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December 2019


NYCweatherNOW
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8 hours ago, bluewave said:

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.
 

A weak Nina or cold neutral would do good for most of us especially after a +ENSO season. The strong +IOD is definitely playing a role in strengthening the Pacific Jet which is also correlated with +ENSO anomalies. It's been a mediocre month. Hoping for a turn around come January-February. 

On a side note, would be nice to experience a Nor'easter as the biggest storms up here are usually between 12-16". Cheers! 

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Variability will likely continue to define to weather into the closing week of December. As a result, much of the region could see perhaps additional snowfall through December 26, along with periodic intrusions of cold air.

A short but sharp shot of cold will follow the system that will impact the region tonight into tomorrow with snow, sleet, freezing rain and rain. Parts of the region could experience the lowest temperatures so far this season. New York City will likely see the temperature fall below 20° with one day where the high temperature remains in the middle or upper 20s.

Another window of opportunity snowfall could be available during the December 21-23 timeframe. During that time, the Arctic Oscillation (AO) is forecast to be negative. However, some of the latest guidance now shows a weakly positive NAO in combination with a negative PNA. As a result, the synoptic pattern looks less promising than it did a few days ago.

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-.

For the December 20-27 period overall, the temperature in such cities as Washington, Philadelphia, and New York could average somewhat above normal despite the cold start to the period.

The ENSO Region 1+2 anomaly was +0.5°C and the Region 3.4 anomaly was +0.5°C for the week centered around December 4. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.05°C and the ENSO Region 3.4 anomaly has averaged +0.53°C. These recent conditions are consistent with a weak El Niño. Nevertheless, a neutral ENSO remains the base case for Winter 2019-20.

The SOI was -15.00 today.

Today, the preliminary Arctic Oscillation (AO) figure was -0.986.

No significant stratospheric warming event appears likely through December 25. Wave 2 activity is forecast to remain relatively weak. Overall, the stratosphere is forecast to remain cold into the middle of the fourth week of December on the EPS.

On December 15, the MJO was in Phase 3 at an amplitude of 1.130 (RMM). The December 14-adjusted amplitude was 1.292.

Differences for the closing days of December between the EPS and GEFS are narrowing. Consistent with the colder idea having prevailed more often than not since late autumn, the EPS has begun to move toward a colder solution for the end of December.

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 63% probability that December will wind up colder than normal in New York City.

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The next 8 days are averaging 34.5degs., or about 1deg. BN.

Month to date is -0.9[38.8].           Should be about -0.9[37.4] by the 25th.

34* here at 6am.    9am- Has been 35* for most of the last 3 hours.    37* at 10am.       35* by 3pm.

EURO lone hold out with 2" for today, and that will have to do for the next 10 to 15 days, as other models are zippo, with unremarkable T's, after the next 2 days.

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Looks like a 2-3 day Arctic outbreak before the mild Pacific influence returns over the weekend.

NEW YORK CITY-CENTRAL PARK
 KNYC   GFSX MOS GUIDANCE  12/17/2019  0000 UTC                       
 FHR  24| 36  48| 60  72| 84  96|108 120|132 144|156 168|180 192      
 TUE  17| WED 18| THU 19| FRI 20| SAT 21| SUN 22| MON 23| TUE 24 CLIMO
 X/N  40| 29  37| 17  26| 18  35| 27  38| 34  47| 37  49| 37  48 28 41
 TMP  35| 31  29| 19  24| 20  34| 29  36| 36  44| 39  45| 39  45      
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25 minutes ago, bluewave said:

Looks like a 2-3 day Arctic outbreak before the mild Pacific influence returns over the weekend.


NEW YORK CITY-CENTRAL PARK
 KNYC   GFSX MOS GUIDANCE  12/17/2019  0000 UTC                       
 FHR  24| 36  48| 60  72| 84  96|108 120|132 144|156 168|180 192      
 TUE  17| WED 18| THU 19| FRI 20| SAT 21| SUN 22| MON 23| TUE 24 CLIMO
 X/N  40| 29  37| 17  26| 18  35| 27  38| 34  47| 37  49| 37  48 28 41
 TMP  35| 31  29| 19  24| 20  34| 29  36| 36  44| 39  45| 39  45      

Problem I have is it's not mild enough. If it's not going to snow prefer 50s. 

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58 minutes ago, bluewave said:

Next few days should be our last Arctic air mass for a while. The MJO forecast to  move near phase 6 means mostly a mild Pacific influence into the longer range. 

Good bring on the spring-like weather.

Had enough of this cold rain and if it's clearly not gonna snow then bring on the warmth.

Tho in reality im looking at the indices particularly the AO and it looks mostly negative. MJO isn't guaranteed to enter phase 6 either so maybe not a crazy torch like 2015.

Signs of a -EPO to start January paired with a -NAO/AO and good climo should lead to better outcomes after the torch ends. MJO could head towards phase 7/8 as well.

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11 minutes ago, SnoSki14 said:

Good bring on the spring-like weather.

Had enough of this cold rain and if it's clearly not gonna snow then bring on the warmth.

The high temperatures after this Arctic shot will be mostly dependent on wind direction. Days with more SE flow and a high pressure  to our NE will mostly max out in the 40’s. But any SW flow days could reach the 50’s between the 23rd and 31st.

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2 minutes ago, bluewave said:

The high temperatures after this Arctic shot will be mostly dependent on wind direction. Days with more SE flow and a high pressure  to our NE will mostly max out in the 40’s. But any SW flow days could reach the 50’s between the 23rd and 31st.

The mostly -AO & neutral to negative -NAO favor the former. Our corner of the CONUS will probably continue to be much cooler vs the rest of the country.

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1 minute ago, nycwinter said:

this is not even cold weather .growing up as a kid  cold weather in december in nyc felt like the weather in siberia then the so called  cold weather in december we are having the last few years..

growing up in the 1960's spoiled me...Decembers were very cold and there was snow for Christmas...1960 had four days in single digits...1968-69 had it's coldest temp in early Dec...1963-64 had its coldest week of the season the third week of Dec...they also had a few torch days and mild Christmas in 1964 and 1965...It snowed 3" on 12/20/64 but was gone by Christmas eve...It was 69 degrees Christmas day 1964...that was a shock to the system...today its becoming normal...

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14 minutes ago, SnowGoose69 said:

That’s such a weak amplitude wave I’m not sure it would have any major impact 

We don’t need very much amplitude in the MJO the to shift the CONUS back to a mild Pacific air mass. Look how much influence the low frequency WP forcing regime has had on the pattern going back to November. 


0266C186-D1D5-4C54-ABFB-08E6025492D7.thumb.png.f67c0ad56de29addaf8f43fd876bcd9b.pngWe


 

 

 

 

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