December 2019

[snowman19]

1 hour ago, bluewave said:

The GFS is currently on its own. The Euro, UKMET, and CMC have a low in the Great Lakes and a separate southern stream low.

Either the GFS/GEFS is going to score a rare coup or it’s going to bust horribly. The Euro/EPS, CMC/GEPS and UKMET are in agreement with a completely different solution with that low in the Great Lakes

[bluewave]

7 minutes ago, snowman19 said:

Either the GFS/GEFS is going to score a rare coup or it’s going to bust horribly. The Euro/EPS, CMC/GEPS and UKMET are in agreement with a completely different solution with that low in the Great Lakes

The 12z GFS just took a step in the direction of the other models. Now has a weak low in the GL and a separate southern stream low to the south.

12z

6z

 

 

[MJO812]

11 minutes ago, snowman19 said:

Either the GFS/GEFS is going to score a rare coup or it’s going to bust horribly. The Euro/EPS, CMC/GEPS and UKMET are in agreement with a completely different solution with that low in the Great Lakes

It's a weak away. This is normal with big east coast storms. All we need is the pac to cooperate and the northern stream to dig.

Not impossible this far out

[donsutherland1]

9 minutes ago, Snow88 said:

It's a weak away. This is normal with big east coast storms. All we need is the pac to cooperate and the northern stream to dig.

Not impossible this far out

During the second half of December, the Atlantic is important, especially for the northern Mid-Atlantic region. Since 1950, there have been 19 snowstorms that brought 6" or more snow to at least one of the following cities: Boston, New York City, or Philadelphia. 37% occurred with an AO- (Boston accounted for most of the AO+ storms) and 21% with an AO-/NAO-.

For the smaller subset that saw 6" or more snow fall in at least two of those cities, the AO was negative in 86% of the cases and an AO-/NAO- pattern was present in 71% of cases. If one lowers the threshold to 4" or greater storms, those respective figures are 77% and 54%.

For now, there remains a window of opportunity. 

[uncle W]

over the last 100 years there have been around 15 snowfalls an inch or more between Dec 21st to the 25th that gave us a white Christmas...1998 was the last time we got snow just before Christmas...1998 did not have a temperature below freezing until a few days before the storm...

[eduggs]

The best wintry event between now and Christmas might end up being the arctic front on Wednesday.

[MJO812]

16 minutes ago, eduggs said:

The best wintry event between now and Christmas might end up being the arctic front on Wednesday.

Giving up on the storm already ?

[NYCweatherNOW]

1 minute ago, Snow88 said:

Giving up on the storm already ?

I wouldn’t give up until Tuesday at least. That’s a big storm and also cmc has the inverted trough going through and dropping a few inches.

[LibertyBell]

On 12/13/2019 at 6:44 PM, etudiant said:

It would be good to have the NYC annual snow fall totals for the 1600s and 1700s,  as that covers the 'Little Ice Age' interval. My guess is that snow totals were above the recent 50" averages, but surely there is some historical record somewhere.

 

I remember years ago burying myself in the New York Public Library and coming upon a "weather almanac" (I forgot its name) that didn't have snowfall records, but had temperature averages going back to the 1700s and 1800s.  Curiously, February seemed to be the coldest month back then and the mean temp for both January and February was under 30 degrees!

Then I came across the Pennsylvania Weather Book which mentioned that during the 1800s there were a couple of occasions when both NYC and Philly accumulated 100" of seasonal snowfall and had snow cover extending from Thanksgiving to St Paddy's Day!

[LibertyBell]

1 hour ago, bluewave said:

The 12z GFS just took a step in the direction of the other models. Now has a weak low in the GL and a separate southern stream low to the south.

12z

6z

 

 

what would it take for that southern stream low to come north ;-)

 

[NYC10023]

52 minutes ago, LibertyBell said:

what would it take for that southern stream low to come north ;-)

 

we all need to turn on our vacuums at the same time

[SnoSki14]

Not looking forward to the cold midweek. That's a potent though thankfully brief shot of arctic air.

Highs in the mid 20s with lows in the mid to low teens look likely. 

[the_other_guy]

That’s OK because that warm up seems to persist right before Christmas

It goes it comes and goes and comes and now I see forecast temperatures in the Upper 40s next weekend.

This week is looking like mix to rain (rain for city) cold to warm to cooler.

Wash, rinse, repeat

Definite pattern taking hold here...

 

[donsutherland1]

Under partly sunny skies (deep blue sky coupled with abundant cumulus clouds), the temperature was mainly in the middle 40s this afternoon. There was also a gusty breeze that was continuing to bring cooler air into the region.

[donsutherland1]

Variability will likely continue to define to weather into the closing week of December. As a result, much of the region could see additional snowfall through December 26, along with periodic intrusions of cold air. Whether the major cities see a 6" or greater snowstorm could depend, in large part, on the state of the teleconnections at the time of any storminess.

The first system will likely bring a light snowfall to the coastal plain and light to moderate snowfall to interior sections before transitioning to sleet, freezing rain, and then rain during tomorrow into tomorrow night. This could be the kind of system that brings 2"-4" across northwestern New Jersey/northeastern Pennsylvania north and eastward to Albany. However, such locations as Islip, New York City, and Newark will likely pick up 1" or less snow.

That storm will be followed by a short but sharp shot of cold. Parts of the region could experience the lowest temperatures so far this season. New York City could see the lowest temperature approach 20° and perhaps one day where the high temperature remains below 30°.

Another window of opportunity could be available during the December 21-23 timeframe. During that time, the Arctic Oscillation (AO) is currently forecast to be negative. However, some of the latest guidance now shows a weakly positive NAO.

Since 1950, 33% of storms that brought 4" or more snow during December 16-31 to just one city from among Philadelphia, New York City, or Boston had an AO- and 19% had an AO-/NAO-. However, from among the storms that brought 4" or more snow to at least two of those cities, 77% occurred with an AO- and 54% occurred with an AO-/NAO-.

Meanwhile, the temperature reached 51° in Anchorage on December 9. That set a new record high temperature for December and meteorological winter. The previous December record was 48° (December 1-2, 1992 and December 26, 1999). The previous record for meteorological winter was 50°, which was set on January 19, 1961 and tied on January 27, 2014.

The ENSO Region 1+2 anomaly was +0.1°C and the Region 3.4 anomaly was +0.3°C for the week centered around December 4. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.23°C and the ENSO Region 3.4 anomaly has averaged +0.67°C. These recent conditions are consistent with a weak El Niño. Nevertheless, a neutral ENSO remains the base case for Winter 2019-20 and the recent cooling in Region 3.4 suggests that the base case remains viable.

The SOI was -14.90 today.

Today, the preliminary Arctic Oscillation (AO) figure was -0.037.

For the December 1-15 period, the AO had a preliminary average of +1.584. Since 1950, 13 years saw the AO average +1.000 or above for the first 15 days of December, which is very likely this year. Only 3 (23%) wound up with a colder than normal December in New York City (which appears likely at present). The most recent such case was December 1988 when New York City had a mean December temperature of 35.9°.

Following a December 1-15 average AO value of +1.000 or above, 85% of winters went on to record less than 30.0" seasonal snowfall in New York City and Newark. One notable exception was winter 2013-14 when 57.4" snow was recorded in New York City and 61.1" in Newark.

No significant stratospheric warming event appears likely through December 24. Wave 2 activity is forecast to remain relatively weak. Overall, the stratosphere is forecast to remain cold into the fourth week of December on the EPS.

On December 14, the MJO was in Phase 2 at an amplitude of 1.296 (RMM). The December 13-adjusted amplitude was 1.297.

Large differences between the EPS and GEFS persist beyond Day 10. The GEFS is notably colder than the EPS with much of North America and the Northern Hemisphere covered by cold anomalies. Both show the coldest anomalies over a portion of northern Asia. The colder idea has more often than not prevailed since late autumn.

When it comes to New York City's 4" or greater snowstorms during the second half of December, the AO is highly important. Since 1950, December 16-31 has seen 15 storms bring 4.0" or more snow to New York City. 73% occurred with an AO-. Further, 80% of the 6" or greater snowstorms during this timeframe occurred when the AO was negative. Even as the PNA and NAO had a lesser impact on the 4" or greater snowstorms, an NAO- was present in 70% of the 6" or greater snowstorms during that timeframe and a PNA+ was also present during 70% of the 6" or greater snowstorms.

Based on sensitivity analysis applied to the latest guidance, there is an implied 65% probability that December will wind up colder than normal in New York City.

[eduggs]

There could be some good snow squalls on Wednesday evening.  The hi-res models are picking it up nicely.  Even the globals show some QPF for the area with the arctic frontal passage despite local downsloping.  I'm thinking there could be isolated 1-2" accumulations.  Upslope regions further up the taconics and also NNW NJ and NEPA are preferred but some squalls should make it to the coast.

Obviously snow lovers want big storms not isolated squalls.  But a ground whitening is always nice around Christmas time.

[CIK62]

Next 8 days are averaging 34degs., or about 2.5degs. BN.

Month to date is -0.8[39.1].         Should be about -1.3[37.3] by the 24th.

35* here at 6am.     36* by 9am.      37* by 11am.     38* at Noon 

GFS has 0" today, with flurries Wed(LES?).    CMC,EURO are 2"-3" today.       CMC is the coldest over the next 10 days.      SREF is 1" Snow and 1.2" liquid.

[bluewave]

Remarkably consistent storm track pattern since last winter. Plenty of cutters through the Great Lakes and storms that hug the coast. Occasionally we see a weak disturbance in the Great Lakes acting to suppress a southern stream low. Rapidly deepening benchmark snowstorms have been missing. This is in stark contrast to our last excellent benchmark season in 2017-2018 which featured a 950mb benchmark blizzard. In some ways, the snowfall gradient is s throwback to earlier times. The heaviest snowfall amounts are higher inland and lower along the immediate South Shore Coast. This is a reversal from 2013 to 2018 where the heaviest snow falls occurred along the coastal plain. How long the is this type of unfavorable dominant Pacific Jet pattern lasts is anyone’s guess.
 

[EasternLI]

Its also a reversal of the torch December's that we have been accustomed to for those years. 

[SnoSki14]

14 minutes ago, EasternLI said:

Its also a reversal of the torch December's that we have been accustomed to for those years. 

December will hoist a positive anomaly if Euro/EPS are correct. Both show a torch pattern after the midweek cold blast passes. 

December could end up +1.5 or better.

[qg_omega]

19 minutes ago, EasternLI said:

Its also a reversal of the torch December's that we have been accustomed to for those years. 

The torch around Xmas looks to persist another year

[EasternLI]

35 minutes ago, SnoSki14 said:

December will hoist a positive anomaly if Euro/EPS are correct. Both show a torch pattern after the midweek cold blast passes. 

December could end up +1.5 or better.

Well verbatim, if the EPS is correct. It's the plains that sees the real torch and we are on the periphery. AN though, yes. Be interesting to see where it ends up. Going to need to put up some big numbers to close out the month if you want +2 or better imo.

[MJO812]

[Franklin0529]

17 minutes ago, Snow88 said:

What's he referring too? Miss to the south?

[MJO812]

3 minutes ago, Franklin0529 said:

What's he referring too? Miss to the south?

Models coming back

[Njshore]

Storm is also much warmer than previous runs.

[Monmouth_County_Jacpot]

Jeez that pac does not want to relax...

[bluewave]

21 minutes ago, BlizzardNYC said:

Jeez that pac does not want to relax...

The MJO moving close to phase 5-6 around the holidays will amp the Pacific Jet up even more. 
 

 

[SnoSki14]

Wow what an inferno, December 2015-esque. 

[MJO812]

1 minute ago, SnoSki14 said:

Wow what an inferno, December 2015-esque. 

Jan 2016 redux please