bluewave

14 out of 17 winter months warmer than average is pretty extreme. We knew something was up when December 2015 went +13.3. It appears to have been a climate shift to warmer winters. 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.....+5.2....so far

Finally, temperatures are just slightly below normal. But nothing outrageously cold for this time of year.

Something really flipped after the super El Niño. We did get that impressive cold stretch from late December 2017 into early January 2018. But the record warmth that followed with the 80° in February boosted the winter temperature departure to above average.

I wonder what would have to happen for us to get extended cold like we saw in 13-14 and 14-15 again?

We know that this isn’t the heat island since the warm minimums are uniform across the whole region. All our stations are in the top 3 or 4 for warmest minimums through January 21st. Even places like BTV still haven’t dropped below 0°. Same lack of cold across urban, suburban, and rural stations. Time Series Summary for WESTCHESTER CO AP, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Min Temperature Oct 1 to Jan 21 Missing Count 1 2007-01-21 16 0 - 2002-01-21 16 0 2 1950-01-21 15 52 3 2013-01-21 14 1 4 2021-01-21 13 1 - 2020-01-21 13 2 - 1995-01-21 13 34 Time Series Summary for IGOR I SIKORSKY MEMORIAL AIRPORT, CT Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Min Temperature Oct 1 to Jan 21 Missing Count 1 2002-01-21 18 0 2 2021-01-21 17 1 3 2020-01-21 15 0 - 2013-01-21 15 0 - 2007-01-21 15 0 - 1995-01-21 15 0 - 1993-01-21 15 0 - 1991-01-21 15 0 - 1987-01-21 15 0 - 1975-01-21 15 0 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 21 Missing Count 1 2013-01-21 22 0 2 2021-01-21 20 1 - 2002-01-21 20 0 - 1932-01-21 20 0 3 1987-01-21 19 0 - 1980-01-21 19 0 - 1908-01-21 19 0 Time Series Summary for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Min Temperature Oct 1 to Jan 21 Missing Count 1 2013-01-21 20 0 2 2021-01-21 17 1 2020-01-21 17 0 - 2007-01-21 17 0 3 1995-01-21 16 0 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 21 Missing Count 1 2016-01-21 2 0 - 2002-01-21 2 0 2 2021-01-21 1 1 - 1932-01-21 1 0

NYC has a shot at its 3rd latest first low under 20° this weekend. The average first date since 2000 was 12-24. Just goes to show the lack of cold this winter so far. KNYC GFSX MOS GUIDANCE 1/21/2021 0000 UTC FHR 24| 36 48| 60 72| 84 96|108 120|132 144|156 168|180 192 THU 21| FRI 22| SAT 23| SUN 24| MON 25| TUE 26| WED 27| THU 28 CLIMO X/N 44| 35 45| 25 34| 19 37| 24 40| 26 38| 28 39| 26 36 24 38 Frost/Freeze Summary for NY CITY CENTRAL PARK, 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 Season Length 1931 02-15 (1931) 16 02-16 (1932) 18 365 2001 02-22 (2001) 17 02-05 (2002) 19 347 2012 01-22 (2012) 18 01-22 (2013) 13 365 1974 02-15 (1974) 18 01-15 (1975) 17 333 1981 03-18 (1981) 17 01-09 (1982) 17 296

Yeah, light accumulations often go in as a T like we saw on 4-16-14. https://nypost.com/2014/04/16/mid-april-snow-falls-across-new-york-city/

A continuation of the summer pattern of recent years when the most impressive warm departures at times went north of us.

Getting 40dbz now on RadarScope. Combo of the heavier rates and giant wet snowflakes.

Getting a moderate to nearly heavy burst now in SW Suffolk. Snow sticking to the pavement and 34°. Large 1 inch diameter snowflakes.

Snowfall approaching moderate here in SW Suffolk with a dusting on colder surfaces and 34°.

Large 1 inch diameter snowflakes here in SW Suffolk and a light dusting in the colder surfaces.

It’s ridiculous how warm the minimums have been in Northern New England this month. Caribou is +17 on the minimums and +8.1 on the maximums. This gives a +13.1 average departure. Climatological Data for Caribou Area, ME (ThreadEx) - January 2021 Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature Avg Temperature Avg Temperature Departure HDD CDD Precipitation Snowfall Snow Depth Sum 521 328 - - 740 0 0.97 7.3 - Average 28.9 18.2 23.6 13.1 - - - - 6.7 Normal 19.8 1.2 10.5 - 981 0 1.59 14.6 - 2021-01-01 23 8 15.5 3.3 49 0 0.00 0.0 5 2021-01-02 22 12 17.0 5.0 48 0 0.33 4.0 5 2021-01-03 25 7 16.0 4.3 49 0 0.00 0.0 9 2021-01-04 26 21 23.5 12.1 41 0 0.00 0.0 9 2021-01-05 29 22 25.5 14.3 39 0 T T 8 2021-01-06 30 19 24.5 13.5 40 0 0.04 0.3 7 2021-01-07 29 21 25.0 14.2 40 0 0.00 0.0 7 2021-01-08 24 21 22.5 11.9 42 0 0.02 0.2 6 2021-01-09 31 20 25.5 15.1 39 0 T T 6 2021-01-10 28 7 17.5 7.3 47 0 0.00 0.0 6 2021-01-11 27 7 17.0 6.9 48 0 T T 6 2021-01-12 32 23 27.5 17.6 37 0 0.04 0.6 6 2021-01-13 32 24 28.0 18.2 37 0 T 0.1 7 2021-01-14 33 26 29.5 19.8 35 0 T T 7 2021-01-15 34 26 30.0 20.4 35 0 T T 6 2021-01-16 33 21 27.0 17.5 38 0 0.38 0.6 6 2021-01-17 33 30 31.5 22.0 33 0 0.15 1.3 7 2021-01-18 30 13 21.5 12.1 43 0 0.01 0.2 8 2021-01-19 M M M M M M M M M 2021-01-20 M M M M M M M M M 2021-01-21 M M M M M M M M M 2021-01-22 M M M M M M M M M 2021-01-23 M M M M M M M M M 2021-01-24 M M M M M M M M M 2021-01-25 M M M M M M M M M 2021-01-26 M M M M M M M M M 2021-01-27 M M M M M M M M M 2021-01-28 M M M M M M M M M 2021-01-29 M M M M M M M M M 2021-01-30 M M M M M M M M M 2021-01-31 M M M M M M M M

They have been getting the areas of the positive and negative 500mb height anomalies correct for North America. But the magnitude of the anomalies will always get refined the closer in we get. Maybe they corrected stronger on the blocking this month due to the lagged effect from the SSW and individual wave breaks? Jan 4 forecast for Jan 25-Feb 1 Jan 11 forecast for Jan 25-Feb 1 Jan 18 forecast for Jan 25- Feb 1

Parts of the region usually see heavier snow squalls when the mid level lapse rates are this steep. Could be the type of morning when the visibility briefly falls to 1/4 of a mile in a few spots. Winds may also beat expectations since the low level lapse rates become so steep by the afternoon.

Yeah, we need to ease up on the south based blocking suppression risk for the OP Euro to work out. The 0z Euro run was showing what needs to happen with the 2 storms. There aren’t that many years with the strongest AO blocking sitting just east of The Canadian Maritimes. The record holders for the previous strongest south based blocking for the entire winter were 2005, 1969, and 1951.

Record low snow extent for North America on January 17th for the last 16 years.

We are doing better than Northern New England with cold temperatures relative to averages. It was a tie for the warmest first half of winter at Caribou. BTV finished at the 4th warmest. NYC is further down the list at 19th warmest. Time Series Summary for Caribou Area, ME (ThreadEx) Click column heading to sort ascending, click again to sort descending. Rank Ending Date Mean Avg Temperature Dec 1 to Jan 15 Missing Count 1 2021-01-15 25.0 0 - 2016-01-15 25.0 0 2 2011-01-15 24.3 0 3 2007-01-15 23.6 0 4 2002-01-15 23.5 0 5 1997-01-15 22.8 0 Time Series Summary for Burlington Area, VT (ThreadEx) Click column heading to sort ascending, click again to sort descending. Rank Ending Date Mean Avg Temperature Dec 1 to Jan 15 Missing Count 1 2016-01-15 34.7 0 2 2007-01-15 33.2 0 3 2002-01-15 30.9 0 4 2021-01-15 30.0 0 5 1997-01-15 29.4 0 Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Mean Avg Temperature Dec 1 to Jan 15 Missing Count 1 2016-01-15 45.7 0 2 2007-01-15 44.5 0 3 1932-01-15 41.9 0 4 2002-01-15 41.7 0 5 2012-01-15 41.2 0 6 1983-01-15 41.0 0 7 2013-01-15 40.7 0 - 1950-01-15 40.7 0 8 1995-01-15 40.6 0 9 1890-01-15 40.2 0 10 2000-01-15 40.1 0 11 1998-01-15 39.9 0 - 1992-01-15 39.9 0 - 1985-01-15 39.9 0 12 2020-01-15 39.8 0 13 1972-01-15 39.7 0 - 1937-01-15 39.7 0 - 1892-01-15 39.7 0 14 2005-01-15 39.6 0 - 1991-01-15 39.6 0 15 1966-01-15 39.2 0 - 1913-01-15 39.2 0 16 1975-01-15 39.1 0 - 1924-01-15 39.1 0 17 1997-01-15 39.0 0 - 1980-01-15 39.0 0 18 1933-01-15 38.8 0 19 2021-01-15 38.6 0

NYC will extend the above 20° streak for at least another week as temperatures still average above normal for mid to late January. KNYC GFSX MOS GUIDANCE 1/16/2021 0000 UTC FHR 24| 36 48| 60 72| 84 96|108 120|132 144|156 168|180 192 SAT 16| SUN 17| MON 18| TUE 19| WED 20| THU 21| FRI 22| SAT 23 CLIMO X/N 52| 35 46| 35 46| 32 42| 26 35| 29 42| 31 37| 24 33 24 38

Heaviest rainstorm for portions of the South Shore since December 5th. 1/16/2021 7:00 AM NY-NS-46 Massapequa Park 1.2 N 1.35 NA | NA NA | NA NY Nassau

I guess it goes with the big snowfall swings that have become common in recent times. It’s been a rollercoaster ride between record highs and lows. The North America snow extent anomalies since October followed this pattern.

Only the 4th time that NYC didn’t drop below 20° by mid-January. 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 15 Missing Count 1 2013-01-15 22 0 2 2021-01-15 20 1 - 2002-01-15 20 0 - 1932-01-15 20 0

We always run the risk of suppression when there is a -strong -PNA trough in the West and a strong 50/50 low to our east.

The definition of luck these days is getting the Pacific to cooperate. Notice how the -PNA amps of the Pacific Jet as it crosses the country around the 22nd. This 200KT Jet max allows the primary low to scoot by to our north. The secondary gets going further to the east as it squeezes under the 50/50.

The biggest change for the first week of February is more poleward extension of the global ridges. So heights are a little higher over the SW U.S. up to the Aleutians and Pole. We may end up with further improvements in later runs. New run Feb 1-7 Old run