Researchers developing experimental winter forecasting tools

Last month, millions of people across the United States were impacted by several inches to feet of snow and the coldest temperatures in decades. Thousands lost power and water, and travel was treacherous as multi-vehicle pile-ups forced interstate shutdowns.

To help lessen these impacts, researchers at the Cooperative Institute for Mesoscale Meteorological Studies at the University of Oklahoma and the NOAA National Severe Storms Laboratory in Norman, Oklahoma, are working to improve current winter road tools. They are focused on predicting and monitoring a variety of winter hazards and the potential impacts of such weather.

“Hazards may include accumulating snow or ice on roadways, slushy roadways, and others,” said Shawn Handler, a researcher at OU CIMMS. His work supports NOAA NSSL. “It’s possible a winter storm may pose a greater threat to one infrastructure more than others, like maybe travel or power outages.”

A mailbox topped with snow.
A snow-covered home and mailbox in Oklahoma. Winter weather ravaged parts of the United States in February, leaving many without power and water. (Photo by James Murnan/ NOAA)

Handler, with a team of other researchers, are developing two experimental products: the Experimental Road Hazards Product and Probability of Subfreezing Road Temperatures (ProbSR) product. These are expected to be integrated into the National Weather Services’ Winter Storm Severity Index (WSSI).

The Experimental Road Hazards Product will provide information on specific hazardous road threats, like ice.
The experimental Probability of Subfreezing Road Temperatures (ProbSR) product uses current and immediately available information to predict if road temperatures are subfreezing.
The Winter Storm Severity Index (WSSI) is an operational product designed to provide impacts-based decision support to NWS forecasters in order to allow them to provide more target messaging to the general public and other government stakeholders. This product is developed and supported by NCEP/Weather Prediction Center.

These tools can be used together to increase the amount of winter-storm information available to National Weather Service forecasters and emergency officials.

Integrating the tools

Aimed to improve winter-weather advisories, the WSSI ingests several different sources of information but none of those sources provide information on the roads. Researchers want to pair WSSI with the ProbSR product, allowing forecasters to have greater confidence about the potential for winter-weather to result in treacherous driving conditions.

“It’s possible a winter storm may pose a greater threat to a certain infrastructure compared to others,” Handler said. “For example, Oklahoma City experienced an ice storm in October and impacts to the power grid outweighed the impacts to road travel, as hundreds of thousands of people lost power for an extended period of time.”

Integrating ProbSR and the road-hazard tool into the WSSI will allow ProbSR to be tested and evaluated as a forecasting tool next winter in a testbed environment.

Hazardous road threats are determined by pairing the road temperature tools of ProbSR with another model providing precipitation classification at the surface, like snow and rain, to create the Experimental Road Hazards Product.

“We are focused on what hazards or threats may be present,” said Handler. “For example, it could be snowing, but if ProbSR has low probabilities, the expected threats to travel may not be as high – such as a wet roadway as the snow is not expected to accumulate. Whereas, if it has been cold enough for a longer stretch of time – a higher ProbSR – and snowing, then accumulating snow would be the resulting hazard.”

Icicles hanging from the edge of a home roof.
Many states experienced the coldest weather in decades. Cold temperatures were accompanied by ice, snow and other winter precipitation. (Photo by James Murnan/NOAA)

Continuing research

Handler said tests with the products are successful, but the team is retraining ProbSR with more recent data from the High-Resolution Rapid Refresh model (HRRR), a high-resolution weather forecasting model used by the NWS. The HRRR updates forecasts hourly over the entire lower 48 United States at a resolution of less than two miles.

The Experimental Road Hazards Product is in the early stages of development. The team continues to investigate ways to improve it, including gathering more inputs, such as precipitation rate and wind speed.

“Precipitation rate will provide information on how fast precip – like snow, rain, ice – is falling, whereas wind speed could be included as a way to assess visibility threats,” he said. “We also want to include more threats utilizing these new inputs, such as reduced visibility from blowing snow.”

The researchers’ next steps regarding the Road Hazards product are to add some of the features described above, and to properly verify the classifications made from the algorithm using traffic camera observations.

Products will be tested by researchers and forecasters in the winter of 2022 in a joint testbed with the NOAA Weather Prediction Center.

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NOAA researchers are working to make traveling in winter weather safer

Story posted on NOAA Research by Katie Valentine.

A team of scientists at NOAA’s National Severe Storms Laboratory and National Weather Service National Weather Service is working on ways to better forecast potentially dangerous winter weather to cut down on these impacts to travelers. Heather Reeves, a researcher at the Cooperative Institute for Mesoscale Meteorological Studies (CIMMS) supporting NSSL, said the project is focusing on the smaller or more short-lived weather hazards — not the big, “snowmageddon” type storms.

“We have gotten really good at predicting when a big event is going to happen and what regions it will impact,” said Reeves, who is leading the research. “The real danger now are these events where people don’t have to stay inside. They can still go out and live their lives, but there may be moments where they need to exercise caution.”

Read the full story at

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Spread the word: We need your precipitation reports!

NSSL is now collecting two types of winter weather reports from the public to help evaluate the performance of a new winter weather precipitation algorithm. NOAA National Weather Service (NWS) radars across the U.S. are in the process of being upgraded with dual-polarization technology that can detect the difference between rain, sleet, snow, and hail.  The algorithm sorts dual-polarized radar data into types of liquid or frozen precipitation to help forecasters quickly assess a precipitation event and better forecast how much will fall.

To help evaluate and refine the algorithm, the mostly student-run NSSL/CIMMS Severe Hazards Analysis and Verification Experiment (SHAVE) started collecting winter weather precipitation reports through phone surveys during the week of February 3, 2012.  SHAVE reports, when combined with the voluntary reports collected by the NWS, creates a unique and comprehensive database of winter weather weather events used to evaluate algorithm performance.  SHAVE previously had been a primarily summer project, collecting more than 45,000 reports of hail size, wind damage and flash flooding since it began in 2005.

NSSL’s Precipitation Identification Near the Ground (PING) project requests public precipitation reports at  from any area within 90-miles of a radar upgraded with dual-polarization radar technology. Researchers compare the reports of precipitation with what is detected by the dual-polarized radar data.  Volunteers have submitted more than 5,000 reports of snow, ice pellets, drizzle and rain since the beginning of the project in 2006.

Both projects are ongoing.

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Winter storm sparks discussion in NOAA’s Hazardous Weather Testbed

HWT map discussion
It was standing-room only in the NOAA HWT for the 27 Jan 2010 map discussion

A major ice storm loomed on the horizon of the National Weather Center in Norman, Okla., during the last week of January. Temperatures were expected to hover around freezing, and a hazardous mix of freezing rain, sleet and snow threatened to shut down much of the state.

The brewing storm was the main topic at the “Map Discussion” on Monday that week. Map discussions are held over lunch every Monday in the NOAA Hazardous Weather Testbed at the National Weather Center. They are a unique opportunity for the many federal, state, local and university weather groups housed together to jointly analyze weather forecast maps. When high impact weather affects the United States, the group meets more often.

“We have 30-40 people attend on a regular basis,” said Patrick Marsh, University of Oklahoma graduate student working for National Severe Storms Laboratory /Cooperative Institute of Mesoscale Meteorological Studies, who co-leads the gatherings.

Greg Carbin from the National Weather Service Storm Prediction Center co-leads the map discussion with Marsh and commented, “When meteorologists of different backgrounds and specialties gather to discuss the day-to-day weather in the NOAA Hazardous Weather Testbed, they are taking part in advancing the science.”

Special map discussions were held as the week went on, and on Wednesday, Jan. 27, there was a record crowd of 74 people. Some of the best minds in meteorology and their students had gathered, united by a common passion for weather and a curiosity to figure out how the storm was going to affect them personally.

It was a tricky forecast. A subtle difference in location or temperature would change the forecast from ice to snow.

“We’ll start off with the National Watch/Warning graphic. As you can see, for basically the northwest 2/3 of Oklahoma and the Texas panhandle, the winter storm watch has been converted to a winter storm warning,” began Marsh. The group spent the next half hour discussing all types of weather forecast maps, including many experimental forecast products.

The Wednesday map discussion was so productive Marsh posted a videocast online ( for those who couldn’t attend but wanted to know what happened. As the dangerous mix of frozen precipitation began to pummel central Oklahoma, a listserv was created to extend the dialogue.

By mid-afternoon on Thursday, freezing rain had already caused a layer of ice to accumulate on trees and roads. By evening, much of central and southwest Oklahoma reported downed power lines, large broken tree limbs and damaged radio towers. More than 100,000 people were without power. In the end most schools and some businesses were shut down for five to six days.

For those who still had electricity, the exchange continued on the listserv from their homes. Why did the precipitation end so abruptly in southwest Oklahoma? Why did the models seem to struggle with the structure and timing of the forecasted precipitation? Teachers, students, practitioners and researchers all brainstormed together to answer nagging questions.

The discussions, inspired by the National Severe Storms Laboratory and the Storm Prediction Center, are intended to bridge forecast operations and research by offering an opportunity to share ideas in an informal setting. “This building exists for researchers and forecasters to work together,” said Marsh.

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NSSL taps community to make precipitation reports

robin on holly bush
A robin rests on a frozen holly bush in Norman, Oklahoma. Photo courtesy of Stephanie Berryhill, Norman resident.

With much of the U.S. well in the grip of winter, NSSL continues its third year of leaning on the local community to help provide observations for research.

The Winter Precipitation Identification Near the Ground (W-PING) project invites public observations of winter precipitation from volunteers within a 90-mile radius of Norman, Okla.

Winter precipitation is particularly difficult to forecast because it may melt or re-freeze very near the ground.  Because radars cannot see close to the ground, NSSL will use public observations of what is actually happening at the surface to compare with what the radar has detected. This information will help researchers improve computer programs and radar techniques to better estimate what is actually falling on the ground.

This is the first time W-PING observations will be compared with data from two radars during 2010 operations.  The testbed NEXRAD radar and a new dual-polarized radar (OU-PRIME) will both be collecting data simultaneously.

This is a perfect opportunity for classrooms, families and closet scientists to be a part of important weather research happening in their backyard.  Volunteers should visit: and click on “I Want to Volunteer!”  There is no commitment, and no minimum number of reports.  The form will request the date, time, location, and precipitation type.

Since the first year of W-PING, NSSL has received over 2,800 individual observations from volunteers.  W-PING is coordinated by Kim Elmore, NSSL/CIMMS.

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