Simplifying winter weather products

Decades after the National Weather Service began issuing watches and warnings, many members of the public don’t know what the difference is. When you throw in different products, the confusion only mounts. Too often, the products are based on meteorological distinctions that don’t necessarily mean much to the public. Take, for example, a nor’easter that struck New England in December. Or the confusion around the landfall of Sandy, which became extratropical shortly before landfall.

Some products you might see in a winter event include blizzard, winter storm, high wind, wind chill, ice storm, lake effect snow, and freezing rain. Plus flood products and special weather statements. How should the public try to understand these differences?

In general, I’m a proponent of getting the important information to the consumer as quickly as possible with minimal effort required. This case is an exception. Trying to cram the important information into the headline leads to public confusion and forces forecasters to spend time trying to decide which of a handful of products are correct instead of focusing on communicating impact.

I’m in favor of a smaller set of products, with specific impacts delineated in the text. A “winter storm” and “blizzard” product with watch, warning, and advisory (maybe) levels would go along way toward making the products more clear to the public. Everyone could spend less time thinking about the differences between the products and more time focusing on the impacts and preparedness.

If you’re interested in the official specification for the current suite of winter products, see

The Sperry–Piltz Ice Accumulation (SPIA) Index

Earlier this winter, posted an article about a new index to rate ice storms. Setting aside the illiteracy of the author (the article talks about how the index was used experimentally in 2009), it’s a good introduction to a new-to-me index that can help meteorologists communicate impacts to the public. The Sperry–Piltz Ice Accumulation (SPIA) Index uses ice accumulation, wind speeds, and temperatures to predict the impact of winter storms on public utilities (particularly power lines). The algorithm appears to be protected by copyright, which is disappointing, since it limits the ability of the scientific community to evaluate the methodology.

Communicating impact is one of the major challenges in forecasting. Even when the forecast is technically precise, the general public often doesn’t know what to do with the information. Widespread use of the SPIA Index can help people and utility crews prepare. Unfortunately, the closed nature of the index may limit its adoption.

The Weather Channel is naming winter storms

On Tuesday, The Weather Channel announced that they would be naming winter storms beginning this season. The reaction on Twitter was swift and mocking, and perhaps for good reason. The Weather Channel insists that there is real benefit to this, including raising awareness and improving communication. The research supporting these assertions was conspicuously absent.

Supporters of this idea insist that the naming of tropical storms was received with similar ridicule. I wouldn’t be surprised, but the ideas are not entirely consistent. For one, tropical systems spend most of their time over the ocean, and there are few landmarks to use as reference points. Since multiple storms may be in existence at once, some naming scheme is required. Tropical systems also have well-defined and consistent criteria for naming. The Weather Channel’s scheme is vaguely defined and depends on geography, time of day, day of the week, etc.

The Weather Channel has the weight to try to make this work. With their recent acquisition of Weather Underground, they are the most influential private sector weather player. However, I can see AccuWeather ignoring the names out of spite, and the National Weather Service ignoring them out of indifference. Will local media use the names? Without the backing of an organization like the WMO, I don’t see all of the players coming together on this.

Europe has apparently been naming extratropical systems, and I’m not sure what effect (if any) it has had on the public. I’m not necessarily opposed to the naming of winter storms (though it’s sorely tempting to use a slippery slope argument), but I need convincing that it’s a useful act. Perhaps next spring we’ll have some data to work with. Or not. This seems to be more about ratings than science.

Winter storm forecast for Tippecanoe Co ARES

Prepared Monday, 31 January 2011 at 8:00 PM for Tippecanoe County Amateur Radio Emergency Services

Current conditions

An area of snow and sleet stretches from St. Louis to Champaign to Fort Wayne. Reports of 1″ of snow in Lafayette and 0.1″ of ice in Brownsburg have been received already this afternoon. Larger precipitation amounts are likely to have been received in places where convective development has occurred. Precipitation is likely to be ongoing for the next few hours as the system moves generally east-northeast.

Tippecanoe County is under a Winter Storm Warning from 7 PM this evening until 7 PM Wednesday. The surrounding counties of Warren, Fountain, Montgomery, Clinton, Carrol and White are included. Benton County is under a Blizzard warning from 4 PM EST Tuesday until 4 PM EST Wednesday.

Forecast: 0-12 hours

Models are in agreement that the precipitation will continue into the overnight hours. Although snow is expected to be the dominant type, periods of sleet and freezing rain will be included, especially before midnight. Heavy snow can be expected during portions of the evening hours as the stronger precipitation in Illinois moves east-northeast. Precipitation should slacken by 8 am, with 2-3″ of snow and potentially some ice on the ground. The exact amounts will depend on the mix of precip types.

Forecast: 12-24 hours

Tuesday morning will be relatively quiet. By mid-afternoon, winds will pick up to 15 knots, and snow will begin falling more heavily. Precipitation should remain light-to-moderate snow through the end of the period. Depending on the timing, an additional 4-6″ of snow may accumulate during this period.

Forecast: 24-36 hours

Tuesday night the snow returns in earnest, accompanied by winds of 20-25 knots. Heavy snow is likely through much of the period. The bulk of the weather impacts will occur from sunset on Tuesday into early Wednesday morning. Snowfall rates in excess of 2″ per hour are possible, leaving street crews unable to maintain passage on roads. By sunrise Wednesday, an additional 8-10″ of snow may have fallen, meaning total snowfall of 14-19″ is possible.

Forecast: 36 hours and beyond

Light snow will continue through the day on Wednesday, with perhaps another 1″ of accumulation. Winds will remain greater than 15 knots, creating the possibility of blowing snow. Temperatures will begin to drop Wednesday night and into Thursday as the winds shift to the north. Below-zero lows should be expected on Thursday and Friday mornings.

General impacts

The Lafayette area will be fortunate enough to miss the crippling ice storm that will impact the Interstate 70 corridor, including Indianapolis. Road crews should be able to keep streets passable through Tuesday afternoon. Travel will become difficult, if not impossible from Tuesday evening until at least Wednesday afternoon. Rural areas may remain blocked by snow until Thursday. Widespread power outages should be expected to our south and southeast, potentially lasting several days.