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Model Mezzanine - 3rd times a charm


Baroclinic Zone

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Have you guys missed the developing blocking up north?

You gotta get the IMBY syndrome out of your head if you want to analyze the pattern. That system on 2/29-3/1 ends up too far NW. That's the way it goes with a +NAO. That was said only like 1452 times hen talking about the pattern.

You cannot predict the nuances in the shortwaves at lead times of 10 days. If the shortwave for 2/29 was weaker or the PV lobe up north didn't rotate west and phase with it, then you'd be looking at a snow event.

If you take "chances for snow events" as equivalent for "guaranteed snow events", then that is on you. We had a chance this week and missed and next Tuesday is probably also a miss. The blocking increases even more beyond that so we'll keep taking our hacks.

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Have you guys missed the developing blocking up north?

You gotta get the IMBY syndrome out of your head if you want to analyze the pattern. That system on 2/29-3/1 ends up too far NW. That's the way it goes with a +NAO. That was said only like 1452 times hen talking about the pattern.

You cannot predict the nuances in the shortwaves at lead times of 10 days. If the shortwave for 2/29 was weaker or the PV lobe up north didn't rotate west and phase with it, then you'd be looking at a snow event.

If you take "chances for snow events" as equivalent for "guaranteed snow events", then that is on you. We had a chance this week and missed and next Tuesday is probably also a miss. The blocking increases even more beyond that so we'll keep taking our hacks.

You talking about -AO or -NAO?   NAO looks neutral to slightly below at best.  AO is more robust as per lastest modeling with a dip to -2STD

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 Exactly, not knocking anyone here, this has been a difficult winter to forecast, but several mets were saying the same exact thing last week about this week into the first of March; it seem like every "favorable" period gets knocked back a week or so by a favorable set up that winds up a cutter. March could turn out to be the perfect storm per se, but it seems like the pattern is pretty much locked where it has been since mid January.

lol. Awesome screen name.

 

...That is all.

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You talking about -AO or -NAO?   NAO looks neutral to slightly below at best.  AO is more robust as per lastest modeling with a dip to -2STD

 

 

NAO is not going to go negative...at least in the sense where it helps us a lot. It might go negative on the spreadsheets.

 

I'm referring to blocking north of AK and into the arctic ocean. That increases with time on the ensembles.

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There's nothing wrong with saying this could be a special stretch for Chicago. They are getting a snowstorm tomorrow, models are teasing them early next week although it may end up too far north for them, and then same thing later on next week. This is what is shown on models and particularly the latest run of the GFS. This is the model thread not the pattern thread, correct?

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There's nothing wrong with saying this could be a special stretch for Chicago. They are getting a snowstorm tomorrow, models are teasing them early next week although it may end up too far north for them, and then same thing later on next week. This is what is shown on models and particularly the latest run of the GFS. This is the model thread not the pattern thread, correct?

Euro again with another run with blocking further north. We cut we bleed and congrats Green Bay this run. Fwiw

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Models arent looking good at all for snow. They all show cutters.

Maybe that's a good thing?  

 

When they show something good, it seems a few days later they morph into something not so good.  Maybe now that they show something like cutters, it will morph into something a lil better?   The bright side is, it Can't get any worse with regards to winter weather.  

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The mets said not to pay attention to the op run details so maybe things will trend in our direction

 

Everyone should understand that it's a pattern that will likely give chances....but there's flaws to it as well...no -NAO is one (as we've said for weeks). Secondly, we don't know if these shortwave undercutting the EPO ridge are going to be strong or weak...stronger oens are probably not good unless they are timed well with confluence in SE Canada.

 

 

We saw this week's chance trend poorly...and next week is another that could easily trend poorly...the PV rotates around and instead of diving SE and we end up with another cutter. After that? Who knows, but we'll still have cold delivery into most of Canada, so stay tuned....

 

For those who don't like uncertainty, then probably best to ignore guidance until a more coherent pattern signal shows up (such as spring warmth across a good chunk of the CONUS). But until that time comes...we'll probably be dealing with models shifting storm tracks 300 miles at a time.

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While optimally, it would be nice for atmospheric patterns to align in accordance with the progression of the astronomical calendar, weather does not work that way. Although people are becoming concerned that the clock is ticking - and rightfully so (climatology will make snowfall increasingly more difficult at the coast as one heads deeper into March) - the pattern itself will offer opportunities.

 

The medium range geopotential height rises over the W NAO domain are an extension from the EPO based/NW Canada block and a northwestward protrusion of the mid Atlantic ridge. In other words, the NAO domain height rises that one sees next week represent a "pseudo" -NAO, as the heights aren't effectuating any blocking. This makes sense through next week considering the current-->medium term orientation of the vortex and Pacific forcing. The Feb 29th-Mar 1 short wave likely won't be a snow maker for I-95, and the Mar 3rd short wave should not be a significant snow maker either for the BOS-DCA corridor. There's no mechanism (yet) in place to preclude an inland tracking low.

 

There are a couple factors which will be different than they've been the past couple months once we move beyond March 4th-5th, however. The first of which is the propagation of MJO induced upward motion eastward into octant 8, which correlates to the development of a negative bias to the NAO approximately one week following, as per the literature. That would implicate an improved NAO domain beginning March 6th or so and beyond.

 

Additionally, the positioning of the stratospheric vortices is such that tropospheric height rises sufficient to form a block will be very difficult to achieve prior to March 5th-6th. The models are in general consensus that the wave-1 attack in early March will finally push the vortex well to the south of the pole, potentially ending in a final warming or vortex destruction in the second week of March. As the vortex is shunted off the pole beyond March 6th, you see the ECMWF and GEFS ensembles becoming more interested in a real/legitimate -NAO initiation during this time frame.

 

Given the aforementioned reasoning, I would lean toward the first 5-6 days of March producing no significant snow for I-95. Beyond that time frame, there is sufficient reason to believe that a window of opportunity will open up for a coastal event (sometime in the March 6th-15th period probably). The reason why (IMO) we saw next week's event diminish is because the NAM/NAO blocking isn't as robust, and that is a direct reflection of the still present/potent strat circulation nearby.

 

Of course, there is an obvious disclaimer with all long range thoughts, but if the factors noted do come to fruition, the detection of the onset of a real -NAO signal beyond March 6th is grounded in science. Northern New England could pick up some snowfall over the next 7-10 days, but I'd generally say it's a no-go for I-95 / coast prior to March 6th or so.

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Everyone should understand that it's a pattern that will likely give chances....but there's flaws to it as well...no -NAO is one (as we've said for weeks). Secondly, we don't know if these shortwave undercutting the EPO ridge are going to be strong or weak...stronger oens are probably not good unless they are timed well with confluence in SE Canada.

 

 

We saw this week's chance trend poorly...and next week is another that could easily trend poorly...the PV rotates around and instead of diving SE and we end up with another cutter. After that? Who knows, but we'll still have cold delivery into most of Canada, so stay tuned....

 

For those who don't like uncertainty, then probably best to ignore guidance until a more coherent pattern signal shows up (such as spring warmth across a good chunk of the CONUS). But until that time comes...we'll probably be dealing with models shifting storm tracks 300 miles at a time.

 

Amazing the number of times this season we've seen big snows progged north of Montreal...this week looks no different, the Euro has a massive area of like 12-24" across like the entire southern half of Quebec and Ontario through Day 7.  

 

This winter will definitely go down as one in which a -NAO would've been pure gold. Or white gold.  Even without the -NAO, its a lot closer than it seems (at least up here) as most of these cutters have ended up being big snow dumps just like 100 miles north in Quebec.

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Amazing the number of times this season we've seen big snows progged north of Montreal...this week looks no different, the Euro has a massive area of like 12-24" across like the entire southern half of Quebec and Ontario through Day 7.  

 

This winter will definitely go down as one in which a -NAO would've been pure gold. Or white gold.  Even without the -NAO, its a lot closer than it seems (at least up here) as most of these cutters have ended up being big snow dumps just like 100 miles north in Quebec.

It's funny that we often discuss a "gradient" pattern.  Well, a gradient pattern has winners and losers, I guess we know which side of the gradient we ended up on.

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Hard to snow when it's warm too.

You need both! Tada

We've also had it be near or below zero at least 3 times and then rain with 36 hours, so "bring the cold first and then take your chances" doesn't seem to have worked much better lol.

I'll still take the QPF anytime. That's paying off big-time about 100 miles north of here this winter.

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We've also had it be near or below zero at least 3 times and then rain with 36 hours, so "bring the cold first and then take your chances" doesn't seem to have worked much better lol.

I'll still take the QPF anytime. That's paying off big-time about 100 miles north of here this winter.

I didn't say that. I said you need both. To clarify - at the same time
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