textproduct: Twin Cities

KEY MESSAGES

- Dense fog ongoing this morning will begin to dissipate by 9-10am.

- Rain likely beginning Tuesday with chances lingering into Wednesday, especially in southern MN.

- Temperatures near to just above average through next week.

DISCUSSION

Issued at 300 AM CDT Mon Sep 28 2026

Dense fog is the main story this morning thanks to calm winds and relatively warm dew points, which has allowed temperatures to immediately crash down to dew points resulting in significant radiation fog. Nighttime microphysics satellite imagery shows a bank of stratus stretching across portions of southern MN with the dense fog forming quickly as soon as the cloud cover retreats, and as of around 230am local time the fog has become so dense in spots that it is widespread within the satellite imagery as well. With the fog incredibly dense, it will also take awhile to burn off this morning as temperatures will be very slow to rise due to lack of solar insolation as well as being past the autumn equinox meaning our sun angle is becoming weaker by the day. Once the fog burns off, we should see temperatures rebound quickly with highs today in the upper 60s to low 70s which is just a touch above average for this time of year.

The leading edge of potential rain showers arrives overnight tonight into early Tuesday as a surface low begins to develop along the leading edge of an approaching trough, reaching eastern Minnesota by the late morning to early afternoon and continuing to spread eastwards later in the day. A strong Canadian low will spin up late Tuesday into Wednesday and when combined with the boundary already over the area from the initial weaker surface low, could result in some training rain showers and potential localized flooding. At this point the most likely area for training rainfall would be south/southeast Minnesota into western Wisconsin, however over the last 24 hours guidance has trended slightly northwards compared to the last few days. As a result of this northward shift within primarily the GFS/GEFS, the NBM QPF forecast has also increased with the highest rainfall amounts over southern/southeast Minnesota and western WI on the order of 2 or more inches. While the exact numbers are still changing with each forecast package, the overall trend is the thing to monitor for now. As far as convection is concerned, forecast soundings show a small sliver of instability which could result in some rumbles of thunder, however the profile is very saturated with very high PWATS indicative of a rain loaded atmosphere as opposed to a convective one. We are also still relatively warm which will result in a higher freezing level, and with our lack of instability we may not see an individual updraft on a mesoscale strong enough to produce much in the way of lightning. We expect most of the area to see at least a half inch of rainfall with the lowest amounts in western Minnesota before the boundary stalls into Wednesday over the south/eastern part of our area.

Behind the departing system towards the late week and next weekend, temperatures will cool down with highs falling back into the low to mid 60s with a lack of other significant rainfall on the horizon. Ensemble guidance shows relatively little in the way of precipitation until at least Sunday of next weekend, and even then it is a minority of ensemble membership within the GEFS/EPS showing any precip at all, let alone measurable. This continues throughout the rest of the period with no significant precipitation signals throughout, rather we stay in the 60s for highs and upper 40s to low 50s for lows without any significant weather systems through the rest of the period.

AVIATION /12Z TAFS THROUGH 18Z TUESDAY/

Issued at 607 AM CDT Mon Sep 28 2026

Dense fog remains locked in across the area for mostly all terminals, with the exception of AXN. IFR to LIFR categories will continue through 14-15z with VIS dropping to below 1 mile for most, MSP has been fairly consistent over the last hour between 2-3 miles. Dense fog will hold through the mid morning hours, with slight and gradual improvements after sunrise. VIS conditions will eventually become P6SM by 14-15z timeframe. MVFR with isolated instances of IFR CIGS hold and stick around through much of the day with improvements to VFR during the late afternoon and evening timeframe. Winds through the day will be S/SE at 5-10 knots.

KMSP...IFR conditions will continue through mid-morning with VIS reductions of 2-3 miles. VIS conditions will improve gradually after sunrise becoming greater than 5 miles by 15z. MVFR with isolated instances of IFR CIGS will continue into the afternoon with improvements to VFR during the late afternoon and evening hours.

/OUTLOOK FOR KMSP/ TUE...MVFR/-SHRA likely, chc IFR. Wind SE 5-10G20 kts. WED...VFR, chc -SHRA/MVFR. Wind S to SE 5-10 kts. THU...VFR. Wind NW 10-15 kts.

MPX WATCHES/WARNINGS/ADVISORIES

MN...Dense Fog Advisory until 10 AM CDT this morning for Anoka- Benton-Blue Earth-Brown-Carver-Chippewa-Chisago-Dakota- Douglas-Goodhue-Hennepin-Isanti-Kanabec-Kandiyohi-Lac Qui Parle-Le Sueur-McLeod-Meeker-Mille Lacs-Morrison-Nicollet- Pope-Ramsey-Redwood-Renville-Rice-Scott-Sherburne-Sibley- Stearns-Steele-Stevens-Swift-Todd-Waseca-Washington- Watonwan-Wright-Yellow Medicine. WI...Dense Fog Advisory until 10 AM CDT this morning for Barron- Chippewa-Dunn-Eau Claire-Pepin-Pierce-Polk-Rusk-St. Croix.