Forecasters predict gentle storm season


How do you determine nor’easter activity on the east coast by monitoring the western Pacific Ocean?

Not very easily.

However, National Weather Service meteorologists have concluded that this year’s weak El Niño failed to produce “persistent enhanced convection,” and hasn’t stirred the global precipitation patterns very much.

In addition, the North Atlantic Oscillation (NAO) never moved into a negative phase, and that means fewer nor’easters along the Atlantic seaboard.

The NAO affects circulation patterns over the U.S., North Atlantic and Europe during the winter. In a positive phase, the jet stream moves northward, in a negative phase it returns to its normal position off the east coast.

Dave Nicosia at the National Oceanic and Atmospheric Administration (NOAA) had earlier anticipated a negative phase, but that situation never developed.

“The opposite occurred,” Nicosia pointed out. “The NAO is strongly positive and has made for less nor’easters. Our climate models indicate that it will persist as a positive phase through at least February.”

If the jet stream returns southward, that could bear out Nicosia’s earlier outlook for a stormy season.

However, at least for now, NOAA’s Climate Prediction Center (CPC) anticipates below average precipitation from Delaware to Maine, through April.

CPC’s Ed O’Lanic noted the generality of the seasonal forecasts. “That doesn’t mean we won’t have nor’easter activity — it just means we’ll have less,” he said.

O’Lanic noted the inability of current technology to pinpoint storms with much accuracy, more than a week out.

“What we can say about storminess over the next few months is that there will be more in the south and southwest and less in the northeast,” he added.

Nicosia said the NAO remained a wild card.

“There is so much uncertainty in seasonal forecasting when the signals are weaker – especially the El Niño Southern Oscillation (ENSO),” he explained. “A strong ENSO signal usually means more confidence in a seasonal forecast ... a weaker signal means less confidence.”