November 3, 2010
NOAA released its winter outlook on October 21 and I wanted to take a look at it and digest what it had to say before I blogged about it here. There is nothing earth shattering about the winter outlook this year, but nonetheless it is always worth talking about.
First and foremost understand this: the seasonal outlook does not project where and when snowstorms may hit or total seasonal snowfall accumulations. Snow forecasts are dependent upon winter storms, which are generally not predictable more than several days in advance. This little disclaimer is necessary for all the winter weather knuckleheads out there.
NOAA says that a moderate to strong La Nina will be the dominant climate factor influencing weather across most of the U.S. this winter. La Nina often brings cooler than normal water temperatures across Equatorial regions of the Pacific Ocean. This is unlike its counterpart, El Nino, which is associated with warmer than normal water temperatures in the same regions. Both of these climate phenomena, which typically occur every 2-5 years, influence global weather patterns and often lead to extreme weather events. For example, last winter brought record-breaking rain and snowfall to many parts of the country, which lead to severe flooding. Other parts of the country recorded heat extremes and drought. This was all due to El Nino. Even though La Nina is the opposite of El Nino, it still has the potential to bring about wild weather.
Mike Halpert is the deputy director of the Climate Prediction Center, a division of the National Weather Service, and is quoted in NOAA's Winter Outlook as saying the following: "La Nina is in place and will strengthen and persist through the winter months, giving us a better understanding of what to expect between December and February. This is a good time for people to review the outlook and begin preparing for what winter may have in store."
Halpert also added this: "Other climate factors will play a role in the winter weather at times across the country. Some of these factors, such as the North Atlantic Oscillation, are difficult to predict more than one to two weeks in advance. The NAO (which we talk about frequently on this blog during the winter months) adds uncertainty to the forecast in the Northeast and Mid-Atlantic portions of the country."
The NOAA Winter Outlook breaks down many different regions of the country and lists specific forecast details. I'll post the maps below for the entire country, but for now, let's just discuss the region closet to us...the Northeast and Mid-Atlantic. After a record-breaking year for snowfall last winter for many cities in this region, how will the upcoming winter compare?
According to NOAA, the Northeast and Mid-Atlantic have equal chances for above, near, or below normal temperatures and precipitation. This doesn't seem very enlightening, so let's dig a little deeper. NOAA also says that winter weather for these regions is often driven not by La Nina but by weather patterns over the northern Atlantic Ocean and Arctic Ocean. These are often more short-term, and are generally predictable only a week or so in advance. If enough cold air and moisture are in place, areas north of the Ohio Valley and into the Northeast could see above-average snowfall.
While this seems like the easy way out, it simply is the most accurate projection of what could happen this winter. La Nina doesn't have a lot of bearing here, so to make a wild prediction about snowfall or extreme temperatures doesn't make a lot of sense for our region. For now, stay patient and let's see how things develop going forward through December. Last year, we had a fairly decent snowfall early in the season (before Christmas)...this should have been a sign of what was to come in February. Let's keep an eye on December and see how our weather pattern develops. Cold air and moisture are the two main ingredients for a good snowfall...we actually will have both of those in place tomorrow. If this was December or January...we might be in trouble. Find the maps below for both temperature and precipitation outlooks for the winter ahead. Stay tuned...