May 2020 General Discussions & Observations Thread

[NorthShoreWx]

Here are the coldest May days at my location since 1996.  We've hit 32 in May twice (5/1/2008, 5/14/1996).  Sub 40 has been rare since 2008 but was common before 2008.

2019 42 5/13+
2018 43 5/1
2017 40 5/4
2016 41 5/9
2015 39 5/3+
2014 42 5/3
2013 40 5/15+
2012 43 5/12
2011 42 5/6
2010 41 5/10
2009 40 5/19
2008 32 5/1,  39 5/20
2007 38 5/8+
2006 41 5/24
2005 36 5/4+
2004 37 5/5
2003 36 5/5
2002 36 51, 38 5/22
2001 37 5/8+
2000 36 5/1
1999 39 5/15+
1998 35 5/14
1997 37 5/8
1996 32 5/14

+ also occured earlier in the month
 

[Rtd208]

Looking beyond any possible frozen precipitation for some areas Friday/Saturday both Mt.Holly and Upton are also mentioning wind advisories may be needed for Saturday with a tightening pressure gradient. 

[Ace]

Give me any type of frozen precip falling from the sky on Friday night and I'll consider that a massive win...

[SnoSki14]

Dreadful day. 46F now with showers.

We always get a few of these days each May.

[bluewave]

Today was the 8th -10 departure in NYC since April 17th. There were only 2 days with a -10 departure in NYC for all of December through March.
 

TEMPERATURE (F)
 TODAY
  MAXIMUM         52   1113 AM  92    1986  68    -16       74
                                      1949
  MINIMUM         48    253 PM  32    1891  51     -3       51
  AVERAGE         50                        60    -10       63

[donsutherland1]

Under gray skies, the arrival of light rain, and temperatures in the upper 40s, few people were outdoors this evening. The unseasonably chilly weather imposed social distancing in the parks where the effort had shown visible signs of fraying in recent days when sunshine was in abundant supply.

[doncat]

Have never had a freeze at my station in May...lowest is 33°. Have been as low as 36° on the 18th, and 39° on the 21st for late cold.

[MJO812]

Gefs lol

[donsutherland1]

The system for today's light rain is now moving away. Light rain was still falling across eastern Long Island and eastern Connecticut. This evening's low temperature of 45°, was the coldest May reading since May 15, 2019 when the thermometer dipped to 44°. In the wake of the system, tomorrow should see sunshine with readings rebounding into the lower 60s.

However, the respite will be short-lived. Another storm could bring a cold rain to the region on Friday. As exceptionally cold air for the season works into the storm's circulation, the rain could change to snow, particularly north and west of Newark and New York City. Parts of central New York State eastward into New England could feature a rare accumulation of snow in May.

Generally cooler than normal to much cooler than normal conditions will now likely predominate until toward mid-month. Overall, the first 10 days of May could see readings average 2.5° to as much as 5.0° below normal in the northern Middle Atlantic and southern New England regions.

During the cold, New York City could see among its lowest May readings since 2000. During 2000-2019, there were 25 days on which the temperature fell to 45° or below in May; 15 days on which the temperature fell to 44° or below; 4 days on which the temperature fell to 43° or below; and, 3 days on which the temperature fell to 42° or below.

The last time the temperature fell below given thresholds in May were as follows:

Below 45°: 44°, May 15, 2019
Below 44°: 42°, May 13, 2019
Below 42°: 41°, May 10, 2010
Below 41°: 40°, May 6, 1992
Below 40°: 38°, May 1, 1978
Below 38°: 36°, May 9, 1977
Below 36°: 35°, May 9, 1947

Moderation may commence near mid-month.
 
The ENSO Region 1+2 anomaly was +0.1°C and the Region 3.4 anomaly was +0.4°C for the week centered around April 22. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.46°C and the ENSO Region 3.4 anomaly has averaged +0.56°C. Neutral and occasionally warm ENSO conditions will likely prevail through mid-May. ENSO Region anomalies, which cooled slightly during the last week of April, could continue a steady cooling during May.

The SOI had an increased tendency for positive values during April. During this month, the SOI was positive on 17 (57%) days. During the February-March period, the SOI was positive on 38% days. This shift in tendencies may further reinforce or reflect the idea that ENSO region anomalies could begin to cool.

The SOI was -10.17 today.

Today, the preliminary Arctic Oscillation (AO) figure was -0.363.

On May 5, the MJO was in Phase 5 at an amplitude of 0.645 (RMM). The May 4-adjusted amplitude was 1.041.

The MJO was recently in Phase 1 at an amplitude in excess of 1.500 for two days. During the 1981-2019 period, the MJO was in Phase 1 at an amplitude of 1.500 or above for two or more years in six cases: 1988, 1990, 1995, 1997, 2005, and 2010. During May, three (50%) were cooler than normal; two (33%) were near normal; and, one (17%) was warmer than normal. Ultimately, two-thirds of those cases went on to have a warmer to much warmer than normal summer.

 

[CIK62]

The next 8 days are averaging 52.5degs., or about 8.5degs. BN.

Month to date is  +0.2[59.0].         Should be  -4.8[55.3] by the 15th.

The next 17 days on the GFS ENS are averaging 53.5degs., or about 9degs. BN.   You have a nice choice on the 16th, 68* (ENS)or 90*(OP).       ENS has run much lower overall than OP for days now.

48* here at 6am.       50* by 8am.       55* by 10am.        60* by 1pm.        66* by 3:30pm.

[LibertyBell]

On 5/6/2020 at 3:09 PM, bluewave said:

I believe that 5-22-02 was the latest freeze for the coldest spots on Long Island.

Frost/Freeze Summary for WESTHAMPTON GABRESKI 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	Season Length
2002	05-22 (2002)	32	10-15 (2002)	31	145
2016	05-20 (2016)	32	10-11 (2016)	31	143
2008	05-20 (2008)	31	10-07 (2008)	31	139
2003	05-19 (2003)	32	10-03 (2003)	29	136
2000	05-16 (2000)	30	10-09 (2000)	32	145
2013	05-15 (2013)	32	10-19 (2013)	32	156
1999	05-15 (1999)	31	10-06 (1999)	31	143

2002? that was our mildest winter on record followed by mid 90s in April LOL

 

[LibertyBell]

On 5/6/2020 at 2:55 PM, NorthShoreWx said:

When I was a kid the guidance was always to put the sensitive plants out after May 15.  Even though things have warmed since then and a lot of years you can get away with planting the tomatoes early, it seems that May 15 is still the date if you want a high degree of confidence.

I would say Memorial Day weekend to be completely safe.

 

[LibertyBell]

Chris weren't there earlier records, like from the exceptional 1966-67 cold season that had the Hamptons below freezing as late as June?

And below zero as late as the first day of Spring?

 

[Rtd208]

Another nice day today after a cool start this morning.

Picked up 0.13" of rain for the day yesterday.

Current temp 68

[bluewave]

20 minutes ago, LibertyBell said:

2002? that was our mildest winter on record followed by mid 90s in April LOL

 

The record warmth took a break that May.  It was the 5th latest 41 or lower reading on record in NYC. The temperatures rebounded again in July after a close to average June.
 

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
1961	05-27 (1961)	41	10-28 (1961)	40	153
1925	05-25 (1925)	41	10-10 (1925)	36	137
1963	05-24 (1963)	39	09-24 (1963)	40	122
1907	05-21 (1907)	40	10-19 (1907)	39	150
2002	05-19 (2002)	41	10-15 (2002)	41	148
1976	05-19 (1976)	38	10-18 (1976)	38	151

[uncle W]

1963 and 1976 continued the record cold outbreaks during the summer months...the last time NYC saw 50's in July and August was in 2007...2000 ...1992...1990...the 1980's did it twice...the 1970's seven times...the 1960's three times...1963 was hot and cold until August when it was just cold...

[LibertyBell]

1 hour ago, bluewave said:

The record warmth took a break that May.  It was the 5th latest 41 or lower reading on record in NYC. The temperatures rebounded again in July after a close to average June.
 

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
1961	05-27 (1961)	41	10-28 (1961)	40	153
1925	05-25 (1925)	41	10-10 (1925)	36	137
1963	05-24 (1963)	39	09-24 (1963)	40	122
1907	05-21 (1907)	40	10-19 (1907)	39	150
2002	05-19 (2002)	41	10-15 (2002)	41	148
1976	05-19 (1976)	38	10-18 (1976)	38	151

I remember that was a really dry and hot summer at JFK, the lawns around here were yellow and brown....even in September.  Somewhat like 1983.

[donsutherland1]

Under mostly sunny skies, the temperature rose into the middle 60s. Two photos:

[donsutherland1]

Under mostly sunny skies, temperatures soared into the middle 60s across the region.

This latest taste of spring will be short-lived. Another storm coming out of the Tennessee Valley could bring a cold rain to the region later tomorrow. As exceptionally cold air for the season works into the storm's circulation, the rain could change to snow tomorrow night, particularly north and west of Newark and New York City. Parts of northeastern Pennsylvania, northwestern New Jersey, central New York State eastward into New England could see a rare accumulation of snow in May.

Generally cooler than normal to much cooler than normal conditions will now likely predominate until toward mid-month. Overall, the first 10 days of May could see readings average 2.5° to as much as 5.0° below normal in the northern Middle Atlantic and southern New England regions.

During the cold, New York City could see among its lowest May readings since 2000. From 2000 through May 6, 2020, there were 26 days on which the temperature fell to 45° or below in May; 15 days on which the temperature fell to 44° or below; 4 days on which the temperature fell to 43° or below; and, 3 days on which the temperature fell to 42° or below.

The last time the temperature fell below given thresholds in May were as follows:

Below 45°: 44°, May 15, 2019
Below 44°: 42°, May 13, 2019
Below 42°: 41°, May 10, 2010
Below 41°: 40°, May 6, 1992
Below 40°: 38°, May 1, 1978
Below 38°: 36°, May 9, 1977
Below 36°: 35°, May 9, 1947

Moderation will likely commence near mid-month.
 
The ENSO Region 1+2 anomaly was +0.1°C and the Region 3.4 anomaly was +0.4°C for the week centered around April 22. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.46°C and the ENSO Region 3.4 anomaly has averaged +0.56°C. Neutral and occasionally warm ENSO conditions will likely prevail through mid-May. ENSO Region anomalies, which cooled slightly during the last week of April, could continue a steady cooling during May.

The SOI had an increased tendency for positive values during April. During this month, the SOI was positive on 17 (57%) days. During the February-March period, the SOI was positive on 38% days. This shift in tendencies may further reinforce or reflect the idea that ENSO region anomalies could begin to cool.

The SOI was -11.24 today.

Today, the preliminary Arctic Oscillation (AO) figure was -0.545.

On May 6, the MJO was in Phase 6 at an amplitude of 0.605 (RMM). The May 5-adjusted amplitude was 0.640.

The MJO was recently in Phase 1 at an amplitude in excess of 1.500 for two days. During the 1981-2019 period, the MJO was in Phase 1 at an amplitude of 1.500 or above for two or more years in six cases: 1988, 1990, 1995, 1997, 2005, and 2010. During May, three (50%) were cooler than normal; two (33%) were near normal; and, one (17%) was warmer than normal. Ultimately, two-thirds of those cases went on to have a warmer to much warmer than normal summer.

 

[CIK62]

The next 8 days are averaging 52degs., or 9.5degs. BN.

Month to date is  -0.4[58.6].        Should be about  -6.4[55.1] by the 16th.

The GFS ENS for the next 17 days is averaging 52.5degs., or 10degs. BN.          Yesterday's 90* for the 16th., is now 68* on the OP, and the 90* has slipped 6 days.       OP really much warmer than the ENS starting the 20th.

50* here at 6am.        53* by Noon.     45* by 10pm.

[bluewave]

Models have temperatures very close to record lows early Saturday.

EWR...33

NYC....35

LGA....37

JFK....38

ISP......36

BDR....37

 

[JerseyWx]

2 hours ago, bluewave said:

Models have temperatures very close to record lows early Saturday.

EWR...33

NYC....35

LGA....37

JFK....38

ISP......36

BDR....37

How ironic would this be after the winter we just came out of.  You'd expect something like this to have happened back in 2015, but instead that May was when we started the warming trend which would last into the following December and beyond.

[bluewave]

2 hours ago, JerseyWx said:

How ironic would this be after the winter we just came out of.  You'd expect something like this to have happened back in 2015, but instead that May was when we started the warming trend which would last into the following December and beyond.

We saw something like this during the 15-16 winter. December went +13 and then NYC dropped below zero in February for the first time since 1994. Extreme blocking seems to be the common denominator.

 

[Stormlover74]

Another afternoon in the 40s

[NorthShoreWx]

20 hours ago, LibertyBell said:

I would say Memorial Day weekend to be completely safe.

 

I recall frost on the cartops around May 20 -22 sometime in the late 80s or 90s, but it didn't seem to damage any vegetation at the time.  I wouldn't use that as a reason to wait the extra 2 weeks.

[NJwx85]

Big pattern shift starting next week.

 

[jm1220]

2 hours ago, NJwx85 said:

Big pattern shift starting next week.

 

Looks like more of a broad westerly flow developing instead of a trough building over the Maritimes, so hopefully that can keep the backdoor fronts away. Hard to predict much sustained warmth here when the ridge can't build east of us and has to battle that Maritimes trough-the backdoor front is only one flinch of that trough away. 

[donsutherland1]

A storm will track east-northeastward across the region tonight. As exceptionally cold air for the season works into the storm's circulation, the rain could change to snow or flurries before ending, north and west of Newark and New York City. Parts of northeastern Pennsylvania, northwestern New Jersey, central New York State eastward into New England could see a rare accumulation of snow in May. Except for higher elevations, any accumulations should be light.

Earlier today, Buffalo, Cleveland, Detroit, and Rochester saw a trace of snow.

As the storm moves away, the potential exists for near record to record low temperatures in parts of the region tomorrow morning. New York City could see its first May temperature in the 30s in more than 40 years.

Daily record low temperatures for May 9 include:

Albany: 27°, 1956
Allentown: 31°, 1947 and 1956
Atlantic City: 32°, 1947 and 1981
Binghamton: 27°, 1966
Boston: 35°, 1977
Bridgeport: 37°, 1966, 1976, and 1977
Harrisburg: 32°, 1947
Hartford: 28°, 1956
Islip: 36°, 1977, 1985, and 1987
New York City-JFK: 38°, 1977
New York City-LGA: 37°, 1947
New York City-NYC: 35°, 1947
Philadelphia: 33°, 1933
Poughkeepsie: 27°, 1950 and 1956
Providence: 29°, 1956
Scranton: 31°, 1966
White Plains: 33°, 1977

From 2000 through May 8, 2020 8 pm in New York City, there were 27 days on which the temperature fell to 45° or below in May; 16 days on which the temperature fell to 44° or below; 4 days on which the temperature fell to 43° or below; and, 3 days on which the temperature fell to 42° or below.

The last time the temperature fell below given thresholds in May were as follows:

Below 45°: 44°, May 15, 2019
Below 44°: 42°, May 13, 2019
Below 42°: 41°, May 10, 2010
Below 41°: 40°, May 6, 1992
Below 40°: 38°, May 1, 1978
Below 38°: 36°, May 9, 1977
Below 36°: 35°, May 9, 1947

Generally cooler than normal to much cooler than normal conditions will now likely predominate until toward mid-month. Overall, the first 10 days of May could see readings average 2.5° to as much as 5.0° below normal in the northern Middle Atlantic and southern New England regions.

Moderation will likely commence near mid-month.
 
The ENSO Region 1+2 anomaly was +0.1°C and the Region 3.4 anomaly was +0.4°C for the week centered around April 22. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.46°C and the ENSO Region 3.4 anomaly has averaged +0.56°C. Neutral and occasionally warm ENSO conditions will likely prevail through mid-May. ENSO Region anomalies, which cooled slightly during the last week of April, could continue a steady cooling during May.

The SOI had an increased tendency for positive values during April. During this month, the SOI was positive on 17 (57%) days. During the February-March period, the SOI was positive on 38% days. This shift in tendencies may further reinforce or reflect the idea that ENSO region anomalies could begin to cool.

The SOI was +5.38 today.

Today, the preliminary Arctic Oscillation (AO) figure was -0.946.

On May 7, the MJO was in Phase 6 at an amplitude of 0.325 (RMM). The May 6-adjusted amplitude was 0.605.

The MJO was recently in Phase 1 at an amplitude in excess of 1.500 for two days. During the 1981-2019 period, the MJO was in Phase 1 at an amplitude of 1.500 or above for two or more years in six cases: 1988, 1990, 1995, 1997, 2005, and 2010. During May, three (50%) were cooler than normal; two (33%) were near normal; and, one (17%) was warmer than normal. Ultimately, two-thirds of those cases went on to have a warmer to much warmer than normal summer.

Based on sensitivity analysis applied to the latest guidance, there is an implied 67% probability that New York City will have a cooler than normal May. That probability will increase markedly through mid-month as the coldest anomalies of the month take hold. May will likely finish with a mean temperature near 61.0°.

 

[Rtd208]

Moderate rain falling here.

Current temp 43

[Rtd208]

Snow mixing in with the rain here.

Current temp 38