bluewave

Boston just experienced one of its greatest 10 minute temperature drops for the month of May.

This is the first time in May that our local stations made it to 90° by 10am. Newark Liberty MOSUNNY 90 62 39 NW18G30 29.97F HX 90 https://www2.nysmesonet.org/networks/nyc 13th St./16th / Alphabet City Temp: 90°F Brownsville Temp: 92°F Corona Temp: 90°F Lefferts / South Ozone Park Temp: 90°F

This is the first time that JFK made it to 80° at 8am in May. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=153&network=NY_ASOS&zstation=JFK&month=may&var=max_tmpf&_r=t&dpi=100&_fmt=png

We are coming off 4 warmer summers in a row from 2018 to 2021. Numerous heat and humidity records have been set since 2018. The only other 4 year warm streaks were 2010 to 2013 and 2005 to 2008. The 5th summers had cooler temperatures in 2009 and near normal in 2014. Our last summer with near average temperatures was back in 2017. https://www.ncdc.noaa.gov/cag/divisional/time-series/3004/tavg/3/8/1895-2022?base_prd=true&begbaseyear=1981&endbaseyear=2010 https://www.ncdc.noaa.gov/cag/divisional/time-series/2801/tavg/3/8/1895-2022?base_prd=true&begbaseyear=1981&endbaseyear=2010 Near normal and cool years bolded Year JJA……NYC boroughs and Long Island…Northern New Jersey 2021….+1.1….+1.2 2020…+2.6….+2.9 2019…+1.5…..+1.8 2018…+1.7……+1.8 2017…..+0.2….0.0 2016….+2.5….+2.5 2015….+1.4…..+0.8 2014…..-0.1…..-0.1 2013….+1.2…..+1.3 2012…..+1.7…..+1.7 2011…..+2.2…..+1.8 2010….+3.9…..+3.4 2009….-0.6…..-0.6 2008….+1.2……+1.4 2007…..+0.3…..+0.6 2006…..+1.7……+1.6 2005…..+2.6…..+3.3 2004…..-0.3….-0.6 2003…+0.4….+0.4 2002…..+1.6….+2.3 2001…..+0.7…..+0.6 2000…..-1.2…..-1.3 1999…..+2.7…..+2.9 1998….+0.7…..+0.7 1997….-0.3……-0.8 1996…..-0.6….-0.4 1995….+1.4…..+1.8 1994….+1.5…..+1.8 1993….+1.4…..+1.3 1992….-2.0…..-2.3 1991…..+1.8…..+1.7

The May minimum temperatures were especially warm from White Plains to Danbury with the persistent onshore flow. Average minimum temperatures at White Plains were the 5th warmest on record for May. While the Danbury record only goes back to 1998, it was the warmest on record for May. Time Series Summary for WESTCHESTER CO AP, NY - Month of May Click column heading to sort ascending, click again to sort descending. Rank Year Mean Min Temperature Missing Count 1 2012 55.0 0 2 2018 53.9 0 3 1991 53.8 1 4 1998 53.2 1 - 1965 53.2 0 5 2022 52.8 2 6 2011 52.6 0 7 1985 52.2 2 8 2015 52.1 0 9 1959 51.9 0 10 1964 51.8 0 Time Series Summary for DANBURY MUNICIPAL AP, CT - Month of May Click column heading to sort ascending, click again to sort descending. Rank Year Mean Min Temperature Missing Count 1 2022 53.2 2 2 2012 52.6 0 3 2018 51.4 1 4 2004 50.8 0 5 2015 49.6 0

Yeah, it looks like a nighttime backdoor after peak heating. The extension of the subtropical ridge into SE Canada has been giving us frequent backdoors and onshore flow in recent years. Sometimes we see it linking up with the Greenland block. So high pressure over SE Canada is typical in this pattern.

I believe Boston holds the US backdoor after 90s record dropping from 91° to 59° in one hour during April 02.

Backdoors this time of year usually stall out in Central NJ. That’s what the 12z guidance today is indicating. So we should see a big temperature drop on easterly flow especially here on Long Island.

Tuesday could feature a very impressive temperature drop especially east of the Hudson. Near record highs in the 90s could drop sharply at night. It will all depend on how fast and far west the backdoor makes it before stalling out. It may come down to nowcast time for the higher resolution models.

The +SOI gave us the -PNA and the La Niña contributed to the record ridge over SE Canada. But we got a more amplified version of the typical May La Niña background state. Rare combination of unusually cold spring La Niña SSTs, +SOI, and negative IOD.

Tuesday looks like it could be the 3rd 95° day of the season so far. Very warm WNW flow ahead of the backdoor. Quite a difference between our area and New Hampshire. JFK could beat the record high of 92° set in 1988. Data for May 31 - JFK INTERNATIONAL AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature Precipitation Snowfall Snow Depth 1988-05-31 92 65 0.00 0.0 0 1991-05-31 91 69 1.08 0.0 0 1986-05-31 91 69 0.01 0.0 0

It’s been tough to get a completely dry Memorial Day weekend with an official 90° heatwave covering all 3 days. The last time this happened was back in 1999. This was followed by one of our hottest July 4th weekends. Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature Precipitation 1999-05-29 90 62 0.00 1999-05-30 90 63 0.00 1999-05-31 90 64 0.00 Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature Precipitation 1999-07-03 88 73 0.00 1999-07-04 99 79 T 1999-07-05 103 81 0.00

I started the June thread for anyone that wants to discuss the extended pattern,

Looks like June will start out with a blocking pattern. So probably near seasonable temperatures. We’ll have to wait a while for extended 90° heat which has been coming in 1 or 2 day intervals this spring.

It gave us another over the top warm month. Our area is running +1 to +2 for June. New England is +3 to +5.

Unusual amount of amplitude to our blocking and MJO waves heading into early June. So we get a few days in the 90s followed by back door cold fronts with high pressure building into New England. Record SE Canada block for May has been pumping the high pressure over New England.

Yeah, the backdoor comes through later on Tuesday with cooler SE flow for Long Island on Wednesday.

The highs on Saturday topped out in the low 70s from Long Beach to Fire Island. The 90°s didn’t start until you got to near or just north of the Southern State. Pretty typical for strong sea breeze days. Tuesday could be a rare westerly flow heat event for us. So probably the first 90s of the season for JFK. The record high is 92° set back in 1988. Models have 850 temperatures around +20c with westerly flow through early afternoon..The timing of the backdoor cold front will be key as to how high into the 90s we make it.

It may be related to the coarse model resolution unable to pick up where the actual sea breeze front is located. The Euro had low 90s near Commack on Saturday. But it missed the 90° at ISP. It will be interesting to see how the model performs when they increase the resolution to around 4km in the coming years. One of the features of the raw Euro 2m forecast is that it sometimes limits the 90° temperatures to Monmouth County like it has on Monday. But when the flow is SW, those 90° readings often end up expanding north from EWR to LGA and the North Shore. The mid 90s it forecast for CNJ on Saturday made it up to EWR and Central Queens. The raw ECMWF also has too much of an onshore flow bias at Newark . The NWS MDL lab used to generate ECMWF MOS. So it corrected the raw 2m and wind direction biases. Similar to the GFS and NAM MOS. I am not sure if they still have that on their AWIPS terminals. Most model raw 2m temperature forecasts are too cool when there is strong WAA and full sun away from the immediate sea breeze. So we can get a better idea of the high temperature potential from the 850mb temperatures. The future of all modeling may be machine learning automatically correcting model biases beyond what the current MOS does. So in the meantime, we have to try and adjust the models manually to correct their known biases.

Memorial Day may make a run on 90° in the usual warm spots.

Yeah, the extension of the ridge into SE Canada has been pushing extreme severe storms further north than usual for this time of year.

The benchmark for early June heat in our area was 2011 when the Newark suburbs hit 103°. Data for June 1, 2011 through June 10, 2011 Click column heading to sort ascending, click again to sort descending. State Name Station Type Highest Max Temperature NJ CANOE BROOK COOP 103 NJ NEWARK LIBERTY INTL AP WBAN 102 NJ TETERBORO AIRPORT WBAN 101 NJ HARRISON COOP 99 NY BRONX COOP 97 NY LAGUARDIA AIRPORT WBAN 97 NJ CALDWELL ESSEX COUNTY AP WBAN 97 NY PORT JERVIS COOP 96 NJ PLAINFIELD COOP 96 NY MINEOLA COOP 96 NY WEST POINT COOP 95 NY NY CITY CENTRAL PARK WBAN 95

Memorial Day weekend is on track to follow the post 15-16 super El Niño script. At least one day with rainfall. Best chance for rain this year appears to be on Saturday with improvement by Sunday or Monday. Memorial Day weekends at Newark with Memorial Day bolded Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Date Max Temperature Precipitation 2021-05-29 52 0.58 2021-05-30 53 1.15 2021-05-31 76 T Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Date Max Temperature Precipitation 2020-05-23 71 0.79 2020-05-24 68 T 2020-05-25 73 T Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Date Max Temperature Precipitation 2019-05-25 70 0.00 2019-05-26 90 0.20 2019-05-27 82 0.00 Go Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Date Max Temperature Precipitation 2018-05-26 92 0.00 2018-05-27 78 0.87 2018-05-28 71 0.00 Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Date Max Temperature Precipitation 2017-05-27 74 0.00 2017-05-28 71 T 2017-05-29 61 0.14 Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Date Max Temperature Precipitation 2016-05-28 96 0.00 2016-05-29 88 0.03 2016-05-30 83 1.57

The reason is that models struggle with closed lows in these blocky patterns. They all seem to agree on rain from Friday into Saturday. The 12z Euro gets the front to our east by later Saturday. So a backloaded Memorial Day weekend with Sunday and Monday better than Friday and Saturday.

This May is just an extension of recent summers since 2018 with record blocking in SE Canada. Over the top warm ups are common in this pattern like we saw a few weeks ago with the record heat in Northern New England. Then we get intervals with the ridge flattening out like this past weekend. So places away from the sea breeze make a run on record highs. But the deep westerly flow heat events that make it to JFK like we saw from 2010 to 2013 are absent. Then there is the occasional cutoff low getting stuck underneath the block. So a fairly predictable pattern. May 2022 Summers since 2018