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November 2020 General Discussions & Observations Thread

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3 hours ago, wdrag said:

I see it in 12z/23 CMC.  

No question phasing for a big storm is complicated (not a high prob) and if comes in pieces, how it all transpires makes a sig difference in ptype outcomes this time of year. Monitoring. If this potential continues another two days, may start a 48-72 hr topic on wet wind event, followed by ptype-accumulative western-northwestern suburbs snow.  Sooooo. early right now and prefer not give this second storm idea much credence, yet.  Another post somewhere in NYC forum a day or 3 ago had also mentioned the colder more interesting look to DEC around here.  In the end, we've got to keep in mind stats-climo.  

Do you think the Euro is showing  its bias in holding too much energy back to the SW? Its12z depiction of a SE coastal low looks much different than the 12z GFS,CMC, and UKMET.  The GFS, UKMET, and CMC have a warmer storm track closer to our area.


8CFB0E32-082E-4592-9872-7556A8B49470.gif.ea74f83cf7e92d32eece750a2cf5eb05.gif
ED73F6AF-21FA-4D4E-81F5-6ED03DA93613.gif.75d82f631ce983e2e4218f3ad1a77483.gif

EC2A49A3-E416-4A91-8022-7BA33F8DC0C5.gif.9e50d1c3a92b5849d29ea233ba02f7e4.gif

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18 minutes ago, Allsnow said:

12z eps is fire for snow potential to start December 

Eps also shows a small signal for early December

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25 minutes ago, psv88 said:

Seems about right. The PWS in our area are generally around 1.50". My fire pit is filled with water, so we had a ton

Okay, cool.  Thanks for confirming.

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Tomorrow will be fair but cool. Most of the region will see high temperatures top out in the middle and upper 40s. Wednesday should be somewhat milder. Readings will rebound into the upper 50s and lower 60s for Thanksgiving Day as a storm passes to the north and west of the region.

Tomorrow through Thursday, a storm will move out of the Plains States toward the Great Lakes Region and into Canada. This storm could bring a significant rainfall to the Central Plains States into the eastern Great Lakes Region. North and west of the storm track, including southern Minnesota, southern Wisconsin, Michigan's Upper Peninsula, and parts of Ontario (excluding the greater Toronto area), a moderate to significant snowfall is possible.

December could see above normal temperatures redevelop during the first week of the month after starting off on a cool note. However, the possible development of a period where the AO is negative and PNA is positive could delay the warmup. However, both historic experience following exceptionally warm November cases and the latest weekly and monthly guidance still suggest a warmer than normal December is the base case.

The ENSO Region 1+2 anomaly was -0.7°C and the Region 3.4 anomaly was -1.5°C for the week centered around November 18. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.90°C and the ENSO Region 3.4 anomaly has averaged -1.42°C. La Niña conditions will likely prevail at least through the winter.

The SOI was -7.83.

Today, the preliminary Arctic Oscillation (AO) figure was +2.264.

On November 22 the MJO was in Phase 3 at an amplitude of 0.962 (RMM). The November 21-adjusted amplitude was 1.344.

Based on the latest guidance, no significant stratospheric warming event is likely through the end of November.  

Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 10/11 (91%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO. A predominant EPO+/AO+ pattern is very likely for winter 2020-21. It is likely that the Middle Atlantic and southern New England areas will see a warmer than normal winter with below normal snowfall.

Since 1950, there have been four La Niña winters that started with a warm December in the Northeast and warmth across much of Canada, as is the current forecast on the monthly EPS, latest weekly EPS and latest CFSv2 monthly guidance: 1974-75, 1998-99, 1999-00, and 2011-12. All featured a warmer than normal winter and among the winter months that followed December, only January 2000 was colder than normal in the East. Median seasonal snowfall figures were as follows: New York City: 12.9" and Philadelphia: 13.1".

Since 1970, there were 9 winters that saw the AO and EPO average +0.25 or above. Mean snowfall for Boston, Harrisburg, New York City, Philadelphia, and Washington, DC averaged 50% of the most recent 30-season mean. The largest snowfall deficits relative to the most recent 30-season mean figure were located in the Philadelphia to New York City corridor. In addition, 33% of cases saw less than 10" seasonal snowfall in New York City and 44% saw less than 10" seasonal snowfall in Philadelphia.

Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a warmer than normal November. November will likely finish with a mean temperature near 51.6°.

The implied probability for a November mean temperature of 50.0° in Central Park is now approximately 95%. Since 1869, there have been 19 cases where November had a mean temperature of 50.0° or above. 14/19 (74%) went on to have a warmer than normal December, including 9/19 (47%) with a December mean temperature of 40.0° or above (2.5° or more above normal). The winter mean temperature for those 14 cases was 37.5° (2.2° above normal). The winter mean temperature for the subset of December cases with a mean temperature of 40.0° or above was 38.9° (3.6° above normal) and four of those cases wound up having an average winter temperature of 40.0° or above.

 

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4 hours ago, bluewave said:

Do you think the Euro is showing  its bias in holding too much energy back to the SW? Its12z depiction of a SE coastal low looks much different than the 12z GFS,CMC, and UKMET.  The GFS, UKMET, and CMC have a warmer storm track closer to our area.


8CFB0E32-082E-4592-9872-7556A8B49470.gif.ea74f83cf7e92d32eece750a2cf5eb05.gif
ED73F6AF-21FA-4D4E-81F5-6ED03DA93613.gif.75d82f631ce983e2e4218f3ad1a77483.gif

EC2A49A3-E416-4A91-8022-7BA33F8DC0C5.gif.9e50d1c3a92b5849d29ea233ba02f7e4.gif

I don't know. The following are a bunch of words.  I'm a little confused about NAEFS evolution.  

Typically it's the GFS that is too slow coming out of the SW USA but in this case, it's faster and I like it (it doesn't lock up in desert sw). Whether I like it and am more right than wrong???

What I do see is quite a bit of potential the first two weeks of Dec for southern stream short waves coming up off the east coast. In other words... precip threats  but whether snow or rain???  The NAEFS is trending confidently below normal across Dixie early December, and above normal southern Canada. That is a broad displacement and an active southern stream (I think).  Could be wrong ,especially if the future cycles of the NAEFS lose the modeled departures. I may comment tomorrow or Wednesday?   Todays cycle has quite a bit of 200MB jet constantly south of 37N, especially early Dec and it is modeled the predominant jet in N America.  Doesn't seem Nina like? More Nino-like to me,  at least temporarily.  No?????

It's modeling-subject to large errors beyond 7 days as you noted earlier?  Yourself and others probably understand whether what is ensemble modeled, can realistically happen Dec 1-14. For me, it's probably best to not broadcast too much hope but be aware of what appears to be a somewhat better pattern of "opportunities" to begin DJF.  Maybe we can an inch or two of snow out of this pattern in NYC in early Dec? 

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The last 7 days of November are averaging 51degs.[46/55].       Making it 46degs., or +3.0.

Month to date is 53.2[+4.3].          November should end at 51.5[+4.0].       Using the uncorrected 51, November would end at 52.7.

Our chances for any Action/Jackson look dim.      The only item I see is that Tampa's 32 straight month run w/o a BN one---will be in jeopardy at the start of December.     Under the hood BN air and we may miss a lot of it.

42*(61%RH) here at 6am.         48* by 2pm.         49* at 3pm.

 

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NYC holding in 1st place for warmest November by a narrow margin with several more 60° days possible.

KNYC   GFSX MOS GUIDANCE  11/24/2020  0000 UTC                       
 FHR  24| 36  48| 60  72| 84  96|108 120|132 144|156 168|180 192      
 TUE  24| WED 25| THU 26| FRI 27| SAT 28| SUN 29| MON 30| TUE 01 CLIMO
 X/N  49| 40  56| 49  62| 51  61| 51  62| 43  49| 45  56| 42  45 35 48


 

Time Series Summary for NY CITY CENTRAL PARK, NY - Month of Nov
Click column heading to sort ascending, click again to sort descending.
Rank
Year
Mean Avg Temperature 
Missing Count
1 2020 53.2 7
2 2015 52.8 0
3 2001 52.7 0
4 1979 52.5 0
5 1948 52.4 0
6 1975 52.3 0
7 2011 51.9 0
- 2006 51.9 0
- 1994 51.9 0
- 1931 51.9 0
8 1902 51.4 0
9 2009 51.1 0
10 1999 50.8 0
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No topic yet on what I think is a probable Nov 30-Dec 1 big storm with greatest magnitude here (wind/rain and low prob backside covering of snow I84 high terrain). This per ensemble departures from normal. 

00z/24 EC came back to 45-55 MPH gusts in the op run.  

Continued Nino look first half Dec BUT I think the 500 ridge may be a touch too far east in early Dec, however some interesting coastal opportunities seem to be presented in the ensembled guidance.  Also I respect the considerations presented on Pacific firehose impressions and maybe a cruddy looking pattern. To me it's not as bad as now. 

Not sure how AO is considered so positive. I don't see it developing that way at all. There is a general suppressed blocking trend in the modeling (see GEFS confidence graphic attached at 216 hours - RMOP--- very confident).

MJO evolution to me (novice) has mixed messaging though overall no outrageous warm signal for us (am I missing something????just let me-us know) - and generally trending possibly to a weak phase 1 or 8??

Euro weeklies: Best to look at 500MB,  then 850 MB temp pattern for unfolding surface response. Warm in Canada doesn't mean above freezing (nighttimes lengthening there with adequate snow cover).   After discussion last year with a met friend on the New England forum, I don't look at the sfc temp weeklies at all beyond week two.  They just don't seem to verify very well. 

I may not be able to respond to any thoughts-corrections until midday-this afternoon.  Have a good day. 736A/24

 

 

Screen_Shot_2020-11-24_at_7_23.52_AM.png

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Morning thoughts...

Today will be variably cloudy and cool. High temperatures in the region will likely reach the upper 40s to around 50° in most of the region. Likely high temperatures around the region include:

New York City (Central Park): 47°

Newark: 50°

Philadelphia: 50°

An unseasonably mild Thanksgiving Day holiday lies ahead.

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22 minutes ago, bluewave said:

We continue to to see the multiyear pattern of the day 8-15 model guidance underestimating ridging and warmth near the Northeast. This is why it’s tough to take the week 2 ensemble guidance at face value for our area. This would consistently show up on the CPC model bias site before they stopped updating. Also notice how the day 10 forecasts weren’t that bad for other areas. Perhaps, it has something to do with the unusually warm SSTs off the East Coast? 

New run

3FBE8270-A239-4B71-94C0-45348414DE2D.thumb.png.5b656671d6d1503309d9ceae20351d68.png

Old run

 

D2224C21-968E-4E76-B2CB-27D06A7B35DF.thumb.png.58d9c513b51e7a709d9c522035de1470.png


New run

99DF75F9-E140-46B4-BE70-E43880FC4588.thumb.png.739cfb77a526d496559219826afd7421.png

Old run


CF871A0C-D122-4A67-ADDC-C4ABEF6B12B0.thumb.png.ead427fab689186718f7ff3283881091.png

 

 

 

The last week of November was never supposed to be cold. Too much pac influence from the lower hgts in Ak. It’s after the 1st when we start seeing a +pna with -nao to suppress the southeast ridge 

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1 minute ago, bluewave said:

Not cold, but not this warm either. Notice how the models are now backing off the colder forecast that had for early December. 

New run

2FE53611-DCE2-49A6-A749-17CC29741B4D.thumb.png.113c1389b1191444e8a40d0d33e77454.png

 

Old run

2FE53611-DCE2-49A6-A749-17CC29741B4D.thumb.png.113c1389b1191444e8a40d0d33e77454.png

 

6DC78EDB-8034-4360-9991-8D86E2F1AB17.png

Lots of pac influence with the +pna and lower hgts near Ack. We have a niño pattern to start December with a Aleutian low/+pna/-nao. We will be trapping a meh airmass under the block. It looks like after the 5th the ridge goes more poleward. 

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19 minutes ago, bluewave said:

The ridge going poleward too far west near Baffin Island won’t really help us with the cold since the NAO will still be neutral to positive. The heights on the current model runs don’t really build into Greenland or Iceland.  +EPO + NAO  +PNA is a mild pattern across the northern tier.

D4C90B25-6DC3-4C48-8DE3-B1D3A30DC64F.thumb.png.45be7dde1abc23df4d27098b01b1fd8f.png

 

Its a much better pattern for the SE than Us or SNE.  It’s one of those patterns where it’s sunny and relatively mild for NNE and it’s snowing in the upstate of Georgia to NC, I’ve seen it before.  It’s a rare suppressed pattern that isn’t cold in December

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19 minutes ago, bluewave said:

The ridge going poleward too far west near Baffin Island won’t really help us with the cold since the NAO will still be neutral to positive. The heights on the current model runs don’t really build into Greenland or Iceland.  +EPO + NAO  +PNA is a mild pattern across the northern tier.

D4C90B25-6DC3-4C48-8DE3-B1D3A30DC64F.thumb.png.45be7dde1abc23df4d27098b01b1fd8f.png

 

It will help cool eastern Canada closer to normal  if it goes poleward. +3 for Canada is plenty cold for snow for us in this pattern. 
 

Good to see that southeast ridge Niña look is not coming for December 

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Don't get me wrong, I'll take this all over the doom and gloom we thought awaited us last week.  But the way I see it, as depicted, we would basically just be suppressing the torch for a time and could expect a snap-back at some point unless we can nudge some ATL or PAC ridging poleward a bit.  I think the current look could work for us coasties yearning for snow later on in December, but I'm not sure it'll get the job done in its first week.  If this is the best pattern we are going to get, I think we'd be better off if it was delayed by a few weeks.

Hoping for some December 2017 fortune here!  My gut tells me that we don't get completely shut out this winter.

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Gfs looks good after November 30. 

Cold air is around, nice ridging up North, I think there's potential for something.

You'd probably want a big phaser for that late November storm though.

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19 minutes ago, SnoSki14 said:

Gfs looks good after November 30. 

Cold air is around, nice ridging up North, I think there's potential for something.

You'd probably want a big phaser for that late November storm though.

Cmc  also looks good

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Good afternoon,  If you can, give me til ~ 530P when I can more thoroughly assess for a topic Nov 30-Dec 1 storm and associated hazards. Doing Christmas things right now. 12z run jumped upon something...suddenly multiple models pretty intense storm.  Not a lock for this strong and would like to review a bunch of ensemble stuff after 4P.  As noted by others   Op runs from GFS, CMC, ICON among the few checked. 

 

 

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12z Euro would be a continuation of our unusually active late fall convection pattern. Has an impressive low topped squall to start December with early morning temps in the 60s.

21054AFB-843F-4977-BBAA-BAFFB6ED6886.gif.3166eb7de21ef61989453f9deec7acd2.gif

7BC0B4EF-E17E-44D4-A213-E81F0FC67EEB.gif.7f4788a5690c17a76b8a17535800e921.gif

 

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54 minutes ago, Allsnow said:

Some real potential for the first half of December to produce snow in this pattern. Hopefully it works out. 

E4D62BD9-E91B-4A4D-976C-7ED9D2775BD0.png

Is the strength  of the La Nina this year similiar to 2010-2011?

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