Highlight: A warm winter ahead for Europe. Next summer is hot again for Europe/Black Sea region. Executive Summary: The Climate Impact Company season 1-3 ahead climate forecast for Europe/Western Russia valid for October and November plus meteorological winter 2023-24 through summer 2024. The 2023-24 cold season across Europe is projected persistently warmer than normal. Cold risk is across Western Russia. Europe remains warmer than normal next spring and followed by a hot summer for Southern Europe through the Black Sea region. Methodology: The season 1-3 ahead climate forecast for Europe/Western Russia is based primarily on current and projected regional SSTA and their historical upper air patterns projected forward one year. SSTA regions of influence are ENSO, the North Atlantic and Indian Ocean environment plus the Norwegian Sea. Climate: The SSTA regions considered to generate the season 1-3 ahead climate forecast for Europe/Western Russia includes El Nino southern oscillation (ENSO), the Atlantic multi-decadal oscillation (AMO), Indian Ocean dipole (IOD), and the Norwegian Sea. Added are recently developed phenomenon in the North Atlantic including the North Atlantic warm hole (NAWH) and presence of marine heatwaves (MHW). ENSO: Despite the distance of the equatorial Pacific from Europe/Western Russia the ENSO climate influence is global and certainly shapes, in-part the prevailing climate pattern across the western half of Eurasia. Currently, El Nino continues to strengthen in the eastern half of the equatorial Pacific (Fig. 1). The North America multi-model ensemble extends to FEB/MAR/APR 2024 and indicates El Nino is likely to persist well into 2024 (Fig. 2). A preliminary projection of ENSO phase for next summer is a return to neutral phase. Normally, El Nino increases the mild influence of maritime westerly flow during the cold season across Europe toward Western Russia. AMO: The sea surface temperature anomaly (SSTA) environment across the North Atlantic basin is the leading contributor to the Europe/Western Russia climate forecast. The North Atlantic basin was record warm during the 2023 warm season. The anomalous warmth was enhanced by a marine heatwave off Northwest Africa. Warm SSTA in the vicinity of Europe promotes high pressure and anomalous warmth and dryness. However, during brief interruptions of low- pressure patterns, due to the increased low-level atmosphere moisture associated with a warmer than normal ocean surface, extreme precipitation events can also occur as observed in Libya/Southeast Europe during late summer. The exceptionally warm North Atlantic SSTA pattern is likely to continue well into next year as the MHW off Northwest Africa continues. IOD: Presence of positive phase IOD is developing in the Indian Ocean. +IOD is present when the western tropical Indian Ocean is anomalous warm. The +IOD pattern produces heavy convection in this tropical longitude including Northeast Africa which shapes the mid-latitude pattern to the north having influence on Western Russia climate. The +IOD pattern strengthens during late 2023 and widens the attendant warm SSTA pattern heading into Q2/2024. The +IOD influence favors a wet climate for the Middle East potentially affecting the Western Russia regime. Norwegian Sea: During modern-day winter, the Norwegian Sea is ice-free. The SSTA pattern in the Norwegian Sea influences the risk of high latitude high pressure which can lead to blocking patterns (negative North Atlantic oscillation) causing cold troughs to form over Europe. Recently, the warm SSTA tendency in this region can also enhance a northern latitude storm track which can flip Southern Europe warm during the winter months. The Norwegian Sea regime implies the prevailing NAO regime. The Norwegian Sea is projected warmer than normal during the 2023-24 cold season slightly favoring presence of -NAO and increased risk of stormy/cold troughs into Europe. NAWH: During the past 10 years the accelerated ice and snowmelt off Greenland has caused the pooling of a stratified cold ocean layer to form south of Greenland, cool the atmosphere aloft, and cause a persistent upper-level low pressure trough to form. Downstream from this trough, semi-persistent (warm influencing) high pressure forms over Europe. The pattern is so consistent that an optimum climate normal (OCN) which identifies the short-term 10-year climate is added to the forecast process for each season. During spring 2023, the NAWH shifted (for the first time) to south of the Canadian Maritimes. The NAWH shifted to west of Europe mid-summer and has temporarily weakened. However, the NAWH pattern is projected to regenerate returning to home base south of Greenland over the next few months. MHW: The tendency for large ocean areas to warm at and below the surface and persist for months (and sometimes years) has emerged during the past 10 years in both middle and subtropical oceans around the world. During the past 6 months, a marine heatwave formed off Northwest Africa and spread to the west of Europe during summertime and more recently to the central subtropical North Atlantic Ocean. Briefly, the MHW also reached across the western and central Mediterranean Sea. The Northwest Africa MHW persists well into 2024 and will continue to contribute to the record warm North Atlantic basin SSTA regime. MHW’s increase the risk of warm and dry climate to Europe with occasional interruptions of extreme precipitation events. Snow cover and soil moisture: During the climate change era, the oceans north of Eurasia are wide open longer before polar ice arrives on the north/northeast coast of Russia while north of Europe always has open water. As the atmosphere chills during autumn due to loss of sunlight, advection snows are common and can lead to early season above normal snow cover especially for north/northeast Russia. The early season snow cover can allow cold air masses to develop early in the winter season and persist through all of winter due to their ability to persist away from any maritime moderating influences. These Russia cold air source regions can back westward into Europe and frequently feature arctic air. Due to the presence of El Nino, the broad maritime westerlies in the middle latitude climate is likely to prevent large aerial coverage of early season snow and gathering arctic air masses. Heading into the cold season, soil moisture influence on climate decreases. Currently, drought is present across parts of Southwest Europe, West-central Russia, and coastal Northeast Russia. Analog years: The analog years are chosen and weighted based on approximations of past years when the projected SSTA regimes discussed were present. Due to the recent warming of mid-latitude oceanic warming, an OCN is added to the analog years. ENSO analog years include 1997-98, 2006-07, 2012-13, and 2015-16 while the very warm AMO analogs are recent (2016-17, 2017-18, 2021-22, and 2022-23). The IOD analogs are 1997-98, 2006-07, 2015-16, and 2018-19. The Norwegian Sea analogs are inclusive to OCN. There are different weightings applied to the analog years, dependent on the amplitude of similarity to the current regime. Fig. 1: Global SSTA for the past one month and regions of influence on the Europe/Russia climate (and climate forecast). Fig. 2: The NMME global SSTA forecast for FEB/MAR/APR 2024 and regions of influence on the Europe/Russia climate forecast. JUN/JUL/AUG 2023 verification: The Climate Impact Company outlook for meteorological summer 2023 across Europe and Western Russia was very warm to hot (Fig. 3) with dryness (except wet Southeast Europe) for Central/East Europe plus the spring wheat belt in Russia (Fig. 4). Observed weather was warmer than forecast (Fig. 5) with wet climate for much of Central Europe plus Spain and strong dryness in Western Russia (Fig. 6). Fig. 3-6: The Climate Impact Company temperature/precipitation anomaly climate forecast for JUN/JUL/AUG 2023 across Europe/Western Russia. Verification is below. October 2023: Mid-autumn features an intense upper trough north of Caspian Sea in West-central Russia. The upper trough inspires a wet and cool climate in this region. In response to the upper trough, an amplified upper ridge is forecast for Western Europe and centered on U.K. Western Europe is warmer and drier than normal for mid-autumn. Another upper trough is projected for the eastern Mediterranean Sea causing wet weather in that vicinity. Fig. 7-8: The Climate Impact Company constructed analog temperature and precipitation anomaly forecast for October 2023 across Europe. November 2023: The upper air pattern does not change during late autumn. The upper trough shifts to northeast of Caspian Sea and could create some unusually cold air for early winter. Widespread above normal precipitation stretches from Ukraine eastward across Kazakhstan which will include some snowfall. The upstream upper ridge pattern remains in-place and keeps West and Central Europe somewhat warmer than normal. Dryness dominates South-central Europe during late autumn. Fig. 9-10: The Climate Impact Company constructed analog temperature and precipitation anomaly forecast for November 2023 across Europe. DEC/JAN/FEB 2023-24: The winter 2023-24 upper air pattern across Europe/Western Russia is forecast to feature an upper ridge over Southwest Europe and upper trough in Northwest Russia. While the presence of the upper ridge strongly favors a warmer than normal winter season, the upper trough in Northwest Russia struggles to produce cold air due to the mild influence of open water north of the northwest coast of Russia. The entire region is warmer than normal based on the regional SSTA constructed analog. Stratospheric warming events more likely to occur during an active sun could cause a “sneaky” cold outbreak. However, outside of SSW events, a mild winter is likely across Europe. The precipitation outlook indicates above normal rainfall for the British Isles eastward to Eastern Europe with rain/snow mixed across much of Western Russia. Normally, during El Nino, Southern Europe is wetter. Fig. 11-12: The Climate Impact Company temperature/precipitation anomaly climate forecast for DEC/JAN/FEB 2023-24 across Europe/Western Russia. MAR/APR/MAY 2024: Presence of a buoyant upper ridge shifts but has bold (warm) influence across most of Europe and Western Russia next spring. Typical of El Nino climate, Southern Europe to Southwest Russia is quite wet. North of the wet belt, Northern Europe is dry. Fig. 13-14: The Climate Impact Company temperature/precipitation anomaly climate forecast for MAR/APR/MAY 2024 across Europe/Western Russia. JUN/JUL/AUG 2024: Expect a hot summer as an upper ridge is broadly stretched from South-central Europe to North-central Russia. The hottest anomalies are centered in the Black Sea region. Most of Southern Europe is generally drier than normal. Northwest Russia is the wet zone for next summer. Fig. 15-16: The Climate Impact Company temperature/precipitation anomaly climate forecast for JUN/JUL/AUG 2024 across Europe/Western Russia.