02/16/2023, 7:30 pm EST

U.S. Season 1-3 Ahead Outlook: Plenty of warmth; Wet East.

Executive Summary: The Climate Impact Company season 1-3 ahead climate forecast is updated. The outlook is based on a transition from a La Nina climate pattern into an El Nino regime later this year plus influence on climate of very warm SSTA either side of North America. Results generate more high risk climate for the U.S. including the return of hot and dry conditions across the Southwest and West U.S. for the upcoming warm season. During the 2023 warm season, a wet regime possibly producing extreme flooding at times is forecast for much of the eastern half of the U.S. Climate: The North America season 1-3 ahead climate forecast valid for meteorological spring, summer, and autumn 2023 is based on the evolution of El Nino. Additionally, the influence of an expected resurgent warm phase of the Atlantic multi-decadal oscillation weighs heavily on the 2023 outlook. In the North Pacific, marine heat waves NEP22A and NEP23A are expected to shift toward the North America West Coast likely ending a 3-year cool phase of the Pacific decadal oscillation. The east-shifting warmth in the North Pacific also weighs heavily on the North America season 1-3 outlook. Soil moisture and soil moisture trend is added to the forecast methodology in the April update. All dynamic models are indicating El Nino by mid-year. Analogs are not as aggressive. The International Multi-Model Ensemble (IMME) projects a formidable El Nino signature across the equatorial Pacific in July (Fig. 1). Interestingly, and unusual is the equatorial West Pacific is also warmer than normal. Normally, the equatorial West Pacific cools during El Nino. In the middle latitudes, both the North Pacific and North Atlantic are projected warmer than normal. In fact, given the El Nino forecast coupled with the warm SSTA north of Australia and the warm SSTA in the middle latitudes there is risk of an annual climate for 2023 registering warmest on record. In the North Pacific, marine heat wave NEP22A is south of Alaska and marine heat wave NEP23A is well west of California. The IMME July SSTA forecast indicates each “warm blob” will shift east toward the West Coast of North America. If so, the 2020-23 cool phase of the Pacific decadal oscillation (+PDO) fades and could shift into the warm phase which is typical of El Nino episodes. In the North Atlantic, formidable warmth is forecast propelling the Atlantic multi-decadal oscillation (AMO) to exceptional warm phase. Interestingly, the cool pool of water south of Greenland, a prominent feature since 2014, seems to fade given the surrounding warmth. The North America forecast for much of 2023 is based on climate correlation with very warm SSTA either side of the continent and in the Pacific tropics. Fig. 1: The International Multi-Model Ensemble (IMME) global SSTA forecast for July 2023 and relevant regions pertinent to the North America climate forecast. The conditions described are rare. Consequently, the forecast is based on average scenario of the 3 warmest SSTA analogs on record, most of them recent. The analog years are 2015, 2014, and 2009. The 2015 analog features an aggressive El Nino. The 2014 analog indicates early stages of El Nino. The 2009 analog represents El Nino onset during JUN/JUL/AUG. The mid-latitude SSTA warmth is most dramatic in 2015 and slightly less impressive for 2014 and 2009. Unfortunately, the 2009 analog is not useful due to climate patterns shifting due to the eruption of Mount Redoubt. Consequently, another choice for the 3rd analog is required. The 1998-2001 lengthy La Nina is similar toward the 2020-23 La Nina event. In 2001, ENSO stayed neutral, which is possible in 2023 although considered an outlier forecast. In summary, the analog years are 2015, 2014, and 2001 which cover all ENSO possibilities and identify the anomalous warmth of mid-latitude SSTA patterns. MAR/APR/MAY 2023: The spring outlook maintains remnant La Nina-like climate. Most obvious in that regard is the cold risk to the Upper Midwest States. Anomalous warmth and dryness is dominant across the West and Southwest U.S. A warmer than normal pattern is also forecast for the Southeast States plus Florida. However, wet conditions are likely for this zone including excessive rainfall risk for the Mid-south U.S. to central Gulf States. The Upper Midwest also receives above normal precipitations which is mostly in the form of snow during March. Eastern New England is likely drier than normal. Fig. 2-5: The Climate Impact Company upper air/temperature/precipitation anomaly climate forecast for MAR/APR/MAY 2023. (Previous below) JUN/JUL/AUG 2023: The summer forecast is consistent with anomalous hot/dry climate poised to settle on the western half of the U.S. Widening drought is likely. Extreme heat risk is most likely on the West Coast and across the Southwest States to Texas. The 2023 wet monsoon is less intense than last year. The eastern half of the U.S. is wetter than normal. There may be an early season tropical cyclone or two in the Gulf region before the stronger EL Nino climate develops which will prevent hurricane risk. The Northeast U.S. is very warm and exceptionally humid during the summer season. Fig. 6-9: The Climate Impact Company upper air/temperature/precipitation anomaly climate forecast for JUN/JUL/AUG 2023. (Previous below) SEP/OCT/NOV 2023: The autumn forecast trend is warmer. The entire Lower 48 States are warmer than normal during autumn. Late season heat driven by Santa Ana wind is implied for California. The Mid-south States turn much drier while California also stays dry and New England trends drier. Wet climate is limited to Western Washington, Iowa/Wisconsin, Florida, and the Coastal Carolinas. Fig. 10-13: The Climate Impact Company upper air/temperature/precipitation anomaly climate forecast for SEP/OCT/NOV 2023. (Previous below)