April 1, 2011

April 1 through April 14
...High likelihood of above normal precipitation and increased storminess...

The Northeast U.S. is about to enter a period of dramatic phase change to the North Atlantic Oscillation; going from the Negative phase to a Positive phase. It is often during these times of transition that major storm system can impact the region and that is certainly going to be the case during the next 10 days. Based on all indications, the Northeast has a high likelihood of a very active storm pattern with above normal precipitation over the next 10 to 14 days.

The first system will produce a period of strong northeast winds and moderate to heavy precipitation from late Thursday night through early Saturday as it intensifies and moves through the Gulf of Maine. This storm system will be followed a period of northwest flow during the weekend of April 2-3.

Two potentially wet weather systems may affect the Northeast beginning April 5th as a frontal boundary becomes stationary across south coastal southern New England. By April 6th or 7th, one low pressure system is forecast to develop and move into western New York then may redevelop into an intense coastal storm as it crosses eastern New England on the 7th and 8th. With strong high pressure over the Canadian Maritimes, the potential exists for an extended period of heavy precipitation and strong onshore winds. Rain is most likely toward the coast with ice and snow possible well inland in the headwaters of the larger rivers of interior Maine.

A several day period of dry weather and northwest flow should follow this storm system between the 9th and 11th. Then it appears that one more storm system could impact the region with more northeast flow and at least moderate amounts of precipitation in the April 12-14 time frame.

River flows are likely to increase substantially over the lower parts of the Merrimack, Saco, Kennebec, and Penobscot rivers during this 2 week period. What is quite uncertain at this point is just how much the headwaters will contribute given the storm track along the coast and the likelihood of frozen precipitation in the high terrain.

Last updated: April 5, 2011