December 2017 Discussions & Observations Thread

[Tatamy]

35 minutes ago, Ja643y said:

Normally don't post, but wondering if anyone sees the possibility for some LI Sound enhanced snows on the north shore with the NW winds bringing Arctic air traveling over the warm water. I know it' a rare phenomenon, but seems the set-up might be right in the next few days?

You don't typically get LI sound effect snows on a NW wind with an Arctic airmass.  In fact in 20 years spent living on the north shore I never saw it happen.  As LBSF posted the fetch is not long enough.  The only place out on LI that might get such snows would be out on the north fork with the correct wind vector and favorable atmospheric conditions.  You can get sound enhanced snows in a synoptic scale event with a northeast surface wind on the north shore.  That is fairly common.  There are other circumstances where you can get ocean effect snows especially on the east end with favorable atmospheric conditions.

[ForestHillWx]

33 with a north west wind at 7mph. Noticeably colder than this afternoon. 

[cardinalland]

It is very lightly snowing here with strong winds.

[Rtd208]

Temperature dropping rapidly here from 41 down to 37 over the last hour.

[ict1523]

Light snow in the south Bronx.

[Morris]

35 in the park.

[Cfa]

Moderate to occasionally heavy snow on the LIE.

[dmillz25]

Down to 34 here

[LongBeachSurfFreak]

Just had light snow on the UWS, any standing water is going to flash freeze 

[LongBeachSurfFreak]

4 hours ago, Tatamy said:

You don't typically get LI sound effect snows on a NW wind with an Arctic airmass.  In fact in 20 years spent living on the north shore I never saw it happen.  As LBSF posted the fetch is not long enough.  The only place out on LI that might get such snows would be out on the north fork with the correct wind vector and favorable atmospheric conditions.  You can get sound enhanced snows in a synoptic scale event with a northeast surface wind on the north shore.  That is fairly common.  There are other circumstances where you can get ocean effect snows especially on the east end with favorable atmospheric conditions.

Speaking of lake effect the Ontario band tonight is bonkers. Perfect fetch for the tug hill they have to be have 4”+ hour rates 

[Tatamy]

13 minutes ago, LongBeachSurfFreak said:

Speaking of lake effect the Ontario band tonight is bonkers. Perfect fetch for the tug hill they have to be have 4”+ hour rates 

Actually took two vacations up near Lake Ontario this past summer.  We drove the length of the lake shore from Niagara Falls up to Sodus Point east of Rochester.  It was nice to be able to relate the radar images from what we see during the winter time to what the area is really like.  There is a lighthouse in Golden Hill State Park up near Barker, NY where you can stay any time of the year.  It is right on the lake.  The sunrises and sunsets are to die for.  If you want to take a vacation and enjoy the Lake effect experience this could be a good choice of course it is nicer in the summer.  It runs $200 per night and is a suite with three bedrooms (former keeper's quarters).  They have camping there too.  The facility is old and shows its age but is still a great experience.  The area to the north and east of Rochester is a big time area for Lake effect snows in the winter.  The shore there reminds me of the north shore of LI (Suffolk Cty).  They have wineries there to boot.  There is a great beach at Sodus Point.  There is a lot to see up there.

[snywx]

25 minutes ago, LongBeachSurfFreak said:

Speaking of lake effect the Ontario band tonight is bonkers. Perfect fetch for the tug hill they have to be have 4”+ hour rates 

http://www.nysmesonet.org/mesonow#?stid=COPE

 

[Morris]

Cheap midnight low incoming, saving today's departure.

[Rtd208]

Current temp down to 31 here.

[snywx]

21° here... 

[Rtd208]

Current temp is 21 here.

[CIK62]

Next 8 days averaging 35degs., 1 or 2 degrees BN.

Month to date is +1.7@NYC, so we should be back at the starting gate for month, as we go into the last 10 days of the year.

[doncat]

19° here...Sometimes I can't understand temp forcasts...Last evenings  nws low temp forcast was mid-upper 20's...Looked at models and saw nothing that warm.

[Morris]

20 in the park. Will we get our first teens? I don't know what the NWS forecast was thinking?

[CIK62]

Continuous R/S/R threats in around Chirstmas day, say 22-28th.

[dmillz25]

19 here

[JerseyWx]

17° here

[Paragon]

17 hours ago, bluewave said:

That cold pool appeared following the record summer Greenland melt in 2012. Shortly after that, we switched to a more +NAO regime. It was quite a record -NAO run from June 2009 to March 2013.

Is some of this also due to the slowing of the Gulf Stream?  That should mean colder and stormier weather in Western Europe too.

 

 

[Paragon]

26 minutes ago, CIK62 said:

Continuous R/S/R threats in around Chirstmas day, say 22-28th.

Yeah, I'd think mix/rain for the coast, snow further inland.

[Paragon]

12 hours ago, Tatamy said:

You don't typically get LI sound effect snows on a NW wind with an Arctic airmass.  In fact in 20 years spent living on the north shore I never saw it happen.  As LBSF posted the fetch is not long enough.  The only place out on LI that might get such snows would be out on the north fork with the correct wind vector and favorable atmospheric conditions.  You can get sound enhanced snows in a synoptic scale event with a northeast surface wind on the north shore.  That is fairly common.  There are other circumstances where you can get ocean effect snows especially on the east end with favorable atmospheric conditions.

Best place for OES is Cape Cod.  An interesting case for sound enhanced snow can be made with the Dec 1995 snowstorm that dumped 14" of snow at LGA but only 8" at NYC.

 

[Paragon]

10 hours ago, LongBeachSurfFreak said:

Just had light snow on the UWS, any standing water is going to flash freeze 

Too bad we didn't get any snow on the south shore.

[Paragon]

8 hours ago, Tatamy said:

Actually took two vacations up near Lake Ontario this past summer.  We drove the length of the lake shore from Niagara Falls up to Sodus Point east of Rochester.  It was nice to be able to relate the radar images from what we see during the winter time to what the area is really like.  There is a lighthouse in Golden Hill State Park up near Barker, NY where you can stay any time of the year.  It is right on the lake.  The sunrises and sunsets are to die for.  If you want to take a vacation and enjoy the Lake effect experience this could be a good choice of course it is nicer in the summer.  It runs $200 per night and is a suite with three bedrooms (former keeper's quarters).  They have camping there too.  The facility is old and shows its age but is still a great experience.  The area to the north and east of Rochester is a big time area for Lake effect snows in the winter.  The shore there reminds me of the north shore of LI (Suffolk Cty).  They have wineries there to boot.  There is a great beach at Sodus Point.  There is a lot to see up there.

It's going to be a great place to see the April 2024 total solar eclipse as long as the weather holds.

 

[Paragon]

21 hours ago, donsutherland1 said:

Last night, the EPS diverged from the continuity of its recent runs. Instead of featuring a deep trough along the East Coast in late December, the EPS displaced the trough to the west, leading to ridging along the immediate East Coast. Such a pattern is consistent with the generic composite for La Niña events. So, is it time for panic? Is winter, which got off to a fairly fast start in terms of snowfall, effectively winding down?

In both cases, the answer is “No.”

The data for winters in which a December storm brought 4” or more snow to Boston, New York City, and Philadelphia, strongly suggests that such storms have indicated a snowy to very snowy winter. 6/7 (86%) of cases saw 40” or more snowfall for New York City.

So far, in terms of the first 12 days of December, all such days featured a negative AO and positive PNA. Since 1950, there were 17 La Niña events. The persistent AO- during this period also has been associated with above average snowfall for the La Niña winters.

The following La Niña winters saw two thirds or more days during the December 1-12 period with AO- figures (seasonal snowfall figures for Central Park are included):

1955-56: 33.5” seasonal snowfall
1995-96: 75.6” seasonal snowfall
2000-01: 35.0” seasonal snowfall
2005-06: 40.0” seasonal snowfall
2010-11: 61.9” seasonal snowfall

A linear regression using the percentage of days with AO- figures and PNA+ figures for the 12/1-12 period yielded the following ranges (mean figure +/- standard error) and actual outcomes:

1954-55: Estimated range: 11.4”-35.2”; Actual: 11.5”
1955-56: Estimated range: 27.3”-51.1”; Actual: 33.5”
1964-65: Estimated range: 15.2”-39.0”; Actual: 24.4”
1970-71: Estimated range: 11.1”-34.9”; Actual: 15.5”
1971-72: Estimated range: 17.0”-40.8”; Actual: 22.9”
1973-74: Estimated range: 21.7”-45.5”; Actual: 23.5”
1975-76: Estimated range: 5.8”-29.6”; Actual: 17.3”
1983-84: Estimated range: 13.8”-37.6”; Actual: 25.4”
1984-85: Estimated range: 11.1”-34.9”; Actual: 24.1”
1988-89: Estimated range: 0.0”-11.8”; Actual: 8.1”
1995-96: Estimated range: 26.8”-50.6”; Actual: 75.6” (outlier beyond the standard error)
1999-00: Estimated range: 0.5”-24.3”; Actual: 16.3”
2000-01: Estimated range: 32.1”-55.9”; Actual: 35.0”
2005-06: Estimated range: 33.0”-56.8”; Actual: 40.0”
2008-09: Estimated range: 11.1”-34.9”; Actual: 27.6”
2010-11: Estimated range: 44.8”-68.6”; Actual: 61.9”
2011-12: Estimated range: 0.0”-20.7”; Actual: 7.4”

Seasonal  snowfall for cases with a minimum estimated figure of 20.0” or more:

1955-56: 33.5”
1973-74: 23.5”
1995-96: 75.6”
2000-01: 35.0”
2005-06: 40.0”
2010-11: 61.9”

% with < 10”: 0%
% with < 20”: 0%
% with 20” or more: 100%
% with 30” or more: 83%
% with 40” or more: 50%

Seasonal  snowfall for cases with a minimum estimated < 20.0”:
1954-55: 11.5”
1964-65: 24.4”
1970-71: 15.5”
1971-72: 22.9”
1975-76: 17.3”
1983-84: 25.4”
1984-85: 24.1”
1988-89: 8.1”
1999-00: 16.3”
2008-09: 27.6”
2011-12: 7.4”

% with < 10”: 18%
% with < 20”: 55%
% with 20” or more: 45%
% with 30” or more:  0%
% with 40” or more: 0%

Estimated 2017-2018 range: 30.6”-54.4”

Caveat: Sample size issues could arise.

Overall, there are a number of indications that winter 2017-18 will likely feature above normal snowfall in the New York City region (actually much of the Mid-Atlantic area and New England).

Finally, if one looks at the long-range GEFS, one finds a cluster of ensemble members suggesting that even as the AO- is forecast to give way to an AO+ in the near-term, AO blocking will redevelop in the extended range of the forecast. That idea is consistent with the historic experience described above. It is also consistent with the prior runs of the EPS, which suggests that the 0z EPS may be an outlier for late December. It should also be noted that weekly guidance beyond two weeks has low skill. My best guess remains that winter 2017-18 will see similar cold and snowfall to that of winter 2000-01. A 2010-11-type outcome may still be on the table, but the lack of deep blocking through the medium-term may suggest that the probability of such an outcome has decreased.

All said, there’s no need to panic as a short-term relaxation of the pattern unfolds. Winter is just starting. Things appear to be on course for a snowy winter.

Based on your analysis, Don, that means there were several winters that were more favorable for snowfall than 1995-96 was, but for some reason or other, those patterns didn't fully reach their potential like 1995-96 did?  Oh and didn't 1955-56 get 39.2" seasonal snowfall? That's what my weather almanac says (maybe they reanalyzed it)?

 

The only storms in 1995-96 that didn't reach their full potential that I can recall were the Dec 1995 storm where NYC got 8" (prediction was for 15-20") but LGA did get 14" in that one.  And the April 1996 storm where 6-12" were predicted and NYC somehow only got 0.7" while JFK got 4.5"

 

Blizzard of January 1996 was more of a case of underreporting at NYC rather than anything else, surrounding stations EWR and LGA both recorded 27-28" and NYC only 20"?!

 

[Paragon]

23 hours ago, Drz1111 said:

That’s a snowy look for the EC though.  Nothing massive but lots of opps for advisory level snows in the SW flow at that time of year with good high-latitude blocking.

If we get one more moderate 4-6" event this month down near the coast consider us lucky.  I would think anything more than that is extremely unlikely (less than 10% chance.)

[Paragon]

20 hours ago, bluewave said:

January 2016. It looks like we are on track for our our 7th +NAO December in a row.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.nao.monthly.b5001.current.ascii.table

 

Chris, climatologically speaking is there a reason why + NAO would be more likely than - NAO?  I feel like in my over 3 decades living in NYC + NAO have been much more common than - NAO, furthermore not all - NAO are good, east based specifically.  So, statistically speaking 2 out of 3 NAO states are bad for us.