Long Range Lookout: Very Active Pattern Setting Up

Hour 228 of 12z October 8 Ensembles

Hour 324 of 12z October 8 Ensembles

This is your weekly edition of Long Range Lookout, published October 10.

The ensembles from October 8th (when this post was made) are all showing very strong storms in the long range affecting the United States. While they all have very different scenarios, let me tell you why you should take notice.

You should know if you are an avid weather person that models have trends, i.e. forecasting a heat wave for the last 5 days. Well, ensembles have a similar 'rule'. A general rule of thumb for ensembles is to look for a general pattern. If we look at the ensembles above, we can definitely see that they are all very different, so one would think there is no pattern. However, we aren't looking for a specific storm- we are looking for something they all have in common. A reanalysis of these images reveals that the ensembles all have strong storm systems in their forecasts, meaning we have a pattern.

Seeing as the ensembles are forecasting at least two unusually strong storm systems to come through, one would think that there is some evidence to back this possibility up. However, models have been known to drastically overestimate storms over the ocean. Models typically have a tough time with systems not on North American land, where more data on the system can be gathered.

In conclusion, the next 7-14 days and beyond are looking unusually active. I would not be surprised to see two or more unusually strong storms hit the West Coast and produce severe weather on one side of a frontal boundary and a blizzard on the other side when it moves into the Central and Eastern US.

The North Atlantic Oscillation, or NAO, also looks to be taking a dive, clearing the way for some cold in the Northeast. But that's not all- the Arctic Oscillation (AO) may also plummet as a ridge forms over the North Pole.

The NAO and AO are both oscillations that bring cold to the nation in a negative phase (ridge over Greenland for NAO, ridge over Arctic Circle for AO) and supply warmth to the nation in a positive phase (stormy over Greenland for NAO, stormy over Arctic Circle for AO). This ridge formation over Greenland and the North Pole should create a double-whammy, where some chilly weather should enter the nation. Also, take note of the ridge over the northeast Pacific. This symbolizes a positive PNA, which means more cold and storms for the central and east regions of the country.

Things are looking up, snow lovers!

Andrew