Long Road Ahead To Sustained Spring…
We note the modeling continues to want to keep the North Atlantic Oscillation (NAO) negative into late month. As mentioned in previous discussions, the NAO is “king” late winter and spring.
It should be no surprise that the GEFS 5-day temperature anomaly shows widespread below normal air centered on March 22nd.
This doesn’t mean brief surges of warmth, originating in the southern Plains, can’t shoot into the Ohio Valley for a couple of days. Perhaps we’ll “luck out” and enjoy a briefly milder time for St. Patrick’s Day. This does, however, mean that overall we have a long, long way to go before “stick and hold” spring can arrive, locally, and the balance of the upcoming 2-3 weeks looks colder than average.
Side note: The upcoming couple weeks looks drier than average for our region, while the TN Valley into the Carolinas remains abnormally wet. Our friends in the southern Plains continue to deal with dry times and the drought will only worsen in coming weeks there…
Embedded thunderstorms may target southern Indiana late tonight and Friday morning before more widespread thunderstorms (a couple could become strong) Saturday. The Storm Prediction Center (SPC) has included the southern half of the state in a “marginal risk” of severe thunderstorms Saturday.
All total, additional rainfall between now and Sunday morning should reach 2″ to 3″ across a widespread portion of the southern half of Indiana with locally heavier amounts.
We’ll finally dry things out as we close the weekend and head into early next week as high pressure settles overhead.
Next week will begin a pattern transition from the unseasonably warm weather we’ve enjoyed as of late to a colder regime for the first half of March. We note models continue to tank the NAO and AO.
Accordingly, the models are seeing the trough and associated colder than average pattern returning to the eastern half of the country as we rumble through the first half of March. With such a strong block in place, this can turn into an active pattern for a couple weeks to go along with the cold. Both the GEFS and EPS agree on the overall look.
While there’s no way to get specific on the individual storm threats that will eventually come with this pattern, the potential is present for a few storms to “bowl” underneath the block through the first 10-15 days of the month. Each storm will have the capability of delivering wintry precipitation, but this can also be a tricky time of year where most, if not all, ingredients need to come together to create significant wintry events. In a winter that’s been frustrating to central Indiana snow lovers (frigid, but dry first half and milder, wetter second half), perhaps it would be fitting to get a couple good snow dumps in March (when most are wanting and ready for spring)…
The GEFS might be a bit quick on dropping the arctic hammer, but the consistency of the model is impressive. Meanwhile, the European (even it’s ensemble data) has been much less consistent and has really been struggling the past couple of winters, overall, as a whole.
Let’s also keep in mind that the initial cold onslaught is coming in the face of the MJO still rumbling through the warm phases. We note the European is consistently having to correct towards a more “amped up” MJO- swinging into the cold phases as we approach mid-month. And it’s mid-February that continues to have us concerned for the potential of truly nasty, severe cold.
As for snow, it’ll come in this pattern. Again, don’t get caught up in the operational output, but understand that the pattern over the upcoming 7-10 days favors numerous fast-moving snow systems. While most of these will be light, we’ll have to keep a close eye on things as the potential exists for one of these waves to spin up a moderate event.
Despite the milder air over the past week, January, as a whole, is still running 4° below average at Indianapolis- a byproduct of just how frigid the first half of the month was.
While the January thaw has been nice, times are changing and winter sure seems to be reloading for a very active second half.
Once we get a snowpack laid down, arctic highs oozing southeast will likely lead to bitterly cold air. Recall our expectation for this pattern to yield at least (1) night of double-digit below zero lows, but it’s more towards mid-month that we think the severe cold takes hold.
The Madden-Julian Oscillation (MJO) is forecast to rotate into the colder phase 8 as we rumble from early to mid February. Given the amplitude of the MJO, it should continue to rumble right through the cold phases of 1,2, and 3.
All of these moving pieces that lead up to extended periods of cold, wintry conditions are part of a bigger outcome low solar, easterly QBO winters deal up. What we should experience with this setup is a 6-7 week period of wintry conditions, including times of severe cold. It appears to be a snowier version of what we went through late-December through mid-January. Hang in there, spring will come…eventually.