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November/December Medium/Long Range Disco


WinterWxLuvr

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9 minutes ago, Bob Chill said:

Don't remember if anyone posted this panel from the jamstec seasonal but a repost wouldnt hurt. Lol

Textbook nino precip anomaly forecast. Temps well below normal for DJF too. 

tprep.glob.DJF2019.1nov2018.gif

I only posted a link to it in the winter thread, but yeah looks great. 

Did you see the new Ukmet seasonal ?

Very cold. The precip panel I would like to see more of a positive, but maybe the visual on the map is based on the total of the time period and wshed out or maybe the storm track is South ?? 

For sure though, it looks even colder than the last one. darker blues over us. 

 

 

 

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10 hours ago, Maestrobjwa said:

I was just going to ask a question about what exactly we need to beat the climo in early December to get snow to work even in the corridor, lol

There is no easy answer to this and it's two different answers depending where in our region you are. History has shown places west of the fall fine with some elevation can get a decent snow event in December much easier.  

But I think you are more focused on the urban corridor.  The best 2 ways to get it done there are an incredibly anamolous cold shot or a perfect h5 setup and a perfect track surface storm in tandem with just enough cold to work.  

If you can get a reasonably cold airmass and a perfect track it can happen.  Or very anamolous cold and a wave.  But the problem is getting that.  Both are rare in December.  Cold just typically hasn't had enough time to build enough to press the jet this far south on average.  When we do get cold it's typically a quick shot then out.  But I don't remember too many instances where we got a perfect setup and it failed simply because it was December.  More often the real problem is getting a perfect setup this early is difficult.  By perfect I mean cold enough air mass and a system to take the perfect track.  Even this storm yesterday could have been more snow in DC had it taken the perfect track.  An h5 through PA and a surface storm up the Delmarva inside ocean city is a flip to rain track for 95 even in January.  One of the most impressive things was the result given that unfavorable track.  I wouldn't honestly expect to do any better then I did here with that track even in winter.  Had the h5 tracked 100 miles south and the surface system tracked off the coast instead of inside it D.C. Could have had a warning criteria snowfall.

In the last 20 years there have only been 4 systems pre xmas to get significant snow into the coastal  plain that I can think of.  One was dec 5 2003.  That was a miller a/b hybrid that was pretty weak at the surface and h5 but took a perfect track and had the advantage of a nino stj.  There was a weak frontal wave in 2004 that dropped 3-6" east of D.C.  A clipper in 2007 that maxed out and then of course 2009 which was the ultimate perfect h5 and surface track.  So 4/20 years had a signoficant snowfall on the coastal plain pre xmas.  That's only 20%.  But 2 of those were modoki ninos so it's 2 out of the 4 modoki ninos in the last 20 years.  Not bad odds if we look at it that way.

 

 

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36 minutes ago, psuhoffman said:

There is no easy answer to this and it's two different answers depending where in our region you are. History has shown places west of the fall fine with some elevation can get a decent snow event in December much easier.  

But I think you are more focused on the urban corridor.  The best 2 ways to get it done there are an incredibly anamolous cold shot or a perfect h5 setup and a perfect track surface storm in tandem with just enough cold to work.  

If you can get a reasonably cold airmass and a perfect track it can happen.  Or very anamolous cold and a wave.  But the problem is getting that.  Both are rare in December.  Cold just typically hasn't had enough time to build enough to press the jet this far south on average.  When we do get cold it's typically a quick shot then out.  But I don't remember too many instances where we got a perfect setup and it failed simply because it was December.  More often the real problem is getting a perfect setup this early is difficult.  By perfect I mean cold enough air mass and a system to take the perfect track.  Even this storm yesterday could have been more snow in DC had it taken the perfect track.  An h5 through PA and a surface storm up the Delmarva inside ocean city is a flip to rain track for 95 even in January.  One of the most impressive things was the result given that unfavorable track.  I wouldn't honestly expect to do any better then I did here with that track even in winter.  Had the h5 tracked 100 miles south and the surface system tracked off the coast instead of inside it D.C. Could have had a warning criteria snowfall.

In the last 20 years there have only been 4 systems pre xmas to get significant snow into the coastal  plain that I can think of.  One was dec 5 2003.  That was a miller a/b hybrid that was pretty weak at the surface and h5 but took a perfect track and had the advantage of a nino stj.  There was a weak frontal wave in 2004 that dropped 3-6" east of D.C.  A clipper in 2007 that maxed out and then of course 2009 which was the ultimate perfect h5 and surface track.  So 4/20 years had a signoficant snowfall on the coastal plain pre xmas.  That's only 20%.  But 2 of those were modoki ninos so it's 2 out of the 4 modoki ninos in the last 20 years.  Not bad odds if we look at it that way.

 

 

Awesome explanation as usual! 

So in other words...since, for whatever reason, it's harder to get a sustained cold shot (or a short one that's unusually cold) here in December (why is that? Just our climo?), that's why we don't get as much snow there as the other months?

And that's an interesting parallel with the modoki factor...(which two were? 2009...what was the other year?). Is there a reliable list of modoki el Niño years that goes back further than 20 years? (Just curious)

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15 minutes ago, Maestrobjwa said:

Awesome explanation as usual! 

So in other words...since, for whatever reason, it's harder to get a sustained cold shot (or a short one that's unusually cold) here in December (why is that? Just our climo?), that's why we don't get as much snow there as the other months?

And that's an interesting parallel with the modoki factor...(which two were? 2009...what was the other year?). Is there a reliable list of modoki el Niño years that goes back further than 20 years? (Just curious)

Dec cold has some headwinds to overcome. Snowcover in our source region grows as winter goes on but in Dec, cold air travels over lots of bare ground so it moderates faster. Oceans play a role as well. Both the pac and atl are warmer in December than JFM. The polar jet has a seasonal cycle too. Mean placement is further north on Dec compared to JFM.

This year already has snowcover working for us. North American snowcover has been unusually high all month. 

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5 hours ago, psuhoffman said:

There is no easy answer to this and it's two different answers depending where in our region you are. History has shown places west of the fall fine with some elevation can get a decent snow event in December much easier.  

But I think you are more focused on the urban corridor.  The best 2 ways to get it done there are an incredibly anamolous cold shot or a perfect h5 setup and a perfect track surface storm in tandem with just enough cold to work.  

If you can get a reasonably cold airmass and a perfect track it can happen.  Or very anamolous cold and a wave.  But the problem is getting that.  Both are rare in December.  Cold just typically hasn't had enough time to build enough to press the jet this far south on average.  When we do get cold it's typically a quick shot then out.  But I don't remember too many instances where we got a perfect setup and it failed simply because it was December.  More often the real problem is getting a perfect setup this early is difficult.  By perfect I mean cold enough air mass and a system to take the perfect track.  Even this storm yesterday could have been more snow in DC had it taken the perfect track.  An h5 through PA and a surface storm up the Delmarva inside ocean city is a flip to rain track for 95 even in January.  One of the most impressive things was the result given that unfavorable track.  I wouldn't honestly expect to do any better then I did here with that track even in winter.  Had the h5 tracked 100 miles south and the surface system tracked off the coast instead of inside it D.C. Could have had a warning criteria snowfall.

In the last 20 years there have only been 4 systems pre xmas to get significant snow into the coastal  plain that I can think of.  One was dec 5 2003.  That was a miller a/b hybrid that was pretty weak at the surface and h5 but took a perfect track and had the advantage of a nino stj.  There was a weak frontal wave in 2004 that dropped 3-6" east of D.C.  A clipper in 2007 that maxed out and then of course 2009 which was the ultimate perfect h5 and surface track.  So 4/20 years had a signoficant snowfall on the coastal plain pre xmas.  That's only 20%.  But 2 of those were modoki ninos so it's 2 out of the 4 modoki ninos in the last 20 years.  Not bad odds if we look at it that way.

 

 

I think you're forgetting this...nailed your area..

hif8WLW.png

 

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Signal for a storm is increasing for around Dec 1. Can see it on the EPS too. Temps are marginal verbatim but its a long way off. Pretty nice looking set up though.

This period is probably the next legit shot for a winter storm, although this may end up being a table setter for the next threat. 

gfs-ens_mslpa_nhem_55.thumb.png.5e29d21ba81c57d3e8ebd1655464d9be.png

eps_mslpa_noram_61.thumb.png.267163df33fc48e5ac979c74d15673df.png

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Mentioned a couple of days ago that I liked the roughly 9-10 day (now day 7-8) period for a storm in the east from what I was seeing on the GEFS. Well the GEFS for the most part has backed off at this point. But the GEFS has had a tendency in the past to lose storm signals at roughly this range only to bring then back a couple days later. That may very well be the case here as we are now seeing the EPS hitting hard on that signal though a day or so later.

Below we have the eps at day 8.5. Lows are everywhere from the central/midwest US to off the eastern seaboard.

eps204lows.thumb.gif.23be6038c272303b7e57e9744484fc74.gif

 

This is the EPS a day and a half later. As you can see there is a strong signal for a storm/storms impacting the east coast through this time period. The question is, how does it evolve to get from the above frame to this one.

eps230lows.thumb.gif.a54a5548896dc00544d822cac5cc936f.gif

 

Now the biggest issue for those hoping for wintry type precipitation is below. Had a ridge and higher heights move into the eastern US previously and this is what it left us temp wise. This is no where near getting it done for us. Notice there is no cold to be found anywhere until you are west of the Mississippi.

eps204temps.gif.a5363019f69943038d05b7ad53b49dad.gif

 

 

But there may be hope. Below is just 24 hours earlier from the Nov 16th 00Z run. As you can see we are seeing a much stronger push of cold farther south and east on the previous frame. We are also seeing the warm anomalies coming in weaker as well.

 

nov16eps264temps.gif.71aa30114b556c7b0fd7a4f1729db27d.gif

 

But what we are seeing is still not enough at this point because this what we are seeing at day 10 as the EPS shows the storm heading out. As you can see temps are just now cooling down. So really at this point what the EPS is advertising is storminess in the east, storminess of the wet variety.

eps240temps.gif.9193b4f2347299c93b6cf6cf86dd4173.gif

 

Now how the whole setup evolves is mute at this point for snow lovers unless we can get some cold into the area in time. Looking at the 500 mbs at day 8.5 we are seeing the trough setup at neutral tilt west of the Mississippi. To the northeast of it we see a broad area of ridging into southeast Canada. This will not work as the trough will go negative tilt too soon for our region and the cold will run in after the fact. What we need to see is that whole trough shifted eastward to where we see it at a neutral state over the Mississippi. This would give us a shot at getting the cold into the area quickly enough to give us a shot at frozen. So what I think we need see occur is that when the energy/trough is initially dumping down into the US we need to see it dumping farther east then what is currently doing which is dumping into the west. And to have that I think the key here will be what we see occur with the ridging in SE Canada. We see that feature come in sharper and not as broad I think the upstream implications will be a dump further east shifting of the mean trough eastward as well.

Just an aside but there is always a chance that we see some northern stream energy drop down beforehand bringing cold with it but at this point the models aren't seeing it and I would put the chances of seeing that at a very low probability. 

eps204hr500.gif.7583bc3a89a4a0e7fcd1eb587b296996.gif

 

All in all, I feel strongly at this point that we see a storm during the above time period. But as far as snow the models are not encouraging up to this point. But we have over a week to see the needed changes so you never know.

 

 

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I agree that it is most likely we see a rain storm during that timeframe.  As @showmethesnow said....hopefully this will be the storm that can set the stage...leaving some cold air to work with in it's wake.

Along with the GEFS and EPS signaling a coastal in the D12-14 range we also now have the GFS and FV3 ops showing some decent looks as well at 06z.  The EPS control run last night had beaut....

Bgshqg6.png

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Soi is certainly taking a dip finally....

MJO on most models wants to head for the COD and reemerge in 7/8 and look poised to take the tour as we head toward the first 2 weeks of Dec. Below is the NCEP forecast....probably a little too robust but gives and idea of where we are likely heading.  The deep dip in the soi and this mjo forecast does give credence to the idea of a decent Pac pattern as we roll forward into Dec.

qVCYqyy.png?1

JuXrTzc.gif?1

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1 hour ago, poolz1 said:

Soi is certainly taking a dip finally....

MJO on most models wants to head for the COD and reemerge in 7/8 and look poised to take the tour as we head toward the first 2 weeks of Dec. Below is the NCEP forecast....probably a little too robust but gives and idea of where we are likely heading.  The deep dip in the soi and this mjo forecast does give credence to the idea of a decent Pac pattern as we roll forward into Dec.

qVCYqyy.png?1

JuXrTzc.gif?1

The mjo cycling the cold phases repeatedly is one of the best signs imo. Keep it cycling like that all winter and it would be hard to fail. 

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19 minutes ago, psuhoffman said:

The mjo cycling the cold phases repeatedly is one of the best signs imo. Keep it cycling like that all winter and it would be hard to fail. 

Agreed.  Obviously nothing is etched in stone but the upcoming pattern I think at the very least shows this winter will host periods of a favorable Atl.  Combine that with a fairly steady background state of the MJO rotating through favorable phases and it really gives hope for a great winter.  

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20 minutes ago, WxUSAF said:

DT starting to honk about the 30th. 

https://www.wxrisk.com/is-dt-secsy-sexy/

I still think the cold air is going to be marginal around that time so I’d lean toward the first week of December personally, but hey, I’m good with both working out.

Thing on cold air is we just saw a deep blanket of snow laid down through upstate ny and into Canada - I like having that up there already as it helps any highs in that spot produce. The re-inforcing cold air shot showing for thanksgiving might help with antecedent air too. I guess I am wondering about getting better with cold air maybe by the start of the window of opportunity than we had been thinking.

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21 minutes ago, WxUSAF said:

DT starting to honk about the 30th. 

https://www.wxrisk.com/is-dt-secsy-sexy/

I still think the cold air is going to be marginal around that time so I’d lean toward the first week of December personally, but hey, I’m good with both working out.

Front side of blocking and early climo makes it easy to discount for our yards. If things line up in the mid range I'll jump on board but for now I'll assume the typical progression. 

Nice seeing all ensembles jump on the -ao/nao train. Pretty sig neg event on tap. Next part of this exercise is to see if LR relaxation keeps getting pushed back in time. If it does then I'll feel very confident that early winter has shown it's hand. We'll know in 2 weeks. 

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I like seeing verification like this. Gefs is busting high d10+. This blocking event is trending stronger and faster than even the usually too fast gefs thinks. Good times. 

ao.sprd2.gif

If this keeps up then long range guidance is going to prob verify too warm as we move towards early Dec. I was actually pretty young the last time this happened. Now I'm old and crusty but enjoying the wx porn. 

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31 minutes ago, WxUSAF said:

DT starting to honk about the 30th. 

https://www.wxrisk.com/is-dt-secsy-sexy/

I still think the cold air is going to be marginal around that time so I’d lean toward the first week of December personally, but hey, I’m good with both working out.

You forgot the weenie rule that it will produce its own cold air!

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7 minutes ago, osfan24 said:

You forgot the weenie rule that it will produce its own cold air!

If a storm tracks under us, which the -NAO should support, and there’s a high in NE or the Lakes instead of some damn northern steam low, than I’ll start getting interested.

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4 minutes ago, WxUSAF said:

If a storm tracks under us, which the -NAO should support, and there’s a high in NE or the Lakes instead of some damn northern steam low, than I’ll start getting interested.

Yea, blocking doesn't guaranty cold air. -NAO helps with a good storm track but is often associated with seasonal airmasses. Even with a high in a good spot it can still easily be rain this early. 

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34 minutes ago, Bob Chill said:

Front side of blocking and early climo makes it easy to discount for our yards. If things line up in the mid range I'll jump on board but for now I'll assume the typical progression. 

Nice seeing all ensembles jump on the -ao/nao train. Pretty sig neg event on tap. Next part of this exercise is to see if LR relaxation keeps getting pushed back in time. If it does then I'll feel very confident that early winter has shown it's hand. We'll know in 2 weeks. 

You've been saying two weeks for like a month now

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I think those of us to the west have a chance for a snow shower or two with the frontal passage on Tuesday. That is how we normally see flakes this time of year out here. 

That early Dec chance is looking legit for sure. The GFS and FV3 both have the storm but one is a cutter and the other is squashed. 

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