For the last few days of January and the first few days of February,the NAEFS ensemble is trending milder, indicating above normal temperatures over most of the east (except for the upper great Lakes and New England, where the forecast is for near normal conditions), and near normal temperatures over the west. This may be correct although there is a very fast jet stream forecast through the period and conditions are going to be quite variable. Both the US GFS and Euro models have a very cold air mass moving thru the Northeast on the 27th with morning lows around 16F. A warming trend follows thru the week, peaking 30-31st with temperatures above normal, then a cool down extending into the first 4 days of February. So cold with a temporary 2 day warm-up is probably more accurate then the generalized NAEFS outlook of milder through the extended forecast period. Looks like a fair-to-middlin snowstorm will affect the Ohio Valley, Great Lakes states and New England on or about the 30th.

This week features a significant cool off as arctic air spreads east from the Midwest and Plains, and off the east coast in a few hours. Over New England and the NE, temperatures during the next few days will be the coldest experienced during the last several years, in many cases. Lake effect snows will be intense downwind of all the Great Lakes for the next few days. A low pressure system will develop over west Virginia on Friday, and track to a position just south of NYC by Friday evening, leaving much of the Ohio Valley and NE in a wintery mess on the last business day of the week. Over the west, generally mild conditions will persist through the week courtesy of an upper ridge, although cities in the inter-mountain area like Salt Lake City will remain cool early in the week due to trapped cold air in mountain valleys.

The image is temperatures in degrees C for the next few weeks, in soon to be wintry NYC.