December 2020 General Discussions & Observations Thread

[Cfa]

Mid 60’s and sunny in South Jersey today. Long Island still foggy, glad I’m not there right now.

[wdrag]

What am i to make of the continuously decreasing negative 3.4 Dec anomaly?    and from what I can tell MJO influences may be weakening toward the end of the month? Any implications of both changes on winter snow here?    

GEFS seems to attempt a +PNA toward the end of the month and continues some sort of Greenland + anomaly.  Just seems like wintry options may still be on the table?  

Is there a different read?

Thank you very much for any reply,

Walt

[the_other_guy]

48F Very dense fog. I look out my window and see white.

 

Very unusual to get this density at this time of day

For perspective I took this shot with a bit of interior.

 

1/4 Mile vis at most

[forkyfork]

looking down at an undercast in secaucus from the jersey city heights 

[weathermedic]

Dense fog advisories up for much of the area.

[donsutherland1]

The major synoptic story of the opening of December is the return of the negative Arctic Oscillation (AO). Through today, the AO has been negative on 83% of days, including -1.000 or below on 67% of days. The AO has averaged -1.169 this month.

During the December 10-31, 1950-2019 period, an AO- was the most important teleconnection for a significant Middle Atlantic (6" or more) snowstorm. Since 1950, the following percentage of 6" or greater snowstorms occurred when the AO was negative: Boston: 50%; New York City: 75%; and, Philadelphia: 88%. There were 8 snowstorms that brought 6" or more snow to at least two of the following cities: Boston, New York City, and Philadelphia. 7/8 (88%) occurred when the AO was negative. All storms from the subset from these 8 storms where 10" or more snow fell in at least one of those cities occurred with a negative AO. The most common synoptic pattern when at least two of the aforementioned cities picked up 6" or more snow (63%) was an AO-/PNA+ combination. The most recent such storm was the December 25-27, 2010 "Boxing Day Blizzard."

Colder air will return to the region after the coming weekend. The recent guidance has suggested a fairly impressive cold shot for late next week. The return of the colder air could coincide with some storminess.

There is growing model and ensemble support for a significant Middle Atlantic and New England snowstorm next Wednesday into Thursday. There remains some uncertainty about the storm's track, which could make a large difference in snowfall amounts along parts of the coastal plain. Near record to record cold could develop in northwestern Canada during the middle or latter part of next week.

A sustained warmer pattern could develop toward the winter solstice. The closing 10 days of December could wind up generally warmer than normal. The EPS weeklies and subseasonal guidance are in agreement that the last week of December will likely be warmer than normal. Uncertainty has increased, as the AO is likely to remain negative into the closing week of December and perhaps beyond it.

Historic experience following exceptionally warm November cases suggests that a warmer than normal December remains the base case. Almost 90% of cases with a November mean temperature of 51.5° or above in Central Park (2020 saw the temperature average a record 52.9° in November) went on to record a warmer than normal December and just over three-quarters of such cases saw December register a monthly mean temperature of 40.0° or above. The probability of December's having a 40.0° or above mean temperature has fallen sharply with the development of strong AO blocking.  

The ENSO Region 1+2 anomaly was -0.5°C and the Region 3.4 anomaly was -1.1°C for the week centered around December 2. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.77°C and the ENSO Region 3.4 anomaly has averaged -1.35°C. La Niña conditions will likely prevail at least through the winter.

The SOI was +15.88.

Today, the preliminary Arctic Oscillation (AO) figure was -2.549. That is the lowest AO value since December 26, 2019 when the AO was -2.773.

On December 11 the MJO was in Phase 5 at an amplitude of 1.642 (RMM). The December 10-adjusted amplitude was 1.376.

Based on the latest guidance, no significant stratospheric warming event is likely through the third week of December.

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.

Based on sensitivity analysis applied to the latest guidance, there is an implied 58% probability that New York City will have a warmer than normal December. December will likely finish with a mean temperature near 39.0°.

 

[CIK62]

The next 8 days are averaging 34degs.(28/40).          Making it 29degs., or -7.0.

Month to date ( site still down)

Snow Totals summary:    EURO   16",  GFS  18",   CMC   10".       Non gust wind speeds still 18-25mph.      Monday is a non event except for helping to set up El Gordo.

53*(90%RH) here at 6am.     60* by 1pm.

[CPcantmeasuresnow]

On 12/12/2020 at 4:51 AM, CPcantmeasuresnow said:

I've touched on this subject quite a bit the last two years, but now that we're down to the last three weeks I thought it would be a good time to review where NYC, Central Park specifically, stands in the quest for a 30 inch snowfall average when the new 30 year averages are calculated next month.

For those not aware how it works the 30 year snowfall averages will be calculated for the period from January 1991 through December 2020. In short this will mean say goodbye to the 1980's from the averages, which hold the record as the least snowiest decade recorded.

Assuming NOAA calculates the averages for each month by rounding up or down to the nearest tenth of an inch, the months who have their 30 years completed look as follows:

October..........0.1

November.....0.5

December.....4.9 (29 year avg)  final number to be determined

January.........8.7

February......10.1

March............5.0

April..............0.4

May..................T

The 30 year average calculated now would be 29.7 inches.

To get December to a 5.2 average, or in this case 5.15 which should round up to 5.2, Central Park will need to record 11.3 inches of snow this December, which is what will be needed to get the 30 year average to 30.0 inches. Currently the December 1991 -2020 period averages 4.773 inches which would round to 4.8 and would make the 30 year average 29.6 inches if no snow falls this December.

Here's to hoping that if Wednesday is indeed a surprise heavy snowfall for the city, the Conservancy? doesn't measure 11.2 inches and leave us hanging for the rest of the month.

 

21 hours ago, LibertyBell said:

I see another interesting tidbit in there- February is going to finish with a 10.1 inch average- when was the last time we had a 30 year monthly average in double digits?

 

The answer to that is never. The closest was the period 1891-1920 when the seasonal average was 32.2 inches and February averaged 9.8 inches for that period. The monthly breakdowns for that time period which as stated earlier was the last 30 year period to average more than 30 inches per season was as follows:

......November........December........January..........February...........March.............April................Total..........

 

[LibertyBell]

36 minutes ago, CPcantmeasuresnow said:

 

The answer to that is never. The closest was the period 1891-1920 when the seasonal average was 32.2 inches and February averaged 9.8 inches for that period. The monthly breakdowns for that time period which as stated earlier was the last 30 year period to average more than 30 inches per season was as follows:

......November........December........January..........February...........March.............April................Total..........

 

wow this is some unexpectedly historic stuff.  When I used to sit in my college library and analyze old snowfall records at NYC and Philly (and there were plenty of records going all the way back to the late 1700s and complete documentation of the 1800s), I never expected that we would ever exceed those numbers!  That was part of the reason I loved reading about those times.  I wondered how people handled it without electricity.  But now, although we dont have nearly the kind of hardship that existed back then (yes, even with the current pandemic, life must've been much tougher back then), we can now say we've had bigger snowstorms and snowfall totals in recorded history than ever before!

 

[bluewave]

Today should be the warmest day of the month so far with widespread 60s.

 

KEWR   GFS MOS GUIDANCE   12/13/2020  0000 UTC                      
 DT /DEC  13            /DEC  14                /DEC  15          /  
 HR   06 09 12 15 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 18 00 
 X/N                    63          37          44          29    40 
 TMP  51 50 50 55 60 59 53 47 42 40 39 39 41 41 38 37 34 32 30 38 32 

[CPcantmeasuresnow]

33 minutes ago, LibertyBell said:

wow this is some unexpectedly historic stuff.  When I used to sit in my college library and analyze old snowfall records at NYC and Philly (and there were plenty of records going all the way back to the late 1700s and complete documentation of the 1800s), I never expected that we would ever exceed those numbers!  That was part of the reason I loved reading about those times.  I wondered how people handled it without electricity.  But now, although we dont have nearly the kind of hardship that existed back then (yes, even with the current pandemic, life must've been much tougher back then), we can now say we've had bigger snowstorms and snowfall totals in recorded history than ever before!

 

Here's the list since official records began. Many interesting things of note here.

As I noted when this discussion began. NYC needs to record 11.3 inches of snow this December to get the December average to 5.2 and thus the 30 year average to 30.0. It may be close and depend on who is working the ruler the next three weeks and how much they really care about accurate snow measurements in Central Park. It's been a very inexact science through the last several decades.

[uncle W]

 I get a 30" seasonal average snowfall when rounding out the months totals...without the rounding numbers the total would be 29.9"...

decade.......................Oct.....Nov.....Dec.....Jan.....Feb.....Mar.....Apr.....total

1870-71 to 1879-80......0.1.....0.9.....6.7......9.7......8.8.....4.1......1.6.....31.9
1880-81 to 1889-90........0......1.8.....7.1......8.8......7.6.....6.8......0.7.....32.8
1890-91 to 1899-00........0......3.3.....4.3......8.7....10.6.....7.1......0.8.....34.8
1900-01 to 1909-10........0......0.3.....6.2......9.1......9.2.....4.8......0.6.....30.2
1910-11 to 1919-20........0......0.2.....7.5......4.8......9.5.....8.3......2.3.....32.6
1920-21 to 1929-30......0.1.....0.1.....4.2......8.5....10.1.....2.2......0.9.....26.1
1930-31 to 1939-40........T......2.2.....4.3......6.4......8.5.....3.5......0.8.....25.7
1940-41 to 1949-50........T......0.6.....9.1......7.4......8.6.....4.8......1.1.....31.6
1950-51 to 1959-60......0.1.....0.5.....4.7......5.2......3.4.....8.0......0.8.....22.7
1960-61 to 1969-70........T......0.3.....7.4......7.7....10.6.....4.6......0.1.....30.7
1970-71 to 1979-80........T......0.3.....1.7......7.3......9.5.....2.4......0.1.....21.3
1980-81 to 1989-90........0......0.6.....2.1......7.8......5.3.....2.9......1.1.....19.8
1990-91 to 1999-00........0......0.3.....2.9......6.9......9.1.....5.4......0.2.....24.8
2000-01 to 2009-10........T........T......7.8......6.5....13.3.....3.5......0.4.....31.5
2010-11 to 2019-20......0.3.....1.1.....4.4....12.9......8.1.....6.0......0.6..…33.4

1870-71 to 2009-10........T......0.8.....5.4......7.5......8.9.....4.9......0.8.....28.3
1990-91 to 2019-20......0.1.....0.5.....5.0......8.8....10.2.....5.0......0.4.....30.0

 

[donsutherland1]

Morning thoughts...

Today will be partly to mostly sunny and very mild. Temperatures will likely top out in the upper 50s and lower 60s in most of the region. Likely high temperatures around the region include:

New York City (Central Park): 61°

Newark: 62°

Philadelphia: 63°

Colder air will return beginning tomorrow, along with some rain with snow in parts of the region. A significant Middle Atlantic and New England snowstorm (6” or more snow) is likely Wednesday into Thursday.

The operational GFS is the most suppressed guidance at present. A look at the EPS individual members shows a farther north extent of the significant snow. 

Boston:  6” or more: 92% members; 10” or more: 73% members

New York City (Central Park): 6” or more: 86% members; 10” or more: 55% members

Philadelphia: 6” or more: 35% members; 10” or more: 22% members

[CPcantmeasuresnow]

51 minutes ago, uncle W said:

 I get a 30" seasonal average snowfall when rounding out the months totals...without the rounding numbers the total would be 29.9"...

decade.......................Oct.....Nov.....Dec.....Jan.....Feb.....Mar.....Apr.....total

1870-71 to 1879-80......0.1.....0.9.....6.7......9.7......8.8.....4.1......1.6.....31.9
1880-81 to 1889-90........0......1.8.....7.1......8.8......7.6.....6.8......0.7.....32.8
1890-91 to 1899-00........0......3.3.....4.3......8.7....10.6.....7.1......0.8.....34.8
1900-01 to 1909-10........0......0.3.....6.2......9.1......9.2.....4.8......0.6.....30.2
1910-11 to 1919-20........0......0.2.....7.5......4.8......9.5.....8.3......2.3.....32.6
1920-21 to 1929-30......0.1.....0.1.....4.2......8.5....10.1.....2.2......0.9.....26.1
1930-31 to 1939-40........T......2.2.....4.3......6.4......8.5.....3.5......0.8.....25.7
1940-41 to 1949-50........T......0.6.....9.1......7.4......8.6.....4.8......1.1.....31.6
1950-51 to 1959-60......0.1.....0.5.....4.7......5.2......3.4.....8.0......0.8.....22.7
1960-61 to 1969-70........T......0.3.....7.4......7.7....10.6.....4.6......0.1.....30.7
1970-71 to 1979-80........T......0.3.....1.7......7.3......9.5.....2.4......0.1.....21.3
1980-81 to 1989-90........0......0.6.....2.1......7.8......5.3.....2.9......1.1.....19.8
1990-91 to 1999-00........0......0.3.....2.9......6.9......9.1.....5.4......0.2.....24.8
2000-01 to 2009-10........T........T......7.8......6.5....13.3.....3.5......0.4.....31.5
2010-11 to 2019-20......0.3.....1.1.....4.4....12.9......8.1.....6.0......0.6..…33.4

1870-71 to 2009-10........T......0.8.....5.4......7.5......8.9.....4.9......0.8.....28.3
1990-91 to 2019-20......0.1.....0.5.....5.0......8.8....10.2.....5.0......0.4.....30.0

 

Hey Uncle thanks for the input.

I believe our differences are due to rounding and how NOAA will handle that I'm not sure. Also I'm calculating December right now as if no snow will fall for the month which will give it a 4.8 inch average for 1991-2020. Here are the averages carried out past the one tenth decimal.

I'm assuming they round January down to 8.7 and February down to 10.1. On the other months I'm rounding up and we agree and that accounts for our.differences.

As to what NOAA will do who knows. They had the calculation for 1981-2010 incorrect for 4 years at 25.1 inches. I had to e-mail them several times over the course of a year until to their credit they finally checked and corrected their data in March 2014 and posted the average at 25.8. I still calculate 25.9 for that period but I let it go at that point.

 

 

 

[bluewave]

Great day to finish any yard clean ups with a top 5 warmest 12-13 in tap.

 

Data for December 13 - NY CITY CENTRAL PARK, NY
Click column heading to sort ascending, click again to sort descending.

Date	Max Temperature	Min Temperature	Precipitation	Snowfall	Snow Depth
2015-12-13	67	55	0.00	0.0	0
1923-12-13	64	42	0.10	0.0	0
1984-12-13	63	46	0.00	0.0	0
1946-12-13	63	36	T	0.0	0
1919-12-13	61	42	0.07	0.0	0
1990-12-13	60	41	0.00	0.0	0
1968-12-13	60	36	0.00	0.0	0
1949-12-13	60	36	0.17	0.0	0

[waveryder002]

Just watched Bernie Rayno's Periscope live and he's indicating NYC will mix and is projecting 6-12 inches.  If there's no mixing, 1 foot possible.  Thoughts?

[Stormlover74]

Meanwhile low 60s on tap for today

[SI Mailman]

Christmas Day cutter on the 12z GFS.  

[MJO812]

Eps has more chances

[MJO812]

5 hours ago, SI Mailman said:

Christmas Day cutter on the 12z GFS.  

Not on the 18z gfs

[donsutherland1]

Strong Arctic blocking continues. That blocking will likely pave the way for a significant to perhaps major Middle Atlantic and New England snowstorm Wednesday and Thursday. Significant snowfall is likely in such cities as Boston, New York City, Newark, and Philadelphia, as well as north and west of those cities.

Before then, tomorrow will be cloudy and noticeably cooler. Rain is likely and parts of the region could see snow with some accumulation. A major storm will then develop and move off the northern Delmarva Peninsula and pass south of Long Island Wednesday into Thursday. There remains some uncertainty about the storm's track, which could make a large difference in snowfall amounts along parts of the coastal plain. The probability of a significant snowfall (6" or more) has increased further for such cities as Philadelphia, New York City, and Boston.

Select EPS Ensemble Members:

6" or more:
Boston: 90%
Islip: 86%
New York City: 96%
Philadelphia: 67%
Poughkeepsie: 94%

10" or more:
Boston: 75%
Islip: 65%
New York City: 73%
Philadelphia: 39%
Poughkeepsie: 68%

During the December 10-31, 1950-2019 period, an AO- was the most important teleconnection for a significant Middle Atlantic (6" or more) snowstorm. Since 1950, the following percentage of 6" or greater snowstorms occurred when the AO was negative: Boston: 50%; New York City: 75%; and, Philadelphia: 88%. There were 8 snowstorms that brought 6" or more snow to at least two of the following cities: Boston, New York City, and Philadelphia. 7/8 (88%) occurred when the AO was negative. All storms from the subset from these 8 storms where 10" or more snow fell in at least one of those cities occurred with a negative AO. The most common synoptic pattern when at least two of the aforementioned cities picked up 6" or more snow (63%) was an AO-/PNA+ combination. The most recent such storm was the December 25-27, 2010 "Boxing Day Blizzard."

Near record to record cold could develop in northwestern Canada during the middle or latter part of this week.

A sustained warmer pattern could develop toward the winter solstice. The closing 10 days of December could wind up generally warmer than normal. The EPS weeklies and subseasonal guidance are in agreement that the last week of December will likely be warmer than normal. Uncertainty has increased, as the AO is likely to remain negative into the closing week of December and perhaps beyond it.

Historic experience following exceptionally warm November cases suggests that a warmer than normal December remains the base case. Almost 90% of cases with a November mean temperature of 51.5° or above in Central Park (2020 saw the temperature average a record 52.9° in November) went on to record a warmer than normal December and just over three-quarters of such cases saw December register a monthly mean temperature of 40.0° or above. The probability of December's having a 40.0° or above mean temperature has fallen sharply with the development of strong AO blocking.  

The ENSO Region 1+2 anomaly was -0.5°C and the Region 3.4 anomaly was -1.1°C for the week centered around December 2. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.77°C and the ENSO Region 3.4 anomaly has averaged -1.35°C. La Niña conditions will likely prevail at least through the winter.

The SOI was +16.97.

Today, the preliminary Arctic Oscillation (AO) figure was -2.734. That is the lowest AO value since December 26, 2019 when the AO was -2.773.

On December 12 the MJO was in Phase 5 at an amplitude of 1.525 (RMM). The December 11-adjusted amplitude was 1.637.

Based on the latest guidance, no significant stratospheric warming event is likely through the third week of December.

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.

Based on sensitivity analysis applied to the latest guidance, there is an implied 63% probability that New York City will have a warmer than normal December. December will likely finish with a mean temperature near 39.0°.

 

[LibertyBell]

17 hours ago, CPcantmeasuresnow said:

Here's the list since official records began. Many interesting things of note here.

As I noted when this discussion began. NYC needs to record 11.3 inches of snow this December to get the December average to 5.2 and thus the 30 year average to 30.0. It may be close and depend on who is working the ruler the next three weeks and how much they really care about accurate snow measurements in Central Park. It's been a very inexact science through the last several decades.

The most unfortunate part of the official record is that New York City (as in The Battery at that time) recorded close to 100 inches of snow in the season before official records began.

[CIK62]

The next 8 days are averaging 32degs.(28/37).         Making it 27degs., or -9.0.

Month to date (still missing).    +40/13 = +3.1 to date.         Should be about  -32/21 = -1.5 by the 22nd.        Gotta love that GFS for Christmas:     58,38,42,57,38----last five runs, and last week it was in the 60's.       Now with Christmas back at 38* it goes ahead and adds 20 degrees to the 27,28,29,30.         

Winter Storm Summary(today + Wed./Thurs.)

CMC  0" +17"    EURO  1" + 16"    GFS  0" +8".     Non gust winds still 20-25mph.

NWS going with GFS and does not have even have a Watch for the City!     18" marker ends near City and goes no further east.

45*(57%RH) here at 6am.        38* by 4pm.

[LibertyBell]

21 hours ago, bluewave said:

Great day to finish any yard clean ups with a top 5 warmest 12-13 in tap.

 

Data for December 13 - NY CITY CENTRAL PARK, NY
Click column heading to sort ascending, click again to sort descending.

Date	Max Temperature	Min Temperature	Precipitation	Snowfall	Snow Depth
2015-12-13	67	55	0.00	0.0	0
1923-12-13	64	42	0.10	0.0	0
1984-12-13	63	46	0.00	0.0	0
1946-12-13	63	36	T	0.0	0
1919-12-13	61	42	0.07	0.0	0
1990-12-13	60	41	0.00	0.0	0
1968-12-13	60	36	0.00	0.0	0
1949-12-13	60	36	0.17	0.0	0

wow 12/2015 really did break all sorts of warm records, never would have guessed there was a 30 incher on the way a month later or below zero on Valentines Day lol

 

[donsutherland1]

Morning thoughts...

At 7:25 am, precipitation was moving into the region. Rain had changed to snow in a line running from East Stroudsburg, PA to Poughkeepsie.

Today will mainly cloudy and cooler. Some rain that could end as snow, especially north and west of the major cities is likely. Parts of the area could pick up a minor accumulation. Temperatures will likely top out in the lower 40s this morning in most of the region. Likely high temperatures around the region include:

New York City (Central Park): 40°

Newark: 41°

Philadelphia: 42°

A significant to major Middle Atlantic and New England snowstorm (6” or more snow) is likely Wednesday into Thursday.

The operational GFS, which had been the most suppressed guidance has moved closer in line with the ECMWF and GGEM Models at 6z. A look at the EPS individual members continues to show a significant to perhaps major snowstorm in much of the region.

Boston:  6” or more: 84% members; 10” or more: 78% members; 12” or more: 59% members

Islip: 6” or more: 90% members; 10” or more: 55% members; 12” or more: 37% members

New York City (Central Park): 6” or more: 98% members; 10” or more: 80% members; 12” or more: 43% members

Philadelphia: 6” or more: 49% members; 10” or more: 24% members; 12” or more: 14% members

Poughkeepsie: 6” or more: 94% members; 10” or more: 78% members; 12” or more: 55% members

[the_other_guy]

Sleet falling 38F

[LibertyBell]

47 minutes ago, donsutherland1 said:

Morning thoughts...

At 7:25 am, precipitation was moving into the region. Rain had changed to snow in a line running from East Stroudsburg, PA to Poughkeepsie.

Today will mainly cloudy and cooler. Some rain that could end as snow, especially north and west of the major cities is likely. Parts of the area could pick up a minor accumulation. Temperatures will likely top out in the lower 40s this morning in most of the region. Likely high temperatures around the region include:

New York City (Central Park): 40°

Newark: 41°

Philadelphia: 42°

A significant to major Middle Atlantic and New England snowstorm (6” or more snow) is likely Wednesday into Thursday.

The operational GFS, which had been the most suppressed guidance has moved closer in line with the ECMWF and GGEM Models at 6z. A look at the EPS individual members continues to show a significant to perhaps major snowstorm in much of the region.

Boston:  6” or more: 84% members; 10” or more: 78% members; 12” or more: 59% members

Islip: 6” or more: 90% members; 10” or more: 55% members; 12” or more: 37% members

New York City (Central Park): 6” or more: 98% members; 10” or more: 80% members; 12” or more: 43% members

Philadelphia: 6” or more: 49% members; 10” or more: 24% members; 12” or more: 14% members

Poughkeepsie: 6” or more: 94% members; 10” or more: 78% members; 12” or more: 55% members

Don do you have a probability breakdown for the various amounts for JFK, Allentown and Mt Pocono?  Thanks in advance.  There seems to be a major change between 10" and 12" for some reason....like NYC going from 80 percent to 43 percent.  I wonder if JFK is similar to this.

 

[donsutherland1]

14 minutes ago, LibertyBell said:

Don do you have a probability breakdown for the various amounts for JFK, Allentown and Mt Pocono?  Thanks in advance.  There seems to be a major change between 10" and 12" for some reason....like NYC going from 80 percent to 43 percent.  I wonder if JFK is similar to this.

 

Allentown:  6” or more: 98% members; 10” or more: 67% members; 12” or more: 47% members

JFK: 6” or more: 78% members; 10” or more: 39% members; 12” or more: 25% members

Mount Pocono: 6” or more: 98% members; 10” or more: 78% members; 12” or more: 47% members

[bluewave]

This could be the first time that the AO was positive for nearly every day in November and negative for so many days in December.
 

 

[Allsnow]

Sheet of ice outside currently