bluewave

Boerum Hill on the cocorahs site. https://www.cocorahs.org

Station Number: NY-KN-25 Station Name: Brooklyn 3.1 NW

Brooklyn at 9.43 on the latest update. 08/22/2021 6.16 08/23/2021 3.27

When was the last time we had a heatwave so soon after a tropical storm or hurricane? All the guidance has the 850 mb temps rebounding to the 18-20C range. So the warm spots can make a run on 95° with high humidity.

The dense tree growth over the ASOS could be affecting the rainfall measurements in addition to the high temperatures. Notice how the new hourly record set with Henri was lower than all the other ASOS stations. Hourly rainfall records NYC…..1.94….8-21-21 JFK…..2.88….7-31-96 LGA….2.44….7-15-97 EWR…2.35….7-21-06 ISP……5.34….8-13-14

Updated for 9.43 in Brooklyn. 08/22/2021 6.16 08/23/2021 3.27

The vegetation around the sensor will probably give new meaning to tropical rainforest.

This is the 4th wettest summer on record in NYC through yesterday. Time Series Summary for NY CITY CENTRAL PARK, NY - Jun through Aug Click column heading to sort ascending, click again to sort descending. Rank Year Total Precipitation Missing Count 1 2011 25.23 0 2 1975 22.40 0 3 1989 22.36 0 4 2021 22.29 9 5 2009 21.38 0 6 2006 20.79 0 7 2007 20.62 0 8 1928 20.50 0 9 1903 20.43 0 10 1927 20.01 0

Near to record breaking 500mb heights over Eastern North America and the Western Atlantic altering the storm tracks and weather patterns. The tropical cyclone database goes back to 1851. That area around Bermuda has always been busy place for shipping. So it would be a tougher area to miss storms before the satellite era. Plus all landfalling systems near the Northeast have been well documented in the record books. Their tracks were traced back through the Atlantic. Near to record breaking 500 mb heights in the lead up to Henri

Henri is another example of how extreme the Western Atlantic Ridge has become. This is the first tropical cyclone to make landfall in Rhode Island after tracking within 200 miles of Bermuda. Absent such a strong WAR, Henri would have went harmlessly out to sea. Tracks of 350 tropical cyclones passing within 200 miles of Bermuda

NYC has had measurable rainfall nearly every weekend this summer since the Memorial Day weekend. But this was the wettest weekend by far. So it will be interesting to see if the Labor Day weekend continues this pattern. NYC weekends May 29-30….1.35 Jun 5-6……….dry Jun 12-13…….01 Jun 19-20……14 Jun 26-27……04 Jul 3-4………..34 Jul 10-11..……28 Jul 17-18…….65 Jul 24-25……49 Jul 31-Aug 1…04 Aug 7-8………21 Aug 14-15….dry Aug 21-22….6.35…so far

Parts of Brooklyn are probably over 8” by now with this band stalled out. Kings County... Brooklyn 7.82 in 0145 PM 08/22 CWOP South Slope 6.89 in 0145 PM 08/22 CWOP Prospect Park 6.88 in 0150 PM 08/22 AWS

The waterfall video was pretty wild.

Major flooding of homes in Brooklyn last night.

The rainfall total since yesterday is 3.42” in Wantagh. 1.86” so far under this stalled out band.

I never understood why building codes in Long Beach permitted slope down driveways and basements on a barrier island.

Rain continuing to get heavier here in SW Suffolk as this stalled out band really means business.

Due to the tropical nature of the rainfall, the E-W band along the South Shore is being underestimated a bit by the radar. Getting a heavy downpour here in SW Suffolk that is more impressive than radar indicates.

It’s very disappointing to see how they let the NYC observation station go once the NWS left Rockefeller Center. Central Park Weather: Vegetative Overgrowth Affecting Weather Readings - WABC-TV (New York-WABC, August 22, 2003) - Forecasting the weather is not easy. Government equipment can often be blamed for giving faulty weather information. As Bill Evans explains, a big culprit may be some of the equipment buried in Central Park. Rainfall, snowfall, and the temperature are all vital information recorded 24 hours a day at the weather station located in the heart of Central Park. But meteorologists like Michael Schlacter have serious concerns about the accuracy of the stations data. It sits amid overgrown vegetation and he says thats the problem. The leaves can trigger snow gauges and trees can warp rain and wind measurements. On this hot day, a temperature gauge is in the shade instead of direct sunlight. Michael Schlacter, Weather 2000: "Its kind of like driving a car without a speedometer, odometer, and gas gauge. You are running with false information." The weather instruments at Belvedere Castle have long adorned the top. There used to be a government meteorologist here in the city to keep an eye on them. But now the nearest meteorologist is 60 miles that way. But National Weather Service meteorologists say they knew the weather readings in the park would never be as keenly accurate as the ones at the airports where guidelines prevent foliage from being within 100 feet of the station. Schlacter: "We knew that at times we would have flaky readings, that leaves would fall in gauges, that we would have problems with visibility sensors." [NWS Meteorologist-in-Charge Michael] Wyllie says the weather station is there because it was historically significant to maintain its presence in the park. He says theres been a lot of growth because of the wet spring at so much in fact that temperatures have routinely been recorded lower in the park than at the airports. Wyllie: "We are actually having a micro climate system there because of the vegetation." Imperfect perhaps but nonetheless the system provides the official record of weather for the country's largest city. And Michael Schlacter says its a city that deserves better. Schlacter: "I think New Yorkers deserve a lot better, and I think they deserve the best weather station money can buy." Copyright 2003 ABC Inc., WABC-TV Inc.

The HREF showed the potential but the axis of heaviest rainfall was too far south. https://origin.wpc.ncep.noaa.gov/metwatch/metwatch_mpd_multi.php?md=850&yr=2021 Mesoscale Precipitation Discussion 0850 NWS Weather Prediction Center College Park MD 602 PM EDT Sat Aug 21 2021 Areas affected...South-Central New Jersey...Far Southeastern Pennsylvania Concerning...Heavy rainfall...Flash flooding likely Valid 212200Z - 220400Z Summary...An axis of very heavy rainfall is expected to develop with 2-3+"/hr rates leading to some totals of 3-6 inches. Localized flash flooding is likely. Discussion...As Hurricane Henri moves northward late this afternoon and evening, an axis of very heavy rainfall is expected to develop across portions of south-central New Jersey and far southeastern Pennsylvania. Strong low-level moisture transport from the east (via Henri) is leading to precipitable water values building to 2.1 to 2.3 inches, while an upper-level trough axis and associated jet streak (right entrance region) will provide enhanced lift aloft. This banded feature will likely initiate with a NNW to SSE orientation, gradually pivoting counter-clockwise (from the WNW to ESE) towards midnight (local). The nearly stationary nature of the heavy rain axis will allow for repeating of very efficient rates (2-3+"/hr) as strong moisture transport and upper-level lift allow SB CAPE to remain elevated around 1000-1500 J/kg. Hi-res CAM guidance (12z HREF and more recent HRRR runs) have been consistent in painting a localized swath of 3-6 inches of rainfall from near Atlantic City, NJ to the Philadelphia, PA metropolitan area through midnight local. The 12z HREF 40km neighborhood probabilities depict a greater than 30% chance of 3" exceedance over 3 hours and a greater than 20% chance of 5" exceedance over 12 hours (ending 06z). In addition, the HRRR has been very consistent run-to-run producing a swath of 2-6 inches. Given this guidance and the overall synoptic and mesoscale setup, localized flash flooding is considered likely (with more sensitive urbanized areas of the greatest concern).

NYC just set its new heaviest hourly rainfall total at 1.94”. The 8th heaviest hourly total was set back in July. Notice how many hourly records were set in recent years.

Impressive flooding in Brooklyn last night. Station Number: NJ-HD-1 Station Name: Harrison 0.3 N Observation Date 8/22/2021 7:00 AM Submitted 8/22/2021 6:58 AM Total Precip Amount 4.26 in. Notes -- Taken at registered location Yes Snow Information New Snow Depth NA New Snow Water Equivalent NA Total Snow Depth NA Total Snow Water Equivalent NA Duration Information Precipitation Began -- Precipitation Ended -- Heavy Precip Began -- Heavy Precip Lasted -- Duration Time Accuracy -- Additional Information Additional Data Recorded No Submitted 8/22/2021 6:58 AM Flooding

These rainfall totals may be a record for a hurricane passing this much east of NJ. But you can see the unusual set up with the upper low parked to the SW. These rain bands usually extend south to north up into Northern New England with hurricanes near the SE New England coastline.

Great thread on Twitter today explaining why those charts comparing past heatwaves to today are misleading.