August 2020 General Discussions & Observations Thread

[donsutherland1]

The region saw its coolest readings since just after mid-June this morning. During the afternoon, the temperature rebounded into the lower and middle 80s. Another brief cool shot is possible near mid-week. Noticeably warmer weather could arrive for the weekend.

Out west, extreme heat again prevailed in the Southwest. Select high temperatures included:

Death Valley, CA: 126° (old record: 124°, 2001)
Flagstaff: 88° (old record: 87°, 1992 and 2002)
Kingman, AZ: 110° (old record: 109°, 1915)
Lake Havasu City, AZ: 115°
Las Vegas: 114° (old record: 111°, 1992)
Mesa, AZ: 111° (old record: 102°, 2019)
Needles, CA: 118° (old record: 115°, 1992 and 2011)
Palm Springs, CA: 114°
Phoenix: 115° (old record: 112°, 2011)
Sacramento: 106°
Stockton, CA: 107° (tied record set in 1967)
Tucson, AZ: 107° (old record: 107°, 2013)
Yuma, AZ: 111°

Death Valley reached 125° or above for the fourth consecutive day. That surpassed the previous August record, which was set during August 11-13, 1933 and tied during August 6-8, 1998.

Intense heat will likely continue in that region into the coming weekend although the most severe heat will fade after midweek.

Phoenix has an implied 97% probability of having its warmest summer on record. Phoenix will likely finish with a summer mean temperature of 96.4° - 96.8°. 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°. 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 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.  

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 +10.56.

Today, the preliminary Arctic Oscillation (AO) figure was -1.377.

On August 17, the MJO was in Phase 8 at an amplitude of 1.837 (RMM). The August 16-adjusted amplitude was 1.632.

The MJO's recent passage through Phase 4 at an amplitude of 1.500 or above has been uncommon during the first half of August. During the 1981-2019 period only 1983 and 2019 saw the MJO move through Phase 4 with an amplitude of 1.500 or above during the first half of August. August 1983 had the longest such stretch. Both cases saw the second half of August average generally warmer than normal in the Middle Atlantic region. Both cases also featured 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 77.0°.

Finally, on August 17, Arctic sea ice extent was 4.782 million square kilometers (JAXA). There is an implied 63% 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 4.129 million square kilometers. The lowest 25% bound is 3.609 million square kilometers.

 

[SACRUS]

8/18

ACY: 87
LGA: 86
BLM: 86
EWR: 85
PHL: 84
New Brnswk: 84
TEB: 84
JFK: 84
TTN: 83
ISP: 83
NYC: 83

[CIK62]

The next 8 days are averaging 82.5degs., or 7.5degs. AN.

Month to date is  +1.7[77.5].         Should be +3.5[79.1] by the 27th. 

Even the EURO has 5 90's in a row before returning to Normal by the end of the month.        For the next 10 days:      GFS 7,  EURO 5, GEM 1----90-Degree Days.      Their ENSEMBLES have none.

I do not entertain the idea of this becoming the hottest summer ever with a high of 96* and no where near a record number of 90 degree days.        Apparently the Low T's are keeping us in the running.

71*(80%RH) here at 6am, scattered overcast.

TS about 30miles n.e. of Trenton at 9am.

[donsutherland1]

Morning thoughts...

At 7:50 am, a shower was crossing the Hudson River just north of Yonkers and a thundershower was approaching Englewood. A larger area of showers and thundershowers covered an area running from northern Virginia to eastern Pennsylvania. That area as headed northeastward and will likely affect the Philadelphia, Newark and New York City areas later this morning. Sunshine should return to those areas during the afternoon.

In the wake of the frontal passage, tonight will see temperatures fall into the lower 60s in New York City and 50s in many places outside the City.

Out west, intense heat will again topple records in parts of California, Arizona and Nevada.

Out in the eastern Atlantic, a new tropical depression could develop in over the next 24-48 hours. 

[SACRUS]

68, cloudy and light rain.  Clouds and light rain back to CPA and looks like if we get any clearing it'll be in 4 - 6 hours (1 - 3 PM).  Thu - Fri similar to Tuesday highs low to perhaps mid 80s and cooler less humid nights.  Warmth returns this weekend with chance of 90s starting Saturday *8/22) and Sunday (8/23) in the hotter spots. 

By this coming  Monday (8/24)  a piece of the heat regime has pushed east into the plains and mid west ,and arrives by Tue as the WAR builds west and lingers through Fri (8/28) or Sat (8/30), peaking Wed and Thu (that 2 day strong heat that been tracking the potential) as it looks now with near or >20c 850MB temps.  That furnace out west is impressive and still think we may challenge the seasons hottest temps.  Storms will be likely in the period and the caveat to how hot we can get. 

 

Beyond 8/30 in the longer range back towards normal for a few days  before riding follows the Plain - MW and east progression.

[Rtd208]

Pouring here w/thunder and lightning.

[SACRUS]

Some of the darkest (greenish) clouds ive experienced in many years with strong thunderstorm developed just north into N-Middlesex and Union

[forkyfork]

some light rain here

[lee59]

Unexpected rain here early this morning and more unexpected rain appears to be moving in.

[psv88]

Had a heavy downpour move through, more on the way. This was not in the forecast.

[Stormlover74]

Just now, psv88 said:

Had a heavy downpour move through, more on the way. This was not in the forecast.

I think originally it was sunny, then they added in a 20% chance of showers. Wasn't expecting such widespread activity

[nycwinter]

weather forecasters blew it  for today's weather..

[nycwinter]

i remember lee lee goldberg yesterday afternoon said maybe a shower south of the city  for today...

[Euripides]

Well that was a nice deluge.

Keep them coming as lawn nice and green.

Had two other rounds on Monday with heavy rains around 7:45pm and then around 4am on Tuesday morning.

[forkyfork]

1 hour ago, bluewave said:

Looks like there will be a surge of +20 C 850s nearby next week. So we are probably looking at 95° to 100° heat to close out the month. 

 

this looks drier than previous heat surges. maybe ewr can pull off 100

[SI Mailman]

Just had a nice storm move through. Plenty of thunder and lightning

[Rjay]

[forkyfork]

tornado warning near red bank. the cell looks legit

[Stormlover74]

Sure why not

 

 

[SI Mailman]

Yeah, I got the top end of the cell and it had a lot of lightning

[lee59]

5 minutes ago, Stormlover74 said:

Sure why not

 

 

Ok so a day ago it was suppose to be mostly sunny today and now there is a tornado warning. Yea I think this time the forcast was way off.

[PB-99]

Got TOR warned here in Red Bank. So close, that hook echo passed right overhead 

Lightning was hitting everywhere.

Lost power temp. What a sick storm.

 

[Rjay]

3 minutes ago, PB-99 said:

Got TOR warned here in Red Bank. So close, that hook echo passed right overhead 

Lightning was hitting everywhere.

Lost power temp. What a sick storm.

 

There was likely a tornado on the ground just south of Red Bank

[PB-99]

7 minutes ago, Rjay said:

There was likely a tornado on the ground just south of Red Bank

I was just going to type if someone south of me saw a funnel I would not be shocked 

[bluewave]

15 minutes ago, lee59 said:

Ok so a day ago it was suppose to be mostly sunny today and now there is a tornado warning. Yea I think this time the forcast was way off.

The Euro had chances for convection across the area with the 12z run yesterday. But people often don’t pay attention when the NAM is dry.

12z Tue run

0z Wed

 

 

 

 

[gravitylover]

Hang on down there.

It has been an absolutely beautiful morning up here (so far) but I can see the storm just slightly to my SSW sliding by to the east. That's not going to help me ease the precip deficit I've got going but this has been the typical setup for the last 10 weeks or so, I'm pretty much used to it.

[wdrag]

Yes...I agree on EC  one my go-to's for convection is the KI, very very well modeled by the EC for several cycles and the reasoning for the recent posts about a band of showers this morning NJ-LI. 

Through this afternoon-eve: Think there is a continued risk of isolated hail/svr LI, maybe coastal CT, into mid afternoon, with the more favored area for severe seemingly over the ocean s of LI.  A new southeastward moving line of heavy showers is possible late this afternoon-eve nw NJ into NYC at sunset but that should have less chance of being strong, tho not out of the question briefly a torrent. 

Fri night-Sunday: More heavy showers and thunderstorms.  Fri night-early Saturday is chancey and associated with WAA + moisture transport from the MS-TN low aloft leaking northeastward into the confluence zone. That moisture increase I think sets the stage for slow moving 2-3" pockets of big convection near NYC Sunday afternoon, ahead of the weakening shortwave, in an axis of high CAPE (2000+J), and KI looks fairly large as well along with 90 degree heat. This may become a topic eventually, but not for severe...more so intense rainfall. Right now PWAT is forecast near 1.8"...a little lower than I'd like for Thunderstorm production of 4".

Next week: interesting in it's variety of options, including eventual infusion of tropical event moisture and an approaching cold front from the northwest, developing a swath of rather high KI ahead of it and temps-heat index ahead of the front well up in the 90s with near 100 not impossible on both, for one of those days.  Forecasting 100 in late August is not smart several days in advance so will favor near 100HI eventually next week, but mid 90s temps (non sea breeze coastal plain locations ), in part due to wind direction and recent wetness. Should become interesting for convection. 

On eventual Laura/Marco: for now prior to the 29th,  the greater moisture contribution seems locked mostly south of 35 N latitude by westerly flow at our latitude but should there be any slow downs of northward advance (northward advance track in the Gulf States has to be west of 70 degrees longitude in order of for a moisture contribution in this projected flow pattern),  it then becomes a little more interesting toward the 30th. 

Below, added an update to yesterdays severe reports, Mid-2AM Monday 8/18. 1108A/19

[lee59]

40 minutes ago, bluewave said:

The Euro had chances for convection across the area with the 12z run yesterday. But people often don’t pay attention when the NAM is dry.

12z Tue run

0z Wed

 

 

 

 

Well congrats to the euro for at least giving some showers to the area. So far today here, rainy and cool.

[lee59]

9 minutes ago, wdrag said:

Yes...I agree on EC  one my go-to's for convection is the KI, very very well modeled by the EC for several cycles and the reasoning for the recent posts about a band of showers this morning NJ-LI. 

Through this afternoon-eve: Think there is a continued risk of isolated hail/svr LI, maybe coastal CT, into mid afternoon, with the more favored area for severe seemingly over the ocean s of LI.  A new southeastward moving line of heavy showers is possible late this afternoon-eve nw NJ into NYC at sunset but that should have less chance of being strong, tho not out of the question briefly a torrent. 

Fri night-Sunday: More heavy showers and thunderstorms.  Fri night-early Saturday is chancey and associated with WAA + moisture transport from the MS-TN low aloft leaking northeastward into the confluence zone. That moisture increase I think sets the stage for slow moving 2-3" pockets of big convection near NYC Sunday afternoon, ahead of the weakening shortwave, in an axis of high CAPE (2000+J), and KI looks fairly large as well along with 90 degree heat. This may become a topic eventually, but not for severe...more so intense rainfall. Right now PWAT is forecast near 1.8"...a little lower than I'd like for Thunderstorm production of 4".

Next week: interesting in it's variety of options, including eventual infusion of tropical event moisture and an approaching cold front from the northwest, developing a swath of rather high KI ahead of it and temps-heat index ahead of the front well up in the 90s with near 100 not impossible on both, for one of those days.  Forecasting 100 in late August is not smart several days in advance so will favor near 100HI eventually next week, but mid 90s temps (non sea breeze coastal plain locations ), in part due to wind direction and recent wetness. Should become interesting for convection. 

On eventual Laura/Marco: for now prior to the 29th,  the greater moisture contribution seems locked mostly south of 35 N latitude by westerly flow at our latitude but should there be any slow downs of northward advance (northward advance track in the Gulf States has to be west of 70 degrees longitude in order of for a moisture contribution in this projected flow pattern),  it then becomes a little more interesting toward the 30th. 

Below, added an update to yesterdays severe reports, Mid-2AM Monday 8/18. 1108A/19

I think your call of not forecasting  near 100 degree temperatures this far out, is smart. Climatology really makes 100 hard this time of year, even at the hot spots like LaGuardia and Newark. Average temperatures are already on the way down and by the end of August will be down some 3-4 degrees.

[Stormlover74]

1 minute ago, lee59 said:

I think your call of not forecasting  near 100 degree temperatures this far out, is smart. Climatology really makes 100 hard this time of year, even at the hot spots like LaGuardia and Newark. Average temperatures are already on the way down and by the end of August will be down some 3-4 degrees.

But who would've thought we could reach the mid 90s in early October last year?