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Stormlover74

January 2021 General Discussions & Observations Thread

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Through the first 50 days of meteorological winter, the AO has averaged -1.900. It has been negative on 96% of days. It has been at or below -1.000 on 84% of days and at or below -2.000 on 50% of days. This blocking will likely continue into at least the closing days of January.

Overnight into tomorrow morning, some snow showers and show flurries are likely. Parts of the region could pick up a coating of snow. There could be some additional opportunities for snowfall during the remainder of January, as blocking continues. However, significant or major snowstorms are probably not very likely.

There continues to be ensemble support for some light snow or flurries in parts of the region during the January 21-23 timeframe during the passage of a strong cold front. Another timeframe highlighted by the ensembles is January 25-28. The latter period may have greater potential. However, neither period is likely to produce a significant snowfall (6" or above) for the Washington, DC to Boston corridor.

AO-/PNA- patterns are typically not snowy. The frequency of measurable snowfall is just over 90% of climatology in Boston and Philadelphia and around 80% of climatology in New York City for the January 21-31, 1950-2020 period. The frequency of 2" or more daily snowfall was just above 90% of climatology for Philadelphia, but fell sharply to 50% of climatology in New York City and 65% of climatology in Boston. For daily snowfall amounts in excess of 2", the frequency fell sharply for Philadelphia. As a result, such patterns typically have produced significant snowstorms (6" or above snowfall) in the northern Middle Atlantic and southern New England regions during late January. The biggest snowfalls during an AO-/PNA- pattern during the January 20-31, 1950-2020 period were as follows: Boston: 7.3", January 21, 2011; New York City: 4.2", January 21, 2011; and, Philadelphia: 3.0", January 20, 2000.

Afterward, the evolution of the AO will determine whether potential for measurable snow events will continue into February.

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 +22.99 today.

Today, the preliminary Arctic Oscillation (AO) figure was -2.012.

On January 18 the MJO was in Phase 4 at an amplitude of 0.636 (RMM). The January 17-adjusted amplitude was 1.007.

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 87% probability that New York City will have a warmer than normal January. January will likely finish with a mean temperature near 35.2°.

 

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17 hours ago, bluewave said:

Yeah, we need to ease up on the south based blocking suppression risk for the OP Euro to work out. The 0z Euro run was showing what needs to happen with the 2 storms. There aren’t that many years with the strongest AO blocking sitting just east of The Canadian Maritimes. The record holders for the previous strongest south based blocking for the entire winter were 2005, 1969, and 1951.

0727CF59-0744-4733-B039-126ED78D3E50.gif.d3eb0541714ee245d9551ae1e8f34ff9.gif
C24F04A6-EE6E-4DD5-BEDB-5F2D50AB9360.png.25b35d40291a7ca57736d46423996f09.png

 

2005 and 1969 were both pretty good winters

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17 hours ago, donsutherland1 said:

There are some differences from the pattern shown in that late December post concerning January 1-20. In this case, there is model consensus that the EPO will go negative for a time before returning to positive levels. That opens the door for some snowfall potential for the Middle Atlantic region, but that’s not a good pattern for significant (6” or above) snowfalls. It will be interesting to see what the ECMWF shows today after the 0z run had a sizable snow event.

I wonder about our tendency to now get bigger precip bombs, if analogs from 30+ years ago can still be used.

a storm that would have given us 4-6 inches of snow 30 years ago may be more likely to give us 8-10 inches now, and likewise a storm that was going to give us half an inch of rain 30 years ago may be more likely to give us an inch.

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9 hours ago, bluewave said:

The storm potential around January 25th will feature one of the rarest teleconnection combinations that we have ever seen in January. A -1.5 or lower -PNA has only coincided with a -1.5 or lower -AO during  3 Januaries since 1950. The only 3 times  that I could find were focused around 1-9-56, 1-5-59, and 1-2-65. Such a strong January -PNA has usually occurred with a +AO. So late January will continue the competing influences theme that we have seen since the fall. Needless to say, all these odd combinations make seasonal and medium range forecasting that much more difficult.

F3EA8D78-6093-4258-A707-E5E57F9ACD83.gif.8ed046323b83b76c3c039c21518adbb7.gif
DF0CB16D-CF61-4F84-BBA2-257A2420B518.thumb.png.9b2c659c81520385355b510a4f03f6d2.png

 

that actually looks like an omega block that we see when wavelengths shorten in March.

One thing that we haven't discussed yet, since blocking in various regions has become more common now, can climate change result in shortening wavelengths to even occur in January?  Perhaps we are seeing that now.

 

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11 hours ago, bluewave said:

It’s ridiculous how warm the minimums have been in Northern New England this month. Caribou is +17 on the minimums and +8.1 on the maximums. This gives a +13.1 average departure.
 

Climatological Data for Caribou Area, ME (ThreadEx) - January 2021
Click column heading to sort ascending, click again to sort descending.
Date
Max Temperature 
Min Temperature 
Avg Temperature 
Avg Temperature Departure 
HDD 
CDD 
Precipitation 
Snowfall 
Snow Depth 
Sum 521 328 - - 740 0 0.97 7.3 -
Average 28.9 18.2 23.6 13.1 - - - - 6.7
Normal 19.8 1.2 10.5 - 981 0 1.59 14.6 -
2021-01-01 23 8 15.5 3.3 49 0 0.00 0.0 5
2021-01-02 22 12 17.0 5.0 48 0 0.33 4.0 5
2021-01-03 25 7 16.0 4.3 49 0 0.00 0.0 9
2021-01-04 26 21 23.5 12.1 41 0 0.00 0.0 9
2021-01-05 29 22 25.5 14.3 39 0 T T 8
2021-01-06 30 19 24.5 13.5 40 0 0.04 0.3 7
2021-01-07 29 21 25.0 14.2 40 0 0.00 0.0 7
2021-01-08 24 21 22.5 11.9 42 0 0.02 0.2 6
2021-01-09 31 20 25.5 15.1 39 0 T T 6
2021-01-10 28 7 17.5 7.3 47 0 0.00 0.0 6
2021-01-11 27 7 17.0 6.9 48 0 T T 6
2021-01-12 32 23 27.5 17.6 37 0 0.04 0.6 6
2021-01-13 32 24 28.0 18.2 37 0 T 0.1 7
2021-01-14 33 26 29.5 19.8 35 0 T T 7
2021-01-15 34 26 30.0 20.4 35 0 T T 6
2021-01-16 33 21 27.0 17.5 38 0 0.38 0.6 6
2021-01-17 33 30 31.5 22.0 33 0 0.15 1.3 7
2021-01-18 30 13 21.5 12.1 43 0 0.01 0.2 8
2021-01-19 M M M M M M M M M
2021-01-20 M M M M M M M M M
2021-01-21 M M M M M M M M M
2021-01-22 M M M M M M M M M
2021-01-23 M M M M M M M M M
2021-01-24 M M M M M M M M M
2021-01-25 M M M M M M M M M
2021-01-26 M M M M M M M M M
2021-01-27 M M M M M M M M M
2021-01-28 M M M M M M M M M
2021-01-29 M M M M M M M M M
2021-01-30 M M M M M M M M M
2021-01-31 M M M M M M M M  

Did you get a load of Bismarck ND average temp anomalies?  +10 for December and +20 so far two thirds of the way through January!

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14 hours ago, bluewave said:


January 16th to February 15th has been our peak period for 12”+ snowstorms in the OKX forecast zones since 2010.

Roughly 2 week snowfall periods for the 2010's and number of 12"+ snowstorms

Oct 29-Nov 15.....3

Nov 16-Nov 30....0

Dec 1- Dec 15.....0

Dec 16-Dec 31....3

Jan1-Jan 15.......4

Jan16-Jan 31.....5

Feb 1-Feb 15.....6

Feb 16-Feb 28...1

Mar 1- Mar 15....6

Mar 16-Mar 31...1

Apr 1-Apr 16.....0

Can you do one of those for 6"+ snowstorms too?  Thanks!

Wait.....we had 3 12"+ snowstorms between Oct 29 and Nov 15?!

 

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18 hours ago, bluewave said:

The 0z Euro was as good  a thread the needle as you will ever see for the 26th. Could be a first with winter wavelengths for such a deep -PNA trough in the West tracking perfectly from west to east under -AO block. The next system actually has more of a +PNA as heights build out West. So root for the Euro over the other guidance if you like rabbit out of a hat snowstorms. People would quickly forget the snow drought over the last month.

F8EC0477-F013-4355-98AC-0CC868B841F4.thumb.png.20fd116925791714811bcb7127a92261.png
FFC9B4F0-66EC-4413-93C9-5658E6F9E79E.thumb.png.ed9dede0e394037bda0d8f5e5a08e4de.png

 

awesome to see one of these.  time to put the pacific to bed once and for all.

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19 hours ago, North and West said:


It’s the tranquility that does it for me, in regards to reminding me of my childhood. Just nothing going on precipitation wise.

I’m concerned about drought later in the year.


.

especially with some predicting an extreme heat summer!

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fwiw and definitely not a focus for me in this conversation. I think we need to get through this morning, and 25th-26th... but fwiw... a clipper event or another w-e east event is modeled by some of the  ENS sometime between the 28th-30th.  Not big but just another chance. How much is realized these next 10 days?? 

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The next 8 days are averaging 32degs., (27/36).          Making it 27degs , or -5.0.

The 06Z is a warm run.      Shows some morsels of snow for today.     No BN 20 readings for the month.          EURO/CMC are colder with their 0Z runs, as was the 0Z GFS.      The 26th. is DOA and has been removed to the 30th ----or maybe it will rise again like the Phoenix. 

38*(59%RH) here at 6am.      36* at 7am with wet snow.        35*(80%RH) at 7:15am.        I hope everyone feels better sexually after the short snow release.       Beach here has a tinch of white.     Yay!          39* by 1pm.          32* by 6pm.

The way it looked on radar at about 7:30am................

1611145920-BRA2Eyd2MZo.png

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Morning thoughts...

Following this morning’s light snow and flurries, it will become partly sunny. Temperatures will likely reach the lower 40s in most of the region. Likely high temperatures around the region include:

New York City (Central Park): 41°

Newark: 43°

Philadelphia: 43°

A strong cold front could bring another period of light snow or flurries on Friday.

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7 hours ago, LibertyBell said:

I wonder about our tendency to now get bigger precip bombs, if analogs from 30+ years ago can still be used.

a storm that would have given us 4-6 inches of snow 30 years ago may be more likely to give us 8-10 inches now, and likewise a storm that was going to give us half an inch of rain 30 years ago may be more likely to give us an inch.

Certainly, with a warming climate, moisture content has increased.

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8 hours ago, LibertyBell said:

Did you get a load of Bismarck ND average temp anomalies?  +10 for December and +20 so far two thirds of the way through January!

A continuation of the summer pattern of recent years when the most impressive warm departures at times went north of us.

 

 

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20 minutes ago, Allsnow said:

Euro ensemble mean snowfall for next week is 10 inches between 3 storms 

Very active pattern

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A weak disturbance brought a round of light snow and snow showers across the region today. Snowfall amounts included:

Allentown: Trace
Bridgeport: Trace
Islip: 0.2"
New York City: Trace
Newark: 0.3"
Philadelphia: Trace

The remainder of the week will be fair and seasonably cold. A much colder air mass will arrive for the weekend. Parts of the region could struggle to reach freezing on Saturday and Sunday.

As Arctic blocking persists, next week could feature one or perhaps two more opportunities for snowfall, with the greatest risk focused on the January 25-28 timeframe. However, a widespread significant snowfall (6" or above) still appears relatively unlikely. A light or moderate snowfall is more likely.

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.

Afterward, the evolution of the AO will determine whether potential for measurable snow events will continue into February.

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 +4.86 today.

Today, the preliminary Arctic Oscillation (AO) figure was -2.124.

On January 19 the MJO was in Phase 5 at an amplitude of 0.425 (RMM). The January 18-adjusted amplitude was 0.638.

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 90% probability that New York City will have a warmer than normal January. January will likely finish with a mean temperature near 35.0°.

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