April Snowstorm for the Ages: Upper Midwest Gets Plastered

A blizzard that would have been impressive in January knocked Upper Midwesterners for a loop from Friday into the weekend, with record snowfall amounts for any April across wide areas. Winds gusted to more than 40 mph with snowfall rates of 2"/hour or more in some locations. The National Weather Service office in Green Bay, Wisconsin, called it a “once-in-a-lifetime snowstorm.”  Snow totals for Wisconsin included 31.6" near Carlsville, 30.6" at Tigerton, and 30.5" near Stiles.

According to weather.com, at least three deaths have resulted from the storm, dubbed Xanto by the Weather Channel. Freezing rain and high winds along a front extending east from Xanto brought down trees and knocked out power across parts of Michigan, southern Ontario, and upstate New York. As of midday Monday, some 229,000 utility customers across Michigan remained without power. The Detroit News labeled the storm a “mini-apocalypse…that included flooded freeways, power outages, ice-encrusted buildings and fires started by downed power lines.”

Xanto not only demolished April snow records—it was one of the heaviest snowstorms ever observed at any time of the year at several locations. Below are records established as of 11 am CDT Monday, April 16, with snow still falling at some locations. One clue to how widespread this high-impact snow has been: each of the records smashed below was set in a different year.

Wausau, WI:  20.7” (Apr. 13-16, as of 11 am CDT Mon)
Heaviest April snow on record, beating 12.1” on Apr. 15-16, 1993
2nd-heaviest snow on record, behind 22.1” on Mar. 5-6, 1959

Green Bay, WI:  24.2” (Apr. 13-16)
Heaviest April snow on record, beating 11.0” on Apr. 4-5, 1977
2nd-heaviest snow on record, behind 29.0” on Mar. 1-2, 1888

Rhinelander, WI:  18.2” (Apr. 13-16)
Heaviest April snow on record, beating 13.0” on Apr. 6-7, 1923, and Apr. 3-4, 1945
3nd-heaviest snow on record, behind 29.0” on Feb. 20-21, 1937, and 20.2” on Feb. 28-29, 2012

Minneapolis-St. Paul, MN:  14.9” (Apr. 13-15)
Heaviest April snow on record, beating 13.6” on Apr. 14, 1983
13th-heaviest snow on record (all-time record is 28.4” on Oct. 31-Nov. 3, 1991)

Almost a 30" drift along the side of our office building. Now imagine having almost this much snow everywhere like our friends at @NWSGreenBay. #itCouldBeWorse pic.twitter.com/CiX8vZloIb

— NWS La Crosse (@NWSLaCrosse) April 16, 2018

Will it ever end?

Yet another winter storm is heading for the Upper Midwest. Fortunately, this one will be much weaker and more localized. Still, parts of far southern MN and far northern IA could pick up as much as 5-8” of snow, perhaps accompanied by some freezing rain or sleet. The Twin Cities may get another couple of inches of snow, adding to their phenomenal total for the calendar year thus far of 70.3” (already the highest on record for any January-to-June period).

When the temperatures finally warm up in earnest—which could be another week or more, based on current forecasts—there will be a real risk of snowmelt flooding across parts of the Upper Midwest, especially if any rapid warming is accompanied by heavy rain.

Figure 1. Departures from average temperature for the first half of April (Apr. 1-14). Image credit: NOAA/NWS Weather Prediction Center.

Record-cold start to April in much of northern U.S.

A persistent series of cold shots and snows has kept nearly all of the United States below average in temperatures during the first half of April (Apr. 1-15). It’s been rare in recent years to see below-average temperatures overspreading this much of the nation for a whole two weeks. Most of the Northern Plains and Upper Midwest are running an impressive 8-15°F below average

The first half of April has been the coldest ever observed in most locations from eastern Montana to northern Michigan (see Figure 2), and for a few spots as far south as Little Rock, Arkansas, where the average of 51°F for Apr. 1-15 is 9°F below normal. On Monday morning, Apr. 16, Little Rock got down to 32°F, the city’s second-latest freeze in 139 years of recordkeeping (beaten only by 31°F on Apr. 19, 1983).

The unusually late freeze bookends a Little Rock winter that also saw the city’s earliest frozen precipitation on record (sleet on Oct. 27, 2017) and an unusually early first freeze (Oct. 28).

Figure 2. Ranking for the period April 1-15, 2018, as compared to all Apr. 1-15 periods on record, going back in most cases more than a century. Those marked 1 have experienced their coldest Apr. 1-15 period on record this year. Image credit: Southeast Regional Climate Center.

Spring recreation: frozen in place for now

Minnesotans eager for open-water fishing will have to wait longer than usual. This spring’s “ice-out” date, a key marker of Minnesota spring climate, will likely be among the latest in the last several decades. Overall, ice-out dates have shifted earlier in the spring over the past century, in line with warming spring temperatures, although the trend in recent decades hasn’t been statistically significant.

The 2010s have seen some wild variability, as evident in an analysis put together by the Minnesota Star-Tribune. Lake Mille Lacs saw its earliest ice-out in almost 70 years of recordkeeping on Mar. 25, 2012—and its latest ice-out on record the very next year, on May 15, 2013.

Figure 3.  The latest ice-outs on record are during the last 10 days of April across most of the Twin Cities region and during the first two weeks of May across central Minnesota. Given the forecast for the coming week, some of these records may be in jeopardy. According to the Minnesota Department of Natural Resources, “The definition of lake ice out can vary from lake to lake. For the citizen observers reporting data, ice out occurs when the lake is completely free of ice. Or, it may be when it is possible to navigate from point A to point B. Ice out may also be when a lake is 90 percent free of ice. Observers use consistent criteria from year to year when reporting lake ice out dates.” Image credit: Minnesota DNR.

Severe weather rakes the South

Thunderstorms packing high winds and a few tornadoes surged from the Southern Plains late Friday to the mid-Atlantic on Sunday. The NOAA/NWS Storm Prediction Center logged a preliminary total of 32 tornado reports on Friday (through 8 AM EDT Saturday), plus 3 on Saturday and 18 on Sunday. Falling trees led to at least two deaths, one near Shreveport, Louisiana, late Friday and another on Sunday night in Greensboro, North Carolina. Tens of thousands of homes in North Carolina remained without power on Monday, according to a weather.com roundup. The coming week looks relatively quiet on the severe weather front, with only marginal conditions expected until at least Friday.

Figure 5.  Mia Polaski surveys the damage to her family's home in Elon, VA, on Monday, April 16, 2018, after a tornado struck on Sunday evening, injuring several people. Up to two dozen homes were destroyed or severely damaged in the Elon area, according to local officials. Image credit: Jay Westcott/The News & Advance via AP.

Figure 6.  The fire weather outlook for Day 2 (Tuesday, April 17, 2018 issued on Monday morning, April 16) calls for extremely critical conditions across a large swath from New Mexico to Kansas. Most of this region, plus nearly all of Arizona, has been flagged for critical Day 1 fire weather risk on Monday (not shown). Image credit: NOAA/NWS/SPC.

Extremely critical fire weather returning to Southern Plains on Tuesday

A multiday stretch of devastating fires across Oklahoma may get an unwelcome boost on Tuesday from yet another surge of extremely hot, dry, and windy conditions.

The NOAA/NWS Storm Prediction Center has outlined a vast region from most of New Mexico into western Oklahoma and southwest Kansas for “extremely critical” fire weather. This is the most dire category used in official SPC outlooks. Conditions across parts of the area may actually end up toward the higher end of the extremely critical range—considered “historic”—with widespread wind gusts topping 40 mph, temperatures above 90°F, and relative humidities as low as 3%.

More than 300,000 acres have been scorched across Oklahoma during the past week, leaving at least two people killed and more than 30 homes destroyed. The largest of the fires, the Rhea complex, was only 3% contained as of Monday morning, and a state of emergency is in effect for most of Oklahoma through at least Tuesday. We’ll have more on the fire threat in our next post on Tuesday.