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July 2020 General Discussions & Observations Thread


Rtd208
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Under bright sunshine ahead of an advancing backdoor cold front, the temperature soared into the lower and middle 90s in many parts of the region. Central Park reported a high temperature of 96°. That was New York City's highest temperature since July 1, 2018 when the temperature also reached 96°. During the evening strong thunderstorms, some of which produced small hail, moved through parts of the region.

Philadelphia had a 92° high temperature, marking its 5th consecutive 90° or warmer day. With a high temperature of 96°, Washington, DC registered its 11th consecutive day on which the temperature reached 90° or above. That is Washington's longest heat wave since July 11-22, 2019 when the temperature reached 90° or above on 12 consecutive days.

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 Initially, extreme heat is unlikely, but that could change as July progresses, especially if the emerging drought continues to deepen. One or more heatwaves are likely in July across the region, including New York City.

The ENSO Region 1+2 anomaly was -1.1°C and the Region 3.4 anomaly was -0.1°C for the week centered around July 1. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.65°C and the ENSO Region 3.4 anomaly has averaged -0.32°C. Neutral-cool conditions will likely prevail through mid-summer. The probability of the development of a La Niña event during late summer or early autumn has increased in recent weeks.

The last time the six-week moving average for ENSO Region 1+2 was as cold as the current figure during July or August occurred in 2013. Winter 2013-14 had neutral-cool ENSO conditions. January and February featured ENSO Region 3.4 anomalies that were -0.50°C or below.

The SOI was +3.38.

Today, the preliminary Arctic Oscillation (AO) figure was +0.062.

On July 5, the MJO was in Phase 1 at an amplitude of 2.493 (RMM). The July 4-adjusted amplitude was 2.237.

That was the 16th consecutive day the MJO was in Phase 1. The last time the MJO had a longer stretch in Phase 1 occurred during September 21-October 8, 2019 when the MJO was in Phase 1 for 18 consecutive days. In addition, the MJO has been in either Phase 1 or Phase 2 for 36 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.

 

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The next 8 days are averaging 83degs., or about 5degs. AN.

July 7-11  AN,      July 11-14    NORMAL or less?,      July 15-22    AN++ > then back to NORMAL late.

73* at 6am, overcast.       75* at 7am, brighter skies.        79* and 80%RH by Noon.        81* and 77% by 3pm, cloudy, breaks.

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Steam bath days are here.

Steamy 77/71 off of a warm low of 69 here.  Partly cloudy ENE wind flow should cap temps in the upper 80s (max) if we have enough sun and less active than yesterday (monday) but some pm fun along the coast.   Wed looks to be more stormy land with enough sun like Monday could make a run at 90 and add fuel to storms (further erasing the dryness from May/Jun).  Thursday a more tame day  and good beach time again temps near 90 well see if recent storm rains slows temps beating guidance.

  The Sub tropical ULL (whatever it my be at the time it passes) should ride coastal DE to LI Fri PM to Sat PM bringing more rains. Once we clear the ULL Sat we should less wet and more warm Sat - Tue. 

Looking beyond , by 7/15 looks to start another hot period.  Recent runs building ridge into the Mid West now showing possible linkage with the Western Atlantic ridge in the period. We'll see how it evolves but a very hot airmass over mid section is spreading into the region by mid month.  Can we pull off a century mark reading outside of LGA this year.  This is the period to watch. 

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1 minute ago, forkyfork said:

WAR retrograde signal showing up toward day 10. i've posted before that it's the only way we'll get any extended heat this year a la july 2013

ecmwf-ens_z500a_atl_11.png

There is some guidance with a few runs showing this in the 7/15 - 7/20 period starting D 7 or 8.  Some prior runs showed very strong ridge building into the mid west 600 DM, perhaps thats the linkage needed to kick the weakness and onshore tendences.  Even with that we are running warm (above to much above) that would push it further..  

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1 minute ago, Poker2015 said:

None here either...surrounded by it, but nothing...outside of a 15 min downpour last thursday afternoon, we have had absolutely nothing...

Yup, super dry here.  Rained here yesterday for about 4 minutes.  

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