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Long Range Forecast Update February 4, 2011

Posted by mikeheard in Uncategorized.
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La Nina is still in control of our weather despite the data showing January was a warmer and drier than normal month for SW Montana.

Climate Prediction Center long range forecasts has a strong La Nina signature both in the short term 30 day forecast and the longer range 90 day forecast.

Here is the February Outlook for Temperature and Precipitation

February Temperature

February Precipitation

Most of Montana should experience a colder than normal February and wetter than normal as well. Southern Montana including Bozeman to Dillon is in the EC range on temperature, meaning equal chances of normal, below normal or above normal temperatures, whereas, the northern half of the state has a 30 to 40% chance for below normal temperatures.

Here is the 90 day outlook:

90 Day Temperature Forecast

90 Day Precipitation

90 day forecast (Feb through Apr) is calling for a 40-50% chance for below normal temperatures and a 30-40% chance for above normal precipitation across Montana.

Again the long range forecast has a strong La Nina signature. If the weather pattern holds to the above forecast trend there should be healthy snowpack in the mountains by the end of the season by May and in turn plenty of summer water for irrigation and recreation. The bigger question is will there be too much and is flooding a concern?

La Nina forecast models are projecting the ENSO event in the equatorial pacific (colder than normal sea surface temperatures) will continue into in the spring months but slowly weaken through April. Computer models vary widely after that point so it’s too early to predict if the La Nina patter will continue to impact the late spring and early summer months.

If we continue to see these extreme cold events followed by brief warm periods, Ice Jams will continue to be a problem for flooding across the state.

One of the potential weather effects that I will be watching closely is IF the weather pattern remains cold and snowy through April, with above normal snowpack, colder temperatures keeping that snowpack in place, and we turn the corner into late May and early June with a rapid warm up and experience a wetter than normal rainy season. That potential scenario could lead to river and lowland flooding in Southwest Montana.

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