/Issued 4:50 PM CST, Wednesday, December 14, 2016/
Late afternoon water vapor satellite image; Upper level analysis.
Here's my preliminary snowfall accumulation map for the Friday-Saturday event. Additional changes to the amounts and shifts north/south are possible during the next 24 hours.
Tonight's low temperature forecast. Source: http://graphical.weather.gov/
Thursday's high temperature forecast. Source: http://graphical.weather.gov/
Weather Summary for northeast Minnesota and northwest Wisconsin
A large upper level low pressure system was centered north of Lake Superior today. A reinforcing shot of arctic air pushed through the Northland in the form of an arctic front which moved through earlier in the day. Gusty winds and very cold temperatures were observed throughout the area today with highs in the single digits below to around 5 above zero. Winds were out of the west at 10 to 20 mph with gusts of 25 to around 35 mph. 3 PM wind chills were generally in the -15 to -25° range with the Grand Marais Airport checking with a wind chill of -32°.
Note: This arctic blast is quite impressive with 500mb heights down to 4800 over northern Ontario Province to around 5040 in northern Minnesota and northwest Wisconsin; 850mb temperatures ranged from -26 to -34° C from northeast Minnesota to central/northern Ontario Province with 500mb temperatures of -44 to -50° C across this same corridor.
Forecast Discussion for northeast Minnesota and northwest Wisconsin
.Short Term Forecast...
Tonight (December 14)
Arctic high pressure will move from the western High Plains late this afternoon to south central Iowa by daybreak while a ridge extends north into the Upper Midwest. Patchy clouds will be found over the Northland tonight but overall expecting mostly clear to partly cloudy skies. Bitterly cold with low temperatures in the teens and 20s below zero. Winds out of the west at 10 to 20 mph with higher gusts possible. Wind chills will range from 20 below to around 35 below zero tonight. Note: Areas of blowing snow which developed today will likely continue at least through the evening hours.
Thursday (December 15)
High pressure will head into the Ohio Valley while low pressure moves into the central Rockies. Partly cloudy skies on Thursday with highs in the single digits below to single digits above zero, winds will be southwest at 10 to 20 mph.
Partly to mostly cloudy Thursday night. Might be some light snow or flurries late in the night across southern portions of the Northland but snowfall accumulation should remain less than 1". Lows tomorrow night will range from around 10 below to 5 above with southerly winds at 5 to 15 mph.
Friday and Saturday (December 16-17)
Accumulating snow is expected across most of northeast Minnesota and northwest Wisconsin from Friday into Saturday morning. Low pressure is forecast to move east/northeast out of the central Plains on Friday with a trough extending north into the Upper Midwest -- Some 'milder' air lifting north into an arctic airmass should lead to an area of snow that will likely affect east central Minnesota and northwest Wisconsin beginning Friday morning or more so during the afternoon with snow then continuing Friday night before ending from west-east on Saturday. Note: The chances for snow will diminish farther north with not much snow expected with this system for the Iron Range and Borderland the way it looks now.
Snow ratios will be high with this event thanks to the cold airmass that's in place, will probably have 15:1 to possibly as high as 25:1 ratios, so this will be a fluffy/dry snowfall.
North/northeasterly winds coming off Lake Superior should cause lake enhanced snow Friday night-Saturday morning along the South Shore of Lake Superior from northern Douglas County to Bayfield, Ashland, and Iron County, with lake effect snow showers then developing once the system snow moves out Saturday afternoon into Saturday night in northwest wind favored areas along the South Shore of Lake Superior. Snow totals an excess of 8" is quite possible between Friday afternoon and Saturday evening along the South Shore.
High temperatures on Friday are forecast to range from the upper single digits to around 20 degrees, lows Friday night and highs Saturday ranging from the single digits below zero across northern Minnesota to the teens above zero in northwest Wisconsin.
Forecast for Duluth and Superior
Event: *Wind Chill Advisory*
Timing: Until Noon CST Thursday
Event: *Winter Storm Watch for Superior*
Timing: Friday afternoon through Saturday morning
.Tonight... Frigid. Breezy with patchy blowing snow. Clear to partly cloudy. Low 9 below to 14 below. Wind west at 15 to 25 mph. Wind chills 25 below to 35 below...Occasionally falling close to 40 below after midnight.
.Thursday... Very cold. Partly cloudy. High 0 to 5 above. Wind west to southwest at 10 to 20 mph. Wind chills 25 below to 35 below through Noon.
Normal temperatures for Thursday
Sunrise Thursday: 7:47 AM CST
Sunset Thursday: 4:21 PM CST