The end of February sure won’t feel like February overall for the East as a ridge of high pressure dominates the weather pattern. We’re going to discuss what weather you can expect for the rest of this month as well as the start of March. Now the models are still having some trouble predicting what will happen as we get into March, but we’ll discuss the different possible outcomes for you. We’ll also discuss how the precipitation will play out across the country later in this article.
For the remainder of the month of February, a ridge of high pressure will be positioned over the Eastern US while a trough sits over the West. With a ridge, that brings sinking air and warmer temperatures, whereas a trough brings rising air and cooler temperatures. This is a classic La Niña pattern. The EPS model below, which is the ensemble mean of the European model, highlights where that ridge and trough will be located. The ridge is highlighted in the red and orange colors and the trough is in the blue and green colors. The very bright colors of the ridge over the East indicates that it is very strong and will bring highly anomalous temperatures.
Temperatures will be way above average under this ridge, likely being as much as 30-40 degrees above normal at times. That translates to actual high temperatures into the 70s and 80s in the South and 50s, 60s, and maybe even 70s for much of the Northeast. Now while that seems nice, there is reason to believe this warmth won’t last forever.
Based on all of the model guidance we are looking at, they all keep this strong ridge in place with the pattern staying locked through the very end of February. This is when the picture starts to become a bit uncertain. There is a Sudden Stratospheric Warming (SSW) event that has occurred in the stratosphere of the Northern Hemisphere, which has split the Polar Vortex into two, as shown below. The combination of the trough over the West and this split of the Polar Vortex is responsible for the cooler weather across this region.
At the same time, the models are consistently trending upward with the transition of the North Atlantic Oscillation, or NAO. This is uncharted territory because a SSW event during a La Niña and a falling NAO is very uncommon and almost unforeseen. Currently, the NAO is in a positive phase. This is partly responsible for the trough over the West and the ridge over the East.
As we get into next week, the NAO is forecast to transition into a negative phase. It’s uncertain how much of a role this will have in our weather pattern based on the other factors identified. Based on the past, there are indications that the NAO will affect our weather despite these other factors, but its affect will likely not be maximized. In a typical negative NAO, there is a monster ridge of high pressure that develops over Greenland. This is called a Greenland High, and the modeling has been hinting at this development for days now. This Greenland High brings in warm air into the Arctic while it forces that cold air into Europe and most of the United States. It all depends on where exactly that high will be centered over Greenland or northeastern Canada. That will determine where the cold air will stream southward into the US.
One last factor that is being factored into our forecast is the MJO. MJO stands for Madden-Julian Oscillation. It’s complicated to understand but it’s basically an area of enhanced convection that moves around Earth near the Equator and has effects on the weather globally. The MJO is currently in phase 7 and has been in that phase for weeks. By the end of the month, however, it is forecast to go through phases 8 then 1 but at a much lower amplitude. Typically during these phases, it brings cooler weather to the Eastern US, but based on other model data, that doesn’t look to happen in February. Therefore, even though the MJO is a factor in long-range forecasting, the MJO conflicts with the other guidance and does not look to have a big role in the upcoming pattern.
As of now, we’re thinking the rest of February overall will be mild for the East until we get into March when the risk for cooler weather and below average temperatures returns. We don’t think this cold will be significant, but it will be a sharp contrast to this current warm stretch of weather. There is the potential the East and West Coasts are cold while the Central US is on the warmer side or the East remains warm and the West stays cold. At this time, we really don’t know what will happen in March but the cold risk exists.
The pattern has been conducive for active weather and it will remove favorable for the active weather to continue likely into March for portions of the country as rounds of disturbances move in from northwestern Canada. Much of the country is dealing with a drought, especially in the Southern Plains where an extreme drought is present for some areas. To the east, a drought is also plaguing much of the region but inches of rain have fallen and some flooding as occurred in the Mid-Altanitc, Ohio Valley, and Southeast. The long-range outlook definitely paints a hopeful picture. All of the model guidance that we have observed all show a very similar outlook, highlighting the very active weather with precipitation far above average from eastern Texas through the Ohio Valley. If days of heavy rain occur in this region, which is certainly possible, then there is the concern for flooding. Droughts typically end in floods! Meanwhile on the East and West Coasts, it will be on the quiet side.
That quiet weather and the warmth is not looking great if your hoping for a significant winter storm in the Northeast, but we still have over a month to go of the winter season, so the chance for snow certainly isn’t over across the Northern Tier of the nation.
To wrap our long-range thoughts up, here’s our official graphical outlook for the rest of February: