January Med/Long Range Disco

[mdsnowlover]

Late range Atari, too amusing not to share.

funny ha ha or sarc?? euro gives us 1 or 2 in a clipper

[WxUSAF]

GEFS would imply a really cold blast next week around Tuesday.  Cold/dry, warm/wet.    

[CAPE]

GEFS would imply a really cold blast next week around Tuesday.  Cold/dry, warm/wet.    

Thats normally what we get in a crappy pattern. Although if its a really crappy pattern we can also do warm/dry.

[psuhoffman]

Thats normally what we get in a crappy pattern. Although if its a really crappy pattern we can also do warm/dry.

This is a really crappy pattern. There is almost no chance of a worthwhile storm of any significance in this pattern. Until either the Pna or nao changes anything that amplifies at all will cut. I have better things to do then waste hours praying for some sheared out crap to stay south enough to give us some insignificant pity snow or a measly inch or two from a clipper. A -epo can save us from the nao but it can't overcome a -Pna also. Just going to be cold between storms. Id prefer the last pattern where it was at least warm and nice and I could go for a run and save on my electric bill.

[Ji]

This is a really crappy pattern. There is almost no chance of a worthwhile storm of any significance in this pattern. Until either the Pna or nao changes anything that amplifies at all will cut. I have better things to do then waste hours praying for some sheared out crap to stay south enough to give us some insignificant pity snow or a measly inch or two from a clipper. A -epo can save us from the nao but it can't overcome a -Pna also. Just going to be cold between storms. Id prefer the last pattern where it was at least warm and nice and I could go for a run and save on my electric bill.

just dont get why we have a -PNA...when the PDO is out of orbit

[NinjaWarrior2]

12z GFS has a light clipper system on the 7th. Something I believe 0z Euro had. Para has it too but even weaker, then Para drops the PV on us

[Heisy]

Looked like we were making progress then boom the 00z EURO looks like crap lol

[usedtobe]

just dont get why we have a -PNA...when the PDO is out of orbit

Looks like we get a pseudo +pna after our storm tracks to the great lakes and the pacific ridge shift east a tad.  That might open the door for a clipper but is basically a dry pattern.  Thenn the ensemble shift the ridge back west and we warm back up. 

[Bob Chill]

Winter cancel uncancel cancel uncancel

 

https://www.aer.com/science-research/climate-weather/arctic-oscillation

 

Snippets

December 30, 2014 Summary

• A positive AO and North Atlantic Oscillation (NAO) trend are expected in the short term.  This is associated with a strong pulse in wave driving.
• In the short term temperatures will turn mild across Eurasia with the positive trend in the AO.
• The strong wave driving will result in a sudden stratospheric warming (SSW) and a splitting of the polar vortex.  In the near term this will help build ridging across Western North America and cold temperatures across the United States after the New Year. 
• Following a SSW a negative AO is favored for up to 60 days.  However anomalous low pressure across the Barents-Kara seas and northern Eurasia destructively interferes with externally forced negative AO conditions and introduces uncertainty longer term.

Impacts

The Northern Hemisphere circulation is undergoing a re-organization precipitated by a strong pulse in vertical wave activity.  The immediate impact on sensible weather will be a spike in the AO and milder temperatures across northern Eurasia and the Eastern United States.  However simultaneously, the pulse in wave driving will trigger a SSW in the form of a polar vortex split.  Longer term this favors a mean negative AO and colder temperatures across the Northern Hemisphere continents.  There is still much uncertainty in the evolution of the weakened polar vortex but we favor the more highly disturbed forecast of the ECMWF.

However longer-term prospects for the AO continue to hinge on the anomalous polar low in the Barents Kara-seas region that has temporarily weakened.  It is predicted to strengthen again across the north slope of Siberia and eventually move back over the Barents Kara seas region.  Perhaps the current temporary relaxation is a foreshadowing of a longer term weakening trend but for as long as the Barents-Kara seas low persists, it destructively interferes with an externally forced negative AO (from the SSW).  The biggest impact would to inhibit the flow of Siberian air into Europe.  It’s impact would be less on North American temperatures where in the near term, ridging across western North America and a polar low in eastern Canada will direct arctic air into the lower 48.

 

The models do disagree on the strength of the polar vortex weakening.  The GFS predicts a relatively quick polar vortex recovery and is predicting that the polar vortex will return to normal and even slightly above normal strength by the end of the period (Figure 2).  The quick recovery in the polar vortex is directly attributable to the large deficits in the WAFz predicted by the GFS this period (Figure 3).  The ECMWF in contrast shows continued wave driving after January 5 that continues to perturb and weaken the polar vortex even beyond January 5.  Based on the ECMWF forecast, the SSW will get close to a major SSW (defined as a zonal mean easterly wind at 10 hPa and 60°N) and would likely achieve major SSW strength with further wave driving.  The GFS has displayed a bias all winter of under-predicting the vertical WAFz and over-predicting polar vortex strength.  Therefore we favor the ECMWF forecast of a more perturbed and longer duration polar vortex weakening.

 

Regardless, with positive AO conditions at the surface temperatures should be seasonable to even seasonably mild across Europe and East Asia.  However the Central and Eastern US will be cold as the developing stratospheric warming preferentially builds heights over the Bering Sea region forcing a ridge over Alaska and the West Coast of North America that drives Arctic air into the lower 48.

3-4 week  

Typically the circulation anomalies associated with a SSW, high PCH, an equatorward displaced Jet Stream and negative AO conditions propagate down from the middle stratosphere to the surface in one to two week’s time.  Based on the SSW alone we would expect an overall mean negative AO this period with cold temperatures across the Eastern United States and northern Eurasia.  Though even based on the polar vortex split there is still much uncertainty which regions will turn cold that will in part be determined by the evolution of the polar vortex post the stratospheric warming and not all regions are cold (Europe, eastern United States, East Asia) post a sudden SSW even a major SSW.

However this winter there has been an additional level of uncertainty due to anomalous area of low pressure in the Barents–Kara seas region, which has destructively interfered with the negative AO forced/associated with high Eurasian snow cover.  The models last week were predicting that low pressure to split into two with each piece being absorbed into the climatologically favored polar lows in East Siberia and Hudson Bay.  Though this has happened, allowing for increased wave driving and wintery weather across Europe, the models now forecast for the low pressure to reform, though based on the vortex split likely on the inland side of the Eurasian north slope.

It is hard to predict how long this area of low pressure will persist, which is likely to be at least somewhat supported by the relatively extensive North Atlantic sea ice extent compared to recent years and to the North Pacific side of the Arctic.  As long as low pressure remains near the Barents-Kara seas any tropospheric influences from the stratosphere this time period will be favored across North America relative to Europe.  However if a piece of the polar can move over Europe then this could help force much colder weather into Europe.

Longer Term
30–day  

Typically mean negative surface AO conditions are favored 1-2 weeks following a SSW for up to six more weeks.  Therefore based on the predicted SSW during the first week of January, mean negative AO conditions are favored through the end of January and into early February.  However as discussed above the persistent polar low in the Barents-Kara seas region is destructively interfering with any externally forced negative AO, introducing uncertainty into the forecast of a negative AO and cold temperatures across the Northern Hemisphere continents.

 

 

 

 

 

 

[Ian]

I wonder if some of these guys even look at the actual weather or just spend their days in spreadsheets and modeling. 

[CAPE]

I wonder if some of these guys even look at the actual weather or just spend their days in spreadsheets and modeling. 

Trying to figure out where the pattern is going to go is all geeky and mathy.

[Ian]

Looks like Matt Rogers isn't worried yet. So 40" for DC is still on the table. 

 

http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2014/12/30/what-does-snowless-december-portend-for-the-rest-of-winter/

[AlaskaETC]

I wonder if some of these guys even look at the actual weather or just spend their days in spreadsheets and modeling. 

 

I take it you are not Cohen's biggest fan?

[Ian]

I take it you are not Cohen's biggest fan?

Honestly don't follow him much. I still don't really believe in long range forecasting... there are exceptions to the rule but in general there seems to be a lot of quackery. 

[Ian]

And no dissing intended there. It's folks like that who help make breakthroughs but it should be considered at the edge of real science still for now IMO. 

[AlaskaETC]

I thought Cohen was somewhat respected?

[Ian]

I thought Cohen was somewhat respected?

not sure what that means quantitatively.

[AlaskaETC]

not sure what that means quantitatively.

As in considered a knowledgeable scientist and meteorologist, not a quack.

[Ian]

As in considered a knowledgeable scientist and meteorologist, not a quack.

I wasn't really saying he is a quack. He has a PhD and a huge body of research.  But the field is still pretty young... and lots of people join in with garbage to support their weeniesm. 

[SnowNiner]

Winter cancel uncancel cancel uncancel

 

https://www.aer.com/science-research/climate-weather/arctic-oscillation

 

Snippets

 

I think he thinks the anomalous low pressure across the Barents-Kara seas and northern Eurasia destructively interferes with his winter outlook and index....it's his "but, but!!". 

[Bob Chill]

I wasn't really saying he is a quack. He has a PhD and a huge body of research.  But the field is still pretty young... and lots of people join in with garbage to support their weeniesm. 

 

It's pretty clear his work is valid but just like any "piece of the puzzle" it's not bullet proof and always worthy of a bust. This year sucked for weenies because it was a near perfect evolution in Oct so strong support of a -AO was favored by virtually every met and weenie in the universe. If this SSW is actually meaningful and produces expected results then it's still only a partial win. Dr. Cohen for the last month has been backpedaling and basically saying things aren't going as planned..."yet". 

 

I'm very much in a wait and see mode overall with a hedge towards things not going as planned. If/when the -AO with legs is actually occurring I'll go ahead and oil up the shovel in case I need it.

[Ji]

Looks like Matt Rogers isn't worried yet. So 40" for DC is still on the table. 

 

http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2014/12/30/what-does-snowless-december-portend-for-the-rest-of-winter/

we could have a 35 inch Feb like we usually get in El Ninos

[Ji]

Honestly don't follow him much. I still don't really believe in long range forecasting... there are exceptions to the rule but in general there seems to be a lot of quackery. 

not sure why you wouldnt believe in long range forecasting. Everyone forecacasted a $hitty winter last year and it was historically good and everyone said this would be a good winter and its been historically bad

[Ian]

not sure why you wouldnt believe in long range forecasting. Everyone forecacasted a $hitty winter last year and it was historically good and everyone said this would be a good winter and its been historically bad

 

sidenote, jason should have contacted you as a winter cancel expert. 

[Amped]

I thought Cohen was somewhat respected?

Correlation does not always imply causation. If I wanted to I could probably find some cloud over the Amazon Jungle that predicts DCs snowfall the following winter 90% of the time, it could just be the result of me staring at maps and indexes for too long.

[Bob Chill]

I have as much skill with SSW as Shaquille has at the free throw line but I have to assume the upcoming period will do "something" to the NH circ patterns. And that lr models will be especially bad until it's figured out. If we stay in the crapper it won't surprise me but things could start changing in a relative hurry over the next 1-2 weeks. I'm all in until I'm out. 

[dallen7908]

Based on the CWG article, it appears that a snow-less December neither increases or decreases our snow-accumulation potential during the remainder of the winter; I'm counting that as a win.  

[gymengineer]

Looks like Matt Rogers isn't worried yet. So 40" for DC is still on the table. 

 

http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2014/12/30/what-does-snowless-december-portend-for-the-rest-of-winter/

I find it interesting 86/87 is being used as the example of a turn-around winter where we can still get well-above average snowfall. 

 

By this day in December 1986, we would have just begun to parse the rain/snow line for the big New Year's Day coastal storm (got down into the mid 980's mb). Prolific snow would have already fallen in interior PA, NY, and New England, and the winter was showing itself as a predominantly negative NAO one. 

 

In other words, 86/87 by now was already a fine winter for interior areas that tend to get a lot of snow before January and the coastal plain would have already been anticipating it to be our turn given how stormy the winter started overall. (IAD would end up with 5" in a couple of days.)

 

We probably won't get blanked--- even the trying winters of 91/92 and 94/95 had a couple of decent snowstorms. I just think that we can let go of the 86/87 route (snow getting closer to the coast storm-by-storm) for getting to a historic winter. If we end up above average somehow, 86/87 will still be a bad analog for how the winter progressed. 

[Ji]

all we need is a feb 83 or Feb 03 or Feb 10 and were good. Im in until Feb passes and none of that happens

[EastCoast NPZ]

Based on the CWG article, it appears that a snow-less December neither increases or decreases our snow-accumulation potential during the remainder of the winter; I'm counting that as a win.  

??

 

Only 5 instances out of 18 has a snowless Dec resulted in AN snowfall.  The effect is rather evident.