textproduct: Marquette

KEY MESSAGES

- Patchy dense fog is possible again through this morning, mostly in the Keweenaw and near Lake Superior.

- Widespread rain chances return tonight. Rainfall amounts between 0.25 and 0.75 inches are likely by Tuesday afternoon, greatest south-central. Amounts between 1 and 1.5" are possible in areas of more persistent showers and thunderstorms.

- Dual directional gales 35-40 kts are possible (50-80% chance) this afternoon through Tuesday.

- Mostly dry and cooler weather the remainder of next week.

UPDATE

Issued at 251 AM EDT Mon Apr 27 2026

Going forecast remains on track this morning. RAP analysis shows a ~995mb low pressure over the OK Panhandle, with a 500mb trough positively tilted from Manitoba to California and embedded shortwaves embedded ahead of the trough. These shortwaves and eventually the parent trough itself will be the driving factor of disturbed weather in the near term.

Forecast QPF has trended downwards slightly for most, which if it verifies, is good news for the river basins that remain in flood stage. Given the convective nature of the showers, the spread remains high though, as the 00Z HREF QPF by 8 AM Tuesday in the central UP is spread from around 0.4 inches (25th percentile) to 1.4 inches (75th percentile). The region with the lowest spread is the west, where the 75th percentile has fallen to around a third to a half inch. Upstream convection in the Lower Midwest will cut off deep moisture transport which will limit CAPE and thus severe thunderstorm potential, though sufficient instability and shear will be present for some thunder.

The surface track passing right through the region will result in a tight pressure gradient and large isallobaric components to the wind, and for this, a Gale Warning will be hoisted for mainly the east half of Lake Superior, where the leading southeasterlies will have little friction to slow down the winds along the long fetch of that part of the lake, though the HREF is highlighting the western lake for the trailing gale potential more than the NBM is (around 50% probability vs around 10% probability). Will hold off on boosting post fropa winds in the west for now, but it is something that is worth keeping an eye on.

Otherwise, once the low departs on Tuesday, high pressure will ward off any meaningful precipitation until the weekend. Fire weather will be the only potential for concerns, but uncertainty in the details of the wind pattern and how efficient the air will dry will preclude any deviations from the NBM with this package.

DISCUSSION

Issued at 243 PM EDT Sun Apr 26 2026 Amended at 251 AM EDT Mon Apr 27 2026

Quiet weather is expected through this morning with patchy dense fog development possible mainly in the Keweenaw. Bufkit soundings out of CMX highlight this potential as light easterly winds advect in the marine layer under a sharp inversion, further aided by weak upsloping into the Spine. Otherwise, temps fall into the low 40s to upper 30s tonight.

Broad troughing across the western CONUS digs into the northern periphery of the sub-tropical jet early this morning, sending a sharp shortwave and deepening surface low pressure into the Plains this morning that is slated to lift north into the Great Lakes by the afternoon. Ample moisture (PWATS between 1 and 1.25") and isentropic lift will be the impetus for widespread rainfall and a few embedded thunderstorms through early tuesday afternoon. There remains some uncertainty regarding the northward extent of elevated instability into the UP, but given the strong LLJ wouldn't be shocked to see some stronger showers and embedded storms work across the south- central. By Tuesday afternoon ensembles suggest a widespread 0.25-0.75" with pockets of 1-1.5" possible in the south-central where more persistent showers and thunderstorms are most likely. CAM ensembles (HREF/REFS) support this notion, highlighting a 40-60% chance for QPF >1" largely confined to Menominee/Delta counties. Higher QPF solutions have the potential to bring about area river rises and minor flooding. Precipitation ends from west to east through Tuesday behind the surface cold front, replaced by drier conditions and incoming high pressure.

Surface high pressure once again becomes the dominating factor the remainder of the work week and possibly into the weekend, favoring drier weather. Mid level troughing becomes situated over Eastern Canada and the Midwest/Northeast, resulting in a cooler pattern with highs and lows between 5 and 10 degrees below normal; highs in the 40s to mid 50s and lows in the upper 20s to 30s. Medium range guidance struggles to resolve the mid level pattern into the weekend, thus confidence in any future precip chances remains low. That said, the troughing pattern and cooler northerly flow likely persists into May, captured well by the CPC outlooks out to 3-4 weeks showing below normal temps favored in each outlook.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 140 PM EDT Mon Apr 27 2026

VFR conditions begin to drop to MVFR, first at IWD over the next couple of hours and then at CMX and SAW around 00Z, as low pressure moving through the region brings in a round of rain showers. There is a ~20 percent chances of TSRA, but this has not been included in the TAF. Ceilings look to drop further to IFR or lower between 03- 06Z, and steadier showers and br/fg may lead to IFR visibility as well at CMX. In addition, LLWS looks to return tonight to SAW and CMX particularly thanks to the strong shearing profile caused by the low's center moving through the UP. A slow improvement to MVFR is expected after sunrise Tuesday, and IWD may even rise to low-end VFR near the end of the forecast period.

MARINE

Issued at 243 PM EDT Sun Apr 26 2026 Amended at 251 AM EDT Mon Apr 27 2026

Easterly winds increase today to 20-30 kts as low pressure moves to Wisconsin. There are two potential periods of gales as this low moves northeast over Lake Superior. The first period is southeast gales late today into Tuesday morning over the east, particularly near the international border waters. Probabilities for gales of at least 35 kts are generally 40-60% over the eastern open water zones, except up to 80% along the international line. How far southwest from the international line the first gales will occur depends on the low pressure track impacting the strength of the low level stability over the water. The second period comes behind a cold front with strong cold air advection and modest pressure rises yielding westerly gales on Tuesday, strongest winds over the east half of the lake (30-60% chance of gales to at least 35 kts).

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... Gale Warning from 5 PM this afternoon to 5 PM EDT Tuesday for LSZ244-245-250-251-264-265.

Gale Warning from 8 AM to 4 PM EDT Tuesday for LSZ248.

Gale Warning from 11 AM to 4 PM EDT Tuesday for LSZ249.

Gale Warning until 6 PM EDT Tuesday for LSZ266-267.

Lake Michigan... None.