In Depth: Beyond the 10 Day
ROCHESTER, N.Y. (WHEC) — Currently across the United States, we have a large upper level ridge over the Western US pushing the jet stream into Western Canada, and we have a trough over the Eastern US keeping us on the colder side of things. A piece of the Polar Vortex is sitting over Hudson Bay in Canada, and this has helped bring in the colder air we have been dealing with for some time now. This look will continue through the rest of the month, but as we flip the calendar into February things are going to change.
Through this week, our current setup will continue and this will keep the cold air in place locally. We will also see another round of Arctic air swing in towards the middle of the week. Other than another round of bitter cold, there is nothing much that sticks out for anything significant. We will see a bit of light lake effect set up through the middle of the week with the cold air in place and the winds out of the north, but no heavy snow looks likely across our region. We are still watching the East Coast for next weekend, but even that does not look like it will amount to anything for us locally. There is a good chance it will trend a bit west on numerical modeling as we go through this week, but we would have to see significant changes for us to see impacts. Areas along the I-95 and into New England may see some snow out of this, but for Western NY and the Finger Lakes it is not likely. Even with a swing and a miss for significant snow, light lake effect may try to setup as low pressure sits over the Atlantic. Through this weekend we will remain on the cooler side of things, but our pattern will be changing favoring seasonable and milder weather locally into early February.
As we go into this weekend, the ridge that has been persistent over the Western US this month will begin to break down and set up just to the south of Alaska. We will also see the piece of the Polar Vortex, which has sat over the Hudson Bay, lose its grip and slip eastward creating room for troughing to setup over Western Canada and the Western US. Then as we go into next week, a weak upper level ridge will build just off shore the the East Coast and help push in the milder air across the East. Models have not signaled a strong upper level ridge which means our snow chances will not disappear, but the ridge will push the jet stream north and favor Great Lakes Cutters once again but not guarantee them.
Our next "large" storm chance will come next Wednesday/Thursday (Feb 2/Feb3). Obviously being over a week away the track will shift, but we will be watching our for an area of low pressure to setup over the Central US. As mentioned above, the jet stream will begin to shift a bit further north next week favoring Great Lakes Cutters but not guaranteeing them. This is due to the lack of strength with the upper level ridge, and although the milder air will be pushed in locally our snow chances are not eliminated. I say this because even with the northern push the jet stream will still likely be to our south, just not as far south as it is currently. This is also why I am not a big fan of a large warmup locally, more or less seasonable temperatures expected next week. Back to the storm though, track will be important because if this storm were to slide south of Rochester than we would have a chance for snow. However by the overall upper level dynamics of it, it does look like it will swing over us or to the north. Another thing to watch with this storm will be the potential for mixing. We are now in the heart of Winter with cold air readily available which means the battle between warm and cold will occur, and with the lack of a strong warm air surge there is no reason to not think that our next event may be a mixing event. This is NOT a forecast for a large icing event, but just be aware for mixing to become more of an issue than it has this season.
Following this system, another one will likely be on its heels (Feb5/Feb6) as the jet stream will remains active over the Eastern US. This overall look has given me flashbacks to the overall look that we were tracking in December and we all now how those ended up. With that said I’d expect a system to cut north again, but as mentioned above the chance for icing will exist depending on track.
For the rest of the month, there are some other factors that will play a role in February’s pattern. The one oscillation we have been talking a lot about lately has been the MJO, and the MJO has moved into its "non-existent" phase (at least that’s what I call it, it still exists but has less of a global impact). This means that other oscillations will take the reigns across the Northern Hemisphere and begin to control the overall weather pattern. Most of the oscillations are forecasted to have little impact except for one, the PNA (Pacific-North Oscillation). This oscillation was in the negative phase through December and was a large reason why we saw milder air with limited snow during the month, but in January it had little impact. In February, this oscillation will drop back negative but not as strong as it was in December, at least not yet. The lack of strength will be good for us locally moving forward as it won’t create the large dip out west and ridge out east that we saw in December, but it will be the overall pattern control until the MJO takes over again. The bad news though is that models are showing the MJO to move into phase 4 when it may take over again, and that is a warm phase in the Winter over the Eastern US. Things can change, but the other factor leading to a milder February will be the Polar vortex.
This month the Polar Vortex has been stretched and created the surges of arctic air that we have seen, and what we will see through the rest of the month. After being stretched in January, it will likely revert back to a consolidated circulation and hang out over Western Canada. This will keep the arctic cold locked up in that area, but also limit our chances for cold air to move in ahead of storms. The good news is that this is only a look into the second week of February, and that it won’t be coupled wit a strong +AO (Arctic Oscillation). If it was, then at this point in the season we would have been able to say goodbye to Winter. Good thing we don’t have to yet as there is still plenty of time to see more snow (especially in March), but for now our big Winter storm chances are taking a break. Our next update will come this Wednesday, January 26th.
Temperatures: Below average this week before returning near average (around 33-34) next week.
Precipitation: Below average this week before turning above average next week
February 2nd-February 3rd: In the middle of our pattern flip, track will be important to determine precipitation type, but a Great Lakes Cutter seems likely at this time.
February 5th-February 6th: With the pattern flipped and the jet stream further north, signals are showing a storm cutting once again through the Great Lakes.