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January 2021 General Discussions & Observations Thread


Stormlover74
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17 hours ago, Eduardo said:

I think it's because, since the Earth orbits the sun elliptically, the speed of its rotation varies slightly during different times of the year.  Thus, not every solar day is exactly 24 hours long.  IIRC, solar days are slightly longer during the (Northern Hemisphere's) Winter Solstice and slightly shorter during the Summer Solstice--although I might very well have that backwards.  In any event, we still set our clocks based on a 24-hour day (y'know, to keep life orderly) and the difference in time between how we set our clocks and how fast the Earth is actually rotating yields that impression of "asymmetry" you noticed.  In short, the asymmetry is created by the discrepancies between solar days and 'clock days.'

 

I hope this is right.  Been a loong time since I took Earth Science. 

Sounds right lol.  I noticed that when I do night time photography of the stars I have to adjust my timings to account for the "sidereal day" which is the time between when the stars will be at the same position in the skies as they were the previous day- the sidereal day is 23 hr 56 min long, so the stars reach the same position in the sky as they were the previous night, four minutes earlier.  The reason for this discrepancy is because both the rotation and revolution of the earth need to be factored in.  

Maybe the solar days are slightly longer in the winter in the Northern Hemisphere because the earth is actually closest to the sun in January, which is winter for us, but in the Southern Hemisphere winter happens in July, when the earth is furthest from the sun.

 

 

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15 hours ago, donsutherland1 said:

Colder air drilled into the region with a few snow flurries and snow showers. A much colder air mass will cover the region during the weekend. Parts of the region could struggle to reach freezing tomorrow and again on Sunday.

The closing week of January will likely be colder than normal across the region. Milder weather will likely return during the first week of February. Some of the guidance suggests that temperatures could surge to much above normal levels for a time.

Meanwhile in northern Canada, Nunavut experienced another day with near record and record high temperatures. High temperatures included:

Coral Harbour: 22° (old record: 20°, 1963)
Iqaluit: 33°
Kimmirut: 36° (old record: 14°, 2003)
Kinngait: 29° (old record: 17°, 1980)
Kugaaruk: 19° (old record: 6°, 1995)
Naujaat: 25° (old record: 3°, 1995)
Pangnirtung: 32° (old record: 20°, 2000)
Qikiqtarjuaq: 15° (missed record from 2013 by 0.2°C)

The abnormal warmth will likely continue in Nunavut through tomorrow.

As Arctic blocking persists, next week could feature two opportunities for snowfall. The earlier event (January 25-27 timeframe) will likely focus its heaviest snows on the Philadelphia to New York City area. The latter event (January 28-29 timeframe) will likely focus its heaviest snows in an area running from Richmond to Washington, DC.

A widespread significant snowfall (6" or above) still appears relatively unlikely, especially for the first event. A light or moderate snowfall (2"-4" or 3"-6") remains more likely. However, some of the guidance suggests that the second storm could rapidly intensify, so there is a greater degree of uncertainty for that event in terms of amounts.

AO-/PNA- patterns typically do not produce significant or major snowstorms for the Middle Atlantic or southern New England regions in late January or early February. During the January 20-February 7, 1950-2020 period, there have been 5 storms that brought 4" or more snow to at least two of the following cities--Boston, New York City, or Philadelphia--during an AO-/PNA- pattern. None of those storms brought 6" or more snow to two or more of those cities. Therefore, until the potential events are within 72 hours or less and the guidance suggests otherwise, the base case is against a widespread significant or major snowfall.

The ENSO Region 1+2 anomaly was -0.3°C and the Region 3.4 anomaly was -1.2°C for the week centered around January 13. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.73°C and the ENSO Region 3.4 anomaly has averaged -1.08°C. La Niña conditions will likely prevail at least through meteorological winter.

The SOI was +1.14 today.

Today, the preliminary Arctic Oscillation (AO) figure was -2.238.

On January 21 the MJO was in Phase 6 at an amplitude of 1.071 (RMM). The January 20-adjusted amplitude was 0.684.

Following a significant stratospheric warming event, the stratosphere is now cooling. The cooling will likely accelerate during the second half of January. As is typical for vortex-splitting events, the major piece of the polar vortex migrated to Eurasia. The end result has been an absence of severe cold in much of North America.

The significant December 16-17 snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish.

Based on sensitivity analysis applied to the latest guidance, there is an implied 95% probability that New York City will have a warmer than normal January. January will likely finish with a mean temperature near 35.2°.

 

what's keeping the second storm from riding up the coast, Don?

 

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Just now, HVSnowLover said:

So close and yet so far, we usually know how there things end but might be congrats up to LI 

One thing I notice for sure is the NAM at 84 looks a heck of a lot more like the GFS and CMC with the shortwave out in the SW than it does the Euro.  The CMC did come slightly southeast this run  

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On 1/22/2021 at 9:38 AM, bluewave said:

14  out of 17 winter months warmer than average is pretty extreme. We knew something was up when December 2015 went +13.3. It appears to have been a climate shift to warmer winters.
 

NYC

Dec 15....+13.3

Jan 16....+1.9

Feb 16....+2.4

Dec 16....+0.8

Jan 17....+5.4

Feb 17....+6.3

Dec 17....-2.5

Jan 18.....-0.8

Feb 18....+6.7

Dec 18....+2.6

Jan 19....-0.1

Feb 19....+0.9

Dec 19....+0.8

Jan 20....+6.5

Feb 20....+4.8

Dec 20.....+1.7

Jan 21.....+5.2....so far

then again it's probably better that this happened in the winter rather than the summer....could you imagine summers getting that extreme?  I love my 100 degree days but no way would I want that to happen every week!

 

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1 minute ago, MJO812 said:

Gefs keeps things interesting 

Historically these things usually end up with the GFS being wrong.  I can count a handful of occasions where at this range the GFS and GEFS loved a storm and the Euro/EPS hated it where the GFS won.  In a La Niña winter you do have to sometimes give the the GFS more credit.  No question the NAM does resemble the GFS a bit more at 84 with the shortwave than the Euro  

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Just now, bluewave said:

120 hrs isn’t going to fix the suppression problem.

No, but the modeling could EASILY adjusted the latitude of the key players 100 miles or more in that timeframe, and that's all it would take and then some.  By 2pm the euro could show a nice hit and the GFS nothing a few hours later.  There is a nice storm signal and that's really all that's important at this point.  

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22 minutes ago, bluewave said:

You will need much more than a 100 mile change to make this work.

Well, if you take the GFS as depicted at hr 126 and move the features NW by 100 miles then much of central NJ would be into significant snow.  What's "much more"?  If we move those features NW by 200 miles we'd be looking at P-type issues.   Anyway, I would feel no more confident in a snowstorm next Friday even if the GFS showed exactly the right setup at this range.  

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12Z GFS is another Nothing Burger.        5" from 0.40" LE and a 2mT barely 32*, or actually >32*?

The 18Z GFS (not shown) likes   Feb. 01 and Feb. 05 for some snow.       Not even a Nothing Burger any more in Jan., just a water balloon painted to look like a Big Mac.

As for breaking below 20 degrees tomorrow morning all, models (GFS CMC EURO and  National Blend are calling for 22 only.     The NWS using its NDFD is calling for 19 degrees-----Whoopee!

1611403200-3ZYgdx3Cuts.png

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