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September 2019 General Discussions & Observations Thread

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7 hours ago, bluewave said:

Even Long Island could reach 90 with more of a westerly flow.  Just remarkable for the first week of October.

ED91F4E7-E430-4E75-AA69-2B85C619E0E5.thumb.png.f20c8de3a872fecbcfc4cddce3b93b1e.png

 

I'll take the under on those temps for Suffolk county. Euro can be over done at this range with that. If I'm wrong, I'll admit it. 

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Nam 18z was a bit faster with the cold front still some very warm temps for Wednesday. Phillys projected high is 91. Let’s see if we get a record here for Wednesday, very warm... enjoy it this week cause colder air is coming in and so is fall!

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Following a brief push of cooler air for tomorrow, there is potential for much above normal warmth to start October. The heat will likely peak on October 2 with readings in the middle and upper 80s into southern New England. Locations, including Washington, Baltimore, Philadelphia, Newark, and possibly even New York City could reach 90°.

The PNA is forecast to plunge over the next two days. Typically, a strongly negative PNA (-1.50 or below) during the October 1-3 period has translated into readings averaging 2°-4° above normal in the Middle Atlantic and southern New England regions. The warmth has been even more pronounced when the strongly negative PNA has coincided with a negative SOI.

Afterward, a period of cooler than normal readings will move into the region during the latter part of the first week of October. This pattern could last 7-10 days.

A historic early-season snowfall brought additional snow to Great Falls today following yesterday's September daily record snowfall of 9.7". So far, Browning, MT had picked up 40" snow. 4" or more snowfalls during the September 20-30 period in Great Falls have been followed by warmer than normal Octobers in the Middle Atlantic region in 5 of 7 (71%) cases. The last three (1941, 1954, and 1984) saw a mean temperature above 60.0° in New York City. The late September pattern provides perhaps another indication that a warmer than normal October lies ahead.

Events during September, including the SOI's falling to -35.30 on September 19, the MJO's being in Phase 1 at an amplitude of 2.000 or above during the September 20-30 period for more than two days, and the possible ongoing evolution toward a generally positive AO regime, favor a warmer than normal October based on past outcomes. However, recent guidance has increased uncertainty regarded to the AO's longer-term evolution. That situation bears watching, but the base case remains a warmer than normal October.

Courtesy of low sea ice, there is a near 100% implied probability that Utqiagvik (formerly Barrow) will record its warmest September on record. It is very likely that Utqiagvik will register its first 40.0° mean temperature for September with an average temperature near 40.7°. A 40.7° mean temperature would we so warm that it would rank as the 27th warmest August and also the 37th warmest July out of 99 years on record. The existing monthly record of 37.7° has stood since 1998.

The ENSO Region 1+2 anomaly was -1.3°C and the Region 3.4 anomaly was -0.2°C for the week centered around September 18. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.77°C and the ENSO Region 3.4 anomaly has averaged -0.16°C. The recent strong cooling in Region 1+2 indicates that the prospects for a neutral-cool ENSO during the winter have continued to increase. Such a scenario is now more likely than not.

Since 1991 when weekly ENSO region data was available, five years have seen September record 2 or more weeks with -1.0°C or cooler weekly anomalies in Region 1+2: 1996, 1999, 2007, 2010, and 2017. 4/5 (80%) of those cases went on to feature warm December-February temperature anomalies in the Middle Atlantic and southern New England regions. Those cases include La Niña winters. However, the larger pool of neutral-cool ENSO winters, many of which predate the weekly ENSO regional data, have often featured frequent Atlantic blocking. For now, there is a mixed winter signal.

The SOI was +0.95 today.

Today, the preliminary Arctic Oscillation (AO) figure was -0.521.

Since 1950, there have been five prior cases when the AO averaged -0.500 or below in both July and August: 1950, 1958, 1960, 1968, and 2015. The average temperature for September was 69.1° (69.8° after adjusting for ongoing warming) and 58.9° (59.6° adjusted) for September through November in New York City. The 1981-2010 baseline normal figures are 68.0° and 57.5° respectively. The majority of cases saw a warmer than normal September and all cases featured a warmer than normal fall.

A warmer than normal September is now all but certain. A warmer than normal fall remains likely. The potential for autumn 2019 to rank among the 30 warmest cases on record has increased in recent weeks. For New York City, that would translate into a September-November mean temperature of at least 58.8°.

On September 28, the MJO was in Phase 1 at an amplitude of 2.275 (RMM). The September 27-adjusted amplitude was 2.473.

Based on sensitivity analysis applied to the latest guidance, the implied probability of New York City having a warmer than normal September is near 100% and the probability of a monthly mean temperature of 70.0° or above is 82%. Should September 2019 have a mean temperature of 70.0° or above, 2019 would be the 5th consecutive year with such September warmth. Prior to the current stretch, the record was 2 consecutive years (1930 and 1931; 1970 and 1971; 1979 and 1980; and, 2010 and 2011).

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Last day of September has a mean of 64degs., or 3degs. AN.

Month to date is  +2.4[70.5].       September should end at  +2.3[70.3].

The first week of October is averaging 65degs., or about 4degs. AN.

First 3 days of October:   EURO:  77, 91, 78.  GFS:  78, 88, 78.      Does not look that cold after that anymore.   "As the Earth Burns" serial extended?      Remember the famous Tag-Team of "HOTn'HOTTER"---in town to stay?

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70 degree Septembers have become the new normal around here. The first decade for LGA with 9 out 10 years  finishing 70+. While the temperatures has been steadily rising throughout the year, the fall rise has been a little faster than the other seasons. So September has become like a 4th month of summer.

Time Series Summary for LA GUARDIA AP, NY - Month of Sep
Click column heading to sort ascending, click again to sort descending.
Rank
Year
Mean Avg Temperature 
Missing Count
1 2005 74.9 0
2 2015 74.1 0
3 2016 73.8 0
4 2007 73.0 0
5 2018 72.8 0
6 2010 72.5 0
7 2019 72.3 1
8 1998 71.6 0
9 2017 71.5 0
10 2002 71.3 0
11 2012 70.7 0
- 2011 70.7 0
- 2004 70.7 0
- 1985 70.7 0
12 1983 70.6 0
13 2014 70.4 0
- 2008 70.4 0
14 1999 70.2 0

 

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1 hour ago, Snow88 said:

This whole week looks nice and crisp except for 1 hot day .

and areas to the north of NYC may not get that warm if the NAM is correct with a 2pm frontal passage give or take.    Other models are slower.

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18 hours ago, SnoSki14 said:

I'm sure we'll end this flash drought with some massive deluge.

That would be amazing. We just do not need it all in a few hours as the ground will just run must of off. We need a long protracted synoptic rain event 

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Just now, winterwx21 said:

The cool shot for the end of the week is looking less and less impressive. We'll probably be back in the 70s by sunday.

Yup though it's clearly a much more active, less hot pattern. We should see a lot more fronts coming through. 

October, especially 1st half is still pretty mild. 

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22 minutes ago, SnoSki14 said:

Yup though it's clearly a much more active, less hot pattern. We should see a lot more fronts coming through. 

October, especially 1st half is still pretty mild. 

last night's Euro has rains, but mainly north of NYC-bone dry continues to the south....

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58 minutes ago, NYCweatherNOW said:

How come nobody is talking about the record breaking blizzard in Montana! 

 

58 minutes ago, NYCweatherNOW said:

How come nobody is talking about the record breaking blizzard in Montana! 

cause we're all members of a vast left-wing commie conspiracy to take away your cookies, but you already knew that from the intraweb

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1 hour ago, NYCweatherNOW said:

How come nobody is talking about the record breaking blizzard in Montana! 

I posted the following last night: " A historic early-season snowfall brought additional snow to Great Falls today following yesterday's September daily record snowfall of 9.7". So far, Browning, MT had picked up 40" snow."

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A warm September concluded today. 2019 marked the fifth consecutive year during which September had a mean temperature of 70° or above in New York City.

In the New York City area, September has increasingly become an extension of summer. Prior to 2000, a monthly mean temperature of 70° or above was relatively uncommon. Prior to 1950, Central Park saw such warmth about once every 5.4 years. From 1950-1999 (during which New York City has had a mature urban footprint), such warmth was recorded approximately once every 4.5 years.

Since 2000, 70° Septembers have occurred about once every 2.0 years. There have been 10 such Septembers during the 2000-2019 period, which is just below the figure of 11 recorded during 1950-1999. Since 2010, New York City has had 7 cases where September had a mean temperature of 70° or above, including the last four years.

During the last 30 years, September has had a mean temperature of 69.0 degrees, which is the warmest 30-year period on record for September. During the last 10 years, September has had a mean temperature of 70.5 degrees, which is the warmest 10-year period on record for that month. Records go back to 1869. The 1981-2010 normal temperature for September is 68.0°.

A dramatic warmup will tomorrow. The heat will likely peak on October 2 with readings in the middle and upper 80s into southern New England. Locations, including Washington, Baltimore, Philadelphia, Newark, and possibly even New York City could reach 90°.

Afterward, a period of cooler than normal readings will move into the region during the latter part of the first week of October. This pattern could last 7-10 days, though not every day will be cooler than normal.

Events during September, including the SOI's falling to -35.30 on September 19, the MJO's being in Phase 1 at an amplitude of 2.000 or above during the September 20-30 period for more than two days, the historic late September snowfall in Great Falls, MT, and the possible ongoing evolution toward a generally positive AO regime, favor a warmer than normal October based on past outcomes. However, recent guidance has increased uncertainty regarded to the AO's longer-term evolution. That situation bears watching, but the base case remains a warmer than normal October.

The historic September Northern Rockies snowstorm had dumped among the following snowfall amounts: Babb, MT: 52.0"; Browning, MT: 48.0"; Great Falls, MT: 19.3"; and, St. Mary, MT: 45.0".

Utqiagvik (formerly Barrow) recorded its warmest September on record with its first 40.0° mean temperature for September. The preliminary monthly average was 40.8°. A 40.8° mean temperature was so warm that it ranked as the 27th warmest August and also the 35th warmest July out of 99 years on record. The previous monthly record of 37.7° has stood since 1998.

The ENSO Region 1+2 anomaly was -0.5°C and the Region 3.4 anomaly was +0.5°C for the week centered around September 25. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.73°C and the ENSO Region 3.4 anomaly has averaged -0.07°C. The recent strong cooling in Region 1+2 indicates that the prospects for a neutral-cool ENSO during the winter have continued to increase. Such a scenario is now more likely than not.

Since 1991 when weekly ENSO region data was available, five years have seen September record 2 or more weeks with -1.0°C or cooler weekly anomalies in Region 1+2: 1996, 1999, 2007, 2010, and 2017. 4/5 (80%) of those cases went on to feature warm December-February temperature anomalies in the Middle Atlantic and southern New England regions. Those cases include La Niña winters. However, the larger pool of neutral-cool ENSO winters, many of which predate the weekly ENSO regional data, have often featured frequent Atlantic blocking. For now, there is a mixed winter signal.

The SOI was +8.20 today.

Today, the preliminary Arctic Oscillation (AO) figure was -0.375.

Since 1950, there have been five prior cases when the AO averaged -0.500 or below in both July and August: 1950, 1958, 1960, 1968, and 2015. The average temperature for September was 69.1° (69.8° after adjusting for ongoing warming) and 58.9° (59.6° adjusted) for September through November in New York City. New York City finished September with a mean temperature of 70.4°. The 1981-2010 baseline normal figures are 68.0° and 57.5° respectively. The majority of cases saw a warmer than normal September and all cases featured a warmer than normal fall.

Following September's warmth, a warmer than normal October lies ahead. The potential for autumn 2019 to rank among the 30 warmest cases on record has increased in recent weeks. For New York City, that would translate into a September-November mean temperature of at least 58.8°.

On September 29, the MJO was in Phase 1 at an amplitude of 2.044 (RMM). The September 28-adjusted amplitude was 2.331.

Based on sensitivity analysis applied to the latest guidance, the implied probability of New York City having a warmer than normal October is approximately 60%. That is an exceptionally high probability for such an outcome just before the start of the month.

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September ended at  +2.4[70.4].

Rainfall was just 0.95", maybe least since October 2013.

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September 2019 was a continuation of the 2010’s endless summer pattern. 9 out of 10 years featuring above normal temperatures.

SEP....EWR...NYC...LGA

2019...+2.6....+2.4....+3.0

2018...+3.2...+2.7....+3.7

2017...+2.7...+2.5....+2.4

2016...+3.6...,+3.8...+4.7

2015...+5.2....+6.5...+5.0

2014..+1.6....+1.7....+1.3

2013...-1.0....-0.1.....-1.0

2012...+1.3...+0.8....+3.4

2011....+3.0..+2.0....+1.6

2010...+3.4....+3.1...+3.4

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26 minutes ago, SnoSki14 said:

AN is the new normal, that's pretty clear from the data above. 

Nowadays a cold September would be near normal. 

September has shown one of the fastest rates of temperature increase across the region since 1981. The temperature has been rising at +1.3 degree F/ decade at LGA and +1.4 at Albany.

806418DC-DE14-491D-93FF-70543460E497.thumb.jpeg.40f5fdb3dff6c4ac8fa01edb91025f43.jpeg

19DDDD64-4748-4405-89CD-16D003A19E68.thumb.jpeg.9145a312967a2482199b286a496068b5.jpeg

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I would love to read more about the large Sept/Dec warm ups vs the March snows and the June near-normals for the area over the last decade.

There have to be many theories out there

One thing that the 2010s will be remembered for... Global Warming became local.

 

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