May 2021

[IrishRob17]

85/50 split here

[psv88]

And we’re down to 72

[donsutherland1]

The temperature soared into the middle and upper 80s in most of the region today. Newark was the region's hot spot with a high temperature of 91°. At Chibougamau, QC, the temperature reached 83°. That broke the daily record high temperature of 80°, which was set in 2010. Tomorrow and Friday will be fair and cooler in the northern Middle Atlantic and southern New England areas with temperatures holding mainly in the 70s. Lower 80s are possible in central and southern New Jersey southward.

The dominant weather story into at least the closing week of May will be the synoptic impact of a strongly to occasionally severely negative PNA. That development will lead to a warmer to perhaps much warmer than normal second half of May. There will likely be additional days where the temperature makes a run at 90° in parts of the region.

Today, the preliminary value of the PNA was -1.662. That was lowest figure since March 31 when the PNA was -1.775. That was also the lowest figure in May since May 31, 2018 when the PNA was -1.767. The PNA is forecast to remain at or below -1.000 until around May 24. During the May 16-31, 1991-2020 period, the mean temperature was 65.2° in New York City and 67.0° in Philadelphia. When the PNA was -1.000 or below, the average temperature was 67.7° in New York City and 69.3° in Philadelphia.

During the 1991-2020 period, 30% of days in New York City and 41% of days in Philadelphia had high temperatures of 80° or above. During the 1991-2020 period, 15% of days in New York City and 23% of days in Philadelphia had high temperatures of 85° or above. When the PNA was -1.000 or below during that period, 41% of days in New York City and 50% of days in Philadelphia had high temperatures of 80° or above. When the PNA was -1.000 or below during that period, 24% of days in New York City and 35% of days in Philadelphia had high temperatures of 85° or above.

As had been the case with April, the closing week of May could wind up warmer to much warmer than normal. In the four cases where the MJO reached Phase 1 at an amplitude of 2.000 or above in combination with a cool ENSO Region 3.4 anomaly during the May 1-10 period, as occurred this year, three wound up with warmer to much warmer than normal conditions. At New York City, the mean temperature during the closing 7 days of May was 72.7° during those three cases while it was 72.0° at Philadelphia. The 1991-2020 means were 67.9° and 69.7° respectively. Only May 25-31, 2013 (monthly ENSO Region 1+2 anomaly of -1.38°C) was cooler than normal. However, 90° heat arrived on May 29 in Philadelphia and May 30 in New York City during 2013.

Neutral ENSO conditions have now developed. The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was -0.3°C for the week centered around May 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.75°C and the ENSO Region 3.4 anomaly has averaged -0.38°C. Neutral ENSO conditions will likely prevail into at least mid-summer.

The SOI was +6.22 today.

The preliminary Arctic Oscillation (AO) figure was -0.840 today.

On May 17 the MJO was in Phase 3 at an amplitude of 1.750 (RMM). The May 16-adjusted amplitude was 1.654 (RMM).

In late April, the MJO moved through Phase 8 at an extreme amplitude (+3.000 or above). Only February 25, 1988 and March 18-19, 2015 had a higher amplitude at Phase 8. Both 1988 and 2015 went on to have an exceptionally warm July-August period. July-August 1988 had a mean temperature of 79.1°, which ranked 4th highest for that two-month period. July-August 2015 had a mean temperature of 78.9°, which ranked 5th highest for that two-month period. September 2015 was also the warmest September on record. The MJO's extreme passage through Phase 8 could provide the first hint of a hot summer.

Based on sensitivity analysis applied to the latest guidance, there is an implied 76% probability that New York City will have a warmer than normal May (1991-2020 normal). May will likely finish with a mean temperature near 64.4° (1.2° above normal).

 

[SACRUS]

5/19

EWR: 91
ACY: 89
PHL: 89
New Brnswck: 88
TEB: 87
TTN: 87
BLM: 87
NYC: 86
JFK: 86
LGA: 86
ISP: 85

[uncle W]

91/59 today...

[etudiant]

15 minutes ago, donsutherland1 said:

The temperature soared into the middle and upper 80s in most of the region today. Newark was the region's hot spot with a high temperature of 91°. At Chibougamau, QC, the temperature reached 83°. That broke the daily record high temperature of 80°, which was set in 2010. Tomorrow and Friday will be fair and cooler in the northern Middle Atlantic and southern New England areas with temperatures holding mainly in the 70s. Lower 80s are possible in central and southern New Jersey southward.

The dominant weather story into at least the closing week of May will be the synoptic impact of a strongly to occasionally severely negative PNA. That development will lead to a warmer to perhaps much warmer than normal second half of May. There will likely be additional days where the temperature makes a run at 90° in parts of the region.

Today, the preliminary value of the PNA was -1.662. That was lowest figure since March 31 when the PNA was -1.775. That was also the lowest figure in May since May 31, 2018 when the PNA was -1.767. The PNA is forecast to remain at or below -1.000 until around May 24. During the May 16-31, 1991-2020 period, the mean temperature was 65.2° in New York City and 67.0° in Philadelphia. When the PNA was -1.000 or below, the average temperature was 67.7° in New York City and 69.3° in Philadelphia.

 

Based on sensitivity analysis applied to the latest guidance, there is an implied 76% probability that New York City will have a warmer than normal May (1991-2020 normal). May will likely finish with a mean temperature near 64.4° (1.2° above normal).

 

Don, has there been any previous swing of this magnitude in your experience?

We went from the odds for a sub normal May to a well above normal probability in much less than a week.

[STORMANLI]

3 hours ago, psv88 said:

Just bumped up to 89.4...what you got?

88.7°

[donsutherland1]

27 minutes ago, etudiant said:

Don, has there been any previous swing of this magnitude in your experience?

We went from the odds for a sub normal May to a well above normal probability in much less than a week.

Nothing that I can recall anytime recently. Unfortunately, model data isn’t archived—at least publicly—so one can’t look for such dramatic swings.

[psv88]

12 minutes ago, STORMANLI said:

88.7°

Nice, glad to see our numbers so close. Down to 62 now...one hell of a backdoor

[lee59]

After a mid to upper 80 afternoon, the temperature has really dropped here also the last few hours, down to 63 degrees.

[Will - Rutgers]

east wind will be nice tomorrow, dews will remain low, should be a stellar day outside.

[Pequest]

88/44 split here in rural Warren County.

[CIK62]

The next 8 days are averaging 71degs.(61/81), or about +4.5.

Month to date is   61.3[-0.3].          Should be about  64.1[+1.1] by the 28th.

May 26 continues at 90 for another run----a good dozen in a row.     I will hold the GFS to it.      Again no rain to speak of.

62*(60%RH) here at 6am, m. clear.       65* by 9am.         67* by 3pm.         70* at 4pm.

[donsutherland1]

Morning thoughts...

Today will be partly to mostly sunny and very warm. Temperatures will likely reach the middle and upper 70s in most of the region. Temperatures will likely reach the lower 80s from central New Jersey southward. Likely high temperatures around the region include:

New York City (Central Park): 76°

Newark: 78°

Philadelphia: 83°

Tomorrow will be partly cloudy and mild.

[SACRUS]

Tremendous stretch of weather looks to continue right through the holiday weekend and into the start of June.  Onshore the next two days before winds shift on Saturday and 850 temps rise into the >16c range both days.  Saturday toss up with clouds lingering nearby but should we get on the clear side 90s possible. Sunday looks very hot for a good portion of the area. Mon (5/24) and Tue (5/25) look to cool a bit before next surge of >16c 850 by Wed  (5/26).  Beyond there heights look to rise for the holiday weekend and offer the next shot at 90s.

[STORMANLI]

74° already.

Overperformer?

[SACRUS]

saturday can be sneaky hot if we can clear or winds shift sooner friday overnight.  then Wed and perhaps thu more 90s.  Pegging the first trifecta or longer (heatwave) may push towards the holiday weekend till then transient heat spikes followed by a brief day or two of cooler.

[CIK62]

Why are you talking about heat over the Holiday?    850mb T and 500mb heights fall sharply for the end of May and return June 01.

[SACRUS]

Just now, CIK62 said:

Why are you talking about heat over the Holiday?    850mb T and 500mb heights fall sharply for the end of May and return June 01.

id expect models to trend warmer / strnger ridge for the holiday weekend.

[Brian5671]

17 minutes ago, CIK62 said:

Why are you talking about heat over the Holiday?    850mb T and 500mb heights fall sharply for the end of May and return June 01.

it will be close.  Let's hope that's more like early June.  Would stink to have a crappy holiday weekend after the 2-3 weeks of nice weather we've had

[nycwinter]

weather channel says 92 in nyc sunday

[forkyfork]

i remember when backdoor fronts meant fog and 50s

[nycwinter]

38 minutes ago, forkyfork said:

i remember when backdoor fronts meant fog and 50s

usually happens sometimes in june...

[SnoSki14]

Hottest summer since early 2010s incoming. 

[495weatherguy]

23 minutes ago, SnoSki14 said:

Hottest summer since early 2010s incoming. 

[Brian5671]

2 hours ago, SnoSki14 said:

Hottest summer since early 2010s incoming. 

11 yr solar cycle agrees

[LoboLeader1]

Gorgeous weather here, currently 73 as of 3:45PM

[SnoSki14]

Almost no precip next 10-14 days. 

With that level of dryness expect highs to go above forecast. Some upper 90s on Wednesday or even a rare 100F reading wouldn't surprise me.

If this pattern continues into June & July it's going to get wild. Tremendous fire risks as well. 

[jm1220]

2 hours ago, bluewave said:

The 12z Euro came in even warmer. Now has 90s on Saturday and Sunday. Makes it to100°in Central New Jersey on Wednesday. 
 

 

If we have westerly winds over the weekend we can have temps over perform again east of the city. Based on that Wed map looks like a south wind which means cooler temps but higher humidity. Point and click for me on Sun is 90 for the high, could be 95 if we have the westerly flow. 

[lee59]

The National Hurricane Center says the low off Bermuda will move over warmer waters and likely become a subtropical cyclone. It will be interesting to see if they give it a name if it only becomes subtropical in nature.