bluewave

First 30s of season at places like ISP this morning is close to the average since 2010. A little over a week later than during the 2000’s. First/Last Summary for ISLIP-LI MACARTHUR AP, NY Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. Year Last Value First Value Difference Minimum 04-11 (2019) 10-10 (2010) 149 Mean 04-28 10-19 172 Maximum 05-13 (2010) 11-01 (2017) 190 2019 04-11 (2019) 36 10-19 (2019) 38 190 2018 04-24 (2018) 36 10-18 (2018) 35 176 2017 05-04 (2017) 39 11-01 (2017) 36 180 2016 04-17 (2016) 37 10-11 (2016) 39 176 2015 05-02 (2015) 39 10-18 (2015) 33 168 2014 04-25 (2014) 38 10-20 (2014) 35 177 2013 05-05 (2013) 39 10-21 (2013) 39 168 2012 04-30 (2012) 36 10-13 (2012) 32 165 2011 05-06 (2011) 38 10-28 (2011) 37 174 2010 05-13 (2010) 38 10-10 (2010) 37 149 First/Last Summary for ISLIP-LI MACARTHUR AP, NY Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. Year Last Value First Value Difference Minimum 04-17 (2009) 10-02 (2009) 137 Mean 05-09 10-10 153 Maximum 05-22 (2002) 10-24 (2005) 167 2009 04-17 (2009) 32 10-02 (2009) 38 167 2008 05-20 (2008) 39 10-18 (2008) 39 150 2007 05-08 (2007) 39 10-13 (2007) 39 157 2006 04-29 (2006) 37 10-13 (2006) 38 166 2005 05-13 (2005) 37 10-24 (2005) 36 163 2004 05-05 (2004) 38 10-05 (2004) 39 152 2003 05-18 (2003) 38 10-03 (2003) 34 137 2002 05-22 (2002) 37 10-14 (2002) 39 144 2001 05-08 (2001) 37 10-07 (2001) 39 151 2000 05-16 (2000) 39 10-08 (2000) 39 144

All the extra ocean heat on the Siberian side is really slowing the freeze-up this October. So the the extent is currently the lowest on record for this time of year well below 2012. The Siberian heatwave this year was one of the most extreme events we have seen.

We have been warm and snowy regardless of La Niña, neutral, or El Niño last 20 years or so. The main difference between La Niña and El Niño has been the timing. La Ninas generally start out with the coolest departures early and transition to warm later on. 17-18 had coldest week of winter before January 5th flowed by 80° in February. El Niño is reversed. +13 during December 2015 followed by the historic late January blizzard and below 0° day for NYC in February. The other difference is the El Niño’s usually have a strong STJ and La Ninas a strong NPAC Jet.

La Ninas since 2000 usually end up warmer than average regardless of whether they are weak, moderate, or strong. NYC 00-01...weak.........-1.6 05-06...weak.........+2.2 07-08...strong.......+1.3 08-09..weak...........-0.9 10-11..strong.........-2.3 11-12..moderate...+5.4 16-17..weak...........+4.2 17-18..moderate...+1.1

Yeah, we are well below where 2012 was at this point in October. The the heat on the Siberian Arctic side this year was off the charts. 5.422 7.329 6.871 6.596 5.715 6.515 5.681 5.234 5.108

Another warmer than average winter would not be a surprise. The last 5 winters in NYC have been the warmest 5 year stretch on record. The 1981-2010 average in NYC was 35.1°. The last 5 years that jumped to 38.4°. Monthly Mean Avg Temperature for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Dec Jan Feb Season Mean 40.5 35.2 39.5 38.4 2019-2020 38.3 39.1 40.1 39.2 2018-2019 40.1 32.5 36.2 36.3 2017-2018 35.0 31.7 42.0 36.2 2016-2017 38.3 38.0 41.6 39.3 2015-2016 50.8 34.5 37.7 41.0

Very unusual to see a daily area drop in mid October as the record Arctic warmth is slowing the freeze-up https://cryospherecomputing.tk

Only a brief cool down before temperatures warm back up again.

Some pretty good training of cells last night from just west of JFK up into SW CT. Station Number: NY-QN-33 Station Name: Howard Beach 0.4 NNW Observation Date 10/17/2020 7:00 AM Submitted 10/17/2020 7:18 AM Total Precip Amount 2.48 in. Station Number: NY-NS-27 Station Name: Port Washington 0.8 N Observation Date 10/17/2020 7:14 AM Submitted 10/17/2020 7:18 AM Total Precip Amount 2.39 in. Station Number: CT-FR-25 Station Name: Norwalk 2.9 NNW Observation Date 10/17/2020 7:00 AM Submitted 10/17/2020 7:04 AM Total Precip Amount 2.27 in.

It looks like they may have corrected the longer range cold bias on the parallel GFS v16. But now it seems to have more of a warmer bias instead. So probably fewer long range incorrect snowstorm forecasts. https://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/

Looks like the parallel GFS may have gotten a fix for the cold bias.

The WAR continues to set records. A 5 SD positive 500 height anomaly near Newfoundland for this time of year. The anomalous 592 DM ridge for mid-October will help slow down the front today for soaking rains.

September is right up there also. But this fall so far is less warm than recent years. SEP....EWR...NYC...LGA 2020...+0.9....+0.8....+2.0 2019...+2.6....+2.4....+3.0 2018...+3.2...+2.7....+3.7 2017...+2.7...+2.5....+2.4 2016...+3.6...,+3.8...+4.7 2015...+5.2....+6.5...+5.0 2014..+1.6....+1.7....+1.3 2013...-1.0....-0.1.....-1.0 2012...+1.3...+0.8....+3.4 2011....+3.0..+2.0....+1.6 2010...+3.4....+3.1...+3.4

We are on track for an 11th consecutive warmer than normal October. Oct.......EWR...NYC...LGA 2020..+1.0...+0.9....+1.6...through the 14th 2019..+3.8...+3.0 ...+2.8 2018...+0.8...+0.8...+1.7 2017...+7.2...+7.2...+7.4 2016...+2.3...+1.9....+3.1 2015...+0.6...+1.1....+0.3 2014...+2.7...+2.7....+2.2 2013...+3.0....+3.3...+2.8 2012...+2.2....+1.1....+1.9 2011...+1.5...+0.2.....+0.2 2010...+1.7...+1.2....+2.1

GEFS in full cold bias correction mode as its seeing the stronger WAR pattern. Tough to bet against those very warm SSTs to our east. This is how a -5 forecast for the start of the month turned into a +1 to +3.

The record SST warmth form the Siberian heatwave is slowing down the freeze- up in those regions. https://theconversation.com/arctic-sea-ice-is-being-increasingly-melted-from-below-by-warming-atlantic-water-144106 All this may be feeding into ever more extreme climate change in the Arctic. Throughout summer 2020 the Siberian heatwavecontinually shattered temperature records, including eastern Arctic sea surface temperatures. And while sea ice reflects much of the sun’s rays back into space, open water is dark and absorbs the sun’s heat. So as the sea ice retreated the surface water is warmed, which in turned further warms the atmosphere above, quite apart from the influence of increasing greenhouse gases. There is still much more to learn about the link between the eastwards spread of the influence of Atlantic heat, and the reduction in sea ice it brings, and knock on effects on severe weather at lower latitudes. But it is clear that the Arctic – already warming faster than anywhere else on Earth – could be in the process of transitioning to a “new” state.

It looks like they ran tests without the GFDL microphysics and determined that it was the cause of the cold bias. I am not sure if the new parallel GFS is running one of those suites. Maybe we will get a statement from them once the new parallel becomes operational.

They think that the cold bias is a result of the GFDL microphysics. The whole explanation starts at page #40. I guess changing the microphysics takes time. What is the Cause of This Cold Bias? KEY POINTS: - Suites 1 and 2 (GFDL MP) have a cold bias that increases with lead time - The suites without GFDL microphysics do not show a cold bias increasing w time https://www.weather.gov/media/sti/nggps/NGGPS/EMC MEG Evaluation of GFSv15_Manikin_SIP Meeting_20190514.pdf

It makes more sense to rely on ensemble means beyond day 5 than OP runs. With the rise of social media, the modeling centers need to find a way to limit what type OP data beyond 120 hrs they make freely available. Otherwise, we will just keep getting these incorrect 30 inch snowstorm rumors. https://www.nj.com/weather-guy/2014/02/the_nj_blizzard_that_wasnt_the_anatomy_of_a_social_media_misfire.html

Yeah, extremely amplified pattern coming up. Looks like temperatures rebound back into the 70s Thursday. Then a strong storm that you mentioned with wind and rain. Models have a 590 dm+ ridge around Newfoundland which is close to the record for this time of year near 5 SD. That ridge builds westward over the Northeast day 6-10 for more milder than normal temperatures. Then we’ll have to watch for potential tropical development in the SW Caribbean later in the month.

First 1.00”+ event on the South Shore since the end of September. Wantagh mesonet 1 day: 1.02″

The WAR has been regularly verifying stronger than forecast with the record SSTs since late 2015.

The coolest temperatures should remain to our west as the WAR continues to flex with the warm SSTs to our east.

Stronger Western Atlantic Ridge during the first 10 days of October than the models forecast. So the forecast for a cooler than normal start verified as +1 to +3 across the region. We have seen this model forecast bias frequently in recent years with the record SST warmth to our east. EWR...+1.1 NYC...+1.4 LGA....+2.2 JFK....+1.6 BDR...+2.9 ISP.....+2.0