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07/20/2022, 9:11 pm EDT

U.S. Season 1-3 Ahead Climate Outlook

La Nina climate to persist into early Q2/2023. A warm autumn; very dry Mid-south States. Winter is cold North/stormy East-central. Executive Summary: The Climate Impact Company U.S. season 1-3 ahead forecast valid for meteorological autumn 2022, winter 2022-23 and spring 2023 is issued. The forecast is based on a constructed analog (please see methodology below). High impact highlights include a warm autumn season featuring very dry weather in the Mid-south States. Autumn tropical cyclone risk is highest in Florida and the Mid-Atlantic Coast. Next winter is cold and snowy across the North-central U.S. while the South and East enjoy a mild season.  During winter, the East-central U.S. is stormy. Next spring stays chilly and wet across the North while the South and East are warm. Methodology: The Climate Impact Company Season 1-3 Ahead Climate Forecast for North America is valid for meteorological autumn 2022, winter 2022-23 and spring 2023. The forecast is based on a constructed analog. The leading climate forecast parameters are ENSO and regional SSTA regimes such as the Pacific decadal oscillation (PDO) and Atlantic multi-decadal oscillation (AMO). Given the persistent weak La Nina (and stronger La Nina climate) the ENSO influence on the forecast weighs heavily into next spring. The Pacific decadal oscillation generally coincides with ENSO phase. If so, the La Nina signal is enhanced. The current cool PDO/LA Nina condition is possible into early next year. The Atlantic multi-decadal oscillation (AMO) identifies the amount of warm fuel to propel an active hurricane season ahead and also foreshadow subtropical ridge area locations and their strength. Although more difficult to analog, the North Atlantic oscillation (NAO) phase is also projected for the cold season. The SSTA analog is used coincidentally with the long-lead International Multi-Modal Ensemble (IMME) to correlate with past upper air patterns and their sensible temperate/precipitation anomaly schemes to project the season 1-3 ahead outlook. Climate discussion: A list of prominent climate forecast parameters, their outlooks and influences follow. ENSO: We’re entering a 3rd year of La Nina. The Nino34 SSTA index is marginally cool (Fig. 1) but within the La Nina threshold. However, La Nina climate remains bold! In fact, the La Nina climate intensity as measured by multivariate ENSO index (MEI) was the most intense of the entire 2020-22 La Nina episode last month (Fig. 2). Utilizing ENSO analogs in which a 3rd year of La Nina initiated, all analogs indicate a demise of cold ENSO with neutral ENSO to follow. Notice how the strength of La Nina as year 3 begins in mid-2022 is much stronger than the analogs. So, we’re in unprecedented territory with historical relationships to the current ENSO pattern. La Nina climate is certain to stay strong due to the LARGE SSTA differential between the relative cool equatorial East Pacific and the enhanced warming in the far equatorial West Pacific strengthened by onset of negative Indian Ocean Dipole (-IOD). Climate Impact Company expects La Nina to hang on for the remainder of 2022 and the La Nina climate to lag into early northern hemisphere spring 2023. The ENSO pattern has a see-saw character and bouncing into El Nino later in 2023 after this La Nina pattern finally ends is certainly possible. PDO: Similar to La Nina, the cool phase of PDO enters a 3rd year (Fig. 3). The -PDO weakened last month but remains robust. Historically, -PDO weakens in a 3rd year. The PDO phase is a bit more uncertain vs. ENSO for the remainder of 2022. However, -PDO is likely to linger longer than suggested by the analog. A flip to neutral phase is likely in 2023. The continued -PDO signal will work with La Nina to help sustain both regimes and enhance climate impacts. AMO: Although the Gulf of Mexico and just-off the Southeast Canadian Maritimes the ocean surface is running moderate to somewhat warmer than normal, the bulk of the North Atlantic basin is normal to cooler than normal. As a result, the basin average is marginally warm. The SSTA behavior is similar to many recent years for the first half of the year yielding above average confidence for an expected warm-up for the tropical cyclone season followed by a cooldown during next winter to early spring (Fig. 4). IOD: Onset of -IOD has arrived! The -IOD pattern should last well into Q4 of 2022. -IOD is associated with warming of the water northwest and north of Australia. The warmer waters lead to increased convection supplying moisture for mid-to-late winter weather systems affecting Australia while enhancing drenching rains across Indonesia. This feature also helps to sustain La Nina as previously explained. -IOD events usually last 3-6 months. Once the 2022 -IOD pattern ends, La Nina should follow. OCN: Recent climate forecasts have utilized a 10-year climatology (along with analog years) as an initialization to make the prediction. For the climate forecast issued in this report, an OCN for just the past 2 years is used primarily for the dry climate character a long-term La Nina climate has produced and the expectation that a La Nina climate will continue into 2023. OCN is applied when the current regime is substantially different from the conventional 30-year normal. NAO: The majority of winter seasons during the past 10 years have produced positive phase NAO which is present when the polar vortex is confined to the polar ice cap. Based on that precedent, the likelihood is return of +NAO for the 2022-23 cold season. The only reasonable La Nina analog (2000-01) yielded a near neutral NAO for most of winter. IMME: The leading influence on the cold season forecast by the IMME forecast model is the projection of warm waters just-off the U.S. East Coast (and Gulf of Mexico) while the remainder of the North Atlantic is near neutral coupled with La Nina cooling across the eastern equatorial Pacific (Fig. 5). Fig. 1: The Climate Impact Company constructed analog forecast of ENSO phase through May 2023 utilizing the Nino34 SSTA index. Fig. 2: The Climate Impact Company constructed analog forecast of ENSO phase through May 2023 utilizing multivariate ENSO index. Fig. 3: The Climate Impact Company constructed analog forecast of PDO phase through May 2023. Fig. 4: The Climate Impact Company constructed analog forecast of AMO phase through May 2023. Fig. 5: The International Multi-model Ensemble (IMME) global SSTA forecast for December 2022. SEP/OCT/NOV 2022: Autumn 2022 is warmer than normal across almost all of the U.S. (Fig. 6). The warmest anomalies for the 90-day season are centered on the Southwest States and New England. September is the warmest anomalous month, essentially an extension of August heat. During September, tropical cyclone risk is evident on the Gulf Coast and Atlantic Seaboard. October trends wetter in the Midwest to Northeast States. The Northeast/Mid-Atlantic States are vigorously warm during October. Nationally, November is a dry month, and in the East, a late autumn chill is in the air. The 90-day season is very dry in the Mid-south states where drought strengthens (Fig. 7). The Southwest States to California are dry during autumn season. The East is the wet zone. Fig. 6-7: The Climate Impact Company temperature/precipitation anomaly climate forecast for SEP/OCT/NOV 2022. DEC/JAN/FEB 2022-23: The winter 2022-23 outlook is cold across the North-central U.S. with piling snows most evident in Montana and the Midwest States (Fig. 8-9). Elsewhere, the winter is mild especially across the Southeast States. A classic La Nina climate produces dryness across the southern states plus California. The long-term drought in California is unprecedented. The outlook indicates a robust storm track across the Mid-south States to the eastern Ohio Valley. New England becomes snowy mid-to-late winter. The outlook favors a mild start to winter in the West and Central U.S. while the East is temperate. Mid-winter brings a slightly colder than normal regime across the East. February is very cold in the North-central U.S. while the East is exceptionally mild. Fig. 8-9: The Climate Impact Company temperature/precipitation anomaly climate forecast for DEC/JAN/FEB 2022-23. MAR/APR/MAY 2023: The Northern U.S. cold tendency lingers next spring (Fig. 10). Late season snows will enable the cold. Most of the Central and East is wetter than normal (Fig. 11). The immediate East Coast is dry. The South and East enjoy an exceptionally warm spring season. The Southwest States to Texas are drier than normal. Fig. 10-11: The Climate Impact Company temperature/precipitation anomaly climate forecast for MAR/APR/MAY 2023.