Charts of the day: Know where the NAWH trough/NEP22A ridge features are located.
Discussion: In control…the North Atlantic warm hole (NAWH) and attendant upper trough south of Greenland and the upper ridge associated with the North/Northeast Pacific marine heat wave (NEP22A) are providing significant influence on the North America climate pattern. In the short-term, the NAWH trough south of Greenland expands southwestward across eastern North America to deliver a November chill. The amplified NEP22A upper ridge over northwestern North America this week shifts across the western U.S. in the 6-10-day period as the eastern U.S. trough retreats. The NEP22A upper ridge is reborn north of Hawaii in the 11-15-day period forcing a -PNA pattern (and attendant trough) to cool the Northwest U.S. in the 11-15-day period while the NAWH trough extends to the Northeast States to cool that region. Hollowing the NAWH trough and NEP22A ridge is an essential part of explaining and forecasting the North America climate pattern.
Medium-range 6-10 Day Forecast Valid November 22-26, 2022 (24-hour change right)
Discussion: As indicated above, the NAWH upper trough extends into the Northeast U.S. sustaining the cold pattern. The intensity of the cold in the East is less intense due to lack of snow cover. However, Central Canada trends colder due to snow cover. The NEP22A upper ridge shifts into western North America where the warm pattern is located.
Medium-range 11-15 Day Forecast Valid November 27-December 1, 2022 (24-hour change right)
Discussion: The NEP22A upper ridge regenerates near the Dateline in the 11-15-day period and therefore western North America warmth fades with remnant warmth shifting to the 4 Corners region. Canadian snow cover causes a colder change from 24 hours ago. The NAWH trough maintains a cold risk into the East U.S.
U.S. Medium-range Precipitation Forecast
Discussion: ECM ENS expands the wet regime across the Gulf of Mexico into Texas and the Southeast U.S. in the 6-10-day period. The pattern reverses drier across the Southern U.S. in the 11-15-day forecast.
Extended-range Days 16-20 Day Forecast Valid December 1-5, 2022 (previous below)
Discussion: Forecast models maintain their warm bias in the extended-range most profoundly to the east of the Continental Divide. The Northern U.S. is where anomalous precipitation appears, much of which is snow. Climate Impact Company will issue the daily 16-20-day outlook shortly.