Posts

John Homenuk

Winter Forecast 2017-2018

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Seasonal forecasting is quite the challenge, but one we always look forward to. It seems every year we learn something new about the atmosphere. It is critical to have a fundamental understanding of how the atmosphere works, and the implications that changes from its base state can have on the weather pattern.

Instead of focusing on individual numerical indexes and their verbatim values, we are going to try to paint a picture of the atmosphere and what it will be doing over the next few months based on these phenomena:

  1. ENSO (El Nino Southern Oscillation) and tropical forcing
  2. High latitude behavior and blocking
  3. Analog years based on global pattern evolution

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John Homenuk

AM Update: Warmth returns to east, but for how long?

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Good morning and Happy Wednesday to you all. There is something oddly special about the first day of November in the meteorological community. It’s not a holiday, it’s not the start of any official season. But it has significance for many who forecast or follow the weather – it’s the beginning of “winter season” per se, where the forecasts for the weeks and months ahead start to have more significant implications on what we can expect during winter.

As we move into November this year, the weather pattern will be dominated by a large -EPO ridge, developing in the Pacific Ocean as we speak. We discussed yesterday in detail how these EPO ridges can impact the weather pattern throughout the hemisphere. In this case, the large ridge in the Northern Pacific Ocean will act to dislodge colder than normal air from the arctic regions into British Columbia, and eventually the Northwestern United States as well.

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John Homenuk

Cooler risks increasing, volatile pattern on horizon

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Happy Tuesday! For the past several days, discussions have turned from the presence of abnormal and anomalous warmth towards winds of change, which are signaling the return of cooler air and a volatile weather pattern. Overnight forecast models continue to supplement these ideas, with further confirmation that the pattern is set to undergo wholesale changes across the large majority of North America.

As we have discussed, most of these changes are being driven by the Tropical Pacific and the MJO, where global circulations are being affected heavily by its progression over the next few days. While La Niña’s base state has become entrenched in the atmosphere (30-day moving SOI now up to +11.3), the progression of the MJO will allow for a wave-pattern realignments by Days 5-7.

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John Homenuk

October Outlook: Why anomalous warmth could return

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Several daily temperature records were broken over the past several days throughout the Eastern United States, particularly this weekend when temperatures reached into the upper 80’s and lower 90’s. Much of this warmth was aided and enhanced by the development of a large, sprawling mid and upper level atmospheric ridge. This ridge acted to enhance the flow of a warm, southwesterly flow, which effectively advected warmth into the agriculture regions and eventually into the Northeast as well.

In the near future, a potent cold front is expected to gradually shift east/southeastward into the Great Lakes, eventually making headway towards the Eastern United States. This front will provide some temporary relief in terms of temperature for harvesting in the near future, and will have many thinking that fall weather is finally on the way — but not so fast. There is more to the forecast, suggesting that anomalous warmth could return very soon.

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