Terpeast

Heavy rain for an hour at 41. Stopped for now. Ashburn.

Before the SSWE, I thought vortex was pretty strong this winter. Siberia had record cold much of Jan and Feb

Would have to be modeled to see, but my hypothesis would be a faster jet stream with stronger storms.

And, this is just a bit of speculation (mods, feel free to move this if warranted)… have you observed less separation between NS and SS? With the hadley cell expansion (if that’s indeed happening), are these two streams increasingly being squeezed together to produce just one dominant stream instead of two separate ones? Or am I going too far out on a limb?

If I remember correctly, the Jan 96 storm was a NSer that dove from canada far enough south to become a miller A monster. And that was technically during a weak-mod nina. It was a very cold storm, too.

I think you meant nina, not nino. But I get the idea. My point is that I’m not yet fully convinced that the SER is a cause rather than an effect of some other forcing (likely pac driven - in fluid dynamics, most of the time, you have to look upstream for a cause). But if the SER persists with a totally different pac, qbo, iod, enso phase, then I would have to really consider it as a cause - a new forcing - not as an effect of a known forcing.

We still have a strong and broad aleutian ridge, and I think even though the nina is dead, it will take a while to flush the entire NH pattern out, including the SER. Now if we get a SER popping back up in the middle of a moderate-strong nino in October, then I will definitely be much more alarmed.

Since 1972-73 keeps getting mentioned, I checked temperature records at IAD expecting a DJF torch. But no, DJF temps were close to normal. It only warmed to above freezing whenever precip rolled in. And there was that deep south storm that dropped more than a foot down in Georgia. Must have been incredible bad luck in what should have been a decent winter with a nino.

If you told me this last November, I would have been confident of one hit. Still wouldn’t have gone above climo snowfall because those blocks weren’t going to happen in Jan or Feb

Worth noting that it predicts W atlantic ssts will cool to near to slightly above normal

Safe to say he's not gonna take the bait.

Realistically we may only get up to 16-19” average in the next up period.

Because the high usually falls on the east side of a ridge (and/or west side of a trough), we need the pna ridge to sustain itself like a standing wave to keep the high from moving out too quickly. But the pna ridge kept getting shoved over by that wavetrain crashing into the west, allowing the cold dome to spill off the coast clearing the way for incoming storms to cut. We can trace the culprit to the Aleutian ridge supported by the -pdo in the last 7 years, five of which were ninas and only one a nino that couldn’t overcome the pac state. I think it’s all pretty clear to me “what” the culprit was. Now the “why” behind that culprit - that’s where the debate is.

It’s technically dead now, but I think we need to go through the summer to fully flush this atmospheric pattern out and allow a new one to set in.

What is considered to be the line between a strong vs super? +2.5?

Yeah, the sst gradients was what I was thinking. But I haven’t thought about trade winds and sst differences between east pac and the MC. I’m sure it is a lot more complicated than temp differences between the mid-lats and tropical pac.

Yeah, it’s quite possible that ninas will become more commonplace in this warmer climate. And I’ve alluded to that possibility, too. My biggest fear is that if mid-lat SSTs warm faster than tropical SSTs, will we find ourselves in a permanent la nina state?

Shared my post-mortem post about this winter, and where we go from here - if anyone's interested in reading.

The stats Here are the temp anomaly stats at IAD in F: Dec: -0.8 Jan: +8.4 (!!) Feb: +8.2 Mar: +2.3 (through 17th) Well, what can I say? After correctly predicting a warm Nov and cool Dec, my outlook completely fell apart as soon as the post-Dec cutter arctic cold left the building. Although it didn't feel like an all-out torch, we had constant 50s through the whole winter, including prime climo for snowfall. We hardly got below freezing most nights. What the hell happened? Here are the NCEI anomaly maps for DJF. It's one thing to have a winter with slightly above normal temps (+1 to +3), but THIS is a whole another level. No wonder we got no real measurable snow. Remember, our climo 850mb temps are around -4 to -5 C in Jan-Feb, and even if we were +2 or +3, we would still have gotten snow albeit less than climo. Or a big storm with 0 to -1 850s hugging the fall line putting us above climo. But this was what we were up against (credit to CAPE): Highly anomalous aleutian high that rarely pushed east or poleward, helped dump cold air from Siberia (which had record cold) into the West. What caused this anomalous aleutian high? - Expanded hadley cell (credit to Chuck and PSU) - A moderate but very well coupled La Nina (with a modoki-ish look = terrible for us) - Extremely and deeply negative PDO (record values leading into the winter) So it was no surprise that we had a persistent SER/WAR throughout the whole winter. Even when we had a PNA ridge "trying" to develop over the west, a constant stream of troughs thanks to that aleutian ridge kept pushing the PNA ridge over east, suppressing any preceding wave, then pushing the boundary north of us, and allowing any succeeding storm to cut. I'm sure the warm Atlantic waters did not help us either, but I think that has more of a downstream effect - worth noting that Europe had a record warm winter as well. Could be an effect of the warm ATL SSTs. Even a SSWE could not save us. It did for NE, but the W trough / Aleutian ridge successfully ran the clock out on us. Okay, so where do we go from here? I think the lesson learned here is to not rely too strongly on analogs from the past, earlier than 1990 or so. More weight should be on analogs in the past 10-15 years, even though the sample size is so tiny. My best analog was 1985-86. But that winter was much MUCH colder than this one. It turned out to be a disastrous mismatch, and a failure on my outlook. A better match would have been 2011-12, which was on my analog list. But my personal bias prevented me from putting more weight on it as I should have. As it stands now, this winter is in its own league with EXTREME warm anomalies with no comparison to any winter of the past. It is now a new analog to base future winter outlooks next time we have a La Nina coupled with +QBO. So... is it ever going to snow again? Yes. 100%. But will we snap back to climo again? I agree with PSU that no, we won't. I believe our new normal is 60-70% of previous climo. Meaning ~14" for IAD, or ~10" for DCA should be the benchmark of what to expect in winters going forward given the warmer climate. However, that doesn't mean we won't get a 2' blizzard ever again. Remember our climo 850s, even if we adjust for the warmer climate, are still below 0 for a solid 2 months. If we get an El Nino, -QBO, a sustained +PNA ridge, and an active STJ, we just need a good wave to traverse the south without overamplifying too soon. Then we get hit even with the 0 line straddling the I-95 corridor. And all we need is one good hit to reach climo or above. I don't think we've reached the tipping point where 850mb temps cannot be 0 or below for our area when we get a wave to approach us. The 3-4 bomb cyclones that struck the immediate MA coast in the last several years is proof of that, in my mind. Maybe someday we reach that tipping point and the only place it snows is in the mountains above 2k ft. But I don't think we've reached that point yet. That said, the smaller events we used to get from clippers or from front-end dumps with primary lows to the NW, are fast dwindling and I don't think we get those back. The next El Nino will be the real test of this, though. Could it bring back big winters like 02-03, 09-10, 13-15, or will it just flood the NH with more and more warmth and set a new climate baseline?

The gulf and NW atlantic are so warm though. Wondering if we have any good comps for that plus -pdo/+enso

Yeah and that trough is still dumping into the west coast. Let’s just hit the reset button and get it done with.

See you in the severe wx tracking threads soon-ish.

Fool me once…

This winter was the worst I’ve ever seen in my life, it just refused to snow as if a cruel joke was being played on us. But I am pretty confident that we won’t get back to back shutouts. It can’t get any worse than this. And it almost certainly won’t be this bad next winter.

Idk, there are always exceptions and 2019 was a weak nino that failed to couple. I haven’t really dug into this and not sure I want to bother.