516 FXUS63 KMPX 300923 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 423 AM CDT Mon Oct 30 2023 .DISCUSSION...(Today through Sunday) Issued at 419 AM CDT Mon Oct 30 2023 KEY MESSAGES: - Light snow arrives Monday evening, with the potential for minor accumulations across central & southern Minnesota into western Wisconsin through early Tuesday. - Cold air remains in place through Halloween. Slight warming into the 40s by late week, with the next chance for precipitation into the weekend. It's another cold start to the day across Minnesota and Wisconsin, with most locations forecast to fall into the upper teens and low 20s by daybreak. Another below average day is on tap, with highs in the 30s. Mostly clear skies early this morning will give way to increasing clouds throughout the day. A vigorous shortwave will dive southeast out of central Canada later today, with the best forcing set to arrive over central Minnesota by this evening. This feature will bring the first real chance for minor snow accumulations across much of the area, especially for locations in southeast Minnesota and western Wisconsin. The latest forecast data suggests that two periods of snow potential will exist, with the first round set to start late Monday afternoon north of I-94, moving southeast into the evening. Uncertainty in the start time of snowfall exists due to a fairly large low-level dry layer depicted on forecast soundings, however the environment should be favorable for a quick burst of snow once the dry layer moistens. RAP forecast profiles indicate that a saturated, but shallow DGZ will be supported by moderate omega forcing and steep low-level lapse rates. The first round of snow is projected to begin across the Twin Cities Metro shortly after 7 PM. The upper-level shortwave and associated vort max will pinwheel south tonight into early Tuesday. Though the forcing will be weaker when compared to the initial wave, enough lift will be present in the atmosphere to bring another round of snowflakes through early Tuesday morning. Snow will end from west to east around daybreak Tuesday, with the final flakes set to end across western Wisconsin by mid-morning. Storm total snowfall will not be particularly impressive, though we do want to caution drivers that there may be enough powder present for a few slick spots on the roadways, along with brief reductions in visibility as the snow falls. It's possible that snow may still be falling during the Tuesday morning commute, especially from the Twin Cities and east. Snowfall amounts are forecast to top out around an inch for the Twin Cities metro, with amounts closer to 2" in western Wisconsin. Locations south of I-94 and west of I-35 will see lower amounts, with a dusting to an inch possible. Northwest gusts of 30-35 mph will be possible as the wave departs Tuesday morning, before eventually relaxing as high pressure builds in Tuesday afternoon. Sub-freezing temperatures in the 20s are currently forecast for Halloween evening, so those with trick-or- treat plans will need to bundle up! The extended forecast features quiet weather for mid to late week, with a slight warming trend into the 40s as a southerly component to the winds returns. An upper-level trough is progged to dig into the upper Midwest for the upcoming weekend, with the chance for precipitation to return to Minnesota and Wisconsin. Confidence remains low in how this feature may progress into the region, thus it's too soon to talk specifics on precipitation or precip type. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 1054 PM CDT Sun Oct 29 2023 For the snow at the end of the period (Monday evening/night) we continue to lean heavily on a blend of the Euro hourly forecast and hi-res Canadian. The blend is similar to what we're seeing from the HREF with an initial N-S oriented warm advective band that develops over central MN shortly before 00z, but where this blend differs is with the development of a second E-W oriented band late Monday night on the nose of the 500 mb vort max moving in. That second band will really start impacting MPX terminals after 6z Monday. Before the snow, there's not much to talk about. We'll see winds back toward the SW during the day as the low moves into northern MN, but any clouds will remain VFR until the snow and then strong cold air advection arrives late Monday night. KMSP...Still leaning on the idea that MSP will see two distinct bursts of snow this period. Laid that foundation with this 6z TAF and we have 24 hours to fine-tune that timing. Most models, including the models that make up the HREF, have the first burst of snow, but for the second burst of snow in the 8z-12z Monday window, we continue to lean heavily into the Euro and Canadian model forecasts. /OUTLOOK FOR KMSP/ Tue...VFR. IFR/SN likely early mrng. Wind NW 15-25G30-35 kts. Wed...VFR. Wind SW 10-15 kts. Thu...VFR. Winds W 5-10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ DISCUSSION...Strus AVIATION...MPG