Winter Over? Not so fast...

Update: 1:30pm
I just wanted to add a comment here. I have been reached out to by multiple members of the Channel9 Storm Team to discuss this all further. Additionally, they posted a second post on their Facebook page to give greater clarification to their statement. This is why I started my blog post below praising the Storm Team meteorologists and expressing my great respect for them!

I've considered taking this blog down all together based on the conversations I've had with the Storm Team. I've decided to leave it up, however, because I do feel that public interpretation of forecasts is a crucial topic. I think this whole situation can shed some light on the topic for meteorologists and the public alike. Forecasting is difficult enough. Expressing the forecast to the public is another thing entirely.

Original Post:
Every once in a while, I come across a forecast that, quite honestly, makes my skin crawl. I try not to be judgmental about them- I've made plenty of bone-headed forecasts myself. At the same time though, sometimes something just needs to be said.

Let me preface my forthcoming rant with the following: I have a great deal of respect for the meteorologists at News Channel 9. I have met a number of them and they are great people. Their forecasts are typically very good and they are extremely intelligent. They do a great job.

Just not this time. This isn't meant to be an attack on them in any way, but the record needs to be set straight. It is February 17th. Historically, we could see significant snow well into April. (see April 16-17, 2007 for example). I cannot fathom how anyone can declare winter over at this stage, but that is what Channel 9 did:

First, let's look at the graphic that they are using to declare winter over. It is a probability map put out by the Climate Prediction Center for March, April and May. Areas in orange have a chance of seeing above normal temperatures, while areas in blue may see cooler than normal temperatures. Areas in white have an equal probability of seeing either cold, warm or normal temperatures. Let's zoom in and take a closer look at the Northeast:

Now, there are three possibilities for what can actually happen. We can be above average, below average, or right at normal. So in the white, "equal chance" areas, the probabilities of each of those three outcomes is about 33%. Each shade of orange/blue represents a greater chance of seeing warmer/colder temperatures. The Climate Prediction Center labels each shade with a percent value.  I have marked the 40% line, as it was a bit hard to see. Areas inside that 40% line, that is in the darker orange shade, have a 40% or greater chance of seeing above normal temperatures. The lighter orange shade, which includes Central New York, is predicted to have a 33-40% chance of seeing above normal temperatures. Given that the 33% line is very close to us, it can be assumed that it is more like a 33-35% chance.

That means we have about a 2% chance more than normal of seeing above normal temperatures.

Since the chances of a warm March, April and May are up by about 2%, and probabilities must add up to 100%, we can assume that the probabilities of a colder than normal March, April and May are running at about 31% and a normal period at 33%. Let's look at this forecast in another way:

Honestly, can you see much of a difference? Yes, we have a higher chance of above normal temperatures than anything else. But that increased chance is such a minor increase. If these were medical test results, would we want our doctors declaring definitely that the test was conclusive one way or another with a 35-33-31 distribution? I think not.

The other thing to consider is how accurate these probability forecasts are in the first place. The following as a graphic the Climate Prediction Center publishes along with their seasonal forecasts. It looks confusing, but I will explain it:

First, some background. There are numerous ways to calculate forecast accuracy. The Heidke Skill Score (HSS) is just one of those ways. A HSS of 100 means the forecast was perfect. A HSS of -50 is the worst possible forecast, and a HSS of 0 means the forecast was as good as a random guess.

We are looking at the red lines, which are labeled 'non-CL'. These 'non-CL' lines are the skill of forecasts where either colder than normal or warmer than normal forecasts are made. The year-to-year changes between these red lines are huge. You will notice a horizontal red line at 20. This is the average HSS for non-CL predictions from 1995-2008. The score is 20. Remember, a perfect forecast is 100 and a random guess is 0. A 20 is an extremely poor score and shows just how difficult it is to predict temperatures for the next three months.

Putting these two things together, we have a very slim chance of warmer weather based on a forecast that is much closer to a random guess than a perfect forecast.

With this knowledge, can you see why this upsets me? Meteorologists have an unspoken contract with the public to give accurate, informative forecasts. We have to do this to build trust between the meteorologist and the public. Why? Because when a tornado is bearing down on your neighborhood, or a major snow storm is on the way, or anything else that threatens lives and property, we need people to listen to us. Way too often, meteorologists, particularly in the media, betray this trust with garbage statements like this.

It needs to stop.

Now, I commented on that Facebook post and the response I got was "our forecasts are based on more than just what we are showing here- this graphic just happens to sum things up nicely." My argument is that 1) the graphic really shows nothing, as I explained previously and 2) there is no expression of uncertainty or these other factors. All that is said is 'winter is over.' I'm not against long-range forecasting. I am against long-range forecasts that don't express the inherent extreme uncertainty that they contain. And this is one of the worst offenders I've seen.

Might they end up being right? Sure. They might. If they are, was it skill or luck? I'll let you be the judge.

Arctic Outbreak?

We all knew it was probably only a matter of time before the weather finally turned more winter like. We got a taste of winter yesterday with some lake effect snow, strong winds, and temperatures in the 20s. While we have been warm lately, 500 miles to the north has been frigid. The chill yesterday and, to some extent, today, is just a small piece of that cold pool.

A much bigger piece will be breaking off next week. It will easily be the coldest air so far this season, with highs Tuesday and probably Wednesday staying in the teens. There will be wind. There will be snow. But will this be an 'arctic outbreak'?

There is no set definition for an arctic outbreak, so the use of the term is up to the discretion of the forecaster. It seems to me, however, that 'arctic outbreak' should be a term reserved for record setting or dangerous cold. It is a strong term that grabs people's attention. I do not think it should be overused.

Does the combination of high temperatures in the teens, gusty winds and lake effect snow meet these qualifications?  I am honestly on the fence.

On the one hand, it seems to me that highs in the teens are not all that impressive, given our climatology and the time of the year. Some lake effect snow and wind? That is just normal winter weather here.

Yet, on the other hand, this has not been a typical winter. We have only one high temperature under 30º (on the 24th...the high yesterday was actually 40, albeit that was at midnight). Snow has been scarce to non-existent. Being suddenly thrust into mid-winter weather may catch some off guard and create dangerous conditions.

In the end though, I think I would hesitate to use the words 'arctic outbreak' in my forecasts for the coming cold snap. I believe that the public should be aware that the pattern is changing and, at least for a few days, winter will be here in full.

But I do not want to sensationalize things and blow them out of proportion. This event, after all, is still nearly a week away. I've seen many extreme temperature events forecast this far out, only to have the models gradually and consistently modify temperatures back towards more normal temperatures.

I want to hear what you think though. Join the discussion and post what your definition of an arctic outbreak would be on Facebook by clicking here.

Just how low did it go?

Original post appeared on Syracuse.com on 1/26/11; posted by Drew Montreuil. This version is edited.

You certainly do not need a meteorologist to tell you that the cold was bone-chilling Monday morning. However, you might be interested to know how cold it actually got across Central New York.

Click the map for a bigger view!

I put together a map of reported low temperatures from around Central New York. Most of these low temperatures were reported to the National Weather Service through co-op spotters. Some of the other readings were recorded on personal weather stations that upload data onto The Weather Underground.

As you can see, the temperatures can vary greatly over a short distance depending on a number of factors, including elevation, proximity to water and urban vs rural settings. A great example of this is Groton's reported -8º. This temperature was taken at a high elevation somewhat near the Elementary School. On cold nights, the coldest air settles in the valleys. Therefore, I would not be surprised if someone sees the map and thinks: "But I saw the bank thermometer Monday morning say -15º!" Down in the valley, it probably did drop below -10º. If anyone does have a lower reading from downtown Groton, I would be very interested in it, so please leave a comment!

For comparison to previous years, we have to look at Syracuse, since climate data from the NWS is only available for Syracuse and Binghamton. You may be interested to know that the -13º was the lowest temperature in the past few years. The lowest temperatures for the past few years in Syracuse are as follows:

• 2010: -9º
  
• 2009: -2º
  
• 2008: -4º
  
• 2007: -9º
  

Data from before 2007 was not available on the National Weather Service's Climate site for Syracuse. I can, however, tell you that the -13º is no where near the record low for Syracuse since observations began at the airport in 1971. That record belongs to February 1979, when it was -26º.

The week ahead, plus a bit of history!

This blog post will have two parts. The first part will focus on this week's weather pattern across most of North America. It is an interesting set-up and I will explain what it means for us, especially come later next week into the weekend. Then, I will take you back to this weekend last year. If you thought this past week was rainy, wait until you hear the rain amounts we got last year!


This image tells some, but not all of the story. High pressure to our west will bring us seasonable temperatures for the first half of the week. Meanwhile, on the back side of the high, heat will be building big time, with triple digits all the way to the Canadian border! What this map doesn't show is an upper-level low that will be hanging around the mid-Atlantic and Northeast. This will not only bring scattered thunderstorms, possibly severe with hail, but it will also clog up the flow of weather systems. Usually, systems travel west to east. However, this low will dig in an be very stubborn, forcing the high pressure, and the heat, north into Canada. This will allow the hot airmass to become very strong. Eventually, the low will lose out and be broken down and the heat will come spilling east. This will probably happen later this week, and when it does, we will bake!


July 21st and July 22nd, 2006: A frontal boundary was stalled across the region, with cool air to the north and hot, humid air to the south. We were stuck in the middle of these air masses, right in the battle zone. As low pressure systems moved along this boundary, thunderstorms broke out and "trained" across the region. "Training" is when repeated thunderstorms move over the same area, over and over again. This usually results in excessive rainfall, as was the case last year. On the 21st, thunderstorms rumbled through Groton for most of the pre-dawn hours. These storms dumped 1.14" of rain. Then, the next morning, the same thing happened, but with more numerous and stronger storms. As a result, the 24-hour rain record for Groton (according to my rain stats, which I have been keeping since 2004) was crushed by noon. Those storms dumped 3.31", with another 0.04" coming later in the day. As a result, our two-day rainfall was a whopping 4.49"! By comparison, our four-day rain total this week (Tuesday-Friday) was 1.38".

Have a nice weekend everyone!