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Meteorological Winter Pattern Discussion


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Can see it here better, see the angle of the cold as the flow is over the ridge  

Heisy probably hacked into that one

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1 hour ago, susqushawn said:

 which for early Dec, when I have zero expectation of meaningful snow, is fine by me

There's always DEC 5th for your early season hopes:

In terms of total snowfall 12/5 is the 3rd snowiest of any DEC day

12/5 is tied with 12/26 for the most # of 1"or > events during any DEC day

It is also tied with 12/26 for the 2nd most measurable snow events during DEC

Regarding recent trends over the past 20 yrs. 12/5 has recorded more 1" & total measurable snow events than any DEC day 

Philadelphia snowfall records date back to 1884

Edit: Expanding on recent trends there have been significantly more 1" snowfall events during the beginning of DEC since 2000.

8 - 12/1-12/10

4 - 12/11-12/20

3 - 12/21-12/31

793971232_phillydecsnowclimo.png.68133fba35e4f24a57717b8886312825.png

 

 

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1 hour ago, tombo82685 said:

They don't have 2m anoms for Canada, just the continental US, but you can see southern to middle part of Canada. Those values are reaching 15-20 above normal 

ecmwf-ensemble-avg-conus-t2m_f_anom_1day-7040000.png

Thanks. Not quite as bad as the 850's thanks to the snow cover I would guess, but still needing much to get to the promised land.

I have to admit, a week ago I was thinking we'd be waiting for January before we even had a discussion like we're having over 10-15 day progs. So there's that.

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2 hours ago, tombo82685 said:

Under a +pna western Canada would never be cool or cold, it would always be above normal because it's under a ridge and southerly flow. Eastern Canada during +pna regimes matter more and further north west of there. Thats where our airmass comes from. From now through dec 5th, while we have a bit of pna ridge it's more aligned sw to northeast and not poleward. You want the poleward ridge as it stops the pac puke. The sw to ne orientation of the ridging prior to dec 5th, still allows the pac firehose to get involved just not a full on assault. You can see it better looking at a h5 map and esp 850 temp map. We aren't getting the western Canada airmass, the flow up over the ridge through central and eastern Canada down through Hudson Bay is what we get. Now when we lose the ridge then the chinook blasts through everywhere.

ecmwf-ensemble-avg-namer-z500_anom-7385600.png

ecmwf-ensemble-avg-namer-t850-7428800.png

As Tom said, we are really going to need the PNA+ to go poleward to get much out of this. I'd also like to see the axis of the ridge and eastern trough shift west some. As is today the trough in the east would seem to provide OTS solutions for anything coming up the coast. Long way to go.

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A lot of good disco in here with regards to the upcoming pattern. Some positives, some negatives in the mix to start December. Keep Up the solid work. 
 

if things go right, we can cash in, if things go wrong, we could be looking at a Mehh pattern. 
 

just watch how the ridge axis behaves. If it folds over into Canada, we pollute our source region with pac junk air and cut off the fresh flow. If it maintains a more meridonal flow, we can refresh our source region. The source region itself isn’t the coldest, so can’t afford any missteps. 12z GFS op was an example of something we want to see. 
 

But hey, PNA spike, some cold air around, active STJ. Better than staring down the barrel of a 588DM SE RIDGE with zero percent chance of snow (like last few December’s). 

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I don’t know much about lake effect snow besides the basics, but I’d have to imagine that big ULL day 7-8 would yield some nice spots. I saved up during summer for some road trips. Whos down?

as for the pattern....I feel a lot better now than I did last week so we got that going for us. I think we might squeeze out something 2nd week of December.

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8 hours ago, susqushawn said:

Cool makes sense thanks, I temper the optimism a bit as that Pac jet will be charging up the rear to squash any PNA ridge that forms, keeping our windows of opportunity relatively limited, but non-zero, which for early Dec, when I have zero expectation of meaningful snow, is fine by me

Can see it here better, see the angle of the cold as the flow is over the ridge

 

ecmwf-ensemble-avg-namer-t850-7385600.png

ecmwf-ensemble-avg-namer-t850-7515200.png

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3 hours ago, tombo82685 said:

 

BF6E0227-20EA-48E4-84A3-1BBB5685EA42.gif

The reason this got the dancing Gigi weenie was because of this. We have the Aleutian low, which seeds the +PNA. As long as the Aleutian low is there the PNA will be there in some form. We then have a split flow, with northern stream forming the pna ridge which will have embedded disturbances coming down the back side of the big ridge. Southern stream storms supply the juice. The angle of the cold is aimed right at us. Hook the northern stream impulses with the southern stream ones and you get potential big phasing storms. The ridge axis out west is very good for coastal storms if the northern and southern stream can link up. If they miss, may see a few southern sliders if this h5 map were to materialize. 

ecmwf-ensemble-avg-namer-z500_anom-7385600.png

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I mean for early December you can't ask for anything more. Be aware though, this is still out in fantasy land where the pattern gets really good. As we saw last year when we had a very weenie look that never made it past day 8 and then just vanished. Really need to get this under day 8 for it to have merit. 

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4 hours ago, tombo82685 said:

The reason this got the dancing Gigi weenie was because of this. We have the Aleutian low, which seeds the +PNA. As long as the Aleutian low is there the PNA will be there in some form. We then have a split flow, with northern stream forming the pna ridge which will have embedded disturbances coming down the back side of the big ridge. Southern stream storms supply the juice. The angle of the cold is aimed right at us. Hook the northern stream impulses with the southern stream ones and you get potential big phasing storms. The ridge axis out west is very good for coastal storms if the northern and southern stream can link up. If they miss, may see a few southern sliders if this h5 map were to materialize. 

 

Should also state, the pna ridge going poleward is where it's at. You lose that, you lose the good cold and we are back to the mehness. 

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