Was our recent snowfall typical for a Madison winter?

Posted on December 12, 2022 by WeatherGuys Editor

Our first substantial snowfall of the season visited Madison on Friday morning as a period of moderate to heavy snow fell from around 7 to 9:45 a.m.

Scenes from the Yahara River in Madison Wisconsin during the December 9th snowfall.
Photo credit: M. Mooney

In the end, we accumulated 4.4 inches of heavy wet snow timed perfectly to snarl the morning commute.

Friday’s event was just the fourth snowfall of 4 inches or more since the COVID-19 pandemic started in 2020. We wondered how often a cold season is visited by a storm with that much snow.

Using records from Dane County Airport as well as the prior site of the Madison airport, it turns out that 209 such snowfalls have occurred since 1939 — 75 of them since 2000. Interestingly, 20 of the last 83 winters have had only one 4-inch or greater snowfall, and seven others have passed without a single event of that magnitude.

That means that just shy of one-third of the time, a winter season in Madison comes along in which, at most, only one snowfall of 4 inches or more occurs.

That may seem hard to believe given that our seasonal snowfall averages 50 inches each year. However, the majority of a seasonal snow total in Madison is often made up of a series of quite small amounts.

Though the average number of days on which at least 1 inch of snow accumulation occurs in Madison varies enormously from year to year, the long-term average over the same interval has increased from roughly 12 days each winter to about 15. The record is 27 such days in 2007-08 — when we set the all-time seasonal snowfall record of 101.4 inches — while the record minimum number is just 2 in 1967-68.

Thus, it is hard to tell whether what we experienced on Friday morning will be a common occurrence this winter.

Steve Ackerman and Jonathan Martin, professors in the UW-Madison department of atmospheric and oceanic sciences, are guests on WHA radio (970 AM) at 11:45 a.m. the last Monday of each month. Send them your questions at stevea@ssec.wisc.edu or jemarti1@wisc.edu.

Category: Climate, Meteorology, Seasons

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What does a warm fall portend about winter?

Posted on December 5, 2022 by WeatherGuys Editor

Most of the weather experts we know have rated this fall’s weather as reasonably benign in our region. The past month’s average temperature here in Madison was 1.9 degrees above normal, which rounded out a fall season (September through November) that was 1.13 degrees above normal overall – a measurement that supports this widely held opinion.

NWS climate statistics for Madison and Milwaukee Wisconsin for Autumn 2022

At about 1 mile above sea-level, the areal extent of cold air (minus 5 centigrade, or 23 degrees Fahrenheit) over the entire Northern Hemisphere was the eighth smallest in the last 75 years over the September-November period.

This reflects the fact that the most locations in the Northern Hemisphere were on the warm side of their averages this fall.

When one lists all September-November periods since 1948 from “warmest” (number 1) to “coldest” (number 74) by this measure, one creates what is known as a rank list. The same can be done with the areal extent of the cold air during the winter months (December through February).

In the last 73 cold seasons through February 2022, 38 winters were ranked warmer than their corresponding falls, while 35 were colder.

It is not yet known what circumstances might conspire to change the nature of the cold season so abruptly some years, but it is an interesting question whose answer may bear on the ability to make more accurate seasonal forecasts in the future.

As it stands, it is not really possible to tell if the December-to-February stretch this winter will turn sharply colder after our remarkably warm fall.

Winter Temperature Outlook from NOAA

Steve Ackerman and Jonathan Martin, professors in the UW-Madison department of atmospheric and oceanic sciences, are guests on WHA radio (970 AM) at 11:45 a.m. the last Monday of each month. Send them your questions at stevea@ssec.wisc.edu or jemarti1@wisc.edu.

Category: Climate, Seasons

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What is the prediction on the rise of sea level?

Posted on November 28, 2022 by WeatherGuys Editor

The National Oceanic and Atmospheric Administration, or NOAA, routinely monitors sea level and makes predictions of how it will change with time. The observations are based on a combination of tide gauge data and satellite observations.

Continuously tracking how and why sea level is changing is an important part of informing plans for adaptation to global changes. In a recent speech, former President Donald Trump falsely stated that “the ocean will rise 1/8 of an inch over the next 200 to 300 years.”

In 2022, multiple agencies including NOAA, NASA, USGS, EPA, FEMA and DoD, issued a joint report that updated one published in 2017. The new report projects that sea levels along the U.S. coastline will rise an additional 10 to 12 inches by 2050, with specific amounts varying regionally. The prediction for increased sea level rise is a sustained response to the observed and continued global warming.

Image credit: 2022 Sea Level Rise Technical Report

Between 1901 and 2018, the globally averaged sea level rose by 6 to 10 inches. The current rate of sea level rise is accelerating at almost twice the rate of the past 117 years. Sea level change can be affected by many factors; the current trend of increasing sea level results from global warming. As sea water temperatures increase, the water expands, contributing to the mean sea level rise. When temperatures rise, mountain glaciers and the polar ice caps melt, increasing the amount of water in the oceans.

The 2022 report also finds that the expected increase in sea level will create an increase in the frequency of coastal flooding, even in the absence of storms or heavy rainfall. By 2050, flood damage is expected to occur, on average, more than 10 times as often as it does today, and can be intensified by local factors.

Steve Ackerman and Jonathan Martin, professors in the UW-Madison department of atmospheric and oceanic sciences, are guests on WHA radio (970 AM) at 11:45 a.m. the last Monday of each month. Send them your questions at stevea@ssec.wisc.edu or jemarti1@wisc.edu.

Category: Climate, Severe Weather

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Was our weather this week related to the record event in Buffalo, New York?

Posted on November 21, 2022 by WeatherGuys Editor

It has been a fairly wintry week across the Great Lakes states, including here in southern Wisconsin.

Crews truck snow in to dump in the parking lot of Erie Community College in Orchard Park, N.Y., on Sunday, after lake effect snows dropped 77 inches in the Buffalo suburb. (Photo credit: Mark Mulville, The Buffalo News)

Through Saturday night, it had snowed on five straight days in Madison, a total of 4.4 inches. The same pool of cold air above the ground that led to Madison’s intermittent snow showers stretched all the way across the Great Lakes. In fact, the Saturday morning temperature at 1.5km above the surface at Buffalo, New York, was minus 14 Celsius (about 7 degrees Fahrenheit).

Meanwhile, as the cold season begins, the lakes are as warm as they will be all winter, with water temperatures in eastern Lake Erie last week at or slightly above 14 Celsius (about 57 degrees Fahrenheit). Therefore, the lapse rate — the rate at which temperature decreases with increasing height — above the lake was abut 18.7C/km, well above the 10C/km threshold necessary for absolute instability.

The consequence was that huge amounts of heat and water (in the vapor phase) were extracted from the lake surface and turned into lake effect snow — 77 inches in the Buffalo suburb of Orchard Park.

Though minus 14C at 1.5 km is pretty cold, that is not the coldest it has ever been at that height across the lakes in mid-November. It is likely that this weekend’s event was record-setting primarily because the air was flowing along the long axis of a warmer-than-normal Lake Erie, allowing the cold dry air the maximum amount of time to evaporate water vapor off the lake to produce the snow.

That all-important wind direction was determined by the particular distribution of high- and low-pressure systems across all of eastern North America at the initiation of the lake effect event. Though not random, this distribution is highly variable and must align precisely with the other conditions to transform a run-of-the-mill lake effect snow event into a historic one.

Category: Meteorology, Severe Weather

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How is the 2022 hurricane season going?

Posted on November 14, 2022 by WeatherGuys Editor

The hurricane season is a distinct time of year when tropical cyclones — tropical depressions, tropical storms and hurricanes — usually develop.

Here in the U.S., we usually refer to the Atlantic hurricane season, as it’s those storms that most commonly affect the U.S., which extends from June 1 to Nov. 30.

For the 30-year climate period of 1991-2020, the average for the Atlantic hurricane season includes 14 named storms and seven hurricanes. The average for major hurricanes (category 3, 4 or 5) is three. The previous Atlantic storm averages, based on the period from 1981 to 2010, were 12 named storms, six hurricanes, and three major hurricanes.

Back in May 2022, forecasters at the National Oceanic Atmospheric Administration’s Climate Prediction Center (NOAA CPC), predicted an above-average number of hurricanes for 2022. NOAA forecasted a likely range of 14 to 21 named storms (winds of 39 mph or higher), of which six to 10 could become hurricanes (winds of 74 mph or higher), including three to six major hurricanes (category 3, 4 or 5; with winds of 111 mph or higher).

NOAA provides these ranges with a 70% confidence. The prediction of an above-average hurricane season was attributed to ongoing La Niña that was forecasted to persist throughout the hurricane season, warmer-than-average sea surface temperatures in the Atlantic Ocean and Caribbean Sea, and weaker tropical Atlantic trade winds.

As of mid-November, there have been a total of 14 named storms, eight hurricanes, and two major hurricanes (Category 3 or above). A pretty good forecast, although a lower number of predicted major hurricanes. This is the seventh consecutive year with an above-average hurricane season.

The latest hurricane, Nicole, is likely to be the last one of the season and was the second-latest landfalling U.S. hurricane in history after Kate on Nov 21, 1985.

Hurricane Nicole prior to landfall in Florida via GOES East on November 8, 2022.

Steve Ackerman and Jonathan Martin, professors in the UW-Madison department of atmospheric and oceanic sciences, are guests on WHA radio (970 AM) at 11:45 a.m. the last Monday of each month. Send them your questions at stevea@ssec.wisc.edu or jemarti1@wisc.edu.

Category: Seasons, Tropical

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