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Mid January/Mid February Medium/Long Range Discussion


WinterWxLuvr
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28 minutes ago, psuhoffman said:

I get where you’re coming from. But part of using the guidance effectively is correcting for biases. The guidance won’t be perfect from range.  It’s also incorporating climo and historical reference with the NWP guidance. The most logical correction right now is to assume the gfs is over amplified. But you are correct that could be a mistake. And that’s why forecasting long leads is low accuracy.  

But at day 8 we really shouldn’t expect that level of accuracy. Right now we can say with some confidence based on guidance that there is likely to be a system in the east day 8-10 with about seasonal temperatures that is likely a rain or maybe snow threat. That’s good enough. A day 8 forecast shouldn’t be more detailed. Exactly how strong isn’t necessary. 

You’re right. I probably am too concentrated on the details.

I will say it’s interesting to see at least some progressive ridging developing across the west coast. Still fighting circle of doom in Alaska. We need more stable ridge in the west coast to develop since we’re getting close to February and wave lengths will begin to change in a few short weeks.

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13 minutes ago, Ji said:

looks like a PNA driven pattern as we head into day 15 on EPS...pretty deep trough in the east but its not all that cold but cold enough

So long as that wall remains up across the arctic no pattern in the mid latitudes can get that cold. But perhaps maybe cold enough with luck. Lots of luck. 

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28 minutes ago, psuhoffman said:

So long as that wall remains up across the arctic no pattern in the mid latitudes can get that cold.

Willing to venture a guess when, or if, that wall ever breaks down?

Or, does it evolve in such as way,  later in Feb. to allow a penetration of arctic air to the lower latitudes via a PV elongation or slight displacement event. 

I still like Feb 18 th to the 22 nd simply based on previous behavior of the pv since November. The idea which HM brought up, about a strong winter vortex following a certain period of waxes and waning, such as the vacillation cycle near the 20th of the month.  As we get to early March, as mentioned previously, the IO signal favors cold and who knows,  maybe the descending QBO effect begins to kick in on a subtle scale.  

 

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16 minutes ago, frd said:

Willing to venture a guess when, or if, that wall ever breaks down?

Or, does it evolve in such as way,  later in Feb. to allow a penetration of arctic air to the lower latitudes via a PV elongation or slight displacement event. 

I still like Feb 18 th to the 22 nd simply based on previous behavior of the pv since November. The idea which HM brought up, about a strong winter vortex following a certain period of waxes and waning, such as the vacillation cycle near the 20th of the month.  As we get to early March, as mentioned previously, the IO signal favors cold and who knows,  maybe the descending QBO effect begins to kick in on a subtle scale.  

A descending qbo, IO sst, shortening wavelengths all would suggest increasing chances to break the pattern as we move later in Feb or March.  But beyond that I would be lying if I pretended to have any concrete insight. That PV has been a beast and isn’t going to give in easy. 

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Weep and cry to the record negative cycle in the warm season.

This is one of the best running representations of the NAO I have ever seen. 

Two notes, one the record -NAO from Spring to summer, and the other is the ability,  at a short range,  to forecast the NAO . 

 

 

 

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Just now, losetoa6 said:

One thing that just about all guidance is certain with....is a storm parade with good qpf through the extended  . I'll take my chances in prime climo with this alone . Something has to hit us flush .Far from boring . 

Yeah, that does seem to be where we're headed in terms of a parade of storms.  I would think where you're at, one of these at least might have a good shot to give you a decent paste job even if temperatures are somewhat marginal.  Closer in to the metro DC area, we'd need a lot more help I'm sure.

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Triple Barrel low, looks a lot of the February 25 2010 storm that backed into New England.   It didn't back the low into the coast fast enough for us to get pasted, but I thought it could have given the 500mb setup.  Probably some stupid convective feedback thing that kept it moving north instead of being captured and hurled into the DelMarva.

blDy9s7.png

 

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Half decent +pna driven pattern showing up near the end of Jan into Feb. It's a process and may not yield immediate results but it's no doubt far better than where we've been since mid Dec.

A +pna driven pattern in Feb can actually produce without a -ao/nao. CFS/CanSips/euro weeklies all imply a +pna of various magnitudes for the balance of Feb. PSU covered this in great detail this year already but if you look at all the 5"+ storms in Feb with a +ao/nao nearly every one is +pna driven. 

ETA: considering how this winter has gone start to finish I'm expecting the good looks to deteriorate as we move forward. However, the gfs started showing cold amplification in fantasyland a couple days ago and hasn't wavered since. That + the ens generally agreeing carries some weight. One decent warning level storm and it would erase quite a bit of the nonstop gut punches over the last 6 weeks. 

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@Ji did you look at the 12z euro control? It actually looks just like the gfs with troughs carving, multiple snow events (3), and the best (relatively speaking) entrenched cold towards the end of the run since the first half of Dec. 

I don't have any strong feelings either way for Feb. I will say that it doesn't look hostile yet. Maybe even a little encouraging...

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1 hour ago, Bob Chill said:

Half decent +pna driven pattern showing up near the end of Jan into Feb. It's a process and may not yield immediate results but it's no doubt far better than where we've been since mid Dec.

A +pna driven pattern in Feb can actually produce without a -ao/nao. CFS/CanSips/euro weeklies all imply a +pna of various magnitudes for the balance of Feb. PSU covered this in great detail this year already but if you look at all the 5"+ storms in Feb with a +ao/nao nearly every one is +pna driven. 

ETA: considering how this winter has gone start to finish I'm expecting the good looks to deteriorate as we move forward. However, the gfs started showing cold amplification in fantasyland a couple days ago and hasn't wavered since. That + the ens generally agreeing carries some weight. One decent warning level storm and it would erase quite a bit of the nonstop gut punches over the last 6 weeks. 

+1 to this. Point I made earlier - if we can get PNA ridging with the right axis on the ridge (Idaho) then we can score. I’m confident we align a wave and have some of a cold source to tap, if we can get the PNA to go positive and oscillate in positive territory for a 10-14 day period. I think it’s a 20-30% chance it does that this winter. But still a possibility imo

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2 minutes ago, losetoa6 said:

I just looked at the 18z Control and it has strong energy diving in behind the weekend system . If only there were a bit more separation at h5 . Could be a sneaky event.  Actually 18z Eps has a low in the gulf at day 4/5 hinting at something similar but just not enough separation.  5 days out so something to watch. 

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57 minutes ago, leesburg 04 said:

I think the next few weeks might help decide what's more important. Get the wet first and take our chances or get cold and pray for wet

I look at it this way. Last weekend, when it was plenty cold enough, I wasn’t looking out the window wishing it was colder. No, I was looking at a radar screen that showed no precipitation. Earlier this month when we had snow for like four hours I wished we had more precipitation. In December when it snowed before Christmas about 1 1/2”, I wished it had snowed for more than 2 hours. Earlier in December during our anafrontal fiasco, I wished that we had a wave of precip when there was zip. The past few days when it has been plenty cold I wish we would have had a clipper or something to deliver some precip. In November when it was abnormally cold I wish we’d had some precip instead of the 0.001 that fell and dusted the ground.

We have windows of cold every year without fail. I’ll always say give me the precip and I’ll take my chances. If this active pattern advertised comes, I’ll guarantee you that we score.

Just one persons opinion.

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