Doug Simonian

Update: October NAO and what it means for winter

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As we have alluded to in previous articles, the weather pattern across the globe is currently undergoing changes. A lot of this has to do with recurving Typhoon Wipha, as the large storm generated a trigger to produce a large ridge ahead of it. This helps to create a more amplified pattern, slowing things down. A slower global pattern is what tends to lead to more blocking, and the blocking that we are seeing this month could be a very important player as we head towards winter.

The reason it’s important is because there is a significant correlation — especially recently — between a -NAO in October and a -NAO during the following winter. One reason among many for this is because a -NAO pattern will often establish itself in October, relax a bit during November, and then re-establish itself during the winter. Our previous article highlights the detailed research and correlations, which will help you contextualize what is being written in this article.

The prudent question to ask now would be how the NAO has been doing so far, and if it will stay negative for the rest of the month.

The NAO has been negative this month, and should continue to remain negative for the rest of the month.

The NAO has been negative this month, and should continue to remain negative for the rest of the month. The black line represents the observed values, and the red lines represent the forecast values from the GFS ensembles.

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John Homenuk

Fall foliage peaking in the Northeast this week

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The middle of October is always a beautiful time throughout much of New England, and even down farther south into our area of the Northern Mid Atlantic. Although fall foliage season is always changing a bit, this year has featured a pretty average progression of fall colors. The ongoing lack of precipitation in our area may have delayed the colors slightly, but moderate color is working down towards the coast as of the middle of October. High and peak colors have worked into the area suburbs.

Foliage report from October 16th, 2013. Courtesy The Foliage Network.

Foliage report from October 16th, 2013. Courtesy The Foliage Network.

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John Homenuk

Heading into winter, 5 myths about forecast models

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As part of our winter forecasting feature this autumn, we’re releasing a few posts with information and tounge-in-cheek opinions about winter and meteorology. The first in the set comes this afternoon, where our forecasters sat down to compile a list of the 5 biggest forecast model myths as we head into winter. You can check them out below, to get a quick primer on what to expect over the next several months.

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John Homenuk

Cloudy, drizzly and unsettled through weeks end

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The combination of a weak coastal system, meandering off the Mid Atlantic coast, and multiple mid level disturbances moving through the Northeast US will result in generally unpleasant weather from Wednesday through the end of the week. The coastal system is weak but brings moisture and an onshore flow, as the decaying mid level vorticity slowly retrogrades towards the coast on Wednesday. Low clouds and drizzle are possible, despite the lack of any steady rain, especially near the coasts.

Mid level disturbances shifting northeast from the Mississippi and Ohio Valleys through the Great Lakes and Northeast will bring more unsettled weather through the end of the week — signaling the beginnings of a more active pattern. The weekend is expected to feature improving conditions once the frontal system eventually moves off the coast.

High resolution models showing increasing Precipitable Water values by later Wednesday evening.

High resolution models showing increasing Precipitable Water values by later Wednesday evening.

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