bluewave

This is mostly a -AO though. The NAO is closer to neutral with a neutral to negative PNA. So the ridge axis on the current EPS is too far to the east. This favors late developers that deepen further offshore. Need to slow down that Pacific flow so the ridge can back up to the West Coast.

Yeah, that’s why a solid +PNA is so important.

Lose that weak low over the GL and it might be better. But that fast flow Pacific has me concerned about a fly in the ointment. Also notice that other low racing east just north of Montana.

The uninterrupted unfavorable Pacific began last winter. Before that, the favorable intervals within a season more than made up for the unfavorable ones. It usually takes the -AO falling to -4 to -5 and the NAO -1 to -2 on the CPC official site. But we generally need a robust MJO 8 or a start warming event to pull that off. That extreme a drop can usually get the ridge to retrograde back to the West Coast boosting the PNA.

The -AO and -NAO won’t matter if the fast Pacific flow doesn’t relax. Notice how the record Pacific Jet keeps knocking down the PNA.

Warmest day of the month so far on Long Island. Shirley LGT RAIN 60 58 92 S13 29.42F FOG

The models have a split flow looking pattern. A northern stream low through the GL and a southern stream disturbance. Not much in the way of cold air with a dominant Pacific flow. A really amped low would kick up the ridge ahead of it. Too weak and the southern stream could slide south. We would probably need some type of amazing thread the needle to make this set up work.

Haha. Long Island hasn’t been that cold this month. Islip should be close -1 after the warmth today. This was the 4th day above 50 degrees in December.

It’s like a muddy swamp out there. I just saw a mosquito with temperatures near 60 degrees here on Long Island. Farmingdale FOG 55 54 96 S8 29.45S VSB 1/4 MacArthur/ISP FOG 57 57 100 S10 29.45S VSB 1/4 Stony Brook N/A 59 57 94 W2 N/A Shirley FOG 59 57 93 S9 29.45F VSB 1/2

A top 2 day rainfall total in December for JFK. Maximum 2-Day Total Precipitation for JFK INTL AP, NY Click column heading to sort ascending, click again to sort descending. Rank Value Ending Date Missing Days 1 3.23 2008-12-12 0 2 3.15 2014-12-10 0 3 3.04 2014-12-09 0 4 3.00 1992-12-11 0 5 2.95 1996-12-07 0 6 2.86 1948-12-31 0 7 2.75 1992-12-12 0 8 2.72 2019-12-14 0

Updated for 3.44 in Woodbury, NY. https://nwschat.weather.gov/p.php?pid=201912141224-KOKX-NOUS41-PNSOKX WOODBURY 3.44 704 AM 12/14 CWOP

That is an interesting question. While it was much colder back then, it was also drier than the modern era. There have been tree ring studies from NY that showed significant droughts during those years.Our precipitation has been increasing as the climate has warmed. So perhaps the last 25 years had more 50” seasons around NYC and Long Island than any peak 25 year LIA period.

The Meadowlands will now have snow and 28 degrees 365 days of the year. https://www.inquirer.com/business/big-snow-american-mega-mallski-slope-mall-meadowlands-20191212.html

Most of that rain is tonight into early Saturday. Widespread 2”+ rainstorms aren’t that common in December for us. So this is a significant event.

The December temperature departure may come down to what happens during the last week of the month. But you can see how the fast Pacific flow has kept much of the CONUS mild this month. A small pocket of cold has managed to hold on over the GL and NE. Next 10 days look like more of the same.

The Pacific became favorable from 12-26-10 to 2-2-11. We can remember all the day 10 phantom snowstorms the models were producing from late November to the solstice. We needed the -5 AO in mid December and record 500 mb positive height anomaly over Greenland to eventually build the ridge back closer to the West Coast.

The NAO and the strength of the ridge along the West Coast for the 2010’s. This is the composite for the 16 biggest 10”+snowfalls for NYC metro since 2010.

12z NAM came in even wetter. Looks like the heaviest downpours will be tonight into early Saturday.

Models weakened the high pressure at the onset of the storm over New England from a few days ago.

Yeah, the extreme Pacific Jet pattern also causes these big model flips in the longer range.

My concern is the the fast Pacific flow pushes the ridge axis too far east for a decent storm track. While the day 8-10 means have come in colder than a few days ago, that ridge could eventually shift back over the area day 11-15. We really need extreme Atlantic blocking to counter an unfavorable Pacific.

It doesn’t seem like the Pacific is in a hurry to let that happen. Last few runs shifted warmer and more amplified for the second storm early next week. The models seem to be playing catch up with the very fast Pacific flow.

Another soaker on the way as this raging Pacific Jet pattern continues.

The EPS has a low coming through the Great Lakes with cold high pressure behind it. Ridge axis would be too far east for a major storm. May be tough to back that ridge far enough west with such a fast Pacific Jet.

The East Asian Jet extension and fast flow into the West Coast is probably too much for the models to correctly handle.