Early February 2021 Winter Storm and Cold Air Outbreak
Summary
An area of low pressure developed along an Arctic cold front advancing eastward trough the Upper Midwest, leading to moderate snow over much of Upper Michigan. The snow was initially wet and slushy. However, behind the Arctic front, temperatures plummeted leading to drier snow.
Below-normal temperatures then continued for the next 10 days. The cold air behind the front also caused lake effect snow over parts of the area. The Keweenaw Peninsula was hit hard by several days in a row of lake effect snow leading to snow depths of 40-50 inches by the middle of February.
Meteorology
Loop of 300, 500, 700, and 850 mb showing the NE-SW oriented cold front advancing eastward and a mid-level short wave riding along it, strengthening with time.
One parameter meteorologists look at for the placement of heavy precipitation is frontogenesis - literally the genesis, or creation, of a cold or warm front.
The initial band of frontogenesis was maximized at around 600 mb on Thursday. However, the initial fgen band in the mid levels weakens Thursday afternoon. This weakening is followed by a sharp increase in fgen at 900 mb Thursday evening (after 00z Friday) over central Upper Michigan.
This secondary fgen band was very shallow - it barely shows up at 800 mb and not until much later. It was responsible for a period of 1"/hour snow over much of central Upper Michigan from Iron Mountain to Escanaba to Manistique.
A loop of the radar with the mean sea level pressure overlaid shows the surface pressure trough associated with the cold front, and the development of a new low pressure center along the front over northern Lake Michigan Thursday evening (after 00z Friday).
Snowfall Reports Feb 4-5
Click the points on the map below to see how much snow fell at each location, or scroll below the map to see a full text listing of snowfall totals from this storm.
Early Feb. 2021 Snowfall Local Storm Reports - NWS Marquette, MI
Coldest Temperatures Feb 6-15
Click the points on the map below to see the coldest wind chills at each location, and use the left and right arrows to scroll through multiple days. Note that the time displayed is Zulu time. 12:00 in Zulu time is 7:00 am EST, or 6:00 am CST.
Early Feb. 2021 Temp LSRs
Photos & Videos
Social Media
(Click arrow at right for more)
01 / 05
