A strong winter storm brought heavy snow, sleet and ice to much of Wisconsin February 22nd through the 23rd.
NWS Milwaukee, WI
Storm Overview
Timing of snowfall and winds across Wisconsin with this system starting February 21st with light to moderate snow and continuing through February 23rd with precipitation ending.
Timeline Of The Winter Storm
Environment
The main driving force behind this long duration winter storm was the strong south to north oriented temperatures gradient and a couple weak surface waves that traversed through the Great Lakes Region. These waves of low pressure were associated with periodic enhancement in the precipitation over this two day event.
The Storm Prediction Center's HREF gif of the mean surface pressure and temperature over the contiguous United States from 12Z February 22nd through 22Z February 23rd, 2023.
HREF mean surface pressure and temperature (shaded) depicting the approximate path of a couple relatively weak surface low pressure systems that moved east along a strong temperature gradient.
The strong temperature gradient across the western Great Lakes Region helped set the stage for this long duration event. The baroclinic zone (strong S-N temperature gradient) separated the unseasonable warm air across much of the central and southern Mississippi Valley and the very cold air near the US-Canadian border. Baroclinic zones are areas that are favored for strengthening systems.
North American Mesoscale Forecast System (NAM) map of the 850 mb height contours, winds, and temperatures over the Great Lakes Region.
NAM 850 MB height(contours), wind(kts) and temperature(C). Image exemplifies the persistent and strong N-S temperature gradient(baroclinic zone) across the Great Lakes that helped set the stage for heavy precipitation.
The NAEFS Mean Precipitable Water and Climatological percentile map from 12Z February 22nd, 2023. Highlighting abnormally high moisture moving into the Ohio River Valley.
The NAEFS Mean Precipitable Water and Climatological percentile map from 18Z February 22nd, 2023 Highlighting abnormally high moisture in southern Wisconsin and the rest of the Ohio River Valley and southern Great Lakes Region.
The NAEFS Mean Precipitable Water and Climatological percentile map from 00Z February 23rd, 2023. Highlighting the abnormally high moisture exiting the Great Lakes Regions to the east. Moisture of at least 0.5 times higher than climatology remains in central and southern Wisconsin during this time.
NAEFS Mean Precipitable Water (in) and Climatological percentile over the north and central US for dates and times as listed in images. Source: https://satable.ncep.noaa.gov/archive/#
Moisture with this system was high with precipitable water values above average for this time of year, especially across southern and central parts of Wisconsin. The NAEFS Mean Precipitable Water (in) and Climatological Percentile over the north-central US for the 22nd through the 23rd highlights the abnormally high moisture that was present for this system to tap into.
A 300mb map of wind speed provided by Plymouth State Weather Center.
300mb wind speed (kt, shaded). Jet cores denoted by "j". The upper-level winds were unusually strong which provided the system with plenty of energy to enhance vertical motion across the western Great Lakes.
The 300 hPa jet max that developed roughly over the central plains and moved northeast over the state likely enhanced the lift associated with frontogenesis and the warm air advection in the mid levels. The discussion thus far has focused on the synoptic and mesoscale forcing mechanisms that contributed to the long duration event, but precipitation type forecasting was a big part of this event and a major contributor to the type of impacts seen across the state.
Forecasting Mixed Precipitation
Radar
A long duration radar look from 12 PM CST February 21st through 10 AM CST February 23rd. Radar image is of the western Great Lakes Region.
Long duration radar loop from this winter storm. (Imagery courtesy Iowa State University/Iowa Environmental Mesonet)
Precipitation Accumulations
Snowfall & Sleet Accumulations
The public information statements of snowfall and sleet reports with accompanying maps of total accumulations from National Weather Service Milwaukee, La Crosse, Green Bay, and Duluth.
Ice Accumulations
The public information statements of icing reports with accompanying maps of total accumulations from National Weather Service Milwaukee and La Crosse.
A map of freezing rain/Ice accumulation along the Wisconsin/Illinois border
Freezing Rain/Ice accumulations across Wisconsin/Illinois from February 23rd, 2023
NWS La Crosse's Public Information Statement of the Freezing Rain Reports over the last 24 hours issued at 11:02 AM CST on February 23rd, 2023.
NWS Milwaukee's Public Information Statement of Freezing Rain Reports issued at 2:10 PM CST on February 23rd, 2023.
Freezing Rain/Ice Reports sent to National Weather Service Milwaukee and La Crosse
Regional Snowfall Analysis from the National Operational Hydrologic Remote Sensing Center of Snow Depth in the Northern Great Lakes Region on February 21st and February 23rd. Highlights the amount of precipitation that accumulated across the state over the two day winter storm.
Interactive swipe showing change in snowfall depth between February 23 (left) and February 21 (right). Click and drag on arrow icons to move slider back and forth.
Office of Water Prediction's National Snow Analysis on the left is February 23rd at 6 UTC and on the right is February 21st at 6 UTC. Images highlight the change in Snow Depth before and after this Winter Storm.
Timeline Of The Winter Storm
HREF mean surface pressure and temperature (shaded) depicting the approximate path of a couple relatively weak surface low pressure systems that moved east along a strong temperature gradient.
NAM 850 MB height(contours), wind(kts) and temperature(C). Image exemplifies the persistent and strong N-S temperature gradient(baroclinic zone) across the Great Lakes that helped set the stage for heavy precipitation.
300mb wind speed (kt, shaded). Jet cores denoted by "j". The upper-level winds were unusually strong which provided the system with plenty of energy to enhance vertical motion across the western Great Lakes.
Long duration radar loop from this winter storm. (Imagery courtesy Iowa State University/Iowa Environmental Mesonet)
Freezing Rain/Ice accumulations across Wisconsin/Illinois from February 23rd, 2023
Office of Water Prediction's National Snow Analysis on the left is February 23rd at 6 UTC and on the right is February 21st at 6 UTC. Images highlight the change in Snow Depth before and after this Winter Storm.
