High Pressure Ridge Midwest Days 11-15?

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Euphoria days 11-15 (and in 15 days) Central/East-central U.S.?

Fig. 1-4: The favored mega-cluster (model) upper air projection for days 11-15 (top) and the 360-hour forecast (bottom). Indicated is potential for an upper level ridge to form and provide some drier/warmer weather.

Possible Central U.S. ridge later June: The mega-clusters are forecasting a most likely scenario upper air pattern featuring an upper ridge pattern over the Midwest or Upper Midwest in 11-15 days (Fig. 1-2). In 15 days the mega-cluster indicates the ridge cresting over the Upper Midwest (Fig. 3-4) which implies the evolving ridge process begins in 11 days and peaks in intensity in 15 days. All of this supports a drier and warmer climate in the Central/East-central U.S. flood zone. One caveat…there may still be an “air mass” thundershower problem over parts of the flooded areas as wet soils provide a moisture source for afternoon thundershowers. The target area for this problem would be the Mid-South but the Corn Belt should be mostly dry and warm.

Madden Julian oscillation offers a helping hand: To validate the upper ridge forecast by mega-clusters we need to see the Madden Julian oscillation enter phase_5 (West Pacific tropics). The MJO P5 supports dryness and warmth over the Corn Belt during June. MJO P5 is forecast by all models.

Europe/Ukraine Upper Ridge is There BUT Specifics Uncertain Late June

Late June upper air for EU/RU: The mega-clusters are most sure of a northern Europe upper trough in the 11-15 day period (Fig. 5). However, option 2 is an upper ridge in that same area (Fig. 6). In 15 days the mega-cluster indicates the upper trough is either over Iceland (Fig. 7) or farther east near U.K. (Fig. 8).

The upper trough question is the problem. The ocean surface across the Norwegian Sea and northwest of Europe is near normal to cooler than normal – which is unusual compared to recent climatology. The waters are cooler because there is precedent for presence of an upper trough. Rather than use an either or strategy using the mega-clusters a consensus is preferred.

So…the late June upper air pattern over Europe and Western Russia is most likely to favor the ridge over Eastern Europe and upper trough just northwest of U.K. The sensible weather pattern as July 1 approaches is a streak of rain across U.K. to Northern Europe while a dry regime is centered on the Black Sea region.

Fig. 5-8: The mega-cluster (model) indicates an upper ridge is dominant in the 11-15 day period across Europe into Southwest Russia but uncertain about Northern Europe (top). In 15 days the mega-cluster is more specific about the uncertainty not sure whether a trough is over Northwest Europe or the preferred forecast a ridge over Northern Europe (bottom). Forecast confidence for Europe/Western Russia lowers for late June.