bluewave

Yeah, the November 2019 record early hard freeze following the October record warmth was a recent example of this. The record low 20s in November following the record mid 90s in October just flattened the late blooming fall plants. So November has been our month that we can still get record cold. Areas to our north that used to get late September freezes like Albany had them pushed back to mid-Ocrober. Since NYC has had the average first freeze November for a long time, the freeze date change isn’t as dramatic. First freeze dates Albany…1951-1980….9-29…..2010-2020….10-16 NYC…….1951-1980….11-11…..2010-2020….11-18

Yeah, the low was 48° at HPN. The first 40s and 30s have been getting later faster than the first freeze. My guess is that this is due to the September and October warming faster than November. So the first freeze date is closer to the colder weather arriving in November during recent years. Then as the warming has picked up in December, the first low below 20° since 2010 got pushed back by 12 days compared to the 1952-1980 climate normals period. HPN average first 40s 2010-2020…..9-20……1952-1980…..9-9 ………………………….30s 2010-2020….10-17…….1952-1980…..10-06 ………………………….32 2010-2020….10-30…….1952-1980…..10-26 ………………………….10s 2010-2020 12-17……..1952-1980…..12-05

Long range ensembles seem to be better at seeing the ridges. It usually takes a while longer for the individual shortwaves that produce the precipitation to show up. But we often see upper lows eventually getting stuck somewhere under strong blocks to our north.

Five of our stations have already reached 50” of precipitation for the year. Data for January 1, 2021 through September 29, 2021 Click column heading to sort ascending, click again to sort descending. State Name Station Type Total Precipitation NJ HARRISON COOP 54.25 NY NY CITY CENTRAL PARK WBAN 51.96 NJ NORTH ARLINGTON 0.7 WNW CoCoRaHS 51.05 NJ RINGWOOD 3.0 SSE CoCoRaHS 50.37 NJ WEST CALDWELL TWP 1.3 NE CoCoRaHS 50.27

September was the third consecutive month with our local stations exceeding 10” of rainfall. Several locations exceeded a 1000 year annual recurrence interval for our older climate with Ida. The office of water prediction keeps a list of these events. 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 CT RIDGEFIELD 1.9 SSE CoCoRaHS 12.16 CT RIDGEFIELD 3.7 NNE CoCoRaHS 11.94 CT DARIEN 2.4 NW CoCoRaHS 11.82 NJ NORTH ARLINGTON 0.7 WNW CoCoRaHS 11.70 CT DARIEN 3.6 N CoCoRaHS 11.69 NJ HARRISON COOP 11.47 CT NEW CANAAN 1.9 ENE CoCoRaHS 11.13 CT BROOKFIELD 3.3 SSE CoCoRaHS 10.98 CT WILTON 1.9 NW CoCoRaHS 10.98 CT NEW CANAAN 3.8 N CoCoRaHS 10.81 CT DARIEN 1.8 ENE CoCoRaHS 10.68 NY STATEN ISLAND 4.5 SSE CoCoRaHS 10.66 NJ MAPLEWOOD TWP 0.9 SE CoCoRaHS 10.65 CT NORWICH 2.5 NNE CoCoRaHS 10.61 CT BETHEL 3.5 NNE CoCoRaHS 10.58 CT NORWALK 2.9 NNW CoCoRaHS 10.58 NJ NEWARK LIBERTY INTL AP WBAN 10.50 CT WALLINGFORD CENTER 1.9 WNW CoCoRaHS 10.38 NJ KEARNY 1.7 NW CoCoRaHS 10.36 NJ LINDEN 2.2 NW CoCoRaHS 10.16 NJ TENAFLY 1.3 W CoCoRaHS 10.09 NY NY CITY CENTRAL PARK WBAN 10.03 https://www.weather.gov/owp/hdsc_aep

September 29th is the 2nd latest in the fall that HPN has dropped below 50°. It’s currently at 49°. All the top 5 latest dates have been since 2015. Weather Conditions For: White Plains - Westchester County Airport, NY. KHPN 29 Sep 6:56 am 49 First/Last Summary for WESTCHESTER CO 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 2018 06-12 (2018) 49 10-12 (2018) 47 121 2017 06-09 (2017) 47 09-29 (2017) 47 111 2002 06-08 (2002) 48 09-29 (2002) 48 112 1970 05-30 (1970) 44 09-29 (1970) 42 121 1968 05-28 (1968) 46 09-29 (1968) 49 123 2005 05-25 (2005) 46 09-28 (2005) 46 125 2015 06-02 (2015) 48 09-27 (2015) 47 116 1980 06-14 (1980) 47 09-27 (1980) 44 104 2016 05-21 (2016) 48 09-25 (2016) 44 126

Maybe the big ridge over Eastern Canada and the Northeast means that we are finally getting 500 mb patterns that are coupled with the ENSO. This is a textbook La Niña pattern for the month of October. It could be related to the recent PDO drop and cooler SSTs off of the West Coast. 16-17 and 17-18 were are last two winters that the La Niña or any ENSO state fully coupled.

Getting 10” of rain each month from July to September is an impressive feat even in South Florida. Miami still hasn’t been able to pull it off. But several other stations have. Monthly Total Precipitation for MIAMI INTERNATIONAL AP, FL Click column heading to sort ascending, click again to sort descending. Year Jul Aug Sep Season 1941 15.33 5.01 8.01 28.35 1939 13.85 11.34 6.70 31.89 1947 13.51 6.66 10.71 30.88 2002 12.76 6.55 6.48 25.79 2013 12.70 4.43 10.47 27.60 2017 12.45 8.57 14.97 35.99 1946 11.78 5.13 5.24 22.15 1985 11.23 11.88 8.59 31.70 1988 10.90 7.89 3.09 21.88 2019 10.54 15.74 3.25 29.53 2014 10.29 9.07 7.25 26.61 2020 10.26 7.44 10.92 28.62 Monthly Total Precipitation for MIAMI OPA LOCKA AP, FL Click column heading to sort ascending, click again to sort descending. Year Jul Aug Sep Season 2002 13.11 7.10 4.83 25.04 2014 12.97 8.45 8.88 30.30 2017 11.73 14.11 16.70 42.54 2009 11.53 7.87 9.74 29.14 2013 10.91 4.54 8.23 23.68 2004 10.26 10.88 12.60 33.74 Monthly Total Precipitation for MIAMI KENDALL TAMIAMI EXEC AP, FL Click column heading to sort ascending, click again to sort descending. Year Jul Aug Sep Season 2000 14.74 9.46 6.79 30.99 2006 14.16 9.10 6.21 29.47 2013 11.73 3.48 4.12 19.33 2014 10.92 4.82 5.84 21.58 2020 10.53 2.99 7.82 21.34 2001 10.22 8.74 13.52 32.48 2012 10.10 12.78 11.30 34.18 Monthly Total Precipitation for NAPLES MUNICIPAL AIRPORT, FL Click column heading to sort ascending, click again to sort descending. Year Jul Aug Sep Season 2006 12.16 11.60 7.50 31.26 2017 11.24 15.55 18.03 44.82 2015 10.15 2.78 6.75 19.68

Radar indicating some small hail possible with the stronger storms on Long Island. OKX set a new daily mid-level lapse rate record.

Islip adds another 75° day to set the new September record. MacArthur/ISP PTSUNNY 75 61 61 W10 Time Series Summary for ISLIP-LI MACARTHUR AP, NY - Month of Sep Click column heading to sort ascending, click again to sort descending. Rank Year Number of Days Max Temperature >= 75 Missing Count 1 2021 26 2 2 2005 25 0 3 2015 24 0 - 1980 24 0 4 2019 23 0 - 1998 23 0 5 2017 22 0 - 2007 22 0 6 2020 21 0 - 1968 21 0 7 1972 20 0

This is now the wettest September on record at Newark. Wet September patterns in the past have been much cooler. So this will be the first in the top 5 wettest to average above 70°. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Month of Sep Click column heading to sort ascending, click again to sort descending. Rank Year Total Precipitation Avg Temperature 1 2021 10.32 73.2° 2 1944 10.28 68.2° 3 1999 9.38 69.3° 4 1975 9.00 64.3° 5 1933 8.33 68.0°

Newark sets the new record of 120 consecutive days reaching 70° or higher. Number of Consecutive Days Max Temperature >= 70 for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Rank Run Length Dates Period of record: 1931-01-01 to 2021-09-26 1 120 2021-05-31 through 2021-09-27 2 119 2008-05-23 through 2008-09-18 3 117 1995-05-29 through 1995-09-22 - 117 1994-05-28 through 1994-09-21 4 113 2020-05-25 through 2020-09-14 5 112 2016-06-09 through 2016-09-28 6 110 1966-06-02 through 1966-09-19 7 107 1957-06-09 through 1957-09-23 8 106 2014-05-30 through 2014-09-12 - 106 2010-05-29 through 2010-09-11

Today and possibly tomorrow look like it will be our warmest days for a while as the usual warmer spots reach 80°+. Several locations have had their warmest low max for the month so far. This was the first time that HPN hasn’t had a high below 70° through 9-26. Time Series Summary for WESTCHESTER CO AP, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Max Temperature Sep 1 to Sep 26 Missing Count 1 2021-09-26 70 0 2 2016-09-26 69 0 - 1968-09-26 69 0 3 2015-09-26 68 0 - 2005-09-26 68 0 - 1961-09-26 68 0 Time Series Summary for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Max Temperature Sep 1 to Sep 26 Missing Count 1 2021-09-26 76 0 2 1968-09-26 74 0 3 2005-09-26 72 0 Time Series Summary for JFK INTERNATIONAL AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Max Temperature Sep 1 to Sep 26 Missing Count 1 2021-09-26 74 0 2 1968-09-26 73 0 3 2015-09-26 72 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 Max Temperature Sep 1 to Sep 26 Missing Count 1 2021-09-26 72 0 2 2015-09-26 71 0 - 2005-09-26 71 0 Time Series Summary for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Max Temperature Sep 1 to Sep 26 Missing Count 1 2021-09-26 74 0 2 1968-09-26 72 0 3 2016-09-26 71 0 - 2005-09-26 71 0 Time Series Summary for Boston Area, MA (ThreadEx) Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Max Temperature Sep 1 to Sep 26 Missing Count 1 2021-09-26 70 0 2 1957-09-26 68 0 - 1930-09-26 68 0

Just in time for this new Euro extended range product.

This coming week is another example of needing record blocking to get below normal temperatures in our area.

Sam joins Lorenzo in being the strongest hurricane this far to the east in the Atlantic so late in the season.

It looks like NYC may finally drop below 55° next week. HPN could also see the first 40s of the fall. This would be very late for these temperature benchmarks at both stations. Latest first day below 55° in NYC First/Last 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 Difference 2015 06-04 (2015) 54 10-02 (2015) 48 119 1910 06-08 (1910) 53 10-02 (1910) 54 115 1921 06-05 (1921) 54 10-01 (1921) 52 117 1908 05-16 (1908) 53 09-30 (1908) 52 136 2005 06-02 (2005) 54 09-29 (2005) 54 118 2003 06-17 (2003) 53 09-29 (2003) 53 103 2002 06-08 (2002) 53 09-29 (2002) 54 112 1968 06-21 (1968) 53 09-29 (1968) 53 99 1930 06-01 (1930) 50 09-29 (1930) 53 119 1970 05-30 (1970) 50 09-27 (1970) 54 119 2016 06-09 (2016) 54 09-25 (2016) 54 107 Latest first 40s at HPN First/Last Summary for WESTCHESTER CO 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 2018 06-12 (2018) 49 10-12 (2018) 47 121 2017 06-09 (2017) 47 09-29 (2017) 47 111 2002 06-08 (2002) 48 09-29 (2002) 48 112 1970 05-30 (1970) 44 09-29 (1970) 42 121 1968 05-28 (1968) 46 09-29 (1968) 49 123 2005 05-25 (2005) 46 09-28 (2005) 46 125 2015 06-02 (2015) 48 09-27 (2015) 47 116 1980 06-14 (1980) 47 09-27 (1980) 44 104 2016 05-21 (2016) 48 09-25 (2016) 44 126

Tough to keep up with all the new RI records in recent years.

Record breaking omega block this week with 580 dm heights near Hudson Bay.

Even South Florida is getting a break from the high dew points behind this front.

Updated for 9-23. 9-24….Darien, CT….4.52….North Massapequa, NY….3.05

Front slowing down over eastern sections as the ridge east of New England is still very strong.

Newark is currently in 2nd place for wettest September at 10.08”. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Month of Sep Click column heading to sort ascending, click again to sort descending. Rank Year Total Precipitation Missing Count 1 1944 10.28 0 2 2021 10.08 7 3 1999 9.38 0 4 1975 9.00 0 5 1933 8.33 0 6 1934 8.15 0 7 2011 8.13 0 8 2004 8.01 0 9 1971 7.88 0 10 1966 7.86 0

Yeah, a Florida and SE looking tropical cloud streets pattern.

The one comparison that holds between NYC and Miami is the JAS rainfall in 2021 and 2011 is closer to the South Florida average. Monthly Total Precipitation for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Jul Aug Sep Season 2011 3.03 18.95 9.39 31.37 2021 11.09 10.32 7.73 29.14 Monthly Total Precipitation for Miami Area, FL (ThreadEx) Click column heading to sort ascending, click again to sort descending. Year Jul Aug Sep Season Mean 8.70 10.06 9.15 27.91 2021 8.18 7.29 7.14 22.61 2020 10.26 7.44 10.92 28.62 2019 10.54 15.74 3.25 29.53 2018 8.02 9.58 7.89 25.49 2017 12.45 8.57 14.97 35.99 2016 4.11 13.77 6.05 23.93 2015 5.91 9.02 9.97 24.90 2014 10.29 9.07 7.25 26.61 2013 12.70 4.43 10.47 27.60 2012 8.92 15.92 11.03 35.87 2011 5.71 11.08 4.99 21.78 2010 7.36 8.75 15.89 32.00