March 1-7, 2023
Week 1: March 1-7, 2023
Unseasonably Warm Start to March
Meteorological spring in the Midwest began with widespread above-normal temperatures, with only western Minnesota recording below-normal temperatures (Figure 1). Looking at opposite ends of the spectrum, Kentucky’s temperatures, on average, were 9.6°F above normal and Minnesota’s were 0.4°F below normal. Both maximum (Figure 2) and minimum temperatures (Figure 3) followed this same trend. This week, 116 high maximum and 6 high minimum temperature records were broken or tied (Figure 4).
Multiple Rounds of Severe Weather
The first round of severe weather this week moved through the southern Midwest in the evening on March 1st. A localized surface low and associated cold and stationary fronts set up in southwestern Ohio in the evening which can be seen in the surface map from 7pm EST (Figure 5). Numerous reports of hail of up to a 1.5-inch diameter occurred along the Indiana/Kentucky border between 6pm and 7pm EST. Associated strong wind gusts resulted in power outages and downed trees. (Figure 6) (7pm EST) shows high radar reflectivity values along the Indiana/Kentucky border, where most severe weather was observed. While severe weather did not last very long in the Midwest, heavy rain continued to occur along this stalled frontal boundary before exiting the region in the early morning hours on March 2nd.
The main system this week started to form in Texas in the afternoon of March 2nd due to an abnormally deep upper-level trough with high wind speeds that dipped down through California and the southwest (Figure 7- 3/2, 7pm EST; Figure 8- 3/3, 7am EST). Multiple tornadoes and numerous high wind reports occurred in the Gulf Coast region as the main line ripped through overnight; stratiform precipitation was seen in the southern Midwest at this point. As the surface low continued to intensify and move northeastward throughout the afternoon, severe weather parameters, such as CAPE and wind shear, increased which primed the Midwest’s environment for strong winds and some tornadoes. Surface pressures with this storm were comparable with hurricanes and blizzards. In fact, record low surface pressures were recorded in Louisville (KY), Paducah (KY), and Evansville (IN).
The following sequence of surface maps shows the intensification of the pressure gradient throughout the afternoon as the system entered the Midwest (Figure 9a- 10am EST, Figure 9b- 1pm EST, Figure 9c- 4pm EST). Fifteen tornadoes occurred between 12pm EST and 6pm along the border of Kentucky and Indiana/Ohio and caused damage to infrastructure and uprooted trees. Dozens of high wind gusts were also reported throughout the whole afternoon; downed trees, overturned trucks, and blown off roofs were just a few of the observed effects of these intense straight-line winds. All preliminary severe weather reports from this storm are available here. Temperatures on the northern side of the low were right around the freezing level, causing snow in the Lake Michigan region, with the highest totals in the “thumb” of Michigan (Figure 10, NWS Detroit/Pontiac MI); Lapeer County, Michigan, recorded 10.8 inches of snow from this event. High snowfall rates of heavy, wet snow combined with strong winds resulted in downed trees and power lines, and left many without electricity. Instability closer to Lake Michigan even caused Illinois and Indiana residents to experience thunder and lightning with this snow. The following National Weather Service offices published storm summaries detailing the multiple facets of this storm:
Above-normal Precipitation
Multiple storm systems resulted in above-normal precipitation totals for the southern Midwest and above-normal totals were observed in the north due to consistent snowfall (Figure 11). The highest one-day precipitation maximum of 4.16 inches was observed in Paducah, Kentucky on March 3rd. There were 191 precipitation records broken or tied this week (Figure 12). Consistent and heavy precipitation, especially in the Ohio River Valley, led to very saturated grounds and localized flooding.
Snow Continues in the North
While severe weather fired up in the southern Midwest, the north received multiple bouts of snow that resulted in well above-normal snowfall totals in central Minnesota, northern Wisconsin, and parts of Michigan (Figure 13). Hennepin County, Minnesota (near Minneapolis) reported 18 inches of snow on March 6th. Thirty-one snowfall records were broken or tied this week, most of which occurred in eastern and southern Michigan (Figure 14).
Streamflow and Drought Update
Much of the Midwest was blanketed with above-normal streamflows (Figure 15). Besides one measurement in eastern Ohio, no rivers in the Midwest had below-normal streamflows this week. Drought conditions continued to improve as well; Indiana became entirely drought free, Severe Drought (D2) was removed from Michigan, and Moderate Drought (D1) and Abnormally Dry (D0) conditions were decreased in Missouri and Michigan (Figure 16).