Perhaps the season's last snowfallEarlier the week over April 21-22 a storm system crossed the state bringing snow to many northern Minnesota communities. Some received record-setting values of snowfall, including International Falls which reported 2.4 inches on the 22nd. Others reporting record amounts of snowfall for April 22nd included: Orr with 5.8 inches; Hibbing with 3.5 inches; Kabetogama with 3.0 inches; Northome with 2.7 inches; and Cook with 2.0 inches. The snowfalls at Orr and Kabetogama pushed their seasonal snowfall totals to 71.1 inches and 78.3 inches, respectively. There is a chance of snow overnight Friday and into Saturday morning to start this weekend, but after that the climate outlook favors above normal temperatures through early May, and it is likely this is the last measurable snowfall threat for our region.
Preliminary climate summary for AprilAverage temperatures for April have been about 2 to 4 degrees F warmer than normal for the most part. Every month since last October has been several degrees F warmer than normal. Temperature extremes for April ranged from 88 degrees F at Pipestone on the 2nd and 25th to just 3 degrees F at Grand Marais on April 17th. Minnesota reported the coldest temperature reading in the 48 contiguous states on five dates during the month. At International Falls the mean temperature value for April was barely above the mean temperature for March, the first time this has ever happened.
Many observers reported precipitation that was generally above normal. In some areas it was well above normal, with many reports of over 3 inches and some reports of over 4 inches. Both Wadena and Pipestone reported 4.13 inches as of April 26th. The monthly total rainfalls may be added to over the weekend with chances for showers each day. The most snowfall for the month was reported from Orr with 17.5 inches and Kabetogama with 13.7 inches. April was only the second month of the last July (a period of 9 months) to bring above normal precipitation amounts to the state, the other being February.
April also lived us to its reputation as the windiest month of the year, with many days bringing wind gusts of 30 mph or greater. Both Moorhead and Rochester saw 15 days with wind gusts of 30 mph or greater. The Twin Cities had two days when winds peaked over 40 mph, while Rochester had seven such days, including 51 mph on the 15th. In addition to the wind, April brought some thunderstorms, hail, and even tornado reports. Tornadoes were reported in McLeod and Lyon Counties on April 15th, and then on April 21st, between 5:30 pm and 9:40 pm tornadoes were reported from Clay, Wilkin, Otter Tail, Chippewa, Redwood, Douglas, and Swift Counties. Some agricultural structures were damaged by these tornadoes, but overall they were short-lived and did not inflict widespread damage.
Weekly Weather PotpourriThe NOAA-National Weather Service is seeking comments on its newly designed web site. The public comment period runs until May 18th. If you wish to provide comments to the National Weather Service on the new design and its contents, please go to the "preview" web site.
Earlier this week for Earth Day, students helped NOAA launch new ocean drifters, which are 44 pound buoys instrumented to transmit pressure, temperature, and other measurements via satellite as they drift with ocean currents. These measurements help NOAA scientists gather data from the oceans and better understand the interactions between the oceans and the atmosphere. You can read more here.
Earlier this month a team of scientists from the Mayo Clinic established a laboratory at the base of Mt Everest to study the effects of high altitude on human physiology. The team will monitor nine climbers who are attempting to scale Mt Everest. Scientists say that the stress of high altitude exertion puts climbers under the same conditions experienced by patients suffering from heart disease. The Mayo scientists brought 1500 pounds of medical equipment and set up base camp at an elevation of 17380 ft. Weather conditions in May are usually the most suitable for climbing the mountain.
A study published recently in Tree Physiology documents that certain tree species appear to grow better in urban heat islands produced by cities. Tree physiologist Kevin Griffin of Columbia University found that species like red oak grow much better in New York's Central Park then they do in cooler settings along the Hudson Valley. Generally the higher temperatures of the city appear to stimulate more robust growth in some tree species. You can read more about this study here.
MPR listener questionAre the clouds in winter different from the clouds in summer? They seem to me to be different but I am suspicious that my attitude is clouding (pun intended) my vision. In summer clouds appear to me to be beautiful but in winter they appear to be threatening.
Answer: The mixing depth of the atmosphere changes with the seasons and affects cloud formation significantly. During the winter, long nights/short days, we tend to see more layered cloud forms (stratiform), with low ceilings, and little light penetration. During spring, summer, and fall the mixing depth is greater and we see more vertical cloud forms, with a much wider array of shapes and cloud elevations. The sun angle is higher, days are longer and we get many different perspectives on the illumination of the cloud forms, making for magnificent viewing of the sky. Almost any kind of cloud form is possible to see in Minnesota during these seasons.
Clouds can be equally threatening in all seasons of the year. Certainly during the current season when we see wall clouds, squall lines, or massive cumulonimbus clouds we should feel threatened by severe weather. If you want to gain a broader perspective on all cloud forms, I would encourage you to visit the Cloud Appreciation Society web page.
Twin Cities Almanac for April 27thThe average MSP high temperature for this date is 62 degrees F (plus or minus 11 degrees F standard deviation), while the average low is 41 degrees F (plus or minus 9 degrees F standard deviation).
MSP Local Records for April 27thMSP weather records for this date include: highest daily maximum temperature of 85 degrees F in 1977; lowest daily maximum temperature of 34 degrees F in 1950; lowest daily minimum temperature of 21 F in 1909; highest daily minimum temperature of 60 F in 1938 and 1974; record precipitation of 2.22 inches in 1975; and record snowfall of 8.5 inches in 1907. Snow depth was 8 inches on this date in 1907.
Average dew point for April 27th is 36 degrees F, with a maximum of 65 degrees F in 1986 and a minimum of 8 degrees F in 1934.
All-time state records for April 27thThe state record high temperature for this date is 96 degrees F at Hallock (Kittson County) in 1952; the state record low temperature for this date is 7 degrees F at Halstad (Norman County) in 1909 and at Brimson (St Louis County) in 1996. State record precipitation for this date is 3.76 inches at Cambridge (Isanti County) in 1975; and state record snowfall for this date is 13.0 inches at Lynd (Lyon County) in 1907.
Past Weather Features:This week in 1826 a massive snow melt flood on the Mississippi River swept away Chief Little Crow's Sioux settlement along the river where South St Paul is now located.
A late spring snow storm brought significant snowfall to many areas of the state over April 27-28, 1907. The Twin Cities received 13 inches; Stillwater reported 11 inches; Farmington received 10 inches; New Ulm reported 8 inches, and Milaca and Park Rapids reported 6 inches of new snow.
April 27, 1909 brought very cold temperatures to the state with over 17 communities reporting overnight lows in the single digits F. It was as cold as 17 degrees F as far south as Pipestone as well. It remained cold and unsuitable for farm field work until a warm up occurred on May 3rd.
The very next year, 1910 brought a Heat Wave over April 27-28 as 80 F temperatures reached nearly all communities across the state. Records were set at Lynd and Winnebago (95 F); Albert Lea, Redwood Falls, and Windom (94 F); Moorhead and St Peter (92 F); Winona (91 F) and Montevideo (90 F).
Just after 3:00 pm on April 27, 1942 an F-3 tornado (winds 158-206 mph) touched down in western Minnesota and traveled 40 miles across Lac Qui Parle, Big Stone, and Traverse Counties. A school near Ortonville was completed destroyed, with only the steps remaining. Two students were killed. There were also reports of widespread farm damage along the path of the storm and seven other people were injured.
April 26 to May 4th of 1952 brought an extended spring Heat Wave to the state. At least 18 communities reached temperatures in the 90s F, with strong southerly winds. Most major rivers were in flood stage during this time, having seen rapid loss of abundant snow cover from the winter.
Rainfall nearly everyday brought a halt to field work around the state the last week of April 1975. From the 26th to the 30th it rained everyday bringing more than 3 inches to Stillwater, Faribault, and Elk River, and over 4 inches to Red Wing, Winona, Rosemount, Hastings, St Paul, and La Crescent.