bluewave

It’s been tough to bet against the SE ridge over the last year. Even when we had intervals of cold, the storm tracks were still cutters and huggers. It may be the warmest SST’s lining up west of the date line creating a a very La Niña-like pattern. That WPAC warm pool also leads to stronger MJO phase 4-7 episodes.

Both the VP anomalies and the RMM charts become less reliable after about 10 days. But the MJO usually progresses into phase 6 following such a strong phase 4-5. Nearly all the January cases with amplified phase 4-5 phases continued the warmth into phase 6.

Funny how the day 11-15 forecasts got better as the pattern warmed up. The EPS has pulled into the lead since early December. It could be that the GEFS cold bias really stands out when we actually have a warmer than normal pattern.

This shows how intense the TPV with the strong +AO is.

While it has been a very wet year here, check out the extremes to our west.

The fast PAC jet extending across NOAM strikes again. It’s just too much for the models to correctly handle all the pieces of energy.

The 12z UKMET looks similar to the NAM. Very fast flow with a kicker north of Minnesota. So the storm gets going too far offshore this run.

Record low Arctic sea ice extent for the Chukchi Sea in 2019.

We had the timing down for a while now with the window around the 5-6th. Long Island typically does better than NYC in rain to snow situations. This gets reversed with snow to rain when NYC usually beats parts of Long Island.

The storm probably tracks near or maybe just south of Long Island with a change to snow at the end. Temps will be marginal for accumulations. But we could see something on the colder surfaces if it snows hard enough. Even a C-3 event would be nice before the eventual warm up around the 10th.

Even the EPS is split on track. A number of members take the low right across Long Island and others to the south.

Be careful with those Euro snowfall accumulation maps. While the NAM and other models are warmer than the Euro, the Euro is counting mixed precipitation in the mid 30’s as accumulations.

This goes to show how extreme the heatwave driving those SST’s north of Australia has been.

That rapid SST increase north of Australia near MJO 4-5 may be why some models want to linger the forcing there.

The Euro and GFS agree that the MJO could reach a 2 or greater amplitude in both phases 4 and 5. The last rime this occurred during January was 2013 and 2007. It would be nice if the February pattern improves like it did in those winters.

I am just talking about the dominant storm track. The warmth coming up was addressed in my earlier MJO posts. The mild start to January next few days is a continuation of the late December pattern. But you can see how even a less amplified MJO 4-6 warmed the recent pattern. A much more amplified and warmer MJO 4-5 pattern will begin to be felt around the 10th.

We are starting 2020 with same Pacific dominated pattern as 2019. All models have a continuation of the wet cutter and hugger storm track. This gives new meaning to a persistence forecast.

The 2010’s finish with 8 out of 10 warmer than average Decembers. 2010’s December temperature departures .............EWR....NYC....LGA 2019....+1.1....+0.8....+0.7 2018....+2.9....+2.6....+2.3 2017....-1.9......-2.5.....-2.0 2016....+1.2....+0.8....+2.1 2015...+13.3..+13.3...+12.6 2014....+3.6....+3.0....+2.4 2013...+0.4....+1.0......0.0 2012...+4.6....+4.0....+4.5 2011...+6.0....+5.8.....+5.1 2010...-3.6......-4.7......-3.2

This was the first time that we experienced 9 consecutive +NAO Decembers. Something flipped in the atmosphere following the record snows in December 2010.That was the last time NYC finished the month with 10+ inches of snow and strong -NAO. The Boxing Day Blizzard was the most recent high end KU event for the month. December NAO and NYC snowfall 2019.....+.............2.5 2018.....+0.61......T 2017.....+0.88.....7.7 2016.....+0.48.....3.2 2015.....+2.24......T 2014.....+1.86....1.0 2013.....+0.95.....8.6 2012....+0.17....+0.4 2011....+2.52.....0.0 2010.....-1.85....20.1

That’s the January MJO phase 4-5 composite. Looks like this one has a chance to go above +2 in 4 and 5. Not a surprise given the rapid warming of the WPAC. Phases 5-7 are becoming stronger and more frequent.

This was the wettest December on record at JFK. First time reaching 8.00” or more during the month. The top 3 wettest Decembers were all since 2014. Time Series Summary for JFK INTL AP, NY - Month of Dec Click column heading to sort ascending, click again to sort descending. Rank Year Total Precipitation Missing Count 1 2019 8.03 1 2 2014 7.04 0 3 2018 6.76 0

A poorly installed wind turbine blew down in the Bronx. Larchmont Harb N/A 39 N/A N/A NE38G51

Impressive looking cell for late December. Continuation of the steep midlevel lapse rates that have become more common in recent years.

With two milder days to go, all our stations will finish another warmer than average December. Not much in the way of cold across the US as the Pacific continues to dominate. Through 12-28 EWR....+0.6 NYC....+0.4 LGA....+0.2 JFK.....-0.1 BDR....+0.3 ISP.....+0.7

I would like to wait until the models get within 5 days of any potential event. Just too much volatility in these day 6-10 OP runs. Any snowfall before January 20th is a bonus. But it’s the back half of the winter that typically has our most snowfall. The only exception to the rule this decade was 10-11. NYC snowfall ............By January 19th......After January 19th 18-19....7.1......13.4 17-18....17.9....23.0 16-17....10.1....20.1 15-16....0.4......32.4 14-15....3.7......46.6 13-14....15.0....42.4 12-13....5.1.....21.0 11-12....2.9.....4.5 10-11...31.9....30.0 09-10....13.2...38.2