January Pattern / Stratosphere Update

Lots of chatter today across the weather world about winter possibly being "over" despite most forecasts calling for an active back end. No one said it will be easy to flip the pattern driven by a strong El Nino and a dominant Stratospheric PV. It was always supposed to be a step-down pattern change and I still think we're heading in that direction. People are frustrated and they have every reason to. We seem to have the cold before and after storm events but unfortunate timing and tendency for short waves to cut-off in our atmosphere puts us on the mild side. When the Atlantic and Arctic teleconnectors turned favorable, the Pacific one's turned unfavorable. Can we get the stars to align for us in February? I think we have a fighting chance still.

We're seeing our first real signs of warming in the Stratosphere entering 10hPa and the upper levels. If this occurs, we'll see a Sudden Stratospheric Warming Event take place and displace the Strat PV to eastern Europe. This opens the door for blocking to re-develop in the AO and NAO domains sometime in February (thinking the 7th-10th). The AO should go negative sooner than the 7th, possibly sometime in the first week of the month.

The GFS and GEFS are in fair agreement 10mb and 50mb zonal mean zonal winds will dip below 10m/s for the first time this season. This is a step in the right direction as it indicates a dramatically weakening PV.

The GEFS and EPS are also in agreement of showing impressive 10hPa height extension into the Arctic and displacing the PV. While the model agreement is nice to see, I would like to see how this looks over the weekend. For whatever it's worth. Judah Cohen is confident the upcoming Rosby Wave attack will lead to a SSWE.

The Euro Ensembles on MLK Day show the impressive -NAO block but finally take the PV lobe that was over southern Canada and dig it into the northeast U.S. If the trough goes negative or there's any southern stream phasing, we could see an inverted trough develop along the coast which would promote widespread snow to break out over the area. We'll see how this trends over the upcoming days. Regardless, it'd going to get cold.

Beyond then, the EPS suggest the end of next week will still remain colder than normal with a trough over the east. Unfortunately the Pacific still does not look quite right with the trough just off the west coast. But if we have the blocking over southeast Canada into Davis Strait then maybe we can prevent another storm from cutting on us.

The last week of January I think we'll enter a reload period. The western trough enters the US and a western Canadian ridge develops overtop. This is similar to what we saw earlier in January. With the trough over the west, the southeast ridge will amplify on the east. So, if we do not capitalize on anything between now and the last week of January...we could very well head into February still looking for our first significant snowfall of the season. We have to capitalize on the blocking now before the western trough comes onshore. Like I mentioned before, we need timing and upper air energies to cooperate.

I touched on February in the Stratospheric portion of the writeup, but I will have a February outlook out sometime in late January letting you know whether or not I still feel Central Park, NY will finish the season with above normal snowfall. Yes, I'm going to tell you if my Winter Outlook still has a chance of verifying (from a snowfall standpoint, I'm doing OK with temps so far). Hopefully we start getting some good news around here!

Best,

Francesco Paparatto