The Stubborn Western Russia Trough

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The most impressive upper level feature in the northern hemisphere since springtime has been the persistent and vigorous upper level cool and showery trough over Western Russia. Occasionally, upstream from the deep trough an amplified ridge forms to bring heat wave conditions to Europe centered on France. Otherwise the trough takes over and squashes heat and this time leads to wet weather over France next week after the torrid heat this week.

Europe/Russia: The most interesting (and important) and persistent upper air feature across the northern hemisphere since spring has been the West-central Russia upper trough. This feature has been a prominent cool and showery weather producer for the western half of Russia and due to its intensity has shaped the upper air pattern across Europe and Asia much of the warm season. Occasionally, an upstream ridge has developed over Europe to bring intense heat earlier this summer and also the current week with France hardest-hit. However, the mega-clusters indicate the ridge pattern bringing this week’s European heat fades and the “Big Bear” trough over Western Russia regains intensity. The North Atlantic trough also regains strength and shifts toward Western Europe. Consequently, areas hit by the heat wave this week turn wet (Fig. 1) and Ukraine to Southeast Europe also turn wet (Fig. 2). Anomalous heat departs the pattern including in 15 days (Fig. 3).

Fig. 1-3: Most likely upper air pattern days 6-10 and days 11-15 (top) and most likely pattern on day-15 (bottom) based on mega-cluster (model) for Europe.