bluewave

4.08” at the Wantagh mesonet now.

3.80” now at the Wantagh Mesonet. This is the heaviest rainfall in under 2 hours here in SW Suffolk in at least 4 years.

Wantagh mesonet at 3.13” now. 2.31 of that fell in the last hour. http://www.nysmesonet.org/mesonow#network=nysm&stid=want

Torrential downpours along the South Shore.Wantagh mesonet just picked up 1.05” in the last 15 minutes. Total so far up to 2.06”. http://www.nysmesonet.org/mesonow#network=nysm&stid=want 6 hours: 2.06″

Record moisture instead of heat to go with the near record WAR for September.

With the exception of the super El Niño in 15-16 and March 18, the anomalous NEPAC Ridge has told the story of the winter. 13-14 and 14-15 were cold and snowy as the ridge set up over NW Canada. 16-17 and 17-18 were warm and snowy as the ridge location pulled back to the Aleutians. The last 2 winters were warm and nearly snowless as the ridge locked in just north of Hawaii. It’s no coincidence that my favorite snowstorms since 12-13 were in January 16 and March 18 as we finally got a -NAO/-AO pattern.

South Shore coastal sections missed out on the heaviest of the March snows in 2019. So they had two consecutive well below normal snowfall seasons. But they also did much better than the NYC area from 2013 to 2018. Time Series Summary for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Ending Date Total Snowfall Oct 1 to Apr 30 Missing Count 2020-04-30 6.8 1 2019-04-30 12.8 0 2018-04-30 65.9 0 2017-04-30 39.3 0 2016-04-30 41.4 0 2015-04-30 63.7 0 2014-04-30 63.7 0 2013-04-30 46.9 0 Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Ending Date Total Snowfall Oct 1 to Apr 30 Missing Count 2020-04-30 4.8 1 2019-04-30 20.5 0 2018-04-30 40.9 0 2017-04-30 30.2 0 2016-04-30 32.8 0 2015-04-30 50.3 0 2014-04-30 57.4 0 2013-04-30 26.1 0

The bar is set pretty low. This was the first time that NYC had two consecutive met winters (DJF) under 5”. Time Series Summary for NY CITY CENTRAL PARK, NY - Dec through Feb Click column heading to sort ascending, click again to sort descending. Rank Season Total Snowfall Missing Count 1 1997-1998 0.5 0 2 1918-1919 1.1 0 3 1972-1973 2.6 0 4 1931-1932 2.7 0 5 1991-1992 3.2 0 6 2001-2002 3.5 0 7 2018-2019 3.7 0 8 2011-2012 4.5 0 9 2019-2020 4.8 0 10 1989-1990 5.0 0

The dust bowl was a localized rather than global event. The heat and drought were amplified by the poor land use practices which lead to the extreme soil erosion. The modern localized summer cooler high temperatures in the corn belt are also a result of farming practices. https://www.journals.uchicago.edu/doi/10.1086/383102 Abstract We provide a new and more complete analysis of the origins of the Dust Bowl of the 1930s, one of the most severe environmental crises in North America in the twentieth century. Severe drought and wind erosion hit the Great Plains in 1930 and lasted through 1940. There were similar droughts in the 1950s and 1970s, but no comparable level of wind erosion. We explain why. The prevalence of small farms in the 1930s limited private solutions for controlling the downwind externalities associated with wind erosion. Drifting sand from unprotected fields damaged neighboring farms. Small farmers cultivated more of their land and were less likely to invest in erosion control than larger farmers. Soil conservation districts, established by the government after 1937, helped coordinate erosion control. This “unitized” solution for collective action is similar to that used in other natural resource/environmental settings. https://www.sciencemag.org/news/2018/02/america-s-corn-belt-making-its-own-weather The Great Plains of the central United States—the Corn Belt—is one of the most fertile regions on Earth, producing more than 10 billion bushels of corn each year. It’s also home to some mysterious weather: Whereas the rest of the world has warmed, the region’s summer temperatures have dropped as much as a full degree Celsius, and rainfall has increased up to 35%, the largest spike anywhere in the world. The culprit, according to a new study, isn’t greenhouse gas emissions or sea surface temperature—it’s the corn itself. https://news.wisc.edu/irrigated-farming-in-wisconsins-central-sands-cools-the-regions-climate/ New research finds that irrigated farms within Wisconsin’s vegetable-growing Central Sands region significantly cool the local climate compared to nearby rain-fed farms or forests. Irrigation dropped maximum temperatures by one to three degrees Fahrenheit on average while increasing minimum temperatures up to four degrees compared to unirrigated farms or forests. In all, irrigated farms experienced a three- to seven-degree smaller range in daily temperatures compared to other land uses. These effects persisted throughout the year.

This is a great example of what high enough snowfall rates can do.

It’s easy to lose track of all the new extremes in recent years.

Another warmer than average start to September across the area. The first week came in at +2.3 to +4.1. EWR...+2.7 NYC...+2.3 LGA....+4.1 JFK....+2.5 ISP.....+3.8 BDR...+4.1

More record breaking 500 mb heights.

We had several more 70° minimums since the start of September. So our local sites are still moving up on the list. We could add a few more this week as the higher dew points return. 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 Min Temperature >= 70 Missing Count 1 1973 62 0 2 2011 59 0 3 2005 58 0 4 2010 57 0 5 2020 55 116 - 1993 55 0 Time Series Summary for NY CITY CENTRAL PARK, NY - Jan through Dec Click column heading to sort ascending, click again to sort descending. Rank Year Number of Days Min Temperature >= 70 Missing Count 1 1906 61 0 2 2005 60 0 3 2020 57 116 4 2015 56 0 5 2018 55 0 - 2010 55 0 Time Series Summary for LAGUARDIA AIRPORT, NY - Jan through Dec Click column heading to sort ascending, click again to sort descending. Rank Year Number of Days Min Temperature >= 70 Missing Count 1 2018 78 0 2 2005 77 0 3 2016 73 0 4 2020 71 116 - 2012 71 0 5 2015 69 0 - 2010 69 0 Time Series Summary for JFK INTERNATIONAL AIRPORT, NY - Jan through Dec Click column heading to sort ascending, click again to sort descending. Rank Year Number of Days Min Temperature >= 70 Missing Count 1 2016 55 0 2 2015 53 0 3 2010 51 0 4 2018 49 0 5 2020 48 116 - 2012 48 0 - 1983 48 0 Time Series Summary for ISLIP-LI MACARTHUR AP, NY - Jan through Dec Click column heading to sort ascending, click again to sort descending. Rank Year Number of Days Min Temperature >= 70 Missing Count 1 2018 41 0 2 2010 36 0 - 1980 36 0 3 2020 35 116 - 2016 35 0 4 2013 34 0 - 1999 34 0

First time since 2012 that the 5 day NSIDC extent dropped below 4 million sq km. Also the first 5 year period with 3 years below 4.2 million sq km. 9-6-20.......3.928 September 5-day date 3.387 2012-09-17 4.155 2007-09-18 4.165 2016-09-10 4.192 2019-09-18

Plenty of onshore flow coming up with high pressure to our north and east. So no 90° potential for the foreseeable future. The last time Newark didn’t reach 90° in September was 2011 and 2012 for LGA.

A recent study was able to determine just how extreme the Bering wintertime sea ice low in 2018 was.

Numerous stations across PA also had their warmest summer.

It would be really odd if LGA didn’t have another 90° day this year. LGA never reached 30 days before without any 90° days in the spring or fall. LGA is currently in 4th place with 34 days reaching 90°. LGA finished JJA with the 2nd highest number of 90° days behind 2010. Monthly Number of Days Max Temperature >= 90 for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Year Apr May Jun Jul Aug Sep Oct Season 2010 1 2 12 18 11 4 0 48 2018 0 4 4 10 16 4 0 38 2002 2 0 5 14 13 1 0 35 2020 0 0 5 19 10 0 M 34 1991 0 4 9 10 9 2 0 34 2016 0 3 1 15 10 3 0 32 1983 0 0 5 11 8 7 0 31 2005 0 0 7 10 10 3 0 30 1953 0 1 7 10 9 3 0 30 Monthly Number of Days Max Temperature >= 90 for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Year Jun Jul Aug Season 2010 12 18 11 41 2020 5 19 10 34

According to Brian B, the US record for earliest measurable snowfall after a 100° was 5 days at Rapid City, SD in September 2000. So Denver could potentially see their latest 100° and then one of their earliest measurable snowfalls. 2000-09-17 101 53 77.0 16.8 0 12 T 0.0 0 2000-09-18 93 64 78.5 18.8 0 14 T 0.0 0 2000-09-19 65 48 56.5 -2.7 8 0 0.04 0.0 0 2000-09-20 61 43 52.0 -6.7 13 0 0.00 0.0 0 2000-09-21 66 41 53.5 -4.8 11 0 0.00 0.0 0 2000-09-22 46 34 40.0 -17.8 25 0 0.27 0.5 0 First/Last Summary for Denver Area, CO (ThreadEx) Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. Year First Value Last Value Difference 2019 07-19 (2019) 101 09-02 (2019) 100 44 2002 08-16 (2002) 100 08-16 (2002) 100 0 1962 08-10 (1962) 100 08-14 (1962) 100 3 1876 07-06 (1876) 101 08-12 (1876) 100 36 1969 08-08 (1969) 100 08-08 (1969) 100 0 First/Last Summary for Denver Area, CO (ThreadEx) 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 1961 05-13 (1961) 6.4 09-03 (1961) 4.2 112 1962 04-30 (1962) 0.1 09-08 (1962) 0.7 130 1974 04-29 (1974) 0.2 09-12 (1974) 1.8 135 1989 04-30 (1989) 3.7 09-12 (1989) 2.3 134 1993 04-24 (1993) 1.0 09-13 (1993) 5.4 141 1971 04-22 (1971) 4.5 09-16 (1971) 2.7 146

Looks like we will experience near record 500 mb heights for September. But the high will be to our NE with onshore flow.

Yeah, the number of new weather extremes since around 2010 has almost become too numerous to keep track of. Don, thanks for those stats. I guess our version of that near sea level would be February 8th- 9th, 2017. ISP 2017-02-08 62 39 50.5 18.8 14 0 T 0.0 0 2017-02-09 42 18 30.0 -1.8 35 0 1.30 14.3 1

I wonder if this will be the first time that a part of the US experiences snow so soon after highs near 100°? RECORD HEAT THIS WEEKEND TO POSSIBLE SNOW TUESDAY... Upper level ridge centered over the Great Basin will retrograde westward Sunday over California and Nevada. By Monday, what`s left of the ridge is just off the California coast. This ridge will keep it hot and dry Saturday and Sunday. Highs across northeast Colorado are expected to reach the mid 90s to lower 100s. A low pressure trough across eastern Colorado and a short wave trough passing to the north of Colorado will cause west to northwest winds to increase Sunday. This downslope flow will produce very dry conditions. It will likely offset any minor cooling associated with the short wave trough. A weak cold front drops south across the area Sunday night. Gusty east winds behind it are expected for Monday. This will usher in cooler air into northeast Colorado. For Monday, models still showing a strong open trough over the Northern Rockies. This trough then dives south and strengthens into a closed low over somewhere near the Four Corner Tuesday. A strong cold front associated with this system pushes south through the state late Monday afternoon through Monday night. Precipitation develops Monday evening and becomes widespread overnight Monday night and Tuesday. The 00Z GFS, GEM, and ECMWF are quite impressive with the amount of cold that accompanies this storm system. If the current solutions are right or close, it will be cold enough for snow to fall along the Front Range Urban Corridor and nearby plains. Accumulating snow on trees may cause considerable tree damage and related impacts will be possible. This system is four days away and models will likely change some. Confidence is becoming high that snow will occur in the mountains and foothills Monday night through Tuesday evening. A slight change in storm track or a slightly weaker closed low may keep the lower elevations warm enough for rain. Main message is cold and heavy snow is possible Monday night through Tuesday night. Monitor the latest forecasts and consider changing outdoor or travel plans if cold and snow still look on track.

Just an unbelievable temperature and weather swing in the forecast for the Rockies.