Late March winter returns

The past two weeks (February 23rd - March 8th ) has featured record amounts of precipitation for New England. There are four main storm systems in this period. The first two Keene was cold enough to receive snow. These last two have been heavy rain events resulting in flooding of rivers across the region.

The issue with these last two storms has been a lack of mid latitude blocking resulting in low pressure in the deep south intensifying and tilting negative too early. Low pressure then tracked north up through to NY state. Keene, on the east side of the low, gets hit with warm air advection and a load of moisture from the gulf. Voila. A heavy rain storm.

Working backwards, the reason for no blocking is a continued positive NAO. The last node of stratospheric warming occured about two weeks ago with a peak anomaly centered at 10mb and notable warming extending down past 200mb. The period of propogation was longer than expected but now notable warming has penetrated into the troposphere with another node possible within the next week, and it is only a matter of time before a -AO / -NAO combo.

Significant storminess as what we have seen over the last two weeks and much of the winter will continue through the rest of March. However, we may have the cold supply for some wintry impact as well.

More details later.