Monday, March 20, 2023 4:35 AM

Questions for the March Equinox

Today being the first day of astronomical spring, we now have at least 12 hours of daylight each day. So, there are two big questions on Minnesota minds:

0. How many fish fries can I attend? (OK, that one doesn't count)
1. When will these snow piles disappear?
2. When will it stop snowing?

The current state of the Minnesota snow pack is more than 10 inches statewide and over 20 inches, dark blue on the NWS NOHRSC snow depth map in northeastern and east central Minnesota. Melting? In St. Cloud, that answer is that the entire snow pile will melt within the next 4 weeks, although we are likely to see a later than average melting of the continuous snow pack (April 1 or later will rank in the 15 latest). Note that the streak of consecutive days with at least 1 inch of snow on the ground began on December 8, so by the end of March, we will have seen 118 straight days of snow cover.

1a. Will we have snow melt flooding?

The other issue brought up by the first question is: will Minnesota escape snow melt flooding? I've had the latest outlooks for Minnesota attached to the bottom of this blog for a while. See, as of March 9, that the Red River Valley and Devils Lake have an above normal chance for significant (moderate or major) flooding, northeastern Minnesota into Lake Superior also have an above normal chance, and the Mississippi and Minnesota River Valleys have well above average threats for flooding with the greatest threat along the Mississippi from St. Paul southward. These will be updated on Thursday.

What we need is what we've had on many non-snowy days lately: highs above freezing and lows below freezing. That would allow a nice steady procession of slow melting. However, that 12 hours of sunshine will come back to bite us. That temperature range is typical in early March, but it is a lot harder to accomplish in late March. And, the average temperatures this time of year are the result of a very wide spread in actual temperatures. Note that current records have highs ranging from the teens on the low end to the 60's and 70's on the high end. Now, having snow at the ground means some of the heat that would go into warming the air has to be used to melt the snow, thus our recent difficulty in getting up to or past 40 degrees. St. Cloud has only made it 3 times so far this year, twice in February. But, we are more likely to have both day and night with temperatures above freezing on warm days as the calendar passes from late March to early April.

The other issue is getting a slow melt is whether we have a lot more precipitation. The worst Red River Flood year in 1996-1997 was the result of: 1) over 100 inches of snow in the western Minnesota River and Red River Valleys. 2) Precipitation continuing with major rain and snow on top of the melting snow pack in early April.

2. When will it stop snowing?

So, this brings us to the second major question on Minnesota minds, both from a flood standpoint and a "we're sick of shoveling standpoint:" when will the snow finally end? Unfortunately, the answer for northern and central Minnesota is: you don't want to know about Tuesday....

Not Tuesday or Tuesday Evening....

There is yet another storm along the Oregon-Washington coast (see Mid-tropospheric water vapor loop from Colorado State satellite slider). Note that there is also a South Dakota low pressure system, but there is so little moisture associated with it that it has been having a hard time even generating some clouds (see Shortwave Albedo loop from Colorado State satellite slider). However, it has dragged a cold front through northern, western, and much of central Minnesota (see latest NWS WPC North America zoom-in map). While that front going by just means some slightly cooler high temperatures today (middle 30's instead of upper 30's), that contrast in temperature will allow the west coast storm to lift mild air over the top of the cold air stuck at the ground. That process will begin tonight and continue through tomorrow at midnight.

The next system will have a bit more moisture to work with as some of the Pacific upper-level moisture will survive its trip over the Cascades and the Rockies. That will create a good chance for precipitation in much of Minnesota, beginning in western Minnesota first thing tomorrow morning, and covering the rest of Minnesota during the afternoon. The heaviest precipitation will be on the cold side of the front, so it appears that a swath of northern and central Minnesota could pick up as much as a half-inch of liquid. The amounts will get smaller further to the south.

The amount of cold air available to produce snow will be marginal. It appears that, from Hwy. 12 southward, much of the precipitation will either fall as rain or ground temperatures will be too mild (35 or highs) for the snow to stick during tomorrow afternoon, so there would only be a chance of a coating of wet snow or slush Tuesday evening. That would include the Twin Cities, Mankato, and the southeastern portion of Minnesota.

The best chance for steady snow will be along Hwy. 2 and perhaps Hwy. 200, where there is the potential for between 2 and 5 inches of snow. There is the chance of between 4 and 8 inches of snow along the hills of the North Shore, where extra moisture will be provided by Lake Superior and extra lift will be provided by the hills.

The computers still have disagreement about how quickly the precipitation falls off to the south of the main band. That means Alexandria, Willmar, Little Falls, St. Cloud, Milaca, and Cambridge are the most iffy. I have an accumulation of between 1 and 4 inches. If ground temperatures are slightly warmer and the snowfall remains slushy, we could be down to the lower end of the range or slightly lower (between a dusting and 2 inches). If ground temperatures stay closer to freezing during the snow, like during the last storm, we would have a shot at a plowable snowfall (2-5 inches).

Continued Highs in the 30's, Lows in Teens or 20's After Tuesday, But Shakier Friday On

This storm will not have really cold air behind it, so there will be no repeat of last Friday or Saturday. As noted above, we are having trouble getting temperatures over 40 (the average high) due to the heat loss from the snow cover. Still, Wednesday should have leftover snow melt on pavement as temperatures climb at least into the upper 30's. It will be slightly cooler Thursday with highs in the middle 30's. And, there will be a good east breeze tomorrow into tomorrow evening from the storm, but nothing like the wind we saw last Thursday through Saturday.

Friday becomes more iffy. There will still be a parade of storms in two storm tracks from the West Coast into the Plains. However, the computer forecasts cannot agree on the path or timing of the storms. The US computer forecast has another chance of wet snow or rain on Friday, but the European forecast doesn't support that. So, I have clouds and a small chance for snow right now. The forecasts continue to be iffy through next weekend. However, I don't see any cold like we had last Friday and Saturday through the weekend.

1 Inch From 80!

St. Cloud now has 79.0 inches of snow, passing both 75.5 inches in 2013-2014 (tied for 5th place) and 4.5 inches from 78.5 inches in 2012-2013 (4th place) to be alone in 4th place. There have only been three previous cold seasons with 80 inches or more, the last of which was the record 1964-1965 with 87.9 inches, 51.7 of which fell in March 1965. St. Cloud's March snowfall is now 18.7 inches, which is 7th of the 10 snowiest Marches. We have already seen the 5th snowiest December (22.5 inches), 10th snowiest January (18.6 inches), and tied 1968-1969 for the snowiest meteorologic winter (Dec-Feb).

Detailed St. Cloud, MN, and Vicinity Forecast

Confidence Level: "I Will Have to Remove Five-Foot High Snow Piles to Put Out the Trash"

Monday 3/20/2023: Sunny to partly cloudy and not quite as mild. High: between 32 and 36. Winds: NE 5-15 MPH. Chance of measurable snowfall: 0%.

Monday Night: Clouding up, breezy, and not quite as cool. Low: between 17 and 22. Winds: NE 5-10 MPH. Chance of measurable snowfall: 10%.

Confidence Level: "The Continuing Snow Melt Will Make It Icy Right Where I Have to Change My Balance and Throw the Snow"

Tuesday 3/21/2023: Cloudy with wet snow developing in the afternoon. Breezy. High: between 32 and 34. Winds: E 10-20 MPH. Chance of measurable snowfall: 50%.

Tuesday Night: Wet snow likely through the evening, tapering to flurries or drizzle by midnight. Between 1 and 4 inches of new snow are possible from Tuesday afternoon until midnight Tuesday evening. Breezy and relatively mild. Low: between 30 and 33. Winds: E 5-15 MPH evening, W 8-15 MPH late at night. Chance of measurable snowfall: 70% evening, 20% after midnight.

Wednesday 3/22/2023: Cloudy with perhaps some sunny breaks, breezy, and milder. High: between 35 and 40. Winds: NW 10-25 MPH. Chance of measurable snowfall: 10%.

Wednesday Night: Cloudy evening, partial clearing late, and seasonably cold. Low: between 20 and 25. Winds: NE 5-10 MPH. Chance of measurable snowfall: 10%.

Confidence Level: "The Melting Maven Will Magically Make My Sidewalk Ice Disappear Overnight

Thursday 3/23/2023: Mixed clouds and sun and not quite as mild. High: between 32 and 37. Winds: NE 5-15 MPH. Chance of measurable snowfall: 10%.

Thursday Night: Cloudy with a chance of light snow or flurries?? Low: between 20 and 25. Winds: NE 5-15 MPH. Chance of measurable snowfall: 20%.

Friday 3/24/2023: Cloudy with a chance of light snow or flurries?? High: between 28 and 34. Winds: NE 5-15 MPH. Chance of measurable snowfall: 20%.

Extended: Milder than average early next week??? More precipitation second half of next week????

Forecast Confidence (10 - "The Rabbits Will Thump Even Though I Fed Them"; 0 - "The Rabbits Will Offer To Groom My Bald Spot"): 7 Monday, 6 Monday night, 4 Tuesday and Tuesday night, 5 Wednesday, 4 Wednesday night, 3 Thursday, 1 Thursday night and Friday.

Yesterday's High: 35°F; Overnight Low (through 4 AM Monday): 11°F
St. Cloud Airport 24-Hour Precipitation (through 4 AM Monday): None; SCSU 24-Hour Precipitation (through 4 AM Monday): None

Next Update: Tuesday, March 21, 2023 7 AM

Let me know what you think about this forecast and discussion by emailing SCSU meteorology professor Bob Weisman. Please note that I make the forecast, not the weather!

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