The past couple of days have featured a parade of record highs across the northern tier of the country and parts of the West Coast thanks to the development of a ridge of high pressure that has moved east across the country in the wake of the early week cold shot that hit the East with record cold. Over 600 record highs were knocked between Thursday and Friday in nearly two dozen states in the western and central portions of the country.
Minnesota's first 60 degree reading in the first seven days of January as the thermometer cracked 60 in a few towns in Western Minnesota on Thursday afternoon. Other records were smashed in South Dakota, with Philip hitting 74 and Rapid City hitting 73. Warmth in South Dakota is a bit more common in the winter due to the influence of the chinook downslope wind that warms the air downstream of the Rockies and the Black Hills; however, daily records in these places were smashed by 15 or more degrees. Records were also knocked out in the Pacific Northwest...also due to downsloping on southerly and southeasterly winds that helped boost temperatures. Cliff Mass' blog talks about the causes in more detail in the Pacific Northwest.
Today may feature some additional record highs in the Northeast but the ridge responsible for the significant warming is weakening in response to a flattening of the jet stream nationally. Cooler...and more typical temperatures for this time of the year will be forthcoming starting tomorrow in the Northeast.