HydroClim Minnesota for Early February 2018
A monthly electronic newsletter summarizing Minnesota's climate conditions and the resulting impact on water resources. Distributed on the first Thursday of the month.
State Climatology Office - DNR Division of Ecological and Water Resources, St. Paul
distributed: February 9, 2018
What happened in January 2018:
- January 2018 monthly precipitation totals were below normal for many places in central and northern Minnesota. There were higher than normal precipitation totals in the southeast. Precipitation totals were one half to nearly two inches above normal in this area. In contrast, there were large areas of central Minnesota that fell short of normal by a half to one inch. The largest precipitation event was on January 22, 2018 with a heavy snowstorm that affected southern Minnesota, including the southern Twin Cities. There were also a number of minor snow events which although did not accumulate a lot of snow, did impact traffic at times. The preliminary statewide precipitation total was .87 inches or .08 inches above normal.
[see: January 2018 Precipitation Map | January 2018 Precipitation Departure Map | January 2018 Climate Summary Table | January 2018 Percent of Normal Precipitation Map]
- One significant snowfall event occurred in Minnesota during January 2018. On January 22, Heavy snow fell from southwest to east central Minnesota. 12.4 inches fell in the Twin Cities, the largest snowfall event to fall since February 2011.
[see: Jan 22, 2018 Heavy Snow]
- Average monthly temperatures for January ranged from two degrees above to two degrees below normal. The start of 2018 continued the much below weather pattern that began at the end of 2017, but it was not to last. There were three January thaws during the month, one on January 7-11, another on January 18-22 and a brief thaw on January 26 and 27. This was enough for the Twin Cities to finish one degree above normal, while the statewide average finished at .1 degrees below normal. The warmest temperature for the state in January was 53 degrees at Granite Falls on January 19. Many places saw temperatures in the 40's in this thaw episode. The coldest minimum temperature for the month of -46 notched at Embarrass on January 14th.
[see: January 2018 Climate Summary Table | January 2018 Departure from Normal Temperature Map
Where we stand now:
- Snow Depths range from an inch of snow and less across central Minnesota to about a foot and a half along the north shore of Lake Superior and along the Canadian border in the north central and north east. In the Twin Cities Metro area there is generally 8-10 inches of snow on the ground. The bottom of this snow pack in the Twin Cities dates from mid-January since most of the snow that fell in December melted away with the January thaw of the second week of January. A snow core measurement of the snow pack in the Twin Cities on February 5 depicted 1.7 inches of water. A series of minor snowfalls has blanketed southern Minnesota with a few inches of new snow. The snow depth ranking is below historical averages across much of northern and central Minnesota, with a swath of above average ranking over southwest and east central Minnesota.
[see: Weekly Snow Depth and Ranking Maps | NWS Snow Depth Estimation Map | Midwest Regional Climate Center Snow Depth Map]
- The U. S. Drought Monitor map released on February 8 depicts Moderate drought over west central and north central Minnesota, covering 4% of the state. 27% of Minnesota is under Abnormally Dry conditions, focusing mainly over western portions of the state. The rest of the state is free from any drought designation. The U.S. Drought Monitor index is a blend of science and subjectivity where drought categories (Moderate, Severe, etc.) are based on several indicators.
[see: Drought Conditions Overview]
- The U.S. Geological Survey reports that stream discharge values (where winter measurements are possible) are normal to much above historical medians for the date for the few Minnesota rivers that have data. Most rivers and streams are now impacted by ice.
[see: USGS Stream Flow Conditions]
- In their final report of the 2017 growing season (November 27), the Agricultural Statistics Service reported that topsoil moisture across Minnesota was 0 percent Very Short, 3 percent Short, 85 percent Adequate, and 12 percent Surplus.
[see: Agricultural Statistics Service Crop Progress and Condition | U. of M. Southwest Research & Outreach Center (Lamberton) | U. of M. Southern Research & Outreach Center (Waseca)]
- The potential for wildfires is currently rated by DNR Forestry as Low across Minnesota.
[see: Fire Danger Rating Map]
- Soil frost depths under sod are close to average to a little bit deeper for early February, generally around 15-24 inches in the central and south and around three feet in the Mississippi Headwaters and northwest Minnesota.
[see: Corps of Engineers Snow, Ice, Frost Data | National Weather Service Frost Depth Data | MnDOT Road Frost Depths | University of Minnesota - St. Paul Campus Soil Temperatures Under Sod]
- Minnesota lakes, rivers, and wetland complexes are ice covered. The cold start to November began to freeze lakes across the state, then above normal temperatures followed in late November and early December causing a dangerous situation due to the softening ice. Conditions became more favorable for ice formation for the second half of December. A number of lakes went through multiple ice in/ice off cycles before finally freezing for good for the winter. In the end lake ice on was about a week later than the historical median. Lake and river ice is never completely safe. On February 9, Lake Superior is 57.8% covered by ice, a higher percentage for this date than the last two years. The maximum ice coverage for lake Superior typically happens in late February.
[see: DNR Conservation Officer Reports | Median Lake Ice-In Dates | Great Lakes Ice Cover]
- The February precipitation outlook offers a tilt toward above-normal conditions in Minnesota. February is typically the driest month of the year. Precipitation normals range from near one-half inch of liquid equivalent in western Minnesota to just over three-quarter of an inch of precipitation in eastern sections of the state. The median snow depth at the end of February ranges from under five inches in southwest Minnesota to over 18 inches on the ground in northeastern Minnesota (greater than 30 inches in the Lake Superior highlands).
[see: Climate Prediction Center 30-day Outlook | February Precipitation Normal Map]
- The February temperature outlook leans towards below normal conditions across Minnesota, especially in the north. Normal February high temperatures range from the low teens in the north to near 20 in the south early in the month, climbing to the mid-20s to low 30s by month's end. Normal February low temperatures range from near minus 10 degrees in the far north to the single digits above zero in southern Minnesota early in the month; ascending to the low single digits in the north, mid-teens in the south by the end of February.
[see: Climate Prediction Center 30-day Outlook | January Temperature Normal Map]
- The 90-day precipitation outlook for February through May indicates a tendency for above normal conditions across all but the southwest corner of the state. The February through May temperature projection indicates a tilt towards below-normal temperatures.
[see: Climate Prediction Center 90-day Outlook]
- The National Weather Service produces long-range probabilistic river stage and discharge outlooks for the Red River, Minnesota River, and Mississippi River basins. These products address both high flow and low flow probabilities. Here are the current weather conditions impacting prospects for spring snow melt flooding:
[see: National Weather Service - North Central River Forecast Center]
- present stream flows are normal to above normal relative to historical flows for the date
- soil profiles are moist due to above normal precipitation in 2017,
- frost depths are near to slightly deeper than average.
- snow depths are well below the historical median for the date in much of central Minnesota, the Mississippi Headwaters and the Red River Valley. Snow depth is above historical median from southwest through east central Minnesota.
From the author:
- If the current weather continues, the winter of 2017-18 will finish cooler than normal. The average statewide temperature for December 2017 and January 2018 is about a half degree below normal. From February 1-9 the statewide average for Minnesota was -12.9 degrees below normal. The second half of February would have to be quite a bit above average to counterbalance the cold. Seasonal snowfall has been running below normal across many locations. Through February 9 the Twin Cities is 5.5 inches short of normal, Rochester is 3.5 inches short, Duluth is 1.7 inches short and International Falls is 8.6 inches short of normal. Precipitation for December 2017 and January 2018 is about a third of an inch below normal statewide and February is continuing this dry trend so far.
Upcoming dates of note:
- February 15: National Weather Service releases 30/90 day temperature and precipitation outlooks
- Late-February: National Weather Service releases updated spring flood probabilistic outlooks
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Pete Boulay, DNR Climatologist