Weather outlook

Long-term weather forecast teases influence from potential El Nino

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A brutal beginning to this past winter was followed by the onset of much more normal winter conditions in North Dakota. The season that started with an unprecedented series of blizzards that had many wondering if they could possibly survive several months of such onslaught, changed course to more normal conditions for a North Dakota winter which was much to the relief of an increasingly weather weary populace.

The winter of 2016-17 was under the influence of La Nina, a cooling of Pacific Ocean waters that is considered by climatologists and weather forecasters to be responsible for colder and wetter winter conditions in the United States, North Dakota included. Next winter could be much different if anticipated weather conditions in the Pacific continue to follow historical trends.

La Nina and El Nino conditions have an odd relationship. A strong El Nino is generally followed by a strong La Nina. North Dakota experienced one of its warmest and driest winters on record in 2015-16, thanks to a strong El Nino. Of course, true to form, that winter was followed by this past one which was fueled by a strong La Nina that led to record early snowfall throughout the state.

The Climate Prediction Center says that La Nina has faded to the point where sea-surface temperatures across the central equatorial Pacific are reaching “near-average.” It is what forecasters consider “neutral” conditions. So what’s next?

According to the CPC, most forecast models favor a 60-65 percent chance of continuance of neutral conditions in the Pacific through June. The good news for North Dakotans wondering about facing another tough winter in 2017-18 is that the odds are increasing for formation of El Nino conditions as early as August. There is “increasing chances for El Nino development by late summer and fall,” states the CPC.

The long-range forecasting of the formation of an El Nino is based on study of historical weather patterns but are not necessarily what forecasters would consider a certainty. However, it is at least noteworthy and encouraging for weather watchers to learn that that there is a greater possibility of El Nino affecting weather patterns next winter than La Nina, at least for North Dakota.

While the presence of El Nino is generally welcome across the northern tier of the central United States, it does not always produce a noticeable effects. North Dakota’s warm winter of 2015-16 was considered by forecasters to be influenced by a very strong El Nino. The effect of El Nino next winter, if it forms, will be dependent upon how strong an El Nino develops. Regardless of strength, El Nino is still considered to have a more favorable influence on winter weather than La Nina conditions because it tends to push the northern jet stream into position to keep Arctic cold fronts from engulfing portions of the U.S.

The CPC issued its monthly three-month temperature and precipitation outlooks Thursday. Nearly all of the U.S. is predicted to be warmer to much warmer than normal for the period of May through July. An exception is the panhandle of Idaho, northern South Dakota and nearly all of Montana and North Dakota. Those areas, Minot included, are given an “equal” chance of temperatures falling within the normal range for the three-month period.

As for precipitation, central Montana is forecast to have an above normal chance of receiving more than usual precipitation through July. North Dakota, with the exception of the extreme southwest portion of the state, is forecast to have precipitation fall within historical norms for the same period. The U.S. Seasonal Drought Outlook shows no concerns for North Dakota through the end of July.

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