bluewave

I think we’ll need that -PNA trough over the Western US to back off a bit from what the week 2 EPS has. In March 2018 it pulled just off the West Coast with higher heights over Southern Canada. This allowed a ridge in Minnesota for separation between systems.

The fact that NYC is yet to drop below 20° highlights how little Arctic air has been around. This is only the 5 year that NYC has gone this far into the cold season without one. For Boston it’s only the 6th year not to drop below 16. At BTV it’s only the 10th year not to reach 0 yet. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Min Temperature Oct 1 to Jan 12 Missing Count 1 1975-01-12 26 0 2 2013-01-12 22 0 3 2021-01-12 20 1 - 2002-01-12 20 0 - 1932-01-12 20 0 Time Series Summary for Boston Area, MA (ThreadEx) Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Min Temperature Oct 1 to Jan 12 Missing Count 1 2002-01-12 22 0 2 2007-01-12 20 0 3 1975-01-12 17 0 4 2021-01-12 16 1 - 1955-01-12 16 0 - 1929-01-12 16 1 Time Series Summary for Burlington Area, VT (ThreadEx) Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Min Temperature Oct 1 to Jan 12 Missing Count 1 2007-01-12 5 0 2 2002-01-12 3 0 3 2016-01-12 2 0 - 2000-01-12 2 0 5 2021-01-12 1 1 - 2012-01-12 1 0 - 1987-01-12 1 0 - 1955-01-12 1 0 - 1932-01-12 1 0 - 1924-01-12 1 0

I wonder if the ridge bridge over the top of the -PNA trough today is a result of the EPS seeing continuing influence from the SSW? This raises the question of whether the EPS will correct from what it’s showing now in early February. We really need a strong -EPO -AO connection to counteract the influence of the -PNA.

The latest EPS weeklies keep the window of opportunity open from January 25th to Feb 1st. Jan 11-18 Jan 18-25 Jan 25-Feb 1 Feb 1 - Feb 8

It’s as if the historic December 2015 +13.3 reset the whole winter climate warmer. NYC Dec 15....+13.3 Jan 16....+1.9 Feb 16....+2.4 Dec 16....+0.8 Jan 17....+5.4 Feb 17....+6.3 Dec 17....-2.5 Jan 18.....-0.8 Feb 18....+6.7 Dec 18....+2.6 Jan 19....-0.1 Feb 19....+0.9 Dec 19....+0.8 Jan 20....+6.5 Feb 20....+4.8 Dec 20.....+1.7 Jan 21.....+3.6...so far

It’s ironic that we may get our first -EPO drop since mid-December as the PNA is turning negative just after the 20th. This can often happen as the ridge pulls back to Aleutians and higher heights extend toward Alaska. So it looks like the PNA drop which the models had originally forecast near the start of February is moving up by 6-10 days.

You area has been warm rather than mild. POU is +5.1 through the 10th. The departures are being driven by the warm minimums. POU is +2.3 for the average daily max departure and a whopping +7.8 for the minimums. NYC is +3.6 with a +2.7 max and a +4.5 min departure. BTV is even more extreme at +6.8. They are +2.9 on the max and a +10.7 on the minimum. The more impressive warm departures have been the further north you go.

The Pacific Jet continues on steroids. Looks like a 220KT max today. So no surprise that we will continue with this mild airmass.

It’s always a challenge guessing when snowfall will start up again following a long break. It will be a month this week since the area near the coast saw accumulating snows. Snowfall return intervals after past pauses have been highly variable.

The all or nothing snowfall pattern continues for North America. Rollercoaster ride hitting record highs in October followed by record lows in November. Quick rise in mid-December then a fall around Christmas. Now the snow extent is near the bottom of the list for January 9th.

You have to look at it through the lens of the pattern that we have at the time. When we have a record breaking Pacific Jet pattern, we need all the help that we can get from Pacific blocking. So in the case this December, it took the poleward extension of the ridge through the EPO region to the North Pole to get us the snowstorm. But during other years with a less amped up Pacific Jet, we have gotten by with just the +PNA and +EPO and -AO. That’s why the +EPO during El Niño’s can be OK. The North Pacific Jet weakens while the STJ becomes the strongest. This helps carve out the trough over the SE US and allows the 50/50 low and high over New England hold its ground with a +EPO and weaker Pacific Jet. So +EPO during an El Niño isn’t the liability it can be with a La Niña. That’s why our best La Niña seasons like 95-96 had such frequent blocking near Alaska. While great El Niño’s had the STJ running the show with -AO and +PNA. NYC 2 greatest snowstorms 27.5”....Jan 22-23 -16 super El Niño +EPO 2016 01 20 43.26 2016 01 21 31.89 2016 01 22 48.24 2016 01 23 71.40 2016 01 24 71.56 2016 01 25 14.98 2016 01 26 29.36 2016 01 27 55.70 2016 01 28 160.56 2016 01 29 177.26 26.9”.....Feb 11-12-06....La Niña -EPO 2006 02 09 -53.06 2006 02 10 -93.77 2006 02 11 -74.28 2006 02 12 -35.51 2006 02 13 -69.84 2006 02 14 -214.72 2006 02 15 -288.49 2006 02 16 -309.34 2006 02 17 -330.28 2006 02 18 -298.10 Late November 95 into April 96 historic snowfall pattern for a La Niña

The only -EPO drop of the whole winter so far was a few days before the the snowstorm. So the +PNA and -AO couldn’t get the job done without the -EPO assist. This was when the strong block popped up over the pole. ftp://ftp.cdc.noaa.gov/Public/map/teleconnections/epo.reanalysis.t10trunc.1948-present.txt 2020 12 01 57.33 2020 12 02 -20.52 2020 12 03 1.92 2020 12 04 -3.55 2020 12 05 18.98 2020 12 06 113.53 2020 12 07 160.49 2020 12 08 91.29 2020 12 09 24.46 2020 12 10 -40.49 2020 12 11 -98.53 2020 12 12 -90.08 2020 12 13 -32.48 2020 12 14 -11.99 2020 12 15 48.80 2020 12 16 122.15 2020 12 17 153.25 2020 12 18 199.37 2020 12 19 250.26 2020 12 20 239.82 2020 12 21 120.24 2020 12 22 70.85 2020 12 23 58.12 2020 12 24 69.31 2020 12 25 92.27 2020 12 26 68.14 2020 12 27 3.10 2020 12 28 -1.63 2020 12 29 11.33 2020 12 30 61.32 2020 12 31 60.59 2021 01 01 127.22 2021 01 02 264.17 2021 01 03 296.05 2021 01 04 248.51 2021 01 05 260.79 2021 01 06 249.45 2021 01 07 137.72

The cold 13-14 and 14-15 winters seem like a long time ago. It’s like the super El Niño in 15-16 hit the warm reset button. We knew something extreme was going on when December 2015 went +13.3.

This repeating model error has been so frequent in recent years, that the Upper Plains is one of the few spots on the planet that will see a slight decline in the new 30 year climate normals. Time after time, the coldest temperature departures have been dropping to our west. I guess the Pacific Jet is just too difficult for the models to handle long range.

It looks like the coldest temperatures by later in the month will drop to our west again. Notice how much weaker the Pacific blocking is along the West Coast of North America than originally forecast. The extreme Pacific Jet that brought record low pressure to the Aleutians just won’t relax. New run Old run

At least this -NAO is paying off for parts of Europe. Much easier to put together a record snowfall when an unfavorable Pacific can’t impact your pattern. Shows how just a -NAO can be a big influence for Europe. The AEMET weather agency described the situation as "exceptional and most likely historic". Earlier in the day, children in Madrid could be seen hurling snowballs or playing under snow-covered palm trees, while others snapped photos of the rare whiteout which began in earnest the day after Spain celebrated King's Day -- or Epiphany.

Models are correcting more positive with the EPO for later in the month. This is telling us that the models continue to underestimate the strength of the Pacific Jet. That’s why the EPS are warmer than the GEFS during week 2.

That firehose Pacific Jet won’t be denied. The combo of that Jet and the south based block is suppressing the southern stream. So all the precip is PAC NW and SE.

NYC generally needs a cold winter to get more than 1 event of 10” or more in a single season. The last time this happened was during the cold winters of 13-14, 10-11, 09-10, and 03-04. But one of these days, NYC will eventually get 2 events in a mild winter. https://www.weather.gov/media/okx/Climate/CentralPark/sixplussnow.pdf 12-17-20...10.5 1-24-16.....27.5 2-13-14....12.5 1-22-14....11.5 2-8-13......11.4 1-26-11.....19.0 12-26-10....20.0 2-25-10.....20.9 2-10-10......10.0 12-20-09.....10.9 2-12-06......26.9 1-22-05.......13.8 1-28-04.......10.3 12-5-03.........14.0 2-17-03.......19.8 12-30-00......12.0

We may need a loop like March 1888. Ideally, it would occur a little further east than in 1888. While we have less Arctic air now, the SSTs and moisture content would be higher. So lower ratio with more total liquid equivalent. https://www.wunderground.com/blog/weatherhistorian/the-great-blizzard-of-1888-americas-greatest-snow-disaster.html

I still think that we have a chance to see a 40-50” snowstorm event somewhere between NYC and Boston in the coming years.

And this may help to compensate for #2 also. But I know that there are extended snow cover fans out there that may not feel that way. I am more about snowstorm intensity and quality than how long it remains on the ground. https://www.sciencedaily.com/releases/2019/01/190124115353.htm Even though climate change is expected to reduce the total amount of U.S. snowfall this century, it's unlikely to significantly rein in the most powerful nor'easters that pummel the East Coast, new research indicates.

Yeah, it really gets back to the competing influences discussion that we had during the fall. The record +PMM was associated with the more Niño-like pattern so far this winter. But now that the PMM is quickly cooling, the models are showing a transition to a more Niña-like pattern. I mentioned this the other day. Now this new tweet is picking up on the idea. It shows how quickly the SST have cooled west of Central America. I posted for the SST chart not for references to any specific analog year.

Yeah, it’s a very well identified pattern. https://www.climate.gov/news-features/blogs/beyond-data/climate-change-rule-thumb-cold-things-warming-faster-warm-things Colder places are warming faster than warmer places Colder seasons are warming faster than warmer seasons Colder times of day are warming more than warmer times of day

Climate Central compiled all the charts. It’s through the winter of 2019. So the record warmth last winter wasn’t included. https://www.climatecentral.org/gallery/graphics/winter-warming-local-average-winter-temperature-2019