What are folklore weather forecasts?

Posted on February 5, 2024 by WeatherGuys Editor

Humans have always needed weather forecasts. Farmers and sailors in particular needed to know if storms were approaching. People looked to their surroundings and observed nature and the world around them to try to predict the coming weather.

Over time, various folklore forecasts, often in the form of short rhymes, were devised and passed down through the generations. Although memorable, folklore forecasts are of uneven quality — some good, others laughably bad.

The forecast made on Groundhog Day is an example of predicting the weather based on folklore. If the groundhog comes out of its hole and sees its shadow, we are in store for 40 more days of winter. The predictions made by this folk forecast are correct only about 40% of the time — vastly inferior to what is delivered by modern science. If you flip a coin, you’ll be close to being correct 50% of the time. The popularity of Groundhog Day in the United States has much more to do with clever marketing than it does with forecast accuracy.

Another example comes from ancient mariners:

Red sky at night, sailor’s delight
Red sky at morning, sailor take warning.

Red sky at night! Credit: Benji Johnson

This saying is fairly accurate as it has some meteorologic basis. A clear western sky at sunset allows the sun to shine through the atmosphere, its light reddening as a result of Rayleigh scattering and then reflecting off clouds in the eastern sky. Clouds to the east usually move away; storms in the middle latitudes generally travel to the east under the influence of jet-stream winds.

The reverse is true in the morning, when the red sunlight shines on storm clouds approaching from the west. However, this folklore doesn’t work at all in overcast conditions or at tropical latitudes, where weather often moves from east to west.

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: History, Seasons

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Are drones used in meteorology?

Posted on January 29, 2024 by WeatherGuys Editor

Unmanned aerial vehicles, or UAVs, have been used to make weather observations for half a century. Over the past decade there has been a wider application of drones in meteorology due in part to technological developments.

NASA takes retired Global Hawk military drones and sets them up to fly dangerous missions monitoring some of the most extreme storms for better weather data. (Photo credit: NASA)

Drones can provide critical research observations of weather systems. For about a decade, NOAA has partnered with NASA to fly the Global Hawk high-altitude unmanned aircraft to observe and study how hurricanes form and intensify. High-resolution photographs from low-flying drones are used to understand and document wind and flood damage associated with severe weather. They also help to better assess storm intensity based on the damage.

Routine integration of weather drones into weather forecasting would provide more precise monitoring of localized atmospheric conditions. However, restrictions on flight paths are one barrier to using drones in operational weather forecasting. Federal regulations prohibit drones from being deployed beyond visual line of sight. In addition, drones do not perform well in poor weather conditions. Swarm drone intelligence is also needed to coordinate multiple drones in sensing the boundary layer.

Drones with meteorological instruments, referred to as meteodrones, provide important observations of the lower atmosphere where there is a dearth of data, despite the importance of this boundary layer in weather forecasting. Drone systems are being developed to provide this data, as sustained observations of the boundary layer would improve local weather forecasting.

This spring, the World Meteorological Organization is planning a seven-month worldwide campaign to assess drones’ capability to improve weather forecasting. About 40 drone teams will coordinate and launch their drones to collect atmospheric observations in the U.S., Europe and Asia. The participants will share their data for analysis and study the impact of drone observations, along with established radiosondes and weather balloon data, on weather forecasting.

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: Meteorology, Severe Weather

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Are the Madison lakes ice-covered?

Posted on January 22, 2024 by WeatherGuys Editor

The Wisconsin State Climatology Office, housed at the University of Wisconsin-Madison, monitors and reports on the ice coverage of Madison lakes.

View of Lake Mendota on January 15, 2024 (Photo credit: The Edgewater Hotel)

The office keeps a database of the ice-over and ice-out dates for three Madison-area lakes: Mendota, Monona and Wingra. These records extend back to the winters of 1855-1856 for Mendota and Monona. The record of annual ice cover of Wingra is spotty, but consistent starting in the winter of 1982-83. Due to the long record based on visual observations, it is no surprise that the rules of opening and closing have been handed down by oral tradition.

Ice coverage data for lakes Monona and Wingra are based on a general “50 percent covered” rule. The size and irregular shoreline of Lake Mendota make it challenging to observe, and so ice coverage is based on “whether one can row a boat between Picnic Point and Maple Bluff.” The lore is that in the early era, this rule was developed based on observers’ ability to bring a case of beer in a rowboat to friends on the other shore.

This year, without a rowboat, the observers determined that both Lake Mendota and Lake Monona froze over on Monday, Jan. 15. The recent cold air outbreak helped in covering the lakes with ice. Lake Wingra has frozen and thawed multiple times already this winter but has been frozen over consistently since Jan. 5.

This winter’s freeze-over date for lakes Mendota and Monona is the third-latest on record. Mendota froze over on Jan. 20, 2007, and Jan. 30, 1932. Monona froze over on Jan. 18, 2007, and January 30, 1932.

With the forecast of warmer weather this week, it will be interesting to see whether the lakes remain iced over.

And a big thank you to Ed Hopkins, Lyle Anderson and David Liebl, who annually brave our winter weather to assess ice conditions on the lakes.

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, History, Seasons

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How is this winter stacking up historically?

Posted on January 15, 2024 by WeatherGuys Editor

 We are now a couple of days into what is easily the coldest air we have seen this entire winter.

Temperature anomalies today. (Image credit: University of Maine’s Climate Reanalyzer)

Until a week ago, complaints about the lack of snow were also justified in the southern part of the state. However, two recent snow events have even changed that situation so that, as of Monday, Madison suddenly is 7.3 inches ahead of normal for the snow season, which started July 1.

As far as temperature goes, through Wednesday we had averaged 5.85 degrees Fahrenheit above average per day since Nov. 1 — a remarkably extended period of above-average warmth.

Of course, we’re well below normal now and should be that way for much of the coming week.

The unusual warmth that has predominated has been a hemispheric phenomenon throughout the same period. As measured by considering the areal extent of air colder than 23 degrees at the 850 mb level, which is just about 1 mile above the surface, November was the 21st-warmest in the past 76 years, while December was the 11th-warmest in that same stretch.

Even though we are in the midst of a pretty intense cold wave right now, the first 10 days of January were the fifth-warmest such stretch in the past 76 years.

So, all in all we have had a pretty good run until this past weekend regarding the intensity of this winter. It is difficult, if not impossible, to say what will happen the rest of the way, though it is certainly the case that, at least climatologically, it is the next 20 or so days that we have to worry about most in terms of cold. Once we get past early February, and the day is noticeably longer, it is really difficult for any frigid air manufactured at high latitudes in Canada to make it all the way south to us without being strongly modified as it comes.

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: History, Seasons

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Is there any difference between ‘partly cloudy’ and ‘partly sunny’?

Posted on January 8, 2024 by WeatherGuys Editor

The National Weather Service denotes sky condition using the portion of sky covered by opaque cloud cover.

Cloud cover is indicated by the shading of the centre of the station circle. The table below shows the meanings of the different symbols. (Image credit: MetLink, Royal Meteorological Society)

In meteorology, an okta is a unit of measurement used to describe the amount of cloud cover at a given location. Cloud conditions are estimated in terms of how many eighths of the sky are covered with opaque cloud, ranging from 0 oktas (completely clear sky) to 8 oktas (completely overcast). It does not include transparent clouds, such as thin cirrus.

Mostly clear or mostly sunny is reported for coverage from 1 to 3 oktas, while partly cloudy or partly sunny refers to cloud coverage of 3 to 5 oktas. Mostly cloudy is reported if 5 to 7 oktas of the sky are covered with opaque clouds. When the sky is obscured by fog, 9 oktas is reported for total sky cover, indicating it could not be observed.

Trained weather observers make these estimates, and while the cloud cover measurements are subjective, they still provide useful and scientifically valuable data.

So, partly cloudy is the same as partly sunny, with 3 to 5 oktas of opaque cloud cover. Of course, partly sunny cannot be used in reporting nighttime conditions.

At any particular observation time, there may be different types of clouds at different heights above the ground. In such situations the total cloud amount is reported and defined as the fraction of the sky covered by any type of opaque cloud. Weather reports also will include the fraction of the sky covered by each type or layer of cloud as if it was the only type or layer of cloud in the sky.

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: Meteorology

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