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December Mid-Long Range Discussion


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FWIW- GFS ens and other guidance is pointing towards a potential active MJO. Forecasting for this index has been really bad this year though because it's been really weak. COD most of the time.

Depending on what model you look at, there is some sort of consensus for the MJO to become active in phase 3 and move "towards" phase 4. The move towards phase 4 on the GFS ens is late in the forecast so little confidence can be placed in that alone (and I sure don't fully understand how to look at the index and then sensible wx around the eq and make sense of it). HM is really good with this stuff. Maybe he can pop in sometime and expand on it.

We talk a lot about phase 8-1-2 because it's generally associated with a favorable cold look in the east. Not always but favorable for sure. Phase 3 isn't bad for temps either but we don't talk much about it. Phase 4 is not our friend. Another thing about phase 3 is the precip composite. Shows a wet se and up the apps/oh valley while we're close to normal near the coast. I assume this is because of a similar storm track as we're seeing now but I'm definitely not the person to ask any questions. I'm full of questions.

Here's the precip and temp composites for phase 3-4:

I'm just pointing out an observation. I honestly don't think the MJO is that much of a forcing mech unless the the signal is strong. And it hasn't been strong at all this late fall / winter. Again, maybe HM can pop in and shed light on what looks like a potential run @ 3-4.

Looks like the AO is making a run for neutral or positive territory and so is the NAO. Not like raging positive or anything but it's starting to appear all but likely that we are losing our prolonged solid -ao/nao. But did that period really matter? We got totally trumped by the pac and it sucked. Now the same weenie smashing pac is going to "potentially" trump a neutral to positive ao/nao combo.

This is the d10 euro from 12z. Please excuse my horrifying ms paint skills:

Low heights over the pole and greenland typically = warm here. But the +pna connecting the low heights around AK and the blocking hp in central canada allowing the cold to get into the US and give us some seasonably cool air. At least it looks that way. There sure is a lot of energy diving out of Canada and slipping under the ridge out west too. Not a terrible thing.

Storm track and timing has been sucking. And it usually does for us unless get get that classic +pna/-nao setup. I guess it could happen but no sense praying for that.

Like Wes and Mitch have already been talking about, the GFS has other ideas @ 500 in the lr. It's liking the GL low idea. We can get messy or small events in this setup but anything amplified is going west of us unless there is a perfect 50-50 (we're finding out how "easy" those are to come be right now).

I took yesterday off with models (and I probably needed too regardless of the date. lol). I flipped through a lot this morning and the only hunch I'm having is a "take what you can get" pattern and set expectations accordingly. I'm just not seeing a setup for a 8+" all snow event. Lots can and will change going forward of course but I'm not seeing anything glaring "big snow".

Something can time itself though because the flow is fast and the pattern is very active. But I'm not investing days and days of models when the key ingredient is a transient blocking 50-50 in Canada. Keep on how models handle today's storm as it gets north of maine. That will be a pretty important part of how the next event evolves. I'd be thrilled with a 2-4" all snow event.

I hope I'm wrong and Wes tears this post apart.

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Bob,

Mike Ventice from SUNY wrote a nice piece on the MJO on this thread.

It looks like the next two weeks may be colder than normal but the PNA is what is what will be saving us as the negative OA looks to be on the wane for at least awhile. I suspect it comes back but the next time the MJO and GWO work in tandem but that's just a wag. I do think the MJO working towards Phase 4 is troubling now that it appears that the AO is may go into positive territory. Such an phase would try to bring the EPO back into the positive range and also would try kill our positive PNA and possibly replace it with a negative one. When that happen we could have a two week period comparable to the pattern of early December. Of course what do I know, you got more winter weather out of this event than I thought and I actually know something about short range forecasting. As long as the PNA stays positive, we have some hope for perfect timing and can get snowstorms. If we lose it and the AO, man it get tough.

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Appreciate the link Wes. Just read it and visited the SUNY site. Heh, I'm not ready to kill my brain again. lol. I only know enough to be dangerous with the MJO. Heck, I know enough to be dangerous about everything. lol

I will just continue to pay attention to the index itself and then read the pro's for better understanding. TBH- I think the mid-lr is very uncertain right now. There's just such a mixed bag of things going on right now. I'm still chuckling that we got our revered period of a strong -ao and torched but now it's relaxing and we're cooler with snow threats. There are some ensemble members taking the AO into +4-5 territory out in the future. Reverse psychology? Nah, we suck.

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If Wednesday and the weekend pan out close to what's currently modeled, Martinsburg could end the month above-normal in snowfall in a +5 December.

:santa:

Before today's readings, Martinsburg's average temperature this December was 41.4. There have been 9 other Decs with an avg of 40+ but only one of them had more than an inch of snow for the month (1936 at 5")

Shows how rare the snowfall the past few days has been in a month this warm.

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