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January 2016 Disco/Obs: A New Year, A New Pattern


Rjay

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it will probably hit 70 again in February if the ao/nao is very positive like it was in December...Hopefully that won't happen...

Hopefully, that won't happen.

 

With respect to an AO+/EPO+/PNA+ setup in super El Niño cases, below are 500 mb and temperature anomalies for the composites and the 240-hour EPS means:

 

Teleconnections_ENSO01162016.jpg

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Hopefully, that won't happen.

With respect to an AO+/EPO+/PNA+ setup in super El Niño cases, below are 500 mb and temperature anomalies for the composites and the 240-hour EPS means:

Teleconnections_ENSO01162016.jpg

How is that a +PNA with such troughing/low heights out west? Most people think of a +PNA as having a ridge over the Rockies extending towards a mid-latitude block over the PAC that keeps maritime air out of the CONUS. Besides, why is the West so cold in the +PNA depicted? Not sure why this map is labeled as a +PNA given the features shown....
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How is that a +PNA with such troughing/low heights out west? Most people think of a +PNA as having a ridge over the Rockies extending towards a mid-latitude block over the PAC that keeps maritime air out of the CONUS. Besides, why is the West so cold in the +PNA depicted? Not sure why this map is labeled as a +PNA given the features shown....

Lower anomalies south of ak than over the yukon and nwt. Take a look at the loading pattern on esrl youll see it.

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Lower anomalies south of ak than over the yukon and nwt. Take a look at the loading pattern on esrl youll see it.

I understand the technicalities of the longitudinal and latitudinal boxes and the loading pattern for the PNA, but this is more of a case of such low heights near AK that anything else seems positive. There is no defined western ridge, nor a mid-latitude block shutting off mild Pacific air from entering the CONUS. For all intents and purposes, this resembles a -PNA in terms of the sensible weather: cold, wet west and a drier and warmer east.

What remains to be seen is whether this regime coming in late Jan/early Feb can be serviceable further north in New England and the upper Mid Atlantic. The obvious advantage is the strong STJ and storminess during the coldest climo of winter; however, New England does much better with a traditional Bermuda ridge to the southeast and lower heights near Hudson Bay establishing a gradient rather than the higher heights to the north which may cement the low snow cover, dry pattern. If this pattern is to take us to mid February, those hoping for near climo snowfall must hope that the regime is indeed serviceable.

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Greatest AO reversal from positive in November and December to negative in January.

It went from +4.503 on December 22nd to -4.800..-4.900 today. We can thank the

assist from the near to record Kara block which spread out across the Arctic over to

Greenland. Fantastic animation from the CPC. So this is our second winter extreme

this year following the historic December warmth.

 

http://www.cpc.ncep.noaa.gov/products/intraseasonal/z500_nh_anim.shtml

 

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Greatest AO reversal from positive in November and December to negative in January.

It went from +4.503 on December 22nd to -4.800..-4.900 today. We can thank the

assist from the near to record Kara block which spread out across the Arctic over to

Greenland. Fantastic animation from the CPC. So this is our second winter extreme

this year following the historic December warmth.

 

http://www.cpc.ncep.noaa.gov/products/intraseasonal/z500_nh_anim.shtml

 

attachicon.gifao.obs.gif

Looks like the pattern was just slow to materialize .

You may get your IVT trough light snows today out on LI

. A week of BN . Then the area probably sees it's first snowstorm next weekend while the Euro ensembles have an EC day 11 system before the pullback .

Would love to pull this one out of the hat and see the good period opined about verify 

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This morning's AO was -4.916. That's the lowest AO figure since March 22, 2013 when the AO was -5.240. In cases where the AO dropped to -4.000 or below at this time of January, February typically featured a lot of blocking.

 

More immediately, an AO-/PNA+ pattern promotes a higher frequency of measurable snowfalls in the Mid-Atlantic and southern New England regions.

 

As the pattern has potential and there has been some increased support for the idea of a storm that could impact parts of the area in the January 23-24 timeframe, I took a look at all snowstorms that brought at least 4" snow to Boston, New York City, Philadelphia, or Washington, DC (1950-2015) on January 23 +/- 15 days. I then filtered the sample for the forecast AO and PNA values. Below is the breakdown of such storms by amount in the above four cities:

 

01172016jan8feb7snowstorms.jpg

 

Nothing is guaranteed just yet. All of the above cities had at least one case among those storms where they did not receive any snowfall. But if a moderate or greater snowfall occurs, especially given the ongoing El Niño, somewhere from Philadelphia to Boston (including adjacent interior sections) might have the best chance to receive a significant snowfall.

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This morning's AO was -4.916. That's the lowest AO figure since March 22, 2013 when the AO was -5.240. In cases where the AO dropped to -4.000 or below at this time of January, February typically featured a lot of blocking.

 

More immediately, an AO-/PNA+ pattern promotes a higher frequency of measurable snowfalls in the Mid-Atlantic and southern New England regions.

 

As the pattern has potential and there has been some increased support for the idea of a storm that could impact parts of the area in the January 23-24 timeframe, I took a look at all snowstorms that brought at least 4" snow to Boston, New York City, Philadelphia, or Washington, DC (1950-2015) on January 23 +/- 15 days. I then filtered the sample for the forecast AO and PNA values. Below is the breakdown of such storms by amount in the above four cities:

 

01172016jan8feb7snowstorms.jpg

 

Nothing is guaranteed just yet. All of the above cities had at least one case among those storms where they did not receive any snowfall. But if a moderate or greater snowfall occurs, especially given the ongoing El Niño, somewhere from Philadelphia to Boston (including adjacent interior sections) might have the best chance to receive a significant snowfall.

the first snowstorm in 1965-66 although partly tainted was on January 23rd-24th...then three more events in two weeks including the KU east coast snowstorm on the 30th...I had a bunch of el nino winters that started slow and peaked in February...1965-66 was near the average of those analogs...

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only ten winters since 1950 had a lower ao than todays number...If this is the winters lowest ao number at least we are seeing some wintry weather today...Not a big e but a start...

winter.......AO min. date...

1976-77...-7.433...01/15/1977...

1969-70...-6.365...03/05/1970

1984-85...-6.226...01/19/1985

2009-10...-5.821...12/21/2009

2012-13...-5.688...03/20/2013

1977-78...-5.291...02/05/1978

1968-69...-5.282...02/13/1969

2010-11...-5.172...12/18/2010

1965-66...-5.130...01/28/1966

1962-63...-5.010...01/21/1963

2015-16...-4.916...01/17/2016

2000-01...-4.854...02/25/2001

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