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Part II, Thanksgiving week transient cold shot and the pattern beyond

Typhoon Tip

By Typhoon Tip,
in New England

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Clinch Leatherwood

Clinch Leatherwood

Posted
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Step by step.

This mid-Pac monster has been hinted at/on the models for a few days. If it comes to fruition after that cold pulse we're going to have problems again with warmer weather as it heads for the west coast. This one isn't going to run west of the Aleutians it's headng towards the coast somewhere. We need to make it happen with that cold shot because there's going to be another lull after that. I hope THIS is the storm that breaks down the pattern as it rolls across the Pacific.

gfs_npac_384_1000_500_thick.gif

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Typhoon Tip

Typhoon Tip

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Happy Thanks Giving - hope all is well in your world...

Weather: Pretty clear imo what is happening. The original changes in the WPO/NPO region are parlaying as expected into an eventual rise in the PNA - heavily supported in the ensemble mean, and now the operational runs have bitten. However, what is missing is an antecedent -AO. Unlike during the last 10 days of October, this time the +PNA rise is taking place with less preceding cold loading into the 55-60th parallels. If that timed otherwise, the real cold would come.

If that is what you are after ...all's not lost. The AO and NAO as of last night have a lot of members, more than half at this point, showing indicating a 1.5 at minimum downward correction - that is enough to wonder for at least some blocking regimes to increase in plausibility - question is, is this a one night thing and we lose the signal? That's equally possible. I was looking at the U-Vector anomalies this morning and there is no negative taking place in the polar domain, so it is unclear. However, as last early winter, the AO dove without a lot of stratospheric warming or negative U anomalies.

Meanwhile, the PNA stays elevated ...not hugely so, no. But being above 0.0 SD, and if the above panned out, it would eventually lead to some for of an outbreak. If AO/NAO don't behave..less, but in the least storminess should be on the increase.

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Clinch Leatherwood

Clinch Leatherwood

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Your never ending torch is being extinguished Dec 1, Bos hits 1 inch before Dec 8

since 11/11 including today (as far back as intellicast data goes)

days at or above average highs 10

days below average 4 (which includes today)

We can add at least 3 maybe 4, 5 AOA in the next few days.

If there's 4-5 days of normal or below for every 10-15 above....I don't see what there is to celebrate. The average high is dropping about .3 to .4 degrees per day right now so of course in 10 days the "torch" isn't going to be less torchy compared to early November. Above normal next week is still in the 40s in Boston.

After 12/10ish it'll go back to less cold after a pretty substantial cold opportunity for 4-6 days. Doesn't mean the tundra is here. Again JMHO. The pattern wrecker hopefully is trucking across the Pac at that point and winter starts to settle in later in the month. I'm hoping the PAC cannonball is legit and not a model figmentation and we end up with something diverting up into AK.

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CoastalWx

CoastalWx

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since 11/11 including today (as far back as intellicast data goes)

days at or above average highs 10

days below average 4 (which includes today)

We can add at least 3 maybe 4, 5 AOA in the next few days.

If there's 4-5 days of normal or below for every 10-15 above....I don't see what there is to celebrate. The average high is dropping about .3 to .4 degrees per day right now so of course in 10 days the "torch" isn't going to be less torchy compared to early November. Above normal next week is still in the 40s in Boston.

After 12/10ish it'll go back to less cold after a pretty substantial cold opportunity for 4-6 days. Doesn't mean the tundra is here. Again JMHO.

I think the next several starting tomorrow will be pretty mild. It's still pretty tough to get real cold and snowy at the beginning of December, so if it's days near normal or a little below...I'll be happy. That said, I think we've been so used to the mild temps, that a change to normal is almost like a big pattern change...lol.

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Clinch Leatherwood

Clinch Leatherwood

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I think the next several starting tomorrow will be pretty mild. It's still pretty tough to get real cold and snowy at the beginning of December, so if it's days near normal or a little below...I'll be happy. That said, I think we've been so used to the mild temps, that a change to normal is almost like a big pattern change...lol.

Yep very true. If the departures are the same (they won't be) in early December it'll still be 10+ degrees colder than early last month.

To me December is make/break based on all the stuff you guys have talked about which culminates/is illustrated most easily by that huge system in the PAC in early December. If it comes trucking straight across we end up with another quick ridge in the west ahead of it and a transient cold shot here, if we get lucky on the timing maybe so snow. The first big "op outbreak" occurs around the magic 180 hour where the GFS takes the first big wave and shoots it west of the Aleutians and an enormous high pops out west setting up the big cold shot. Reality or myth time will tell in the next 2-3 days. It's quite possible the severity of the cold on the OP GFS relates to the normal BS that occurs on the GFS around that time.

After that it runs another one up into the Aleutians while cutting another one underneath. I know it's all tied to what's going on elsewhere - all the stuff you guys have talked about, but in simple terms we'll see how the models handle those features in general as the days tick away. Right now I'd say odds favor the systems dumping into BC and flooding the continental US with PAC air beyond 12/10 but we'll see. JMO

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CoastalWx

CoastalWx

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Other than a +NAO and potential se ridge, the pattern doesn't look terrible imo. It appears the vortex is slowly filling and/or lifting west. It's not a classic wintry pattern..but it appears it is one that may offer chances. Whether it is only the interior or all of SNE is another story.

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