Beware: Two Major Storms Possible Between February 5th-10th

If there is one thing that stands out to me so far this winter season, it is the incredible persistence of the -EPO oscillation that has helped usher in arctic air masses into the eastern half of the U.S. The large pool of above normal sea surface temperatures in the northern Pacific insist on staying on the extreme side of positive and do not show signs of normalizing just yet, which is giving off a positive correlation for the EPO to keep remaining in a negative state. Even when our AO oscillation gets into a positive phase, we are still seeing temperatures across the northern tier of the country into the Mid-Atlantic well below average. Although Atlantic blocking has been non-existent in the higher latitudes for the most part, we have still managed to see potent winter storms effect the area and drop a significant amount of snowfall due to the other favorable signals of -EPO / -AO / and +PNA combinations. 

If you're a winter weather enthusiast, your appetizer this weekend will be to enjoy the Super Bowl festivities and a break from the harsh cold temperatures while possibly seeing light snow showers on Monday from a weak wave. Your main course awaits you between the February 5th-10th time period. It will be within this time period that the Northeast could see not just one, but two large winter storms from a series of intense short waves digging into the southwestern U.S. as a result of the -PNA. 

In this blog, I am going to touch on both storm potentials and name February 5th storm #1 and February 8th-10th storm #2. Obviously storm #1 will have the most detail since guidance it will come before storm #2 and could also have an effect on how storm #2 will ultimately materialize. 

STORM #1

This is the 12z EURO 500mb on Tuesday morning, the day before storm #1 is set to hit the area. One thing I guess I should say is I am confident there will be a storm, regardless of whether it's rain, snow, or ice. There is no out to sea solution with this system because the southeast ridge will not allow that to happen. Notice the black circles and the white numbers located within those circles. I am going to explain what those particular anomalies resemble. 

PLAYERS ON THE FIELD FOR STORM #1:

1 - That is where the short wave energy is located and as you can see it is dug deep down into the southwest U.S. and is already at a potent level.  

2 - A piece of the Polar Vortex has broken off and is kind of perpendicular to the short wave energy in the southwest U.S. As the s/w energy moves east-northeast, the piece of the PV is also moving along with it while they try to maintain equal longitude. 

3 - The southeast ridge is pumping over our area for a couple of reasons. The biggest reason is due to the     -PNA since energy is digging into the trough in the western U.S. this time, instead of the eastern U.S. (+PNA). Since there is no Atlantic blocking (-NAO), heights are not able to remain suppressed enough to promote a coastal storm (unless there is a Miller-B scenario, maybe?) 

4 - Extreme Pacific blocking with ridging being modeled over the eastern Pacific, into Alaska, then into the western Arctic through northern Canada. If that does not define a Pacific blocking pattern, I'm not sure what does. 

5 - The Polar Vortex continues to remain in a weak state and lacks consolidation. This is also another reason why heights from the southeast ridge are able to amplify as much as they are. 

STORM #1 Vorticity H5 Map 12z EURO:

If we fast forward to the morning of storm #1 (Wednesday), we can understand why this storm is more likely to cut to our west (from a NYC Metro perspective). Like I explained in the image before, the southeast ridge continues to amplify as the storm continues to deepen in the south-central U.S. (circled and labeled as the number 1). Positive heights extend into the northeast U.S. and the originating storm almost has no choice but to cut to our west. 

The black circled area labeled with the number 1 shows the area of least resistance, the track in which this storm is most likely to take. The end result is a minor thump of snow for NYC before it changes over to all rain while the western side of the storm in the Ohio Valley sees a potent snowstorm. 

The 12z EURO Ensemble is in agreement with the OP that the primary will cut to our west (around the Ohio Valley / western PA region). 

GFS H5 for Storm #1:

The 12z GFS was for the most part in agreement with the EURO model of a primary low cutting to our west and bringing mainly rain to the NYC Metro area. The biggest thing I want to stress with the image above is the extremely weak state of the Polar Vortex. Notice the black circles in Canada. They represent a different piece of the PV rotating around each other. There is not a consolidated PV to help combat the higher heights along the east coast. In conjunction with the +NAO/-PNA, this is going to be a problem if you are looking for wintry weather. 

HOWEVER...

There exists a scenario in which an area of High Pressure develops to our north or over the Great Lakes region which would force the primary storm to transfer its energy off the coast or along the coast. Some guidance does show this, such as the Canadian and its ensemble. Such a scenario would still bring rain to the NYC area, but there could be a changeover to snow once the secondary takes over and cold air comes back in.  

ICE:

The latest 18z GFS shows the ice threat I am talking about for the area north of NYC. This would probably be the region I am most concerned about, as they could see a good thumping of snow to ice then eventually rain. 

To be clear, I'm not exactly forecasting an all rain event for the NYC Metro region for storm #1, but I am favoring that solution as of now given the parameters highlighted above. If the Miller-B type of solution becomes consistent on guidance, it will be because an area of confluence to our north has appeared and the storm is forced to make a transfer. 

STORM #2

Amazingly, we have more consistency on guidance for this day 10 potential system than we do for the day 6 system. Every single piece of viable guidance, including the ensembles, are showing a strong signal for a winter storm between the February 8th-10th time period. I think there are a couple of important things to understand for this possible storm:

1. The southeast ridge will not be AS amplified as it will be for storm #1, which means the lower heights are conducive for a storm system to track further toward the coast instead of cutting to our west (favorable baroclinic zone). One of the reasons for this could be a more consolidated Polar Vortex, instead of a bunch of rotating pieces like we saw in the GFS H5 map for storm #1. 

2. Storm #1 could set up as a 50/50 block or at least promote positive heights around the NAO region that could help storm #2 slow down and phase. 

The 12z EURO Ensembles show a clear and big signal for a coastal storm in this time period and with the Gulf of Mexico opening up for business, this could be one heck of a moisture laden filled storm. There is no sense of even mentioning possible snow amounts, because storm #1 could somehow mess this entire configuration up, but it has big potential. 

We will see what happens and how that time period turns out! The potential is there for a large winter storm but the only thing we can do at this time is monitor the trends and not make sudden conclusions from every single model run between now and then. 

Thanks for reading,

Francesco Paparatto 

*Follow my forum at www.njstrongweatherforum.com*