Long Range Forecast

Long-Range Winter Forecast 2011-2012

Overview

Clearly the most watched weather feature expected to effect our weather this winter is La Niña.  A La Niña event is currently underway and will persist throughout the winter.  There are several preliminary indications that in 2012, La Niña may repeat its 2011 cycle, and gradually weaken in the spring or early summer months. In our area, La Niña is associated with dry, warm winters without much snow.  Nevertheless they tend to produce highly variable temperatures characterized by warm thaws followed by Artic plunges and back to warm again.  La Niña currently in effect will be similar to what they were at this time last year. Two of the more notable hallmarks of La Niña winters are the variability of weather as well as an overall north to south snowfall gradient.  Not all La Niñas are the same and there are other factors that drive our weather.  As for the upcoming winter, using La Niña only as a guide, it is hard to pinpoint where the tightest gradient of snowfall will materialize. However, it is reasonable to expect that northernmost portions of Maryland and Delaware have the best chance to see about normal snowfall.

Month by Month Forecast

NOVEMBER 2011

Winter likely gets off to an early start this season. While November cold and snow is typically favored only inland, that may not be the case this season. From a temperature standpoint, November will likely be cold. In fact, it could be the month of the winter with the coldest temperatures compared to normal. Expect the occasional and brief cold shots of mid-fall to gradually become more numerous and longer lasting in November. It is these repeated cold surges that will set the stage for snow showers to develop, particularly late in the month.

DECEMBER 2011

Both December’s temperature and snowfall patterns will likely have a classic La Niña appearance. This puts areas north of Washington near normal with milder air lurking just to the south. At this juncture, the overrall pattern does not favor major coastal storms in December. Instead, numerous weak clipper-type and inland low pressure systems should dominate. These sorts of systems are notorious for mixed precipitation events with changeovers (usually from snow, to a mix, then rain) for most of the I-95 corridor. However, some moderate snow accumulations are possible for areas like Hagerstown-Westminster-Leesburg region of Maryland-Virginia which will be closer to colder air.

JANUARY 2012

January probably turns out to to be the coldest month of the season nationally, with the focus of the cold in the western half of the country, which will be on average. Early indications point to a New Year’s cold outbreak, and one again late in the month. The active pattern from December is likely to carry over into much of January. Early on, the chance of mixed precipitation events will be at its peak. But as the month progresses, the storm threat may become more supportive of a major coastal storm. While odds favor such a threat in January, it would not be surprising if it held off until early February.

FEBRUARY 2012

As referenced in the January forecast, there is a lingering potential of a major coastal snow storm in February. The threat should diminish during the first week to ten days of the month. Thereafter, warmer weather gradually builds in from the south. This means that the precipitation pattern likely reverts to that of early January, making snow only events difficult to achieve along and east of I-95. As mild air becomes increasingly prevalent later in the month (especially in southern Maryland and Virginia), winter weather should become less frequent towards the end of the month.

MARCH and APRIL 2012

Overall, the final weeks of winter should feature less snow than normal and above average temperatures. It should be noted that many LaNiña seasons feature a few March or April events, even into the Washington DC area. That could very well be the case in Spring 2012, even though the over arching pattern might not be the most favorable for a late snowfall. While the signals are weak at best right now, the most favored time for late season winter weather appears to be in the middle of March. If this colder period does in fact come to fruition, it probably would not last for very long.

Our long-range winter forecast is compiled from a variety of weather forecasting sources. We have learned from our thirty years of closely tracking winter weather that long-range forecasting is not an exact science but that trends can be spotted by using a number of different factors that likely will impact our weather. The month-to-month forecast is provided by Weather Works, our paid meteorological service.  We are not meteorologists, weather forecasters, or even farmers.  We are snow and ice managers that spend a great deal of time trying to decipher an abundance of short-term weather information to stay ahead of each storm in effort to give our customers the best winter maintenance service available in the Washington, DC-Baltimore area.