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August 2020 General Discussions & Observations Thread


Rtd208
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1 hour ago, KEITH L.I said:

So NAO is a big factor.But it is in most winters,Nina or Nino.Nina always seems to be front loaded,probably 75 percent of the time we get a cold December.The warm and snowless strong nina winters bit the dust in a big way in 10-11..From Dec 26th through early February was the most snow cover I ever saw.

I'd like to see a cold Christmas week for a change instead of 70 and Sunny...

DJFM monthly nao for winters with at least 30" of snowfall in Central Park...

season........Dec.....Jan.....Feb.....Mar.....lowest/date...

1955-56......0.17...-0.22...-1.12...-0.05.....-1.114....12/17

1957-58......0.12...-0.54...-1.06...-1.96.....-1.651....1/22

1959-60......0.44...-1.29...-1.89...-0.50.....-2.120....1/16

1960-61......0.06....0.41....0.45....0.55.....-0.781....12/9

1963-64.....-1.27...-0.95...-1.43...-1.20.....-2.397....12/13

1966-67......0.72...-0.89....0.19....1.51.....-2.210....1/8

1968-69.....-1.40...-0.83...-1.55...-1.56.....-1.697....12/6

1977-78.....-1.00....0.66...-2.20....0.70.....-2.172....2/13

1993-94......1.56....1.04....0.46....1.26.....-0.854....12/26

1995-96.....-1.67...-0.12...-0.07...-0.24.....-1.846....12/7

2000-01.....-0.58....0.25....0.45...-1.26.....-1.658....12/7

2002-03.....-0.94....0.16....0.62....0.32.....-1.585....12/10

2003-04......0.64...-0.29...-0.14....1.02.....-1.449....1/28

2004-05......1.21....1.51...-0.06...-1.83.....-1.486....3/14

2005-06.....-0.44....1.27...-0.51...-1.28.....-1.360....2/27

2009-10.....-1.93...-1.11...-1.98...-0.88.....-2.250....1/3

2010-11.....-1.85...-0.88....0.70....0.61.....-2.023....12/1

2013-14......0.95....0.29....1.34....0.80.....-0.529....1/12

2014-15......1.86....1.79....1.32....1.45.....-0.909....12/28

2015-16......2.24....0.12....1.58....0.73.....-1.014....1/12

2016-17......0.48....0.48....1.00....0.74.....-1.002....12/6

2017-18......0.00....1.44....1.58...-0.93.....-1.719....3/1

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Temperatures rose into the middle and even upper 80s across most of the region today. A thick line of severe thunderstorms moved across parts of Massachusetts late in the day with wind gusts in excess of 60 mph and hail. Through 8:05 pm, Boston picked up 1.30" rain. Worcester received 1.72" rain, which surpass the previous daily record of 1.33" from 1970.

Tomorrow and Tuesday could see readings approach or reach 90° in much of the region. There is a risk of strong to possibly severe thunderstorms tomorrow and Tuesday. The month could end on a cool note before temperatures return to above normal levels during the first week of September. In addition, the remnants of Laura could exit off the Middle Atlantic coast late this week.

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.

Parts of the West continued to experience near record to record warmth. Select high temperatures included:

Death Valley, CA: 121°
Denver: 98° (Tied record set in 2009 and tied in 2011)
Flagstaff: 88°
Lake Havasu City, AZ: 111°
Las Vegas: 105°
Needles, CA: 113°
Palm Springs, CA: 113°
Phoenix: 110°
Pueblo, CO: 99°
Tucson: 106°
Yuma, AZ: 110°

At Death Valley, the temperature topped out at 121°. That was the 10th consecutive day on which the temperature reached 120° or above and 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 96.6° - 97.0°. 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. There is currently an implied 61% probability that August will exceed July's monthly record.

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 +9.53.

Today, the preliminary Arctic Oscillation (AO) figure was +0.258.

On August 22, the MJO was in Phase 1 at an amplitude of 1.700 (RMM). The August 21-adjusted amplitude was 1.529.

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 87% 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 22, Arctic sea ice extent was 4.317 million square kilometers (JAXA). There is an implied 89% 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 3.840 million square kilometers. The lowest 25% bound is 3.460 million square kilometers.

 

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No heat wave except vicinity CDW and POU which should continue today and possibly Tue. Typical summer.

Saw interesting UKMET 2m temps for NYC Thu...modeled warmest NYC at 00z, instead of 18z., implying warm air advection but not much shower-thunderstorm activity. Hmmm?  

 

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The last 8 days of August are averaging 81degs., or 7.5degs. AN.

Month to date is +1.5[77.1].        August should end at  +2.9[78.1]-----or correcting a +5* GFS bias----end at  +1.6[76.8].

75*(93%RH) here at 6am, hazy blue sky.       Getting away lucky here at just 80*(80%RH) by Noon.       81* by 12:30pm.        83*(75%RH) at 1pm.       84*(73%RH) at 1:30pm-Heat Index is 91*    Nearest TS now near Allentown.        85*(78%RH) at 3pm, Heat Index is 95*.     Got to 89* at 5:30pm.       86* at 6:30pm.

Quick look at Sept:     Weeks 1,2 near Normal, + bias.       5820-40m 500mb Heights stick around.      Weeks 3,4 near Normal but with a -- bias.    So overall Normal.

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79/ 69 here.  Hot late summer next 36 hours with 90s possible outside of any storms/clouds that may form which are likely later today and Tuesday.  Strong north/ NE flow 12  - 18 hours Wednesday gives a brief reprieve from the late summer warmth before stronger heat returns Thu and Fri (pending on remnants of Laura).  Overnight models, epsecially the ECM now have the remnants of Laura later Fri (overnight) into Sat.  Either way warm and humid this week next 4 of 5 days with thunderstorm potential.

The upcoming weekend will see cooler air in the wake of Laura's remnants later Saturday and Sunday (8/30)  and continue a day or so before return SW flow brings more warmth 9/2. We'll see the timing for Labor Day weekend way out there but looks like a few days warmth followed by brief cool downs 9/2 - 9/7.  Ridging may dig into the EC beyond there  for a period in early/mid next month. 

Next tropical threat could be an East coast one by labor day weekend.

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17 hours ago, bluewave said:

It could be the 5th La Niña-like winter in a row for us. The La Niña background state has been very persistent since 16-17. The SE Ridge was a big player for us last 4 winters. La Niña winter snowfall is usually determined by whether NYC gets 3” of snow in December or not. So we should get an early idea of seasonal snowfall potential. Every La Niña-like  snowfall season since 95-96 with under 3” in December turned out below normal like the last 2 winters.  All  the 3”+ Decembers featured above normal seasonal snowfall. Even the mild La Niña winters like 17-18, 16-17 and 05-06 did well in the snowfall department. 

Monthly Total Snowfall for NY CITY CENTRAL PARK, NY
Click column heading to sort ascending, click again to sort descending.
Year
Oct
Nov
Dec
Jan
Feb
Mar
Apr
Season
2019-2020 0.0 0.0 2.5 2.3 T T T 4.8
2018-2019 0.0 6.4 T 1.1 2.6 10.4 0.0 20.5
2017-2018 0.0 T 7.7 11.2 4.9 11.6 5.5 40.9
2016-2017 0.0 T 3.2 7.9 9.4 9.7 0.0 30.2

 

 

2011-2012 2.9 0.0 0.0 4.3 0.2 0.0 0.0 7.4
2010-2011 0.0 T 20.1 36.0 4.8 1.0 T 61.9

 

2008-2009 0.0 T 6.0 9.0 4.3 8.3 T 27.6
2007-2008 0.0 T 2.9 T 9.0 T 0.0 11.9

 

2005-2006 0.0 T 9.7 2.0 26.9 1.3 0.1 40.0

 

2001-2002 0.0 0.0 T 3.5 T T T 3.5
2000-2001 T 0.0 13.4 8.3 9.5 3.8 0.0 35.0
1999-2000 0.0 0.0 T 9.5 5.2 0.4 1.2 16.3
1998-1999 0.0 0.0 2.0 4.5 1.7 4.5 0.0 12.7

 

1996-1997 0.0 0.1 T 4.4 3.8 1.7 T 10.0
1995-1996 0.0 2.9 11.5 26.1 21.2 13.2 0.7 75.6

 

 

I remember we had a close miss in mid December 2010 and most thought we'd have a very low snowfall season, and then the big multi model bust came that gave us the Boxing Day surprise and the rest, as they say, was history (and historic.)

 

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Numerous stations around the Northeast are having their warmest summer through August 23rd.

Time Series Summary for LAGUARDIA AIRPORT, NY
Click column heading to sort ascending, click again to sort descending.
Rank
Ending Date
Mean Avg Temperature Jun 1 to Aug 23
Missing Count
1 2020-08-23 79.5 0
2 2010-08-23 79.4 0
3 2016-08-23 78.5 0

 

Time Series Summary for IGOR I SIKORSKY MEMORIAL AIRPORT, CT
Click column heading to sort ascending, click again to sort descending.
Rank
Ending Date
Mean Avg Temperature Jun 1 to Aug 23
Missing Count
1 2020-08-23 75.3 4
2 2016-08-23 75.2 0
- 2010-08-23 75.2 0
3 2019-08-23 74.5 0

 

Time Series Summary for HARTFORD-BRADLEY INTERNATIONAL AIRPORT, CT
Click column heading to sort ascending, click again to sort descending.
Rank
Ending Date
Mean Avg Temperature Jun 1 to Aug 23
Missing Count
1 2020-08-23 74.9 0
2 2019-08-23 74.1 0
- 2005-08-23 74.1 0
3 2010-08-23 74.0 0

 

Time Series Summary for Burlington Area, VT (ThreadEx)
Click column heading to sort ascending, click again to sort descending.
Rank
Ending Date
Mean Avg Temperature Jun 1 to Aug 23
Missing Count
1 2020-08-23 72.8 0
2 1949-08-23 72.4 0
3 1995-08-23 72.2 0

 

Time Series Summary for Caribou Area, ME (ThreadEx)
Click column heading to sort ascending, click again to sort descending.
Rank
Ending Date
Mean Avg Temperature Jun 1 to Aug 23
Missing Count
1 2020-08-23 67.7 0
2 1995-08-23 66.5 0
- 1970-08-23 66.5 0

 

Time Series Summary for Manchester Area, NH (ThreadEx)
Click column heading to sort ascending, click again to sort descending.
Rank
Ending Date
Mean Avg Temperature Jun 1 to Aug 23
Missing Count
1 2020-08-23 75.0 0
2 2018-08-23 73.5 2
3 2019-08-23 73.1 0

 

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13 minutes ago, bluewave said:

Numerous stations around the Northeast are having their warmest summer through August 23rd.

Time Series Summary for LAGUARDIA AIRPORT, NY
Click column heading to sort ascending, click again to sort descending.
Rank
Ending Date
Mean Avg Temperature Jun 1 to Aug 23
Missing Count
1 2020-08-23 79.5 0
2 2010-08-23 79.4 0
3 2016-08-23 78.5 0

 

Time Series Summary for IGOR I SIKORSKY MEMORIAL AIRPORT, CT
Click column heading to sort ascending, click again to sort descending.
Rank
Ending Date
Mean Avg Temperature Jun 1 to Aug 23
Missing Count
1 2020-08-23 75.3 4
2 2016-08-23 75.2 0
- 2010-08-23 75.2 0
3 2019-08-23 74.5 0

 

Time Series Summary for HARTFORD-BRADLEY INTERNATIONAL AIRPORT, CT
Click column heading to sort ascending, click again to sort descending.
Rank
Ending Date
Mean Avg Temperature Jun 1 to Aug 23
Missing Count
1 2020-08-23 74.9 0
2 2019-08-23 74.1 0
- 2005-08-23 74.1 0
3 2010-08-23 74.0 0

 

Time Series Summary for Burlington Area, VT (ThreadEx)
Click column heading to sort ascending, click again to sort descending.
Rank
Ending Date
Mean Avg Temperature Jun 1 to Aug 23
Missing Count
1 2020-08-23 72.8 0
2 1949-08-23 72.4 0
3 1995-08-23 72.2 0

 

Time Series Summary for Caribou Area, ME (ThreadEx)
Click column heading to sort ascending, click again to sort descending.
Rank
Ending Date
Mean Avg Temperature Jun 1 to Aug 23
Missing Count
1 2020-08-23 67.7 0
2 1995-08-23 66.5 0
- 1970-08-23 66.5 0

 

Time Series Summary for Manchester Area, NH (ThreadEx)
Click column heading to sort ascending, click again to sort descending.
Rank
Ending Date
Mean Avg Temperature Jun 1 to Aug 23
Missing Count
1 2020-08-23 75.0 0
2 2018-08-23 73.5 2
3 2019-08-23 73.1 0

 

and that's with June being average to below average especially the first 3 weeks

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Saw the SPC upgrade to marginal risk today in our area. A bit surprised.  86/69 here in Wantage at 1240P..  A little uneasy how this unfolds.  amazing 12z models have so little in northern PA at this time and many have very little in our forum area this afternoon.  That's always a bit concerning for me...  modeling 2-3 hours before go time look pretty pathetic today except ICON.  We'll see and should know by 4P if anything decent will develop or spill over into our area.   

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6 minutes ago, forkyfork said:

the euro shifted north thursday and has 95+ potential again

and Fri pending on timing of Laura's clouds/remnants?  Did it back down on 850's 00z or 06z runs?   >16c Thu peaking  >18c between Thu 18z and 18Z friday

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5 hours ago, LibertyBell said:

I remember we had a close miss in mid December 2010 and most thought we'd have a very low snowfall season, and then the big multi model bust came that gave us the Boxing Day surprise and the rest, as they say, was history (and historic.)

 

It took until the end of the month for the Pacific to finally become favorable. The models were showing fantasy day 6-10 snows for much of December before Boxing Day delivered. The record -AO/-NAO streak from June 2009 to January 2011 may be tough to replicate. But who knows with all the weather and climate extremes since then.

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