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July 2020 General Discussions & Observations Thread


Rtd208
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1 hour ago, Cfa said:

84/76 here now as well, I think 90 is out of reach, but not impossible.

I hope we get slammed later on, Suffolk has been missing out this summer.

88/74/96 now, i dont need severe. just water the lawn. had enough damage with last years microbursts...

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Overnight, parts of the region will see some showers and thundershowers. Tomorrow will be similar to today with clouds, some sunshine, and additional showers and thundershowers.

This weekend, heat will rebuild across the area. The potential exists for early next week to see the warmest readings this summer in parts of the region.

The current predominantly warmer than normal pattern will likely persist through at least August, paving the way for a solidly warmer than normal summer throughout the region. Occasional short-lived cool shots remain possible. One or more heatwaves are likely in July across the region, including New York City.

The ENSO Region 1+2 anomaly was -1.5°C and the Region 3.4 anomaly was -0.2°C for the week centered around July 15. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.92°C and the ENSO Region 3.4 anomaly has averaged -0.22°C. Neutral-cool conditions will likely into the start of autumn. During the autumn, La Niña conditions could develop.

The SOI was +16.00.

Today, the preliminary Arctic Oscillation (AO) figure was -0.829.

On July 22, the MJO was in Phase 2 at an amplitude of 1.820 (RMM). The July 21-adjusted amplitude was 1.608.

The MJO has been in either Phase 1 or Phase 2 for 53 consecutive days.

Last year, the MJO went through a very strong passage through Phase 1 during the closing days of May. About four weeks later, a warmer than normal pattern locked in and predominated through early autumn. This year, the MJO was in Phase 1 for 3 consecutive days with an amplitude of 1.500 or above during the June 1-3 period.

Last year, the SOI fell to -42.04 on June 22 when the MJO was in Phase 6. This year, the SOI plunged below -46.68 on June 5, its lowest level in more than three years. The dramatic plunge in the SOI could be the proverbial spark that kicks off a sequence of events leading to the development of a sustained warmer than normal period. The cases that saw both the MJO and SOI thresholds satisfied generally saw 10-20 days where the temperature reached or exceeded 90° in New York City during the July 1-August 31 period.

Since 1990, there have been 11 La Niña events, 6 of which followed an El Niño winter. 10/11 (91%) case saw warmer than normal September. All 6 following an El Niño winter were warmer than normal. September mean temperatures for New York City for those cases were: 11 cases: 69.9°; Subset of 6 cases: 70.8°; Entire 1990-2019 period: 69.0°. The September mean temperature for all La Niña and neutral-cool cases following an El Niño winter (1950-2019: n=13) was 69.9°. Overall, the evolution of ENSO, along with the observed ongoing monthly warming (1.6°/decade in NYC and 1.5°/decade in the Northeast Region during September 1990-2019), favors a warmer than normal September.

Based on sensitivity analysis applied to the latest guidance, there is an implied 99% probability that New York City will have a warmer than normal July. July will likely finish with a mean temperature near 79.8°. The probability of an 80° mean temperature in July remains near 50%.

 

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