bluewave

The potential for a few more 80° degree days showing up over the next week. KEWR GFSX MOS GUIDANCE 9/21/2021 1200 UTC FHR 24 36| 48 60| 72 84| 96 108|120 132|144 156|168 180|192 WED 22| THU 23| FRI 24| SAT 25| SUN 26| MON 27| TUE 28|WED CLIMO N/X 67 81| 69 76| 61 75| 59 74| 59 81| 59 77| 59 75| 61 54 72

Another 80° day at Newark as the endless summer pattern continues. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Jan through Dec Click column heading to sort ascending, click again to sort descending. Rank Year Number of Days Max Temperature >= 80 Missing Count 1 2015 118 0 2 1994 114 0 3 2016 113 0 - 1993 113 0 - 1991 113 0 4 2011 111 0 - 2010 111 0 5 1959 108 0 2021 108 102

The 592 dm height at Caribou today was one of the highest on record for so late in the season.

Congratulations. The 12z UKMET joined the CMC. Heaviest convection later Thursday into early Friday. The front keeps moving enough that both models are now dry for Saturday.

The next big WAR amplification is in early October with the potential for a hurricane to be somewhere underneath.

The 12z NAM joins the slower models with cutoff and cold front later in the week as the WAR builds to record levels for late September over Newfoundland on Tuesday.

Following the briefly lower dew points, 70° dew points will return ahead of the cutoff low this week.

High temperatures beat guidance again as Newark adds another 80° day to the list.

We’ll see if the JMA is correct about that pattern locking in for October.

Record Newfoundland blocking ahead of the big cutoff this week. So the front stalls out for several days. More very heavy training convection potential coming up.

Several stations just had the 2nd warmest 09-12 to 09-18 on record. Time Series Summary for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Rank Ending Date Mean Avg Temperature Sep 12 to Sep 18 Missing Count 1 2005-09-18 78.4 0 2 2021-09-18 77.1 0 3 1957-09-18 75.4 0 4 1931-09-18 74.9 0 5 1994-09-18 74.5 0 Time Series Summary for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Mean Avg Temperature Sep 12 to Sep 18 Missing Count 1 2005-09-18 75.6 0 2 2021-09-18 74.4 0 3 2018-09-18 72.3 0 4 1998-09-18 72.2 0 5 1971-09-18 72.1 0 Time Series Summary for WESTCHESTER CO AP, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Mean Avg Temperature Sep 12 to Sep 18 Missing Count 1 2005-09-18 73.7 0 2 2021-09-18 72.2 0 3 1957-09-18 72.0 0 4 2018-09-18 71.6 0 5 1971-09-18 71.5 0

They just missed the record high of 90° by a few degrees.

It will make 3 months in a row with several local stations going 10”+ Monthly Data for September 2021 for Upton NY NWS CWA Click column heading to sort ascending, click again to sort descending. State Name Station Type Total Precipitation NY STATEN ISLAND 4.5 SSE CoCoRaHS 9.92 CT NORWICH 2.5 NNE CoCoRaHS 9.26 NJ HARRISON COOP 9.25 NJ NORTH ARLINGTON 0.7 WNW CoCoRaHS 9.23 NJ NEWARK LIBERTY INTL AP WBAN 8.79 Monthly Data for August 2021 for Upton NY NWS CWA Click column heading to sort ascending, click again to sort descending. State Name Station Type Total Precipitation NY BROOKLYN 3.1 NW CoCoRaHS 12.41 NJ RINGWOOD 3.0 SSE CoCoRaHS 11.57 NJ WEST MILFORD TWP 2.5 SSE CoCoRaHS 11.29 NJ CHARLOTTEBURG RESERVOIR COOP 10.73 NY WANTAGH 0.3 ESE CoCoRaHS 10.54 NY HOWARD BEACH 0.4 NNW CoCoRaHS 10.34 NY NY CITY CENTRAL PARK WBAN 10.32 NJ HARRISON COOP 10.24 Monthly Data for July 2021 for Upton NY NWS CWA Click column heading to sort ascending, click again to sort descending. State Name Station Type Total Precipitation NY PORT WASHINGTON 0.8 N CoCoRaHS 14.76 CT NORTHFORD 0.8 SW CoCoRaHS 12.54 CT DARIEN 3.6 N CoCoRaHS 12.06 CT DARIEN 2.4 NW CoCoRaHS 11.43 NY NY CITY CENTRAL PARK WBAN 11.09 CT STRATFORD 0.9 W CoCoRaHS 11.04 CT WESTPORT 2.5 ENE CoCoRaHS 11.01 CT NORWALK 2.9 NNW CoCoRaHS 10.98 CT NORWALK 1.4 ENE CoCoRaHS 10.75 CT DARIEN 1.8 ENE CoCoRaHS 10.71 NY ALBERTSON 0.2 SSE CoCoRaHS 10.68 CT STAMFORD 4.2 S CoCoRaHS 10.62 CT DURHAM 2.2 SSW CoCoRaHS 10.58 NY QUEENS 3.7 N CoCoRaHS 10.54 CT NEW CANAAN 1.9 ENE CoCoRaHS 10.48 NJ LINDEN 2.2 NW CoCoRaHS 10.32 CT WEST HAVEN 0.8 W CoCoRaHS 10.29 CT REDDING 1.4 E CoCoRaHS 10.25 CT MIDDLEFIELD 0.6 SE CoCoRaHS 10.24 NY LOCUST VALLEY 0.3 E CoCoRaHS 10.13

Models really slowing down the cold front later in the week due to the UL closing off over the Great Lakes. So heavy convection potential where the front stalls out. Probably several days of closer to normal temperatures behind the front. New run Old run

Since September has warmed so much, LGA only has a +1.4 departure through the 17th. So the departures don’t tell the whole story. In our warmer climate, +1.4 is all that is needed for a top 10 warmest first 17 days of September. Time Series Summary for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Mean Avg Temperature Sep 1 to Sep 17 Missing Count 1 1961-09-17 77.4 0 2 2015-09-17 77.2 0 3 2005-09-17 77.1 0 4 1947-09-17 76.7 0 5 2016-09-17 76.0 0 6 2018-09-17 75.3 0 7 1983-09-17 74.9 0 8 1971-09-17 74.7 0 9 2021-09-17 74.4 0 10 1957-09-17 74.3 0

The Euro has highs in the 70s and lows in the 50s behind the cold front near the coast later next week. Still has a piece of the WAR hanging on. So the coldest departures remain to our west with the blocking.

It’s always interesting to see how the EPS weeklies compare with the SEAS5 seasonal forecast. The Euro seasonal was picking up on the October blocking potential from the forecast issued back in July. South based blocks can still have above normal temperatures in the Northeast like we saw last winter. So the latitude of the block is important. Early July forecast for October

The EPS ends September with higher latitude blocking that becomes more south based over time. 9-27 to 10-4 10-04 to 10-11 10-11 to 10-18

Continuation of the warm pattern for this time of year. More 80s this weekend. But models have now shifted to more blocking for later in September. Old run New run

You know it’s a warm pattern when Islip reaches 81° on a NE wind in mid-September.

Yeah, we needed the strong SE ridge to boost the SSTs for heavier snows. Luckily, the years that the SE Ridge ran the table without blocking like 2012 and 2020 were in the minority. Some of our best snowfalls have occurred a month after the record SE Ridge was replaced by blocking. The historic January 30” blizzard followed the historic +13.3 SE Ridge December 2015. The historic February 2018 SE Ridge and 80° at Newark was followed by the March historic 30” snows on Long Island.

We now have a new AI based sea ice forecasting system.The paper was just published in late August. So their first official forecast was issued a few weeks ago on the ARCUS site. The September daily minimum was very close to their September average monthly forecast. The September average extent will come in a little higher which is always the case due to the higher average extent in early and late September. Name of contributor or name of contributing organization: IceNet1 https://www.arcus.org/files/sio/32360/icenet1_2021_sio_august_individual_report.pdf a) Pan-Arctic September extent prediction in million square kilometers. 4.75 IceNet is a sea ice forecasting AI system which predicts monthly-averaged sea ice probability (SIP; probability of sea ice concentration > 15%) up to 6 months ahead at 25 km resolution on an EASE2 grid. IceNet is based on a deep learning U-Net architecture, and has been trained on climate simulations (CMIP6) covering 1850-2100 and observational data (OSI-SAF SIC and ERA5) from 1979-2011. IceNet’s monthly-averaged inputs comprise SIC, 11 climate variables, statistical SIC forecasts, and metadata. IceNet is introduced in the following pre-print, with the study soon to be published in Nature Communications: https://doi.org/10.31223/X5430P. IceNet was also presented at the Oxford ML and Physics Seminar Series: https://youtu.be/JAKWhEU09Xo. Brief explanation of Outlook method (using 300 words or less). At each 25x25 km ocean grid cell in the Arctic and at each forecast lead time from 1 to 6 months ahead, IceNet produces a probability that the SIC will be less than 15% (no ice), between 15% and 80% (marginal ice), or above 80% (full ice). To compute the SIP map for this SIO submission, we sum the probability of the two ice classes to obtain P(SIC > 15%). IceNet comprises 25 different U-Net models, whose output SIPs are averaged to produce the final SIP forecast. To compute the SIE, we sum the area of grid cells whose SIP > 0.5.

The increased blocking and milder winter temperatures have worked wonders for our snowfall since 2002-2003.

This was only the 2nd 40-40 year for Newark. 41 days reaching 90°after 45.7” of snow. The other 3 years with at least 30” of snow were strong to super El Niño’s. I guess it fits since winter was more El Niño-like. Year /snowfall/ #90°days/peak ENSO ONI 2021…..45.7”…41...-1.3 2010….47.9”….54…+1.6…strong El Niño 2016….32.8”….40.+2.6…super El Niño 1983….31.0”….40.+2.2….super El Nino https://www.climate.gov/news-features/blogs/enso/did-northern-hemisphere-get-memo-years-la-niña That means you can argue that the Northern Hemisphere atmosphere looked a little more like El Niño than La Niña!