Western US Ridge will serve as pattern’s focal point

Much has been made over the past few weeks regarding the potential development of a large ridge, which forecast models once suggested would build into the Ohio Valley and Northeast States, providing widespread heat and humidity. As you may have figured out yourself, this ridge has yet to develop — and it doesn’t look it will at all, succumbing to the overall hemispheric pattern which has kept the ridge angled towards the Western United States.

Medium range forecast models were much too aggressive with the development of the ridge, once suggesting that the core of it would build into the Ohio Valley. In fact, for a few model cycles both the GEFS and ECMWF suggested that heat would build into the Eastern US, but have since backed off. The development of these large ridges is quite common in the summer (in other words, this isn’t all that anomalous), but the positioning of the ridge is often modulated by the surrounding environment. This year is no different.

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The pattern throughout the hemisphere will continue to retard the development of any substantialized or long-term ridging east of the Mississippi River for at least the next two weeks. Instead, the combination of tropical forcing and upper level height response will keep the ridge angled in the West-Central United States. As the Pacific Jet stream remains active, disturbances are likely to surge along the top of this ridge and into the Northern Plains, Great Lakes, and eventually Ohio Valley.

There are a few notable and significant results as this pattern develops. First, above normal precipitation is likely to return across the North/East Plains, Great Lakes, and Ohio/Mississippi River Valley. This will make growing issues in these regions even worse — as multiple precipitation events add to already significant totals. Severe weather also appears probable as favorable wind fields exist for storm organization amid strong instability in the atmosphere.

Second, the western agriculture belt looks likely to fall underneath this ridge, and west of the boundary where storms will be frequent. This will make the drought in these regions even worse over the coming weeks, as most of the storms and disturbances slide east of the region — into areas that really don’t need it. In other words, the developing pattern is a bad scenario on both ends of the spectrum for agriculture.

Drought conditions are likely to worsen across the western regions of the agriculture belt.

Drought conditions are likely to worsen across the western regions of the agriculture belt.

In the Northeast States, the weather pattern largely looks to feature near or slightly below average temperatures and multiple opportunities for precipitation. Forecast models have continually suggested that while ridging develops out west, disturbances will re-enhance troughing across the Northeast States. This suggests that any bouts of heat will be significantly limited, and troughiness with cooler air will have a much greater propensity to develop.

It remains to be seen exactly how cool temperatures get in terms of departure from normal, but at the very least it appears that below normal temperatures will fall into the forecast spectrum through July 15. East of the Mississippi, there are no elements of the forecast which currently point towards ridging, heat, or a lightening of the active pattern any time soon.