12/06/2023, 7:03 pm EST

Daily Feature: Once again, November 2023 snow cover was greater than normal.

  North Hemisphere North America United States Eurasia Canada Alaska 2023 17/58 28/58 43/58 16/58 22/58 6/58 2022 4/57 3/57 6/57 11/57 5/58 8/57 Table 1: Snow cover rankings during November 2023 compared with last year for various parts of the northern hemisphere within the 1966-2023 climatology.    Discussion: The northern hemisphere snow cover during November 2023 was above normal (Table 1) which is consistent with each year since 2009. Climate Impact Company theorizes the reason for the consistent above normal snow cover just prior to the start of meteorological winter is due to cold advections snows across wide open water north of each continent and south of a constricting polar ice cap. The northern hemisphere snow cover in November varied widely. Alaska ranked highest (6th of 58 years) with much above normal snow cover while the continental U.S. was 16th least snowy. The North American snow cover was slightly above normal (Fig. 1). Eurasia ranked 16th most snowy (Fig. 2) and was the primary catalyst to the above normal northern hemisphere snow cover signature. Last November, snow cover was well above normal throughout the northern hemisphere. North America observed their 3rd snowiest November on record last year while the U.S. was 6th snowiest. Interestingly, despite the much above normal snow cover leading into the winter season, the U.S. and Europe winter seasons were exceptionally mild (Fig. 3). Fig. 1: North America snow cover anomalies for the month of November since 1966. Fig. 2: Eurasia snow cover anomalies for the month of November since 1966. Fig. 3: Northern hemisphere temperature anomalies for meteorological winter 2022-23.                                    
12/06/2023, 9:03 am EST

Europe/Western Russia Week 2-4 Outlook: Western Russia (and at times Europe) unable to shake cold risk. Ukraine mostly cold and snowy.

Charts of the day: <18F risk areas next 10 days. Discussion: Arctic air propels well below 0F temperatures across much of Russia the next 10 days. The back edge of the cold air mass forces 18F risk into Central Europe and areas near and east of the Caspian Sea. Week-2 Ahead Forecast valid December 12-18, 2023: Arctic chill shifts eastward, Europe warms. Discussion: Extremely cold arctic air mass in Russia is shifting eastward next week allowing Europe to turn warmer. Western Russia is snowy and may maintain the cold longer than indicated by models. Week-3 Ahead Forecast valid December 19-25, 2023: Regenerating cold. Discussion: Prefer the CFS V2 regeneration of cold across snow covered Western Russia and Eastern Europe. Week-4 Ahead Forecast valid December 26, 2023-January 1, 2024: Southern Europe warmer, Western Russia stays cold. Discussion: Cold weather lingers in Western Russia while Southern Europe tries to rewarm again.
12/06/2023, 9:01 am EST

North America Week 2-4 Outlook: Staying mild through December.

Chart of the day: North America temperature anomalies in 15 days. Discussion: With a harsh arctic air mass in Eurasia now, the tendency is to look ahead for a similar North America risk. For now, none exists through the middle third of December. However, an arctic air mass is likely to generate in Alaska as calendar winter begins. Week-2 Ahead Forecast valid December 12-18, 2023: Cooler changes Southern U.S., otherwise continued warm. Discussion: Energetic southern latitude storm track budges farther south compared to the last outlook inviting a cooler regime across the Gulf States. Much of the U.S. is drier than normal which causes the Mississippi River low water level to descend.             Week-3 Ahead Forecast valid December 19-25, 2023: No sign of cold air. Discussion: Although arctic air is developing in Alaska, Canada remains mild under the maritime Pacific influence. The El Nino storm track is evident across the Southern U.S. where temperate conditions are expected. Week-4 Ahead Forecast valid December 26, 2023-January 1, 2024: Still mild, but Alaska arctic air and potential East Coast storminess to monitor.      Discussion: Late December could prove interesting as all eyes are on Alaska arctic air and whether any southward drift may generate. Additionally, forecast models are indicating a possible stormy/cold upper trough developing on the U.S. East Coast.
12/05/2023, 2:52 pm EST

U.S. Population Weight HDD Forecast Oct-23 to Apr-24