You may have wondered about the accuracy of the different weather forecast services out there, since they often make different predictions about what is going to happen on a given day.

According to a recent Wall Street Journal article, someone up in Ohio wondered the same thing, and started a website called the Forecast Advisor that compares the accuracy of weather forecasts from major providers, including weather.com, the National Weather Service, and Accuweather. The comparisons are done by major city or ZIP Code. If you look at the results for Lawrenceville, for example, you’ll find that the Weather Channel has been the most accurate over the last year, followed by the National Weather Service. You can also look at previous versions of the forecast for a given day, to see how they have changed over time.

The Advisor reports the accuracy of both the National Weather Service and the NWS Digital Forecast. Although they are both produced by the Weather service, the general forecast is for a specific weather zone, for example metro Atlanta. This is the forecast you see on the Lawrenceville Forecast page, and you can see it covers everywhere from Gwinnett to south Fulton counties, which is actually a rather large area. The NWS Digital forecast, on the other hand, tries to produce a forecast for a specific latitude and longitude, accurate to within a several mile radius. That’s the forecast used for the Lawrenceville Pinpoint Forecast, as well as the quick forecast on the home page. Because it covers a smaller area, it tends to be more accurate.

The National Weather Service has developed some new web-based tools to help people understand and use their three month seasonal forecasts. In the past, the long range forecasts, made over three month rolling periods were distributed in the form of maps showing areas where the temperature was expected to be above or below normal.

Now, they are providing a series of graphs and charts at the local level, which in North Georgia includes Atlanta Hartsfield, Athens, Cartersville, Rome, Newnan, and Gainesville. For example, the chart below shows the probability that the actual temperature will exceed a given temperature.

So, you can see that there is an almost 100% chance that the average temperature will be greater than 68 degrees, while almost a 0% chance that the average will be greater than 74. Because the green forecast line is to the right of the red actual line, overall, there is a greater chance of warmer than normal temperatures from August through October. You can look at the latest 3 month outlook for Atlanta here.

In addition to the Probability of Exceedence graph shown above, they have a number of pie charts and tables to illustrate the data in other ways, including temperature ranges and the chances of temperatures being above or below normal.

As January prepares to end, people all over the country are wondering, “Where is Winter?” Temperatures continue to be much warmer than normal, and despite several model predictions and teleconnections, not much has changed in the weather since the beginning of the month. We continue to see a largely zonal air flow from the Pacific, combined with a heat ridge over the Atlantic that is keeping much of the East in a springlike pattern.

If you believe the models, all of this is going to come to an end beginning in the middle of next week. Here is the National Weather Service 8 to 14 day outlook for the period between February 7th and 13th:

The predicted pattern of colder than normal temperatures in the east, and warmer than normal temperatures in the west (plus warm in Alaska, which isn’t on this map), match the typical negative Arctic Oscillation and North Atlantic Oscillation teleconnection cycles. However, both these signals seem to have bottomed out, and are rising again. The forecast models also haven’t been particularly reliable this winter either.

So, we’ll have to wait and see. Expect warm weather this week, with temperatures in the low 60s, with a chance of a storm on Thursday. As we’ve seen this season, temps will be a little lower following each storm, but will rebound quickly. For next week, if the forecasts verify, we’ll see highs in the upper 40s, which is about 5 degrees colder than normal for the second week in February.

I had a chance to get down to the WeatherFest at the World Congress Center on Sunday, and met several prominent meteorologists, including Paul Kocin, the winter weather expert at the Weather Channel and Max Mayfield, Director of the National Hurricane Center, who assured me that last year’s hurricanes had nothing to do with global warming.

I also had a chance to speak to Elliot Abrams, Chief Forecaster for Accuweather. I listened as he explained how a change in the polar vortex at 10 MB of pressure should cause the polar jetstream to move south. Such a change has occurred within the last week or so, but as Elliot was the first to admit, he’ll be the first to chuck the theory if it doesn’t get cold soon.

The American Meteorological Society is holding their annual meeting here in Atlanta from January 28th through February 2nd. Several thousand weather forecasters and atmospheric scientists will discuss issues including climate change, droughts, floods and weather highlights.

While the convention sessions themselves are closed to the public, the organization is sponsoring a WeatherFest on Sunday, January 29th that is free and open to the public. Representatives from the Peachtree City office of the National Weather Service, the National Hurricane Center, and the Storm Prediction Center will be present, along with folks from Accuweather, the Weather Channel, and area TV and radio stations. There will be kid-friendly exhibits as well, so this should be an event for the entire family.

WeatherFest is Sunday, January 29th from noon until 4PM in the registration area for conference halls A and B at the World Congress Center (the part that faces Philips Arena). Find out more at the AMS WeatherFest page.

A month ago, I posted on the relationship of the Arctic Oscillation teleconnection to the colder weather we experienced in December. Essentially, when this indicator goes negative, you can expect colder winter weather in the Southeast, while when it’s positive, the weather is more likely to be warm and dry.

There is another teleconnection that can shed some light on likely winter weather patterns, the North Atlantic Oscillation. The NAO, as it’s called, measures the differences in unusual air pressure in the northern and southern Atlantic. When the index is positive, the eastern United States tends to have milder and wetter winter weather, while when the index is negative, the east coast tends to be colder, with more snow.

The graph below shows recent measurements of the NAO, along with the forecast for the next two weeks:

As you can see, the NAO has been in a positive phase since late December, corresponding to the milder weather we’ve seen so far in January. However, since the second week of the month, its effects have been getting weaker, and if you look at the second graph, which shows the 14 day predicted position, it should go into a negative phase soon.

The third chart shows the Arctic Oscillation prediction. After being in a positive phase in early January, it too is predicted to go negative.

While not as accurate as your typical three day forecast, these two teleconnections provide some indication that we may very well see more normal winter weather for February. The CPC’s 6 to 19 and 8 to 14 day outlooks through the first of the month still call for warmer and wetter conditions than normal through the first of the month, although the warm area shrinks in the longer-range forecast.

The weather service will issue its long range forecast for February tomorrow. It will be interesting to see what they predict.