The La Nina as certainly kicked with SOI values up near 10 which is moderate to strong. This means a screaming jet stream across the Pacific. We will see the NAO relax and the PNA go more toward neutral. These are usually indications of a jet stream that is getting ready to bucking into long wave troughs instead of the closed lows we have seen running around. Long wave troughs are much bigger troughs and contain a lot of potential energy for major storms. We will also see colder air bleeding south into the United States which means instead of storms with marginal cold air, we have storms tapping into polar airmasses, cold enough for widespread snows. Around mid-month, we should see a couple of major storms, one in the Plains that may produce a swath of heavy snow and another in the East that could have widespread snows from the Great Lakes into the Northeast. There’s even more wintry fun for the last two weeks of the Month, but also keep in mind, between storms, temperatures can still rebound to above normal.

One thought on “Mid-Month Extremes Potential as La Nina Kicks In!”
  1. It may warm up aloft but with a snow cover and low sun angle, I don’t believe the 2m temperatures will warm up as much as the GFS graphic above is indicating. It seldom does here over interior Northern New England. Inversions are impossible to break and get the warm air to mix down this time of year in this area without a strong storm plowing up just to our west. If it’s too far west, we get CAD and the mixing doesn’t occur until the occlusion moves through and then it’s usually a brief warm-up. This is based on my many decades of experience in the region and its microclimate.

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