April 9, 2011

Hydromet Outlook for April 11th through April 24th
As has been advertised for the past few weeks, a major large-scale pattern shift has occurred across North America as the NAO has shifted to its positive phase and the PNA has shifted to its negative phase. This regime is forecast to remain in place for the next several weeks. This pattern typically results in a large scale trough in the middle portion of the nation, which will take storm systems west of New England. Several significant storms are likely in the next 14 days, preceded by unseasonably mild weather on strong southerly flow then followed by brief bouts of seasonably cold temperatures on west to northwest flow.

The combination of bouts of mild weather and the potential for above normal rainfall will result in substantial increases in streamflow across interior northern and northeast New England. Absent, however, would be any prolonged periods of northeast flow. Three systems are currently projected to impact the region between April 11th and 24th. The first system will affect the Northeast between April 11th and 12th with light to moderate amounts of rain across interior New England. A second system is expected between April 16th and 18th. This system has the potential to produce strong southeast winds and heavy precipitation as it moves slowly through the region. Around April 22nd to 24th, a third system could affect the region with another bout of strong south to southeast winds and moderate to heavy precipitation.

Please follow the forecast evolution of these weather systems at the following locations:
River stage and flow forecasts: http://www.weather.gov/nerfc
Forecasts for eastern Maine: http://www.weather.gov/car
Forecasts for western Maine: http://www.weather.gov/gyx
Forecasts for eastern Massachusetts: http://weather.gov/box

Last updated: April 12, 2011