bluewave

Pretty good rotation with the warned cell over Suffolk. https://www.spc.noaa.gov/products/md/2021/md1943.html DISCUSSION...KOKX radar imagery has shown a long-lived rotating cluster of convection moving north from the shelf waters of the Atlantic to the south coast of eastern Long Island. The KOKX VAD wind profile shows intense flow fields with an enlarged hodograph. The main limiting factors are scant buoyancy and very weak lapse rates. Nonetheless, the storm-scale forcing associated with the hybrid rotating cluster of convection may enable the risk for damaging gusts to be realized on a localized basis, as the convection moves north from eastern Long Island into CT over the next 1-2 hours.

I think we have moved into a new background state. One where the reduced sea ice near the Kara and Barents seas interacts with the SPV and Urals ridge. Last November into December was a recent example of how the pattern can dramatically reverse. The same went for December 2015 into January 2016. So that may be why seasonal models in the fall have been so far off with the winter NAO state. Our new winter blocking regimes near Greenland have been linked to that Urals ridge. Before 2003, our winter blocking episodes often didn’t have that connection. So it’s very challenging to try and forecast monthly NAO changes during the winter before they actually occur.

Remember, the models didn’t catch onto the winter forecast last year until December was practically starting. These early to mid November runs can have a type of fall forecast barrier effect. So anything beyond week 2 has very little skill.

Maybe since the new December average temperature has risen to around 40°, near to below normal temperatures will be easier with a supporting pattern. ……1991-2020….1981-2010 NYC…..39.1°……37.5°……+1.6° EWR….38.0°……36.5°……+1.5° LGA…..40.0°……38.2°……+1.8°

Yeah, we just don’t want the consolidated look to the polar vortex in the next frame. But that is outside the effective range. A more elongated vortex with higher heights near Greenland and the Aleutians would be better. Still plenty of time to see how it evolves.

The polar vortex shifts over the Hudson Bay in late November on the extended EPS. So Canada gets colder and we get cool downs behind each Pacific short wave. Our temperatures average near to below normal. We just don’t want the polar vortex consolidating near the Arctic at the start December like the EPS has. While this is something to watch for, the EPS skill at these ranges is very low. NOV 15-22 Nov 22-29

Tough to compete against the record warmth last November. Newark has only reached 70° once so far this month. They tied the record with 7 days last November. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Month of Nov Click column heading to sort ascending, click again to sort descending. Year Number of Days Max Temperature >= 70 Missing Count 2021 1 20 2020 7 0 2019 0 0 2018 2 0 2017 2 0 2016 2 0 2015 5 0 2014 2 0 2013 1 0 2012 0 0 2011 3 0 2010 0 0 Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Month of Nov Click column heading to sort ascending, click again to sort descending. Rank Year Number of Days Max Temperature >= 70 Missing Count 2020 7 0 - 1975 7 0 1994 6 0 - 1990 6 0 - 1953 6 0 - 1931 6 0 2015 5 0 - 2001 5 0 - 1982 5 0 - 1938 5 0

The NAM has 50 mph gust potential near the coast with the heavy convection tomorrow.

A -1 to +1 first 10 days of November feels much colder due to the record warmth in September and October. EWR….+0.6 NYC…..-1.1 LGA….+0.8 JFK….+0.3 ISP…..-0.6 BDR….-0.6 HPN….-1.2

Yeah, we would probably need winter version of what happened in late October. Getting one of the Pacific Jet lows to undercut the south based Atlantic Block. While the airmass would probably be marginal, we were able to do it during the 16-17 La Niña.

This may have been one of the greatest August to November SST drops south of Alaska on record.

This was the first time we had an October PDO drop below -3.00 since 1955. But that’s what happens with record 940 mb lows off the PAC NW Coast. It also pumped the record south based -NAO in October. https://www.ncei.noaa.gov/pub/data/cmb/ersst/v5/index/ersst.v5.pdo.dat Oct 2021 -3.06

We had the strong -PNA with the 16-17 La Niña winter. But the EPO was more neutral that year. 95-96 was the most perfect balance of -NAO and -EPO that we ever had from December through March.

It would look like the composite below. Warmer than average winter temperatures. So we would need bowling ball type closed lows to occasionally undercut the ridge for near to above normal snowfall.

The latest EPS is a great illustration of this. Back and forth between warm ups and cool downs. But the coldest departures go to our south.

There seems to be an inverse correlation between the La Niña strength and our winter weather since 2010. The stronger coupled La Ninas in a two year sequence actually had more snow. But before 2010, it was usually the weaker of the La Ninas which were snowier. Coupled La Niña ONI and NYC snowfall Stronger of two years bolded 17-18….-1.0…..40.9” 16-17…..-0.7….30.2” 11-12…..-1.1……7.4” 10-11…..-1.6…..61.9” 08-09….-0.8….27.6” 07-08….-1.6…..12.4” 05-06…..-0.9…40.0” 00-01……-0.7….35.0” 99-00……-1.7….16.3”

I think the culprit with the recent model forecasts was the record early snow and cold in China. That TPV drop into East Asia is pumping the NPAC ridge up further west. So we get a big WPO drop instead of EPO. This gives the La Niña Jet more opportunities to come ashore out West. So we get this back and forth pattern of warm ups and cool downs. To the EPS weeklies credit, they always showed the core of the cold going to our south.

It’s been tough to get the core of the cold into New England this year. The most recent cool down was focused to our south. Looks like the coming cool down from the weekend into next week will do the same. November so far Forecast Last 12 month period warmest on record in Maine

Even before we see what the NAO does in November, the MJO is giving hints in October. We usually have DJFM -NAO and -AO intervals coming off October Maritime Continent forcing like we saw this year. It’s the odd year with very strong forcing over the Western IO that seems to really set off the polar vortex.

The NAO is currently negative and is forecast to go positive for a time in mid-November. Long range EPS and GEFS have it gong negative again later in the month. The phase of the November NAO for the last 10 out of 11 coupled La Ninas has correctly predicted the NYC seasonal snowfall and winter temperatures. The snowiest and coldest La Ninas had a November NAO under -1 for 1995 and 2010. At this point, the -NAO doesn’t look like it will be that negative. The least snowiest and warmest 2011 had the November NAO above +1. So this November isn’t showing such a positive NAO. If we can maintain a neutral to even slightly negative NAO for the whole month, then NYC will have a reasonable chance of reaching 25” or more of snow this coming season. Winter temperatures could average near to above normal following a NAO in that November range. The new 1991-2020 winter average temperature in NYC has risen to 36.2° from 35.1° for the 1981-2010 period. So this could make it easier for NYC to come closer to normal or have a less warm departure than it would have been using the older averages. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.nao.monthly.b5001.current.ascii.table November coupled La Niña NAO and NYC seasonal snowfall and DJF average temperature Season………..Nov NAO……Snowfall….Temperature 2017-2018…..0.00….40.9”….36.2° 2016-2017…..-0.16….30.2”….39.3° 2011-2012…..+1.36….7.4”…..40.5° 2010-2011…..-1.62…..51.4”….32.8° 2008-2009…..-0.32…27.6”….34.2° 2007-2008…..+0.58…11.9”….36.4° 2005-2006…..-0.31….40.0”….37.3° 2000-2001…..-0.92….35.0”…..33.5° 1999-2000…..+0.65….16.3”….36.2° 1998-1999……-0.28….12.7”….38.6° 1995-1996…….-1.38….75.6”….32.2°

Not much change in the extended EPS. MJO 4-6 ridging over the NE PAC with the PAC Jet sending shortwaves through from time to time. Warmer this week with a cool down from the weekend into next week. Last week of November has a colder than average area just to our west. But we’ll see what that looks like the closer we get since week 3 and beyond has lower skill. Nov 8-15 Nov 15-22 Nov 22-29

It looks like a back and forth type pattern. The MJO 4-6 is pumping the -EPO/+PNA. But the very strong La Niña Jet acts to flatten it out. So we get a progression of warm ups and cool downs. The monthly departure may not be determined until the last week of November. Maybe the new weeklies later will provide some clues.

Warm up this week after a colder than average first week of November. Looks like our next chance of significant rain and wind will be Friday. Then we start another cool down during the weekend. Probably a leaf clean up weekend after the storm for the garden interests.

Even in our new snowier climate since 02-03, 17-18 stands out in Suffolk. Data for October 1, 2020 through April 30, 2021 Click column heading to sort ascending, click again to sort descending. Name Station Type Total Snowfall NESCONSET 1.4 SSW CoCoRaHS 46.1 MOUNT SINAI COOP 41.3 Data for October 1, 2017 through April 30, 2018 Click column heading to sort ascending, click again to sort descending. Name Station Type Total Snowfall BRIGHTWATERS 0.7 NNW CoCoRaHS 72.0 NESCONSET 1.4 SSW CoCoRaHS 71.8 Data for October 1, 2016 through April 30, 2017 Click column heading to sort ascending, click again to sort descending. Name Station Type Total Snowfall BAITING HOLLOW COOP 42.7 UPTON COOP - NWSFO NEW YORK COOP 42.1 NESCONSET 1.4 SSW CoCoRaHS 41.2 Data for October 1, 2015 through April 30, 2016 Click column heading to sort ascending, click again to sort descending. Name Station Type Total Snowfall ISLIP-LI MACARTHUR AP WBAN 41.4 CENTERPORT COOP 41.0 Data for October 1, 2014 through April 30, 2015 Click column heading to sort ascending, click again to sort descending. Name Station Type Total Snowfall BAITING HOLLOW COOP 67.9 JAMESPORT 0.6 SSW CoCoRaHS 63.9 ISLIP-LI MACARTHUR AP WBAN 63.7 RIVERHEAD RESEARCH FARM COOP 63.5 UPTON COOP - NWSFO NEW YORK COOP 62.2 ROCKY POINT 2.0 N CoCoRaHS 61.6 Data for October 1, 2013 through April 30, 2014 Click column heading to sort ascending, click again to sort descending. Name Station Type Total Snowfall ISLIP-LI MACARTHUR AP WBAN 63.7 BAITING HOLLOW COOP 62.7 CENTERPORT COOP 60.8 Data for October 1, 2012 through April 30, 2013 Click column heading to sort ascending, click again to sort descending. Name Station Type Total Snowfall UPTON COOP - NWSFO NEW YORK COOP 51.1 ISLIP-LI MACARTHUR AP WBAN 46.9 BAITING HOLLOW COOP 45.1 MOUNT SINAI COOP 44.5 Data for October 1, 2010 through April 30, 2011 Click column heading to sort ascending, click again to sort descending. Name Station Type Total Snowfall CENTERPORT COOP 64.0 MOUNT SINAI COOP 55.9 ISLIP-LI MACARTHUR AP WBAN 55.3 BAITING HOLLOW COOP 53.1 NORTHPORT 1.6 NNE CoCoRaHS 52.5 Data for October 1, 2009 through April 30, 2010 Click column heading to sort ascending, click again to sort descending. Name Station Type Total Snowfall BAITING HOLLOW COOP 57.0 EAST MORICHES 0.6 WNW CoCoRaHS 55.0 ISLIP-LI MACARTHUR AP WBAN 53.8 Data for October 1, 2008 through April 30, 2009 Click column heading to sort ascending, click again to sort descending. Name Station Type Total Snowfall BRIDGEHAMPTON COOP 44.3 Data for October 1, 2004 through April 30, 2005 Click column heading to sort ascending, click again to sort descending. Name Station Type Total Snowfall RIVERHEAD RESEARCH FARM COOP 63.8 BRIDGEHAMPTON COOP 59.3 ISLIP-LI MACARTHUR AP WBAN 58.8 CENTERPORT COOP 54.3 Data for October 1, 2003 through April 30, 2004 Click column heading to sort ascending, click again to sort descending. Name Station Type Total Snowfall CENTERPORT COOP 59.7 BRIDGEHAMPTON COOP 47.9 RIVERHEAD RESEARCH FARM COOP 43.5 Data for October 1, 2002 through April 30, 2003 Click column heading to sort ascending, click again to sort descending. Name Station Type Total Snowfall BRIDGEHAMPTON COOP 63.5 RIVERHEAD RESEARCH FARM COOP 48.7

When you see such a big North Pacific pattern change like this, expect the model storm details beyond 5 days to vary more than usual from run to run.