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08/16/2018, 4:52 pm EDT

Europe Season 1-3 Ahead Forecast

Beneficial wetter than normal climate ahead for parts of Europe Executive Summary: Evolution of a dominant upper ridge pattern during spring and summer 2018 lead to Central/Northern Europe drought and attendant heat. The upper ridge pattern breaks down slowly during autumn. The winter outlook is adjusted from colder than normal in the previous outlook to near normal. Positive phase arctic oscillation is expected to dominate the winter climate therefore continues milder revisions are possible for the winter season. Climate discussion:  During spring a large mass of cooler than normal surface water accumulated south and southwest of Greenland causing the air aloft to also be cooler than normal inviting the polar vortex to extend eastward from snow-covered central Canada into the North Atlantic (Fig. 1). The upper trough was intense and caused a downstream upper ridge to form over Eastern Europe. This pattern became dominant into early summer and the persistent upper ridge over Europe caused drought conditions to emerge in central and northern portions of Europe. The dry soil moisture condition caused a feedback mechanism to the atmosphere amplifying the ridge pattern as it shifted north in July (Fig. 2). The European ridge pattern causing drought and one of the hottest summer seasons on record was initiated by downstream effects caused by the upper trough near Greenland which was initiated by cool sea surface temperature anomalies (SSTA). Fig. 1-2: Evolution of the spring to summer 2018 upper air pattern leading to an amplified upper ridge over Europe. Presence of the upper trough, shifting from eastern Canada/Greenland during spring to the North Pole in July is characteristic of the positive phase of the arctic oscillation (+AO). The AO (and its North Atlantic counterpart the North Atlantic oscillation) are major modulators of Europe climate. The 5-month (April to August) run of +AO is rare and last most closely replicated in 1989 and 1994 (Fig. 3). Fig. 3: The arctic oscillation analog forecast for 2018-19 indicates a possibly strong positive phase continuing from summer 2018. The season 1-3 ahead climate outlooks are based on presence of a persistent +AO regime as observed in 1989-90 and 1994-95. The ENSO regime is cautiously forecast to enter El Nino for winter 2018-19. The North Atlantic basin is marginally warm for the 2018-19 cold season ahead. The Europe season 1-3 ahead forecast is based on presence of a persistent +AO, weak El Nino (and possibly El Nino Modoki) plus marginally warm to neutral Atlantic multi-decadal oscillation (AMO). Outlooks: The season 1-3 ahead forecast is based on a persistent +AO regime, weak warm to neutral AMO and a possible El Nino Modoki regime. SEP/OCT/NOV 2018: The meteorological autumn outlook remains consistent with a chilly northern Europe climate developing while southern Europe to the Black Sea region is warmer than normal. In-between the two thermal regimes a wetter than normal climate is forecast. Fig. 4-5: Climate Impact Company SEP/OCT/NOV 2018 temperature and precipitation anomaly outlook.  DEC/JAN/FEB 2018-19: The outlook for meteorological winter is adjusted less cold in Europe although Southwest Russia remains quite cold. The European winter climate is temperate most likely starting warm and ending cold. The precipitation outlook is above normal for much of western and southern portions of Europe. The precipitation outlook is consistent with the previous forecast except much wetter in U.K.   Fig. 6-7: Climate Impact Company DEC/JAN/FEB 2018-19 temperature and precipitation anomaly outlook. MAR/APR/MAY 2019: The preliminary meteorological spring 2019 outlook indicates most of Europe is normally mild while Western Russia is warmer than normal. Dryness emerges and dominates West/Southwest Europe. Wet weather affects coastal Northwest Europe and also the Baltic Nations plus southern Poland. Fig. 8-9: The preliminary Climate Impact Company MAR/APR/MAY 2019 temperature and precipitation anomaly outlook.