bluewave

There was a transient SE ridge early on in December which showed up ahead of the cutters and hugger storm tracks. The cold would come in behind the storms. November and March have been our few months to feature below normal temperatures and a suppressed SE ridge.

The ridge over the East emerged strong enough to dominate in the monthly means. Same old pattern with the Niña-like ridge axis stuck north of Hawaii. That’s what caused such low snowfall last DJF even with the colder January intervals. So the cutter and hugger storm tracks won out.

Even though the SE ridge didn’t show up In the means into early December, the cutter and hugger storm tracks would briefly kick it up. So in effect, we had a transient SE ridge for our storms. That’s how Albany had 27.9 inches of snow in December to only 2.5 in NYC.

Seems like the SE ridge has been correcting stronger than indicated by long range forecasts as long as the PAC ridge axis has been closer to the Aleutians. We also saw this last winter with the ridge north of Hawaii. Complete opposite of the 13-14 and 14-15 winters. We can remember the long range EPS showing the ridge over NW Canada and still had a hint of the SE ridge. But as we got closer in, the SE ridge would always disappear.

The EPS has been on this MJO phase 4-5 since Christmas. But it’s normal for the models to correct more amplified the closer in they get.

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.