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August 2020 General Discussions & Observations Thread


Rtd208
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No new topic(s) yet...  Sundays risk for cluster 2-3" thunderstorms may be shifting to Monday per EC KI trends but will revisit that and the possible tropical connection for the 28th-29th.  Want to see a little more NAEFS qpf axis etc.  Definite worthy of monitoring the models all week. 538P/21

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Temperatures topped out mainly in the lower 80s across the region today. Tomorrow will see noticeably warmer weather begin to overspread the region.

At the height of the warmth, readings could approach or reach 90° in much of the region early next week. However, the month could end on a cool note before temperatures recover to above normal levels.

The current predominantly warmer than normal pattern will likely persist through much of September, paving the way for a solidly warmer than normal summer and a warm start to fall throughout the region. Occasional short-lived cool shots remain possible.  

Although cooler readings prevailed in the Southwest today, Las Vegas reached 111°. That surpassed the daily record of 110°, which was set in 2009. At Death Valley, the temperature topped out at 124°. That surpassed the prior daily record of 122°, which was set in 1992. Today was also the 8th consecutive day on which the temperature reached 120° or above. That is the longest August stretch since August 6-17, 2012 when the mercury reached 120° or above on 12 consecutive days.

Phoenix has an implied near 100% probability of having its warmest summer on record. Phoenix will likely finish with a summer mean temperature of 96.5° - 96.9°. The existing record is 95.1°, which was set in summer 2013 and tied in summer 2015. July 2020 was Phoenix's warmest month on record with a mean temperature of 98.9°. August 2020 could approach or exceed that figure. Since recordkeeping began in August 1895, two years saw both July and August rank among Phoenix's 20 warmest months on record: 2007 and 2019. It is all but certain that 2020 will become the third such case.

The ENSO Region 1+2 anomaly was -0.9°C and the Region 3.4 anomaly was -0.5°C for the week centered around August 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.17°C and the ENSO Region 3.4 anomaly has averaged -0.45°C. Neutral-cool conditions will likely into the start of autumn. During the autumn, La Niña conditions will likely develop.

The SOI was +23.79.

Today, the preliminary Arctic Oscillation (AO) figure was -1.058.

On August 20, the MJO was in Phase 8 at an amplitude of 1.567 (RMM). The August 19-adjusted amplitude was 1.470.

The MJO's recent passage through Phase 8 at an amplitude of 1.500 or above has been fairly uncommon during the August 10-25 timeframe. During the 1981-2019 period only 2002 and 2004 saw the MJO move through Phase 8 with an amplitude of 1.500 or above during this period. Both cases were followed by a warmer than normal September.

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.

Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 9/10 (90%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO.   

Based on sensitivity analysis applied to the latest guidance, there is an implied 79% probability that New York City will have a warmer than normal August. August will likely finish with a mean temperature near 76.9°.

Finally, on August 20, Arctic sea ice extent was 4.485 million square kilometers (JAXA). Recent days have seen an increase in the melt rate. There is an implied 81% probability that Arctic sea ice extent will reach a minimum figure below 4.000 million square kilometers for the second consecutive year and third time on record. The highest 25% bound is 3.938 million square kilometers. The lowest 25% bound is 3.503 million square kilometers.

 

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The next 8 days are averaging 82degs., or 8degs. AN.

Month to date is  +1.1[76.8].         Should be near  +3.0[78.2] by the 30th.

74*(88%RH) here at 6am, thin overcast.        88*(60%RH) at 5pm.      Home from the beach.

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Good Saturday morning all!  Lot's of weather (potential) ahead...  Thinking of starting two topics but may hold off til evening since I have family in, attention diverted.  Don't like to overcommit too soon. 

First: Heat wave still appears on the horizon starting either today-Sunday in the non marine influenced below 500' foot elevation and lasts into Tuesday afternoon (barring thunderstorm cloud debris interruption). EC 850 has cooled 2-3C for Wed and so unlikely 90 but close (NAEFS not buying all this GFS/GGEM northerly flow cooling Wednesday),  probably HOT Thursday and uncertain heat Friday due to approach of tropical remnants (more on this later). 

Today...a brief shower or thunderstorm possible CT even se NYS/extreme nw NJ later this afternoon-evening. 

Sunday-Monday: Clusters of 2-3" producing thunderstorms.  Not posting as a topic yet.  Sunday may at first be south of I78 in NJ, but could shift up into NYS/CT in the evening per EC KI development.  Plenty of CAPE. PWAT~1.7.  Not enough to be sure of 4" total and so will only start as topic as a conversation centered grouping of reports. 

Tuesday: SPC has a slight risk for our area with the approaching cool front. Wind fields good, just a little concerned mostly nw 850 wind field.  However, I can be convinced by further discussions-modeling. 

Wednesday: A bit cooler... interesting nw flow event may occur across PA/s NJ... bigger KI pooling. 

Thursday: Back to heat and big storms may occur late day?

What I messaged Wx watcher this morning on tropics:  Am holding off til sometime this afternoon-evening on a tropic starter for NY forum.  NAEFS is not defined for the NE, but I think recurvature will result in Laura capturing some of Marco's moisture and sweep east, passing somewhere between ORF-BTV with potential for a a PRE prior to the late 28th/29th passage, this per the nice 250MB jet over Nova Scotia, and the likelihood of a strong front settling southward into the NY forum Friday.  IFFF that happens, not only PRE but also a gusty nor'easter, or if north of us, a gusty southwester.  Need NAEFS to shift north for Fri-Sat and be more defined with an axis--all in the GGEM court now since I think the GEFS/EPS are hinting at this in their 850 wind and qpf modeling. 657A/22

 

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81/72 clouds moving out mostly centered over the southern part of the area S-NJ, but even there should clear out by early afternoon.  Warmer spots first 90s today in 9 days(8/12).   Warmer spots heatwave Sat  -  Tue (8/25).  Storms possible Sun (8/23) and more widespread Mon night. 

Tuesday (8/24)  more 90s, especially in the warmer spots but likely a broader area, before northern flow brings a brief 8 - 12 hour relief on Wednesday (8/25) maybe just northern areas TTN south may still reach 90s.  Stronger heat Thu (8/27) and Fri (8/28) with 850MB temps surging to >18c to near 20c on WSW flow.  Record heat possible these two days.  The remnants of Laura are currently projected to pass through some time Friday and that will determine if Friday can get to record heat levels.

 

Weekend cooler for 48 hours before warmer more humid flow returns by the 31st.  WAR may bring more warmth / heat by 9/4.

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On 8/14/2020 at 6:32 AM, CIK62 said:

The next 8 days are averaging 79degs., or 3.5degs. AN.

Month to date is  +2.8[78.8].        Should be about  +3.0[78.9] by the 22nd.

Almost no rain on any model now thru Wed.     Stays south?

75*(90%RH) here at 6am, thin overcast.          83*(68%RH) by 11am, warming up and drying out.        86*(59%RH) by 3:30pm.     87*(55%RH) at 4pm.       89*(52%RH) at 5pm.

I think you need to use a different formula for calculating how warm is going to be over the next eight days. In reality this period Was -2 for Central Park. It's not  like you're remotely close. The park is at + 1.1 for the month

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Pretty typical summer weather Saturday through Tuesday with 85 to 90 degree readings for most of the area. Then looks like a big fail by the Euro for Wednesday possibly into Thursday with the big heat its showing. Friday looks like tropical remnants could affect the area then  big cool down next week end. 

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24 minutes ago, binbisso said:

Pretty typical summer weather Saturday through Tuesday with 85 to 90 degree readings for most of the area. Then looks like a big fail by the Euro for Wednesday possibly into Thursday with the big heat its showing. Friday looks like tropical remnants could affect the area then  big cool down next week end. 

Looks to run +5 - +7 or more each day today - Tue.  Wed still up in the air of extent of the strong heat by Thu/Fri models look to bring in 95(+) potential heat, then potetntial wet/warm with remnants of Laura Fri PM / Sat.  Cooldown looks similar to this week 2-3 days then flow goes warm again by 9/4.

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