Random Scribbles as Winter 2019-20 Continues to Flail Away

The winter of continued failure continues as any promising signals constantly get muted as we try to pull them inside of day 10.

In terms of snow from here on out, I think the Plains, Midwest, Great Lakes and perhaps northern NY into central/northern New England do just fine.  I think the Ohio Valley and most of the Mid Atlantic struggle, with places like southern New England more on the bubble but probably not great from here on out.  There are a couple of colder windows between now and mid-March, but also a couple of very warm windows in the eastern U.S…

February opens very mild. I am not opposed to 7-10 days where the cold actually presses far enough south to drop Upstate NY and New England to somewhat colder than average, and the northern Mid-Atlantic and Ohio Valley to near average somewhere around the second week of February, but am worried about a prolonged and significant warm-up after the middle of the month along the East Coast, with what may be winter’s last attempt at much of anything then possibly arriving late-February or early March. I agree with many on February likely coming in warmer than normal overall across the Ohio Valley and Mid-Atlantic, closer to normal in New England (but leaning warm in southern New England), and perhaps on the cold side over the central U.S. into the Upper Midwest and Great Lakes.

The second week of February interests me a bit as there will be a prolonged +East Asian Mountain Torque through the first week or so of the month, extending the Pacific jet through about mid-month. This will coincide with when the stratospheric PV is temporarily disrupted, which may increase the odds of a +EAMT actually dropping the EPO substantially. The EPS has trended towards a more -EPO over the last couple of days. The issues is tropical forcing; does it cooperate, or does it support a continued -PNA? Where the Kelvin Wave interacts with the low frequency forcing and amplifies in the Pacific may be key. Amplifying near the Dateline as the CFS has may support a brief rise in the PNA near or just before mid-February; amplifying much farther west as the EPS has would likely maintain and even intensify the -PNA. At the moment I’d lean towards the EPS, but not with 100% certainty. The prospect of a fairly significant -EPO does increase the risk of cold into the U.S. with a legitimate tap of Arctic air, though it will likely dive into the western and eventually central U.S. If the PV gets displaced towards Hudson Bay it may depress heights enough over New England to allow cold to seep south, but we’d need a rise in the PNA to really dislodge bigger cold into the Mid-Atlantic, which seems less than likely.

I am worried that a lot of warm signals occur at the same time just after mid-February after some confluence of colder signals (but not unanimous with tropical forcing question-marks) around the second week of the month. How quickly warmth returns may be influenced by the PV’s location, if the PNA does rise and push the PV to eastern Canada, it may be sneakily slow to warm across the northern tier (though the southern Mid-Atlantic and Southeast are different). It’s currently well-agreed-upon that the stratospheric PV quickly rebounds after the first week of February and is again quite strong around mid-month. This while the EAMT is projected to go negative by the EPS and CFS, while any Pacific tropical forcing from the Kelvin Wave likely dies down. This all suggests a retracted Pacific jet and very negative PNA developing after mid-February along with a +AO and +NAO. Yuck.

How the MJO plays out may modulate the duration and intensity of this warm-up. As Mike Ventrice pointed out on Twitter, there is signal for a strong MJO starting in mid-February. While the mean VP anomaly plots quickly wash out to the lower-frequency forcing in the Indian Ocean and central Pacific on the EPS weeklies from Monday, many individual members have a very strong MJO developing over the Indian Ocean somewhere between February 10th and the end of the month and propagating east. This is initially a very warm signal if it passes through the Maritimes at a high amplitude, which many members show. If this occurs around or just past the middle of February when other signals argue for warmth, it could get very ugly. Could we get 80 degrees into PA or NJ in February for the second time in three years? Maybe that’s too aggressive, but man a lot is pointing to that warm-up.

As much as I hate to seem like I’m wishcasting, a strong MJO would eventually significantly weaken the strat PV in later February or early March and as it worked east into the Pacific would eventually teleconnect to cold. That exact evolution is uncertain but would bring what would likely be the last chance of legitimate wintry weather either at the end of February or beginning of March, perhaps lasting up to a few weeks if stuff breaks right. Maybe the end of the season as we start shifting towards spring brings the best chance of a shake-up to actually happen.

At the end of the day this winter has been a train wreck both as a snow weenie and as someone attempting to forecast weeks out in advance, and I wish I had caught certain trends earlier. A borderline record strong +IOD followed by a stratospheric PV that’s been flirting with daily records at time this month are delivering strong and tough to stop results. As a snow weenie I hope it snows more, and I’m not ready for winter to be over…but a large part of me wants to launch this winter into the sun. Certainly some lessens to be learned.

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