Discussion: We’ve watched the GFS project arctic air for the extended-range for about one week generally indicating high intensity but mostly confined to the Central U.S. Last night the GFS indicated the arctic air may stretch into the East with intensity but most models continued to doubt that scenario. This afternoon the ECMWF forecast projects super cold arctic air into the central U.S. next weekend (Fig. 1) shifting east and southeast with authority for early next week (Fig. 2-3). A snowstorm affects the Interior Mid-Atlantic (Feb. 7) and Northeast (Feb. 8) followed by the big chill (Feb. 9). The zero line reaches as far south as Kansas and Missouri and the central/north Appalachians Feb. 9th. The ECM showed 241 HDD for Feb. 5-11, an increase of 34 HDD from last night. The 30-year normal is 204 HDD (10-year normal 194 HDD).
Fig. 1: Just-issued ECMWF low temperature forecast for Sunday February 7, 2021.
Fig. 2: Just-issued ECMWF low temperature forecast for Monday February 8, 2021.
Fig. 3: Just-issued ECMWF low temperature forecast for Tuesday February 9, 2021.