Strong MJO Causal to Stratospheric Warming Event Later December?
12/04/2024, 8:57 am EST
Warmest U.S. Meteorological Autumn on Record
12/09/2024, 4:45 pm EST
Charts of the day: Stratospheric warming event to emerge.
Discussion: Stratospheric warming emerges over Siberia as calendar-winter arrives. The risk of arctic air generation at ground level increases dramatically in this region. In North America, the stratosphere is cold and supports anomalous warmth at ground level for Canada and the U.S. in 16 days. However, once we’re into January, ECMWF continues to indicate an emerging polar vortex which is steadily broadening and strengthening.
Week-2 Ahead Forecast valid December 15-21, 2024: Warmer.
Discussion: An equal mix of midday GFS and ECM yields a very warm forecast across North America just after mid-month. The forecast is considerably warmer than the outlook, from early this week.
Week-3 Ahead Forecast valid December 22-28, 2024: Normally cold East; Warm West.
Discussion: Upper trough forms in Northeast Canada and elongates into the East U.S. The East cools to normally cold. Upper ridge supports a very warm pattern across the western half of the U.S.
Week-4 Ahead Forecast valid December 29, 2024-January 4, 2025: Onset of a wintery pattern.
Discussion: Upper trough expands over Ontario and Quebec. Across snow cover, the pattern turns quite cold but stays temperate south of snow cover. Heavy snow across the Northern Rockies with a rain/snow event emerging in the Appalachian States.