bluewave

The 60s dew points returned right on schedule. Some spots may challenge their warmest daily minimums next few days. KEWR GFS MOS GUIDANCE 10/20/2020 0600 UTC DT /OCT 20 /OCT 21 /OCT 22 / HR 12 15 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 00 06 X/N 72 63 77 63 75 TMP 62 66 70 70 67 66 66 65 66 72 75 74 71 68 67 65 65 69 73 66 61 DPT 59 60 60 60 61 61 63 63 63 64 64 64 64 62 60 59 58 55 52 50 54 CLD OV OV OV OV OV OV OV OV OV OV BK BK BK OV OV OV BK BK SC SC CL WDR 10 16 21 21 02 03 06 07 12 20 20 21 19 22 23 31 35 36 01 05 05 WSP 01 04 04 04 03 02 02 01 01 06 09 09 05 04 04 04 05 07 06 05 05 Newark Area, NJ Version: 15.4 (created 2020-07-31) Period of record: 1931 through 2019 10/21 62 in 1984 62 in 1979 58 in 2016 10/22 64 in 1979 63 in 1984 62 in 1970

At least for a La Niña October, that drought ridge along the West Coast is out of place.

The PDO isn’t following the La Niña playbook this fall. This was one of the biggest PDO increases during a La Niña in October. But as we have seen since the record North Pacific warming in 2013, these monthly values can really jump around a lot. Last winter we went from positive in December to negative during January and February. It all comes down to how the North Pacific ridge behaves.

Those are the new free maps. All we need now is for someone to generate free ECM MOS. https://www.weather.gov/media/mdl/Shafer-AMS-ext-abstract.pdf

Yeah, looks like this warmer WAR pattern should persist at least into the last week of October.

That area was in a perfect spot to take advantage of the strong block near Greenland this month. The strong WAR seems to have kept the TPV locked in along the west side of Hudson Bay. So a strong -NAO/-AO isn’t much of a help for us if the WAR is too amplified.

We are getting a late October version of our recent summer warm ups. Clouds, high dew points for this time of year, and onshore flow. Same old pattern with the big ridge parked near New England. KEWR GFS MOS GUIDANCE 10/19/2020 1200 UTC DT /OCT 19/OCT 20 /OCT 21 /OCT 22 HR 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 21 00 06 12 N/X 58 74 63 76 64 TMP 64 64 61 60 60 60 61 68 72 71 68 67 66 65 66 71 74 73 70 67 67 DPT 49 51 52 53 55 57 59 61 61 61 62 62 63 64 64 64 64 64 64 63 62 CLD BK BK BK OV OV OV OV OV OV OV OV OV OV OV OV OV BK BK OV OV BK WDR 14 15 14 13 11 11 15 19 22 23 10 04 06 07 14 19 20 19 19 21 29 WSP 05 06 04 03 02 01 03 04 05 05 03 02 02 02 03 05 08 08 06 04 03

2nd big snowfall October in a row for the Great Falls area. Time Series Summary for Great Falls Area, MT (ThreadEx) - Month of Oct Click column heading to sort ascending, click again to sort descending. Rank Year Total Snowfall Missing Count 1 1925 18.5 0 2 2019 17.0 0 3 1975 16.6 0 4 1919 15.5 0 5 2020 14.2 13

It has been the only cooler than average part of the US since the Super El Niño in 2016.

Warm in the East and cold with record early snows in Montana this week. Very familiar La Niña background pattern in recent years. The SE Ridge or WAR continues to dominate. GEFS temperature departures for the next 7 days

The models have plenty of clouds and an S To SE flow this week. So that’s why they hold the highs in the 70s instead of 80s. Still a +10 or higher departure on the warmest days. Maybe somebody in Central Jersey can make a run on 80° with more sun and SSW flow than forecast. KEWR GFSX MOS GUIDANCE 10/18/2020 1200 UTC FHR 24 36| 48 60| 72 84| 96 108|120 132|144 156|168 180|192 MON 19| TUE 20| WED 21| THU 22| FRI 23| SAT 24| SUN 25|MON CLIMO N/X 51 67| 56 72| 61 73| 63 78| 63 75| 60 72| 54 66| 48 44 62

Pretty late in the season for a 588 DM ridge over our area this week.

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