continue to increase out of the southeast this evening into tonight ahead of the cold front approaching from the west, with Gale Warnings in effect tonight through Friday morning over the eastern and central parts of the lake. The highest probabilities for gale force gusts of 35-40 kt will be found over the northern half of the open lake zones near the international border. NBM and some of the high-res guidance is also picking up on a threat for some southerly gale force gusts in the nearshore zones tonight, but expect this threat to be localized enough to cover with small craft headlines for now. Rain and possibly some embedded thunderstorms will spread across the lake from west to east tonight with the cold front. Do not expect any severe weather for the most part, but a few storms may be capable of producing stronger winds are small hail over the western arm near Duluth this evening.

Behind the cold front, expect the winds to become westerly gusting up to 20 to 25 knots Friday night into early Saturday. After that, expect light winds of 20 knots or less to return to Lake Superior for the rest of the weekend thanks to a weak pressure gradient and high pressure ridging.

HYDROLOGY

Issued at 331 PM EDT Thu Apr 23 2026

Dewpoints climb into into 50s Thursday today, combined with significantly warmer than normal temperatures and breezy conditions, will result in accelerating melting of the snowpack through Friday. Latest projections suggest an average of 2" per day of snow water equivalent could melt during this time. An approaching frontal boundary will spread another round of rain with some embedded thunderstorms across the U.P. tonight into Friday, with latest probs of > 1" in 24 hours remaining around 40% in the west tonight through Friday, decreasing to 15-25% in the central and east on Friday. Thunderstorms in the west half which could result in locally heavier downpours tonight. The combination of accelerated snowmelt and moderate to locally heavy rainfall has prompted the issuance of an Areal Flood Watch from this evening through Saturday morning for the western half of the UP. There is uncertainty on impacts given that the highest probability of heavy rainfall are south of the existing snowpack. However, renewed rises on area rivers and streams can be expected into the weekend and early next week. Flooding of low-lying areas, creeks, and streams can also be expected.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Flood Watch from 8 PM EDT /7 PM CDT/ this evening through Saturday morning for MIZ001>005-010-011-084.

Lake Superior... Gale Warning from 8 PM this evening to 2 PM EDT Friday for LSZ264-266-267.

Lake Michigan... None.