bluewave

December has become our most positive +NAO month of the year since 2011.

March has become the new December since 2011. Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Oct Nov Dec Jan Feb Mar Apr Season Mean 0.4 1.4 2.6 11.3 9.5 7.3 0.7 33.2 2018-2019 0.0 6.4 T 1.1 2.6 10.4 0.0 20.5 2017-2018 0.0 T 7.7 11.2 4.9 11.6 5.5 40.9 2016-2017 0.0 T 3.2 7.9 9.4 9.7 0.0 30.2 2015-2016 0.0 0.0 T 27.9 4.0 0.9 T 32.8 2014-2015 0.0 0.2 1.0 16.9 13.6 18.6 0.0 50.3 2013-2014 0.0 T 8.6 19.7 29.0 0.1 T 57.4 2012-2013 0.0 4.7 0.4 1.5 12.2 7.3 0.0 26.1 2011-2012 2.9 0.0 0.0 4.3 0.2 0.0 0.0 7.4 Monthly Total Snowfall for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Year Oct Nov Dec Jan Feb Mar Apr Season Mean 0.0 1.1 2.3 15.5 12.8 9.9 0.6 42.3 2018-2019 0.0 4.3 T 0.9 3.5 4.1 T 12.8 2017-2018 0.0 T 6.0 22.0 1.4 31.9 4.6 65.9 2016-2017 T T 3.2 14.0 14.7 7.4 T 39.3 2015-2016 0.0 0.0 T 24.8 13.2 3.2 0.2 41.4 2014-2015 0.0 T 0.4 30.2 13.4 19.7 0.0 63.7 2013-2014 0.0 0.3 8.1 25.2 24.5 5.4 0.2 63.7 2012-2013 0.0 4.2 0.6 3.3 31.4 7.4 0.0 46.9 2011-2012 0.3 0.0 T 3.8 0.6 T 0.0 4.7

Tough to beat December 2000-2010. A remarkable 5 years with double digit snowfall amounts in NYC. Big shift to a more +NAO during December after 2010. Time Series Summary for NY CITY CENTRAL PARK, NY - Month of Dec Click column heading to sort ascending, click again to sort descending. Year Total Snowfall Missing Count 2019 1.8 15 2018 T 0 2017 7.7 0 2016 3.2 0 2015 T 0 2014 1.0 0 2013 8.6 0 2012 0.4 0 2011 0.0 0 2010 20.1 0 2009 12.4 0 2008 6.0 0 2007 2.9 0 2006 0.0 0 2005 9.7 0 2004 3.0 0 2003 19.8 0 2002 11.0 0 2001 T 0 2000 13.4 0

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. We

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.

Yeah, we were right on the line between 32 and 33 degrees here. Less than a degree made the difference between some icing and none.

Some portions of the South Shore got into the icing. Looks like the winds verified a bit more NE than forecast. Most models yesterday had more ENE.

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.

That’s all you need for minor ice accretion. My last significant events were Valentine’s Day 07 and 2-2-11. But Jan 94 and 78 are still the benchmark ice storms for me.

I remember that one. It was the most significant ice storm on Long Island until January 1994.

But nothing as significant as our big events like Jan 94 when temps were in the 20’s.

From my experience with icing here on Long Island. The most memorable events occur with temperatures in the 20’s. We get more rainfall runoff especially with faster rates in the low 30’s.

33 and rain here in SW Suffolk. Yet another rainfall event approaching 1 inch.

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

Downed trees and wires in PA from the heavy icing.

37 with a light sleet and rain mix here in SW Suffolk.

That’s why ice storm warnings are often issued once the event is underway.

It would be nice if we could run the FRAM model on this to see how much freezing rain accumulates vs just runs off. PDF] The Freezing Rain Accumulation Model (FRAM) - NOAA VLab https://vlab.ncep.noaa.gov › documents › FRAM_VLAB_Presentation.pdf Wet-bulb helps account for evaporative cooling toward saturation. • The air-liquid interface along the edge of a raindrop is saturated. Microscale temperature ...

The record books are more about accurately recording what actually happens. Not getting much in a marginal situation isn’t that bad. But 1-26-15 is a whole different story with such a major underperformance and shift east.

I never saw the NAM go so heavy on freezing rain before. Even if just 25% of that freezes without running off, it will be a problem.

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

No surprise to see the models increase the overall precipitation amounts. That 200 KT jet streak to our northeast is near record levels for this time of year.

A few miles distance can make a big difference as to where the most significant icing sets up. A small change in temperature of a degree or two is all that it takes. Sometimes it just comes down to nowcast time. But areas that see icing will also have to cope with stronger winds on Wednesday with the sharp Arctic front. Then the very cold temperatures.

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.