08/18/2022, 7:49 pm EDT

U.S. Season 1-3 Ahead Forecast Valid Autumn 2022 to Spring 2023

Highlights: Autumn outlook is surprisingly dry in the Gulf region for late TC season, February is the coldest winter month and dryness for California to Texas extends well into 2023. 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 updated. The forecast is based on a constructed analog focused on regional SSTA and attendant climate influences. High impact highlights include a stunningly dry SEP/OCT/NOV for the Gulf States despite tropical cyclone risks. Autumn is warmer than normal across most of the U.S. The winter season is dependent on snow cover to generate important cold. Early season snow cover is lacking and important cold waits for February targeting the Great Plains. Dryness prevails the next 9 months California to Texas. Climate discussion: The season 1-3 ahead climate forecast for North America is based mostly on regional SSTA outlooks including El Nino southern oscillation (ENSO), Pacific decadal oscillation (PDO) and Atlantic multi-decadal oscillation (AMO) plus new SSTA regions of climate influence in the middle latitudes including the Northeast Pacific “warm blob” and North Atlantic warm hole (NAWH). Snow cover projections are added to the winter outlook by October. Soil moisture is a primary forecast tool for summer climate therefore limited use for the autumn 2022 through spring 2023 forecast. ENSO: La Nina has entered a 3rd While oceanic La Nina has varied from weak-to-moderate strength during the 2020-22 cold ENSO episode, the atmosphere has locked-in on moderate-to-strong La Nina climate the entire time including peak intensity now. Forecast models maintain La Nina through 2022 with weakening indicated during the first third of 2023. The La Nina climate may linger well into 2023, however. Typically, the cold season is wet in the Northwest and Ohio Valley during La Nina while the southern tier of the U.S. is very dry. Modern-day La Nina’s generally produce a mild climate during the cold season with cold risk for the Northwest to North-central States. PDO: PDO usually parallels the ENSO regime. The current -PDO pattern is no exception born in 2020 and persisting into late 2022. Last month, the PDO index was -2.86 which one of the top 5 coolest signatures since 1950. Interestingly, the -PDO regime is so extreme due to the immense warming of the northeast Pacific “warm blob” north and northeast of Hawaii. Normally, waters off the West Coast are cooler than normal during robust -PDO. Waters off the U.S. West Coast have warmed but compared to the titanic warming north of Hawaii the relative cooler signature sustains -PDO. Due to the warmer-than-normal -PDO signature, limited reliable climate influence is available to use for the season 1-3 ahead climate forecast. AMO: After a sluggish mid-year when AMO was cooler than the 25-year climatology (featuring the long-term warm cycle), warming has started during the past 2-3 weeks. The AMO should warm for the mid-to-late tropical cyclone season ahead. +AMO adds upper ocean heat that enables tropical cyclones to develop and intensify. In the 25-year climatology there is a tendency for +AMO to linger into mid-winter which biases the East U.S. climate warm. However, by late winter and through spring +AMO weakens and likely fades to neutral phase. IOD: Climate Impact Company is linking the re-intensifying La Nina episode to the evolving -IOD pattern north and northwest of Australia. The warming of the tropical eastern Indian Ocean and far western Pacific Ocean increases convective currents and that rising air is replaced by trade winds from the east near and east of the Dateline. The increasing wind up-wells cool water to reinvigorate La Nina. -IOD is forecast to weaken around Jan. 1st. After -IOD weakens, La Nina should also begin to steadily decay. NAWH: During the past 10 years, a cool SSTA zone has been semi-permanent south and southeast of Greenland with an attendant upper-level low-pressure trough. The trough has a tendency to force an upstream upper-level high-pressure ridge across East Canada. The pattern influences tropical cyclone tracks during autumn and can cause anomalous warmth to linger in the East U.S. to start the winter season. OCN: There is general use of the 10-year normal (minus disagreeable ENSO years) applied to climate forecasts especially in low confidence time periods. The 10-year climate pattern is generally somewhat different (i.e., warmer) than the 30-year normal and consequently that recent bias is added to the forecast. IMME: The global SSTA outlook using the IMME forecast model valid for DEC/JAN/FEB 2022-23 indicates La Nina persists and as usual is coupled with continued -PDO (Fig. 1). La Nina begins to fade FEB/MAR 2023. The waters off the West Coast are near normal but the “warm blob” northeast of Hawaii remains very warm and the SSTA difference with the coastal waters propels the -PDO regime. In the North Atlantic, the NAWH is strengthening south of Greenland but is unable to slow the Gulf Stream as observed in recent years as warm waters off the U.S. East Coast continue their transport via the Gulf Stream toward Europe. Fig. 1: The NMME global SSTA forecast valid for DEC/JAN/FEB 2022-23 with areas annotated having greatest influence on North America climate. Forecast methodology: The seasonal outlooks are based on similar regional SSTA to those discussed and shown by the IMME forecast and their past attendant climate patterns. The forecast is mostly ENSO-biased for next spring. Preliminary summer 2022 verification: With the last third of August still remaining, the preliminary verification for summer 2022 was hot! Hottest anomalies are centered on Oklahoma/Texas (Fig. 2). Only the West Coast was near to below normal. The precipitation pattern is very dry across the Central U.S. and East Coast with patchy wet zones in the West including a robust monsoon signature in Mexico (Fig. 3). The Climate Impact Company meteorological summer outlook for temperature was quite good (Fig. 4). The last third of August likely weakens the current observed hot anomaly centered on OK/TX while the Northwest heat wave likely raises current summer temperature anomalies closer to the CIC forecast. The precipitation outlook was not sufficiently dry in the Central U.S. (Fig. 5). Fig. 2-3: U.S. temperature and precipitation anomalies for summer 2022 so far. Fig. 4-5: The Climate Impact Company temperature/precipitation anomaly climate forecast for JUN/JUL/AUG 2022 issued last May. SEP/OCT/NOV 2022: The projected upper air pattern for meteorological autumn 2022 indicates a strong high-pressure ridge centered on the West-central U.S. and extending to East Canada. The result is widespread anomalous warmth for autumn and a stunningly dry Mid-south/Gulf States forecast. In the Northwest, coastal precipitation is moderate-to-heavy. Meteorological summer ends on a wet note in Texas and the Mid-south States. However, the La Nina climate bias plus OCN strongly favors a much drier pattern reversal in this zone for autumn. A “gutsy” forecast considering previously indicated tropical cyclone risk for mid-to-late season. Dryness in the North-central/Central Great Plains carries on during autumn as rainfall is near normal at best. Dryness in New England continues as drought in that region continues. The upper ridge pattern causes widespread anomalous warmth for autumn and the front end of the cold season (November) is likely warm West and Central U.S. but normally cold for the eastern third of the nation. Fig. 6-7: The Climate Impact Company temperature/precipitation anomaly climate forecast for SEP/OCT/NOV 2022.  DEC/JAN/FEB 2022-23: A polar vortex pattern is present at times during meteorological winter 2022-23. However, the forecast is not super cold due to the lack of snow cover. If early season snow cover can generate and cover much of the northern states a much cold solution is possible. The outlook is adjusted slightly colder Northwest and slightly warmer in the East. The precipitation pattern is not as stormy in the Ohio/Tennessee Valley(s) but also not as dry in the Gulf region. To identify the character of the wintertime month-to-month temperature regime the constructed analog is broken down into 30-day intervals. In December cold weather affects the Northwest States to Montana while the South and East are classic La Nina-mild. In January, westerlies prevail to warm the northern states and likely scour away significant snow cover. In February, early month snows return and a late season polar outbreak is likely. This once is more likely to charge into Texas vs. the East Coast. Fig. 8-9: The Climate Impact Company temperature/precipitation anomaly climate forecast for DEC/JAN/FEB 2022-23.  Fig. 10-12: The Climate Impact Company temperature anomaly climate forecast focused on the months of meteorological winter 2022-23. MAR/APR/MAY 2023: Although oceanic La Nina ends, a La Nina climate may linger into next spring. The forecast indicates very warm conditions in the Southwest and generally warmer than normal across most of the East U.S. The northern tier can still be chilly. The precipitation outlook is not confident about the wet pattern projected for the Southeast. Dryness prevails from California to Texas and parts of the Great Plains. The coastal Northwest is wet. The September 2022 to May 2023 precipitation forecast yields 9-month significant deficits in California to Texas with other zones experiencing deficit in the Great Basin, central Great Plains and New England. Fig. 13-14: The Climate Impact Company temperature/precipitation anomaly climate forecast for MAR/APR/MAY 2023.  Fig. 15: Precipitation anomalies for SEP-22 to MAY-23.