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December Mid/Long Range Discussion

WxUSAF

By WxUSAF,
in Mid Atlantic

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Bob Chill
Bob Chill

No matter how long of a break you take from here, nothing changes. Not.one.thing. 

mappy
mappy

Good morning --  Winter starts Friday (climatological seasons for the win), and our regular snow birds are coming back to roost for the winter. As such our threads are becoming more active, espec

stormtracker
stormtracker

Seconded. And while we're at it, yall remember when posting a model post 200 hours was scorned upon?  Remember how the community would collectively rain hell on a poster who did that?  It's not a

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Weather Will

Weather Will

Posted
Posted
3 minutes ago, Ralph Wiggum said:

+PNA, check. -AO, check. Aleutian low, check. STJ action, check. 50/50 ridge? ....deferring to the experts on that feature. My amateur 500mb deciphering tells me that's a suppressed look but I'm probably wrong.

If there is a blizzard in NC for Christmas, I will be happy for them ....WB 6Z GFS in Fantasy range is cooking up something ....

IMG_2231.png

IMG_2232.png

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psuhoffman

psuhoffman

Posted
Posted
1 hour ago, Ralph Wiggum said:

+PNA, check. -AO, check. Aleutian low, check. STJ action, check. 50/50 ridge? ....deferring to the experts on that feature. My amateur 500mb deciphering tells me that's a suppressed look but I'm probably wrong.

I know we want to rush the progression because Xmas is right there…but that’s just too early on the pattern evolution probably. It’s not impossible we get some snow around Xmas if we get lucky but that’s really early for this process. Step 1 is getting the vortex in Canada to retrograde west. Once it gets off the coast we will start to see cold press in the US. But step two is to get that Atlantic ridge to retrograde and lift into the nao domain. That’s going to take some wave breaking probably and that usually means some rainstorms along the way. That’s probably a few days away from the start of a really good pattern. 

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Eskimo Joe

Eskimo Joe

Posted
Posted
3 minutes ago, psuhoffman said:

I know we want to rush the progression because Xmas is right there…but that’s just too early on the pattern evolution probably. It’s not impossible we get some snow around Xmas if we get lucky but that’s really early for this process. Step 1 is getting the vortex in Canada to retrograde west. Once it gets off the coast we will start to see cold press in the US. But step two is to get that Atlantic ridge to retrograde and lift into the nao domain. That’s going to take some wave breaking probably and that usually means some rainstorms along the way. That’s probably a few days away from the start of a really good pattern. 

Wonder if this weekend's rainstorm starts that process. I think something similar happened in 2009 where we had a rainstorm around the 9th that re-shuffled everything in the Atlantic in time for the 12/19 storm.

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CAPE

CAPE

Posted
Posted
17 minutes ago, Eskimo Joe said:

Wonder if this weekend's rainstorm starts that process. I think something similar happened in 2009 where we had a rainstorm around the 9th that re-shuffled everything in the Atlantic in time for the 12/19 storm.

The origins of that -NAO came from a Scandi ridge retrograding in early Dec. That's the mechanism that really initiated the impressive, sustained NA block that winter. What DT would call a 'real' -NAO.

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Eskimo Joe

Eskimo Joe

Posted
Posted
1 minute ago, CAPE said:

The origins of that -NAO came from a Scandi ridge retrograding in early Dec. That's the mechanism that really initiated the impressive, sustained NA block that winter. What DT would call a 'real' -NAO.

Cool. Hope we get another. The 50/50 low was legit too. I remember on the 12/19 storm, I came back to Philly and the news had a reporter in the Lehigh Valley reporting on partly sunny conditions while Philly was reporting it's 4th consecutive hour of heavy snow. It was amazing.

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CAPE

CAPE

Posted
Posted
Just now, Eskimo Joe said:

Cool. Hope we get another. The 50/50 low was legit too. I remember on the 12/19 storm, I came back to Philly and the news had a reporter in the Lehigh Valley reporting on partly sunny conditions while Philly was reporting it's 4th consecutive hour of heavy snow. It was amazing.

Yep. They go hand in hand. A true atmospheric block involves a sustained ridge/trough configuration. Rex, omega, etc.

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CAPE

CAPE

Posted
Posted

The HL evolution in 2009 really was a thing of beauty. Favorable Aleutian low with an EPO ridge that bridged with the retrograding Scandinavian ridge, pinching off the TPV, which dropped energy into the developing trough underneath/ feeding into the 50-50 position, reinforcing the anomalous higher h5 heights building into the NAO domain.

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WinterWxLuvr

WinterWxLuvr

Posted
Posted
1 hour ago, Eskimo Joe said:

Wonder if this weekend's rainstorm starts that process. I think something similar happened in 2009 where we had a rainstorm around the 9th that re-shuffled everything in the Atlantic in time for the 12/19 storm.

If memory serves it was warm at the beginning of Dec 09. Then we had a rain and the Dec 5 storm developed on the tail of that front. Dec 9 was a snow to rain here in Winchester. Then of course the rest happened. I could be wrong on the development of the Dec 5 storm but that’s my memory

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mattie g

mattie g

Posted
Posted
4 hours ago, Chris78 said:

Looks right on track. At this point 850's and 2m temps are above average but a week later per the weeklies below normal temps are settling in.

I was about to say something about the temps. We just need to accept that it's going to take time for temps to cool down as things reshuffle.

Patience is hard to keep, especially with Christmas in view (and all the winter wishes that go with it), but it's still so, so early.

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paulythegun

paulythegun

Posted
Posted 
Severe Anafront Watch!

SUNDAY NIGHT LWX: 
Colder air will move in behind the front, first later Sunday
afternoon in the Allegheny Highlands and then Sunday night from
northwest to southeast across the rest of the area. With the upper-
level trough axis lagging behind the frontal passage by a few hours
or so, this suggests that there will be some anafrontal
characteristics to the boundary. Therefore, there may be a few hour
period of rain or rain changing to snow behind the cold front before
drier air eventually works its way in overnight. The best chance for
accumulating snow will be along the ridge tops of the Blue Ridge and
Allegheny/Potomac Highlands where cold air will move in sooner.
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ldub23

ldub23

Posted
Posted

Last  paragraph  from Fairbanks discussion

  

Extended Forecast Days 4-7...
It looks to be much colder than we`ve seen lately and the coldest
of the season so far for many locations, especially the West Coast
and Western Interior Sunday night into Monday. The pattern looks
to consist of troughing over the state which would bring more in
the way of Arctic air to the West Coast and Western Interior with
some moderating and chances for Interior snow by midweek. Details
are still being ironed out and we will continue to monitor the
evolving pattern as it is volatile.

 

Its a  bit  below  normal now. As  long as they stay cold its going to be really  hard for  it to get  cold  here.

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yoda

yoda

Posted
Posted
Just now, Eskimo Joe said:

Got a screenshot? 

 

23 minutes ago, ORH_wxman said:

@CoastalWx

Today's "ensembles are completely different from yesterday" session of the EPS....look at the PNA regions bouth south of the Aleutians and the west coast....this isn't even at the end of the run either. It's D11-12.

 

Dec6-7_EPScompare.gif

 

21 minutes ago, ORH_wxman said:

Fwiw, the end of the run does have a pretty nice ALeutian low developing....but again, these things seem to change on a dime right now during this transition period

 

 

Dec7_12zEPS360.png

Will describes it best lol

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TSSN+

TSSN+

Posted
Posted

From LWX

 

As a result, the precipitation may change over to snow for a brief time Sunday night before ending. The greatest chance for this to occur will be to the west of the Blue Ridge, but a fair amount of ensemble members even show it occurring further east. As with many other aspects of the forecast, the finer scale details of the snow forecast remain highly uncertain four days out.

 

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