An unsettled week of transition

Expect several periods of unsettled, occasionally wet, weather this week as we transition into a wintry type of pattern.

October 26 - wx story MPX
Periods of wet weather are likely this week. NWS Chanhassen

Our warm season precipitation, often involving thunderstorms, is driven by such weather factors  as upper level short waves, atmospheric instability, boundaries, low-level convergence, moisture availability and daytime heating.

In contrast, the cold season frequently is characterized by very large low pressure systems, what meteorologists refer to as mid-latitude cyclones, with warm fronts and cold fronts. These storms are driven largely by big loops (troughs) in the jet stream and widespread ascent. This week we will experience a transition from a summery pattern to a more wintry one.

Overnight there have been two major low pressure systems over the country. One is the deep low that continues to bring flooding to the South. Heavy rain has been spreading from Louisiana across Mississippi and Alabama into Georgia, the Florida Panhandle, Tennessee and South Carolina. Flash flood warnings have continued to be in effect. Wind damage from possible tornadoes was reported in southeastern Louisiana.

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Meanwhile, a small but sturdy storm has developed over the Pacific Northwest and will provide seeds of energy to send eastward in our direction during the week.

For Minnesota, a rather weak stationary front draped across the middle of the state has been generating light rain that has been spreading eastward across central Minnesota, mainly between the Twin Cities and Duluth.

This rain is diminishing and will exit the state this morning.

October 26 - 1A sfc map (NOAA)
Surface weather map from 1 a.m. this morning. Weather Prediction Center

High temperatures today will be quite seasonal as they range from the upper 40s in northern Minnesota to the upper 50s in the south. The Twin Cities should top out around 56, just a few degrees above normal.

The deep low in the South is likely to have impacts in our part of the world. Forecast models are expecting a plume of moisture from that storm to surge northward and generate showers into Minnesota later Tuesday.

Oct 26 - US fcst 7P Tuesday
Forecast weather map and 3-hour rainfall aor 7 p.m. Tuesday. NOAA/College of DuPage

Wednesday will be a raw day. Very gust northwest winds and chilly temperatures statewide will bring the word "blustery" into play. Scattered showers are likely, and the Arrowhead probably will see a little slushy snow Wednesday into Wednesday night.

A few flakes might mix with the rain in or near the metro area Wednesday night. The winds and precipitation will be on the back side of one those wintry mid-latitude lows that will form over Ontario by Wednesday and trail a long cold front all the way to Florida.

As that Ontario low moves away, Thursday will be a cool day but dry with diminishing winds. Friday should see the beginning of some temperature recovery.

Looking ahead for the flooded South, yet another large storm is forecast to develop by the weekend. Also, the Gulf of Alaska will become more active and pump another storm into the Pacific Northwest.

October 26 - US fcst Sat 1P
Forecast weather map with 3-hour precipitation for 1 p.m. Saturday. NOAA/College of DuPage

And by Sunday it will be November and Standard Time. Of those two things I am certain.