How the Greenland Blocking Pattern May Translate to Moisture

A large zone of high pressure is coming together in the northern part of the Atlantic Ocean this week. Known as the "Greenland blocking" pattern, this weather phenomena will raise the chance of a winter storm creeping into the Northeast in the days ahead. Here is more information about the Greenland blocking pattern and how it may impact the weather for the northeastern corner of the U.S. Is relief from the brush fire risk on the way? Read on for the details.

How the Greenland Blocking Phase Influences Weather

The Greenland blocking phase is a zone of high pressure that sets up near the island country of Greenland and works to block over large weather features from continuing on the typical west to east movement. The Greenland blocking is connected with the negative climate phase of the North Atlantic Oscillation (NAO). This index monitors the large-scale circulation patterns across the North Atlantic Ocean.

This phase influences weather across the U.S. by sending the polar jet stream to the south, bringing bitterly cold air to the eastern part of the country. The cold air dipping down from Canada often serves as the impetus for wintry precipitation along the East Coast.

The northern edge of the jet stream typically sets up along the Eastern Seaboard, bringing areas of low pressure up the coastline. This movement triggers the development of snow, rain, windy conditions, and coastal flooding. Without the Greenland blocking pattern in places, these elements generally just move out to sea and do not impact land to a great degree.

If the movement of the jet stream goes to the west, the zones of low pressure can then creep into the Northeast and up into eastern Canada. Although sometimes these events can cause blockbuster winter storms, that is not going to be the situation this week.

Instead, the low pressure system is going to run along with the polar jet stream in the coming days. This will result in a circular track that takes the low along the shoreline of the mid-Atlantic and to the east into the Central Atlantic Ocean before it makes a turn to the northeast and back into New England and Atlantic Canada.

What Does This Mean for the Forecast?

So what does this Greenland blocking mean for the immediate forecast in the Northeast? Meteorologists are predicting that rain may fall at times in some areas of New England beginning on Friday as the system tracks back on land. Some of the higher elevations of the region could see snow wet snow out of this weather maker.

Places such as Bangor, Maine will see the highest chance of rain later in the day Friday. The city will see cloudy skies throughout the day with scattered rain showers developing in the afternoon. It will be a blustery day with winds out of the north-northwest at speeds of 10 to 20 mph pairing with a high of just 46 degrees. Overnight lows will drop down to the 40-degree mark.

Another storm could pivot back into the region by later in the weekend or early next week. For example, Montpelier, Vermont could finally see some moisture on Monday. The forecast is calling for overcast skies, a good shot of rain, and highs that top out in the upper 40s. Overnight readings will slip into the upper 30s.

The rain will arrive earlier on Monday in parts of upstate New York. The community of Elizabethtown is forecast to wake up to a soggy morning ride to work or school. Highs will hover in the mid 50s before dropping into the upper 30s when the sun goes down.

Forecasters will continue to fine-tune their predictions about this second possible storm if it looks like it will make it to land.

Looking ahead to the rest of the winter, the Greenland blocking pattern and the associated NAO do not operate on a seasonal basis such as El Niño. Rather these systems operate on weeks, meaning that it is difficult to predict how these patterns will influence the winter weather for the Northeast on a long-range scale.