bluewave

You have to remember the resolution of those forecast maps is very coarse. So we post them for approximations of where the warmest and coolest temperatures will be found. That’s why the NWS generates MOS numbers to correct some of those biases. But the MOS can also struggle with extreme events like Saturday. So we use past experience with the similar 850 mb temperatures and wind directions. The 850 mb temperatures will be near the all-time May highs in this area around +21 to +22 C. This would support upper 90s to near 100° In NJ away from the sea breeze. Then we try to figure out how the sea breeze will influence the highs further east. Long Beach may be in the 70s while Commack is getting close to 90°. JFK would probably be in between those readings into the 80s. The Central Park temperatures need to factor in the wind direction and the dense vegetation around the sensor. The models don’t know that the sensor is in the deep shade. So the forecast highs are usually warm biased. It could be one of those situations where the models have low 90s but the high gets stuck in the upper 80s. Especially if the flow stays SSE. But more SSW flow could make it to 90°. NYC has been famous for upper 80s while surrounding areas record 90s.

This is going to be an onshore flow warm up with a sharp temperature gradient between NJ and the Long Island South Shore. May 1996 was and offshore flow event with Newark and Minolta Long Island reaching 99°. So this is the benchmark for extreme May heat across the area. There were a few COOP sites in NJ that hit 100°. But no major sites that I was able to find. Monthly Data for May 1996 for Upton NY NWS CWA Click column heading to sort ascending, click again to sort descending. State Name Station Type Highest Max Temperature NJ NEWARK LIBERTY INTL AP WBAN 99 NY MINEOLA 1 NE COOP 99 NY OCEANSIDE COOP 98 NY ISLIP-LI MACARTHUR AP WBAN 98 CT NORWICH PUBLIC UTILITY PLANT COOP 98 NJ PLAINFIELD COOP 97 NY LAGUARDIA AIRPORT WBAN 97 NY DOBBS FERRY-ARDSLEY COOP 97 NY MINEOLA COOP 97 CT STAMFORD 5 N COOP 97 CT IGOR I SIKORSKY MEMORIAL AIRPORT WBAN 97 NY PATCHOGUE 2 N COOP 97 NY PORT JERVIS COOP 96 NJ CRANFORD COOP 96 NJ JERSEY CITY COOP 96 NY NY CITY CENTRAL PARK WBAN 96 NJ LITTLE FALLS COOP 96 NJ WAYNE COOP 96 NJ WANAQUE RAYMOND DAM COOP 96 NY SUFFERN COOP 96 NY RIVERHEAD RESEARCH FARM COOP 96 NY WEST POINT COOP 95 NY WEST NYACK COOP 95 NY JFK INTERNATIONAL AIRPORT WBAN 95 NY WESTCHESTER CO AP WBAN 95 Monthly Data for May 1996 for Mount Holly NJ NWS CWA Click column heading to sort ascending, click again to sort descending. State Name Station Type Highest Max Temperature PA PALMERTON COOP 100 NJ PENNSAUKEN 1N COOP 100 NJ TOMS RIVER COOP 99 NJ PEMBERTON COOP 98 NJ PHILADELPHIA/MT. HOLLY WFO COOP 98 PA PHILADELPHIA FRANKLIN INSTITUTE COOP 97

People will be able to save money now since they won’t have to pay for weather model subscriptions to access the long range EPS.

The latest EPS continues the warmer SE Ridge pattern right into early June.

It will be interesting to see if somebody in NJ can record their first 100° day in May on Saturday. Models have 850 mb temperatures around +21 C. This is about as high as we ever saw the 850s this early in the season.The temperature differential between low 70s in Long Beach and upper 90s to near 100° in NJ is as extreme as it gets.

The GEM has the most extreme temperature gradient of all. Strong sea breeze and cooler temperatures east of the Hudson. Has highs of 95-100° in NJ.

Why can’t we take it seriously? It reached 102° at the end of June in Corona Queens. So the 103° at Newark reflected it being a degree warmer in NE NJ than Queens.

Last May into June was another famous post 2010 big temperature swing. It was the latest 52° high temperature at the end of May for Newark. Followed up by the earliest 103° high temperature at the end of June. First/Last Summary for NEWARK LIBERTY INTL AP, NJ 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 2021 05-29 (2021) 52 11-14 (2021) 48 168 1961 05-27 (1961) 49 10-15 (1961) 51 140 1967 05-25 (1967) 48 11-05 (1967) 47 163 1957 05-20 (1957) 52 10-26 (1957) 48 158 1976 05-19 (1976) 52 10-17 (1976) 50 150 First/Last Summary for NEWARK LIBERTY INTL AP, NJ 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 2021 06-30 (2021) 103 06-30 (2021) 103 0 1966 07-03 (1966) 105 07-03 (1966) 105 0 1949 07-04 (1949) 105 07-04 (1949) 105 0 1999 07-05 (1999) 103 07-05 (1999) 103 0 2010 07-06 (2010) 103 07-06 (2010) 103 0 1993 07-07 (1993) 103 07-10 (1993) 105 2

Long Island severe thunderstorms with straight line winds or hail usually peak in July and August. But some years like 2019 the peak is in late June.Tornados have a later peak from August to recently November. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=171&opt=ugc&station=OKX&state=NY&_ugc_state=NY&ugc=NYC103&phenomena=SV&significance=W&cmap=Reds&_r=t&dpi=100&_fmt=png

The EPS first guess for the Memorial Day weekend is much warmer than last year.

We will need for the debris clouds from earlier convection to clear the areas closer to NYC for a better chance of convection later. We’ll have to see if convection can fill in as that clear area over SE PA moves Northeast. The main focus right now is from NE PA up into NY State.

LGA and NYC still haven’t reached 80° yet. So the first 80° day is a month late. This much onshore flow is pretty unusual for our area in May. The purple colors below are near record levels of easterly flow for May. First/Last Summary for LAGUARDIA AIRPORT, 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 First Value Last Value Difference Minimum 03-26 (2021) 09-25 (2020) 134 Mean 04-21 10-06 167 Maximum 05-20 (2019) 10-20 (2021) 207 2021 03-26 (2021) 82 10-20 (2021) 80 207 2020 05-03 (2020) 81 09-25 (2020) 80 144 2019 05-20 (2019) 89 10-02 (2019) 95 134 2018 04-13 (2018) 82 10-11 (2018) 80 180 2017 04-16 (2017) 88 10-10 (2017) 81 176 2016 04-18 (2016) 80 10-19 (2016) 86 183 2015 05-04 (2015) 82 09-29 (2015) 83 147 2014 05-10 (2014) 82 09-28 (2014) 84 140 2013 04-09 (2013) 81 10-04 (2013) 86 177 2012 04-16 (2012) 85 10-05 (2012) 80 171 2011 04-26 (2011) 80 10-10 (2011) 82 166 2010 04-07 (2010) 91 09-29 (2010) 80 174 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 First Value Last Value Difference Minimum 03-26 (2021) 09-10 (2020) 129 Mean 04-16 09-30 166 Maximum 05-10 (2014) 10-19 (2016) 183 2021 03-26 (2021) 82 09-18 (2021) 84 175 2020 05-03 (2020) 80 09-10 (2020) 82 129 2019 04-19 (2019) 80 10-02 (2019) 93 165 2018 04-13 (2018) 82 10-10 (2018) 80 179 2017 04-11 (2017) 80 10-10 (2017) 81 181 2016 04-18 (2016) 82 10-19 (2016) 85 183 2015 04-18 (2015) 80 09-29 (2015) 83 163 2014 05-10 (2014) 83 09-28 (2014) 84 140 2013 04-09 (2013) 82 10-04 (2013) 86 177 2012 04-16 (2012) 88 09-14 (2012) 80 150 2011 04-11 (2011) 81 10-10 (2011) 81 181 2010 04-07 (2010) 92 09-25 (2010) 89 170

Very persistent easterly flow pattern for the whole month so far.

I wonder if this is the first time that the same cutoff low caused rain on two consecutive Saturdays? May 7th May 14th

This has to be one of the longer duration cutoffs we have seen in recent years.