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May 2021


bluewave
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Despite ample sunshine, the northern Middle Atlantic and southern New England regions were cooler than yesterday. Nevertheless, a few locations reached 90° in the Northeast this afternoon. Those locations included: Burlington: 92° (old record: 91°, 1975); Scranton: 90°; and, Washington, DC: 93°.

90° temperatures at Burlington have become more common during the month of May in recent years. Some statistics for May 1981-2020:

1981-2010: Mean Monthly High: 85.2°; 0.3 90° days each May
1991-2020: Mean Monthly High: 86.3°; 0.4 90° days each May
2010-2020: Mean Monthly High: 88.5°; 0.8 90° days each May  

Tomorrow will be fair and pleasant 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. Much warmer weather is likely for the weekend.

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 on which the temperature will make a run at 90° in parts of the region.

Today, the preliminary value of the PNA was -1.584. 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 +8.14 today.

The preliminary Arctic Oscillation (AO) figure was -0.587 today.

On May 18 the MJO was in Phase 3 at an amplitude of 1.702 (RMM). The May 17-adjusted amplitude was 1.749 (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 80% probability that New York City will have a warmer than normal May (1991-2020 normal). May will likely finish with a mean temperature near 64.6° (1.4° above normal).

 

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The next 8 days are averaging 73degs.(63/83), or +7.0.        Three 90's are possible.

Month to date is  61.6[-0.2].          Should be 64.9[+1.9] by the 29th.

No model has rain till next Thurs.

59*(77%RH) here at 6am, m. clear.     61* by 9am.         63* at Noon.

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If the long range guidance is correct, then the humidity will probably increase as we head into June. So this is when we could start to see better chances for rain again. The record breaking ridge just to our west is acting as a block. EPS lifts the ridge axis north to near the Canadian Maritimes to start June. This is where the ridge axis was for the last 3 summers with the warm and moist onshore flow. So it will be interesting to see if we can make it 4 in a row.

75D39E4D-7155-45D1-B342-A31BAB9CB722.thumb.png.df532738bee7a14c874593823aabb1b6.png

EPS May 31- June 7 forecast 


7CA848CB-716D-48DE-B132-3A98A4BE2B9F.thumb.png.3b86bce031790168d92ba1508ad3535d.png


0C3C228C-7FCC-4C88-918A-C5DE0CFBD2CF.png.37a67e77c9b256f331a097818616b32f.png

 

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Morning thoughts...

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

New York City (Central Park): 79°

Newark: 83°

Philadelphia: 84°

A much warmer weekend lies ahead.

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8 of the next  10 days look very warm with 3 - 4 90 degree readings, especially in the typical warmer locations in NJ.  Pending on clouds tomorrow, temps should soar into the upper 80s and low 90s, Sunday looks the same where temps could reach low 90s then followed by  sharp cooldown Monday , before warming back up Tue.  Wed  850 temps peak at >16c and mid 90s are possible in the hot spots .  By the  (5/27) perhaps the first widespread chance at rain with a cold front.  The Holiday weekend  looks warmer and we may see a spike of heat by Sun 5/30, pending on the ridge position.  Beyond there into early June it looks overall warm and we'll see if their is a transition to a wetter period. 

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While specific rainfall forecasts past 5 days can be low skill, the Euro has a chance of rain on Memorial Day weekend. Every Memorial Day weekend for the last 5 years had measurable rainfall one out of the three days. We just missed a deluge in 2015 with 3.73 on Tuesday May 31st at Newark.

Newark Memorial Day bolded

5-25-20…..5-23….0.79

5-27-19……5-26…0.20

5-28-18…..5-27….0.87

5-29-17…..5-29…..0.14

5-30-16……5-30…..1.57…….our last very dry spring

Tuesday 5-31-15……3.73

 

 

ED753305-3F65-462F-96A0-C934D650B743.gif.dd2914c246e12f2312270028ed6469ae.gif
 

 

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Detroit was very close to the all-time May 500 mb height record this morning. Had we seen this anomalous a ridge during the summer, it would probably mean temperatures approaching or exceeding 100° In the Northeast. So it will be interesting to see if Newark can sneak in at least 95° max this month.

D16DDF9A-69D6-4E87-9AE3-8D5EC24581CC.thumb.jpeg.9f51f234741db28cceffe1616d4955a3.jpeg

 

 

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33 minutes ago, crossbowftw3 said:

First 90 of the year here @ exactly 90 degrees at 4:31. Dew points aren't awful though but just enough to make it feel like the inside of a toaster out.

Second May in a row up at BTV with a top three warmest monthly maximum temperature. 
 

RECORD REPORT
NATIONAL WEATHER SERVICE BURLINGTON VT
135 AM EDT FRI MAY 21 2021

...RECORD HIGH TEMPERATURE SET AT BURLINGTON VT...

A RECORD HIGH TEMPERATURE OF 92 WAS SET AT BURLINGTON VT YESTERDAY.
THIS BREAKS THE OLD RECORD OF 91 SET IN 1975.


 

Time Series Summary for Burlington Area, VT (ThreadEx) - Month of May
Click column heading to sort ascending, click again to sort descending.
Rank
Year
Highest Max Temperature 
Missing Count
1 2020 95 0
2 2017 93 0
- 1977 93 0
3 2021 92 11
- 2010 92 0
- 1987 92 0
- 1979 92 0
- 1978 92 0
- 1929 92 0
- 1911 92 0
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1 hour ago, bluewave said:

Second May in a row up at BTV with a top three warmest monthly maximum temperature. 
 


RECORD REPORT
NATIONAL WEATHER SERVICE BURLINGTON VT
135 AM EDT FRI MAY 21 2021

...RECORD HIGH TEMPERATURE SET AT BURLINGTON VT...

A RECORD HIGH TEMPERATURE OF 92 WAS SET AT BURLINGTON VT YESTERDAY.
THIS BREAKS THE OLD RECORD OF 91 SET IN 1975.


 

Time Series Summary for Burlington Area, VT (ThreadEx) - Month of May
Click column heading to sort ascending, click again to sort descending.
Rank
Year
Highest Max Temperature 
Missing Count
1 2020 95 0
2 2017 93 0
- 1977 93 0
3 2021 92 11
- 2010 92 0
- 1987 92 0
- 1979 92 0
- 1978 92 0
- 1929 92 0
- 1911 92 0

I'm betting we see our first 100 since 2013- finally a REAL SUMMER!  Hasn't happened in years.

 

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