Jump to content
  • Member Statistics

    17,608
    Total Members
    7,904
    Most Online
    NH8550
    Newest Member
    NH8550
    Joined

December Mid-Long Range Discussion


Deck Pic

Recommended Posts

  • Replies 1.4k
  • Created
  • Last Reply

Right. I've pointed out a few times I'm not sure how much I'd hug the mean in this scenario as it's probably two camps etc. BUT, the 18z GFS is a huge outlier and also would be a historic storm.. so it's probably wrong IMO.

You can also use the "spread" tool to help you eyeball these things too. Like the 12z GEFS at 156 hour SLP plot:

http://mag.ncep.noaa.gov/GemPakTier/MagGemPakImages/gefs-mnsprd/12/gefs-mnsprd_namer_156_mslp.gif

It takes the average spread at every grid point for the last 30 days and takes the current run's spread and divides it by that number. High spread over the northern Mid Atlantic means uncertainty is ridiculous, of course.

Link to comment
Share on other sites

You can also use the "spread" tool to help you eyeball these things too. Like the 12z GEFS at 156 hour SLP plot:

http://mag.ncep.noaa.gov/GemPakTier/MagGemPakImages/gefs-mnsprd/12/gefs-mnsprd_namer_156_mslp.gif

It takes the average spread at every grid point for the last 30 days and takes the current run's spread and divides it by that number. High spread over the northern Mid Atlantic means uncertainty is ridiculous, of course.

Thanks. What is your target range for the 1st mid Atalantic DC-PHL event that isn't a hybrid? (All snow). January 10-15?

Link to comment
Share on other sites

Thanks. What is your target range for the 1st mid Atalantic DC-PHL event that isn't a hybrid? (All snow). January 10-15?

Lol, oh crap! Well initially I was thinking before the 10th, even though I think the models are rushing the the Aleutian Low / PNA ridge pattern to some degree. The AAM wave timing likes 1/4-1/8 but the analogs say to chill a bit.

Regardless of what happens in the first 10 days, another major punch in the jaw is coming to the stratospheric vortex during that time. It could be just the shot to kill it and the Arctic Air will finally be displaced. From that point, it's a matter of where are the global troughs setting up.

Link to comment
Share on other sites

Let me also say this: after a period of cold and snow chances in early January (first 10 days), it may take a break for a bit. So even though the polar vortex may be breaking down in the stratosphere mid-month, the cold may not be directed quite at us at first. But things will change at the end of Jan into Feb again to allow the cold, snow chances to return.

Link to comment
Share on other sites

Lol, oh crap! Well initially I was thinking before the 10th, even though I think the models are rushing the the Aleutian Low / PNA ridge pattern to some degree. The AAM wave timing likes 1/4-1/8 but the analogs say to chill a bit.

Regardless of what happens in the first 10 days, another major punch in the jaw is coming to the stratospheric vortex during that time. It could be just the shot to kill it and the Arctic Air will finally be displaced. From that point, it's a matter of where are the global troughs setting up.

thanks....I was thinking we may have to wait til February for a 90%+ snowstorm, other than maybe a 1-3" clipper...though that doesn't preclude some interesting mix events, some of which could dump 4-8"+ amounts in the far NW areas, while 1-4" events in DC/Balt Metro...most likely would be snow to Frz Rain/Sleet/Rain, but can't rule out a change to snow at the end either......I think if we can get to 5-8" by February 1, we have a good chance of hitting normal or coming close....I think anyone here would gladly take a 2-4" thump from a weak wave or low to our west, that changes over....sometimes they can even be 80%+ snow events...dont know about you guys...I imagine you will have a good chance at a miller B at some point that misses us and maybe catches ILM north.....

Link to comment
Share on other sites

What you said here is how we could get a snowier outcome, by chance. All of these little things would have to come together to keep the coastal plain mostly snow. I'm worried the Pacific influence will screw over the Canadian setup from being ideal. You cannot safely say, "snow is on the way because of the pattern" at this point unless you are trying to sell something...so you and I will do the same thing as everyone else and hope the pieces fall into place. This puzzle happens to be 1000+ with no edges.

Exactly, it would be more because of luck if the pieces lined up favorably, rather than because we had a block over greenland suppressing the track (which you know would get the credit). The Pacific could be so bad in this case that it works in our favor of progressing things along, instead of allowing the wave to amplify and close off in the southern plains like some of the amped up solutions.

At this point im just taking one step at a time and hoping the little wave on xmas eve night can give us some weenie snows even if it doesnt stick.

Link to comment
Share on other sites

That Christmas shortwave being stronger and farther south on the GFS/GGEM etc. drags the baroclinic zone south with it. The Euro is w-a-y farther north and west with that. The second storm can transfer the low pressure development to the coast pretty quickly if that's the way it goes down. Cold air source to the north is also way better on the GFS...traps the vortex underneath the big Central Canada pig ridge.

f84.gif

Yup it seems like an all or nothing deal with these two waves and our chances at snow in the next few days...Unfortunately we have the european suite saying hell no to that.

Link to comment
Share on other sites

Let me also say this: after a period of cold and snow chances in early January (first 10 days), it may take a break for a bit. So even though the polar vortex may be breaking down in the stratosphere mid-month, the cold may not be directed quite at us at first. But things will change at the end of Jan into Feb again to allow the cold, snow chances to return.

Yeah part of me was wondering when/if we get a break from the favorable period here and see it warm up. In many ways, it's tpugh to even find a time when the AO will rise to positive with any significance. So many waves going on at different levels of the stratosphere in the coming days and weeks, its possible this whole scheme manages to keep the AO no worse than neutral before the ultimate break down you mention. So we're pretty much left finding the ****ty period in an otherwise -AO regime. A fun task as this december has proven.

Link to comment
Share on other sites

Saw a map last night in NY metro where I stated the depiction of a rainer low moving ne from S. Maryland was an advanced portrayal that I had seen be a signifiicant snow maker for DC many times. So now the snow is suppressed into VA and Carolinas so we have sort of made the rounds on the clock from Nebraska to just west of applchns to just se of DC to off NC coast. Every track that could materialize has now been covered so we can move next to what is reallyimiportant-the cold air source. I'd much rather see detailed images of the highs right now then moving the low 500 miles every 6-12 hours. 1035+ Highs can be the real deal, flip flopping lows don't really tell much.

Link to comment
Share on other sites

thanks....I was thinking we may have to wait til February for a 90%+ snowstorm, other than maybe a 1-3" clipper...though that doesn't preclude some interesting mix events, some of which could dump 4-8"+ amounts in the far NW areas, while 1-4" events in DC/Balt Metro...most likely would be snow to Frz Rain/Sleet/Rain, but can't rule out a change to snow at the end either......I think if we can get to 5-8" by February 1, we have a good chance of hitting normal or coming close....I think anyone here would gladly take a 2-4" thump from a weak wave or low to our west, that changes over....sometimes they can even be 80%+ snow events...dont know about you guys...I imagine you will have a good chance at a miller B at some point that misses us and maybe catches ILM north.....

You may be right; you would know this area better than me. Looks like a decent chance for a front-end winter threat with the storm next week and I could see something light just after New Years. If the Aleutian Low, split flow, +PNA pattern commences on or around 1/4, then I think you stand a chance at a pure snow event just afterwards through the 10th.

La Niña-like forcing may become a concern for a time in January and it could time poorly with a -AO relaxation period. I suppose I could call it a "thaw" but it isn't really a thaw when you never were frozen. :axe:

Link to comment
Share on other sites

Agree I have read several posts talking about a thaw and I say WHAT? we have only got to the freezing temp a hand full of times.

You may be right; you would know this area better than me. Looks like a decent chance for a front-end winter threat with the storm next week and I could see something light just after New Years. If the Aleutian Low, split flow, +PNA pattern commences on or around 1/4, then I think you stand a chance at a pure snow event just afterwards through the 10th.

La Niña-like forcing may become a concern for a time in January and it could time poorly with a -AO relaxation period. I suppose I could call it a "thaw" but it isn't really a thaw when you never were frozen. :axe:

Link to comment
Share on other sites

There's a bit of ens spread with the AO but definitely looking to stay negative. PNA continues to improve. Confidence growing for a cold stretch to close this year and start the new one. Precip seems to remain active but who cares that far out. At least it looks like we aren't going to constantly battle a -pna and stormtrack to our west. That was growing tiresome to say the least.

Link to comment
Share on other sites

Are people going to be pissed if we emerge from this pattern in 2 weeks and we only have a couple inches to show from it? I won't.

It is the end of dec, people should know climo it isnt a very snowy month. If we get 2-3 inches then so be it. I havent checked to see what climo is for IAD west for Dec but Im sure it isnt more than 4-5" probably. If people view this as a bust it may be time for them to take a break from here. Whatever falls, Ill be more than happy to enjoy.

Link to comment
Share on other sites

It is the end of dec, people should know climo it isnt a very snowy month. If we get 2-3 inches then so be it. I havent checked to see what climo is for IAD west for Dec but Im sure it isnt more than 4-5" probably. If people view this as a bust it may be time for them to take a break from here. Whatever falls, Ill be more than happy to enjoy.

3.5" is an average December at IAD

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...