05/25/2023, 3:11 pm EDT

North America Season 1-4 Ahead Outlook: Outlook is biased dry North-central/Midwest U.S. through next spring, another hot summer ahead, and winter 2023-24 is mild East.

Executive Summary: The North America season 1-4 ahead climate forecast is valid through meteorological spring 2024 is re-issued. The forecast is based on a constructed analog heavily considering regional SSTA patterns such as ENSO and warm/cool pools of water in the middle latitudes. Forecast highlights include another hotter than normal summer for most of the U.S. except the northwestern Gulf States where wet weather suppresses anomalous heat risk. The Canadian Prairies, North-central U.S. and parts of the Ohio Valley are drier than normal during summer as drought expansion is a concern. Next autumn season brings wet risk in the Gulf States while areas to the north including the Mid-south U.S. and North-central States stay on the dry side. Drought is possible for a fairly significant portion of the Central U.S. Winter 2023-24 is mild again especially for Southern Canada and the East U.S. El Nino-induced wet bias adheres to the Gulf States next winter and spring. Methodology: All climate forecasts are based on a constructed analog. The constructed analog heavily weighs BOTH the sea surface temperature anomaly (SSTA) patterns in the tropics such as ENSO and the middle/poleward oceans including marine heat waves. Warm season forecasts include the influence of soil moisture regimes while cold season forecasts which are within 1-2 months range apply the influence of projected snow cover. Given unique ocean climate characteristics and their influence on climate during the past 10 years, an optimum climate normal (OCN) is also heavily considered. Finally, a season-4 forecast is added to the format. The latest Climate Impact Company season 1-4 outlook is valid through meteorological spring 2024. Fig. 1: Global SSTA forecast valid for June 2023 by the International Multi-model Ensemble (IMME). Fig. 2: Global SSTA forecast valid for October 2023 by the International Multi-model Ensemble (IMME). Climate: The outlook is somewhat reliant on the global SSTA projection for the immediate short-term (June) and longer-term (October) based on the availability of the International Multi-model Ensemble (IMME). Constructed analog El Nino southern oscillation (ENSO), Pacific decadal oscillation (PDO), and Atlantic multi-decadal oscillation (AMO) forecasts are relied upon for outlooks into early 2024. The short-term forecast for June (Fig. 1) indicates a sprawling El Nino, developing positive phase Indian Ocean dipole (+IOD), marine heat waves (MHW) northeast of Hawaii and off the northwest coast of Africa plus unusually warm SSTA in the main development region (MDR) for hurricanes in the outer tropical North Atlantic. The North Atlantic warm hole (NAWH) is also indicated south of Greenland. The outlook is a general guide and not used verbatim. The El Nino forecast is likely overdone as westward warming of the equatorial East Pacific to the Dateline is slower. Theorized is 2015-like eastward shift of the MHW northeast of Hawaii to the North America West Coast to stop in the cool water inflow from the California Current toward the east-central tropical Pacific allowing waters to warm to the Dateline to cause the stronger El Nino as forecast by IMME. Climate Impact Company indicates that process is slow, delayed, or may not happen. Additionally, the NAWH pattern in the North Atlantic is biased farther westward toward the Southeast Canada/Northeast U.S. coastline. By October, IMME projects a stronger El Nino but without the MHW northeast of Hawaii reaching the North America West Coast (Fig. 2). Consequently, the intensity of El Nino indicated by IMME is likely much too strong. Note the warmth of the North Atlantic basin just after peak activity of the hurricane season likely to prolong active tropics into late year. As usual the open oceans south of the polar ice cap warm for late warm season. The soil moisture regime across North America features drought in the central Great Plains which recently is expanding eastward (Fig. 3). Strong drought resides across Western Canada and the Canadian Prairies. Drought patterns are generally supportive of an anomalous high pressure and increased heat risk during the summer season. Developing El Nino eventually eases drought risk, but timing is uncertain. Finally, OCN is applied to the forecast. This condition is warranted due to the evolution of influence on climate by regions of warm and cool SSTA in the middle/northern latitude oceans during the past 10 years. Fig. 3: North America soil moisture anomalies and where drought is located. JUN/JUL/AUG 2023: Confidence is ABOVE AVERAGE that the U.S. summer 2023 season is hotter than normal. Not everywhere observes anomalous heat. The wet zone forecast for the northwest Gulf States suppresses heat risk while dryness across the Canadian Prairies, North-central U.S., and parts of the Ohio Valley enhances anomalous hot risk. New England is also “sneaky” hot and dry. Fig. 4-5: The Climate Impact Company upper air/temperature/precipitation anomaly climate forecast for JUN/JUL/AUG 2023. SEP/OCT/NOV 2023: Much of the U.S. is warmer and drier than normal next autumn. Dryness continues in the North-central U.S. and adds the Midwest and Interior Northeast States. Most of these dry zones are warmer than normal. Wet weather near the Gulf Coast suppresses anomalous warm risk in that region. The West U.S. observes a warmer than normal autumn. Fig. 6-7: The Climate Impact Company upper air/temperature/precipitation anomaly climate forecast for SEP/OCT/NOV 2023. DEC/JAN/FEB 2023-24: Meteorological winter 2023-24 is warmer than normal across Southern Canada and most of the eastern half of the U.S. A typical mild bias for winter caused by El Nino. Stormy weather attacks the Coastal Northwest States and the Gulf region with a near miss for the New England States. The Northern U.S. precipitation regime is near or below normal. Fig. 8-9: The Climate Impact Company upper air/temperature/precipitation anomaly climate forecast for DEC/JAN/FEB 2023-24. MAR/APR/MAY 2024: Next meteorological spring stays warmer than normal due to El Nino for the Northern U.S. and Western Canada and much of the U.S. East Coast. Also typical of springtime El Nino climate, the southern states centered on Texas are very wet while areas to the north including the Midwest States to New England and coastal Northwest are drier than normal. Fig. 10-11: The Climate Impact Company upper air/temperature/precipitation anomaly climate forecast for MAR/APR/MAY 2024.  
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