In March, ECMWF crests an upper ridge across the Southeast U.S. which leads to high risk of unusually warm early spring climate for the Southeast and Mid-Atlantic States. In April, the warm ridge shifts westward and settles on the southern Great Plains where dry and warm mid-spring weather is likely. Late meteorological spring brings an upper ridge to the Great Basin promoting dry and very warm climate across the West and Southwest U.S.

Extreme dryness (and heat) has afflicted Northeast Argentina during the past 2 weeks. However, changes are on the way as the 8-14-day forecast equally weighting GFS and ECM shifts heavy rain across the Northeast Argentina dry zone while East Brazil turns drier. The catalyst to the recent heavy rains across northwest and west continent is El Nino-like warming of the ocean surface off the northwest coast of South America. The rains shift eastward later next week.

The coldest day of winter in the Northeast is projected for Saturday. During the afternoon, the 12Z GFS indicates temperatures not reaching 10F in Boston while wind chill is routinely 10-15F below zero (during the afternoon). The Sunday morning low temperatures are near zero in Boston. The Boston heating degree day for Saturday is probably around 60 with an effective HDD of 70-75.

A sizeable change in the Pacific North America (PNA) index is forecast by all models over the next 2 weeks. The persistent strong positive phase fueling the warm and dry West U.S. climate for much of January finally breaks down. Next week, the PNA pattern shifts to negative phase supportive of a cooler and wetter West U.S. low-pressure trough pattern. In response, the strengthening negative North Atlantic oscillation (-NAO), fueling East U.S. cold fades mid-month likely causing a cold retreat.