Expect wet, then windy weather through Wednesday night

The transition from a summer of thunderstorms to a cold season of mid-latitude cyclones that I wrote about Monday in Updraft continues.

Instead of summertime cumulus and cumulonimbus clouds, eastern Minnesota has been overspread with a layer of gray or blueish-gray altostratus clouds generated by widespread uniform uplift.

Oct 27 - altostratus NOAA — A diagnostic feature of altostratus clouds is that the make the sun dimly visible. NOAA

If these clouds thicken and cause rain, then they are nimbostratus and appear featureless dark gray with the sun not visible.

Today the thickening layers of clouds from Iowa have been spreading areas of rain to the northeast into Minnesota. Rain will expand to cover much of eastern Minnesota and western Wisconsin this evening and continue tonight.

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Oct 27 - radar 3P — Radar showed increasing areas of rain heading for the metro area by mid afternoon. Twin Cities National Weather Service

Wednesday will bring an advancing cold front from the west along with a complicated upper level pattern. The main short-term stories will be a continuation of rain mainly in eastern Minnesota and, later, the development of strong, gusty winds statewide.

Oct 27 - Wednesday wx fcst map — A cold front will mark the leading edge of colder, windy weather on Wednesday. Weather Prediction Center

The blustery winds will push in behind the cold front. You will know they are close when your wind switches from southeasterly to northwesterly. Winds always are named for the direction from which they blow.

Oct 27 - LSE wx story — Here is how the upcoming weather changes are expected to play out for southeastern Minnesota and the La Crosse, Wis., area. La Crosse NWS

Are you ready for some snow?

By later on Wednesday, rain could be mixed with, or change over to, snow at times as it is poised to race southeastward on blustery winds.

Oct 27 - 7P Wed fcst map — GFS model surface forecast weather map with 3-hour precipitation ending at 7 p.m. Wednesday. NOAA/College of DuPage

A second lobe of low pressure will continue the mixed precipitation and strong winds through Wednesday night and into Thursday.

Oct 27 - 1A Th fcst map — GFS forecast surface weather map for 1 a.m. Thursday. NOAA/College of DuPage

As is typical of October, forecasting a changeover from rain to snow is not straightforward. In this case, the main factors limiting the amount of snow that might accumulate include:

ground temperatures remain warm
the air near the surface will not be very cold

So the best estimate early on is that some slushy snow will fall, mainly in eastern Minnesota later on Wednesday and Wednesday night.

The metro area is likely to see rain change to or become mixed with snow Wednesday night. Forecast accumulations, subject to considerable change, are for mainly light but soggy amounts from the metro area north to Duluth and the Arrowhead, while southeastern Minnesota will see little accumulation. Air temperatures above freezing will cause rapid melt on Thursday.

Stay tuned for updates.

Expect wet, then windy weather through Wednesday night

Go Deeper.

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