February 27th 2023 Winter Storm

Ice & Snow Totals

STORM TOTAL FREEZING RAIN REPORTS

Location                   Precip      Duration
                          (Inches)      (Hours)        Lat       Lon

...Lapeer County...
   2 NW Columbiaville      M  0.10            M     43.18N    83.44W

...Oakland County...
   1 NW Clarkston          E  0.20            M     42.75N    83.43W
   4 E White Lake          M  0.20            M     42.65N    83.43W

STORM TOTAL SNOW REPORTS

Location                  Snowfall     Duration
                          (Inches)      (Hours)        Lat       Lon

...Bay County...
   2 NW Bay City           M   3.0            6     43.61N    83.92W
   2 E Bay City            M   4.4            6     43.59N    83.85W
   Bay City                M   5.0            6     43.59N    83.89W
   Pinconning              M   5.0            6     43.86N    83.96W
   Auburn                  M   5.8           14     43.60N    84.08W

...Midland County...
   Oil City                M   4.0           14     43.61N    84.59W
   4 SW Midland            M   4.1            5     43.58N    84.29W
   2 E Oil City            M   4.5          2.5     43.61N    84.55W
   Midland                 M   6.3            5     43.62N    84.23W
   Hope                    M   7.0            6     43.76N    84.34W
   Sanford                 M   8.0            6     43.68N    84.38W

...Huron County...
   Port Austin             M   4.0           12     44.04N    83.00W
   Bad Axe                 M   6.9           12     43.80N    83.00W

...Saginaw County...
   5 S Auburn              M   2.0            3     43.53N    84.08W

...Tuscola County...
   Caro                    M   5.5           13     43.49N    83.40W
   Cass City               M   6.0           13     43.60N    83.18W

...Sanilac County...
   Deckerville             M   5.0            6     43.53N    82.74W
   Lexington               M   5.0           12     43.27N    82.53W

M = MEASURED
E = ESTIMATED

$$

Storm Total Snow

Radar

Environment

A strong upper level shortwave trough translated from the southwest CONUS into the Great Lakes drawing an expansive sub-tropical moisture plume that fueled a large area of rain and wintry precipitation across the southern Great Lakes. An elevated warm front lifted northward in advance of the surface low center which led to a jump in 850 mb temps from near 0C at 7 AM (Figure 1) to almost 5C by 7 PM (Figure 3) with a 50 knot low-level jet nose. This saturated warm layer aloft ensured any frozen precipitation falling above the warm layer would be nearly melted by the time it reached the surface, thus the widespread mix of freezing rain and sleet, supported by the easterly feed of dewpoints in the 20s. The surface warm front remained south of the Michigan/Ohio border by 18Z (Figure 2) as the low occluded and moved due eastward. Along/south of I-96, slight diurnal warming allowed surface temperatures to climb above freezing limiting ice accumulations to elevated surfaces.

Farther south, heavy rainfall occurred with elevated instability as mid-level lapse rates approached 6.5 C/km. This coincided with the strongest axis of FGEN that translated across the Michigan/Ohio border during the afternoon period, particularly within the 925-850 mb layer (Figures 5, 6). Rainfall totals exceeded an inch in several locations across Lenawee, Monroe, Washtenaw, and Wayne counties. Detroit set a new daily record rainfall record of 1.23 inches while isolated reports of an inch and a half were realized further south. Centering along the I-69 corridor, more efficient icing was realized with approximately 0.10-0.25 inches of ice reported. Given slightly cooler surface temperatures, these areas remained below freezing leading to a distribution of predominantly freezing rain through the bulk of the event which was maintained by evaporative cooling.

North of the M-46 corridor, a combination of colder column temperatures, strong vertical velocities, secondary FGEN axis, and efficient wet-bulbing led to a period of heavy snowfall for portions of Midland, Bay, Tuscola, Huron, and Sanilac Counties with isolated areas of thunder snow. Snowfall rates in excess of an inch per hour were noted such as at Auburn, Sanford, and Cass City leading to whiteout conditions at times during the afternoon before the arrival of the dry slot and temperatures near 30F. Given the colder temperatures and the lack of interference from the elevated warm front, this area of enhanced snowfall was able to maintain an all-snow character through the event which helped boost SLRs given a lack of riming or sleet mix.

Figure 1: DTX Sounding Valid Feb 27 2023 12UTC	Figure 2: WPC Surface Analysis Valid Feb 27 2023 18UTC
Figure 3: DTX Sounding Valid Feb 28 2023 00UTC	Figure 4: WPC Surface Analysis Valid Feb 28 2023 03UTC
Figure 5: SPC 925-850 mb FGEN Valid Feb 27 2023 18UTC	Figure 6: SPC 925-850 mb FGEN Valid Feb 27 2023 20UTC