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September 2020 wx discussion


forkyfork
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Temperatures rose into the middle 60s across much of the region today despite bright sunshine.

Another cool night lies ahead. Tomorrow morning, Central Park could have a minimum temperature below 50°. The last time the temperature fell into the 40s in New York City during September was September 24, 2013 when the temperature fell to 47°.

Low temperature estimates include:

Albany: 33°
Allentown: 37°
Boston: 47°
Bridgeport: 48°
Harrisburg: 42°
Hartford: 36°
Islip: 48°
New York City: 49°
Newark: 47°
Philadelphia: 48°
Poughkeepsie: 36°
Providence: 44°
White Plains: 43°

Warmer readings will arrive toward mid-week. Afterward, temperatures will likely remain at above normal levels for much of the remainder of September.

Phoenix has an implied 69% probability of recording just its 13th September on record with a mean temperature of 90° or above. The most recent such occurrence was 2018 with a mean temperature of 91.8°. Phoenix will very likely record its hottest June-September period on record with a four-month mean temperature of 95.1°-95.3°. The existing record is 93.9°, which was set in 2011.

The ENSO Region 1+2 anomaly was -1.0°C and the Region 3.4 anomaly was -1.0°C for the week centered around September 9. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.08°C and the ENSO Region 3.4 anomaly has averaged -0.75°C. La Niña conditions have developed and will likely prevail through the remainder of autumn.

The SOI was +13.73.

Today, the preliminary Arctic Oscillation (AO) figure was +1.521.

On September 19, the MJO was in Phase 4 at an amplitude of 0.915 (RMM). The September 18-adjusted amplitude was 1.284.

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°.

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 60% probability that New York City will have a warmer than normal September. September will likely finish with a mean temperature near 68.4°.

 

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Temperature down to 47 degrees here. Meanwhile in Manhattan (the heat island) the temperature at 7PM was 59 at 8PM 56 and at 9PM it is back up to 58. On nights with very little wind, the range in temperatures can be extreme. My area is reporting temperatures now that range from the mid 40s to low 50s. I have two weather stations in my yard and both normally report very similar temperatures but on nights like this they can be quite different. One is about 5-6 ft. above the ground, as the weather bureau wants, and it says 47.1 and the other which is some 17 ft. above the ground is reporting a temperature of 49.9.

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54 minutes ago, lee59 said:

Temperature down to 47 degrees here. Meanwhile in Manhattan (the heat island) the temperature at 7PM was 59 at 8PM 56 and at 9PM it is back up to 58. On nights with very little wind, the range in temperatures can be extreme. My area is reporting temperatures now that range from the mid 40s to low 50s. I have two weather stations in my yard and both normally report very similar temperatures but on nights like this they can be quite different. One is about 5-6 ft. above the ground, as the weather bureau wants, and it says 47.1 and the other which is some 17 ft. above the ground is reporting a temperature of 49.9.

why is it so damn hard for the city to get below 50 degrees in September?  I have seen it get below 50 in AUGUST.  People need to start ripping out that godawful concrete......

 

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2 hours ago, donsutherland1 said:

Temperatures rose into the middle 60s across much of the region today despite bright sunshine.

Another cool night lies ahead. Tomorrow morning, Central Park could have a minimum temperature below 50°. The last time the temperature fell into the 40s in New York City during September was September 24, 2013 when the temperature fell to 47°.

Low temperature estimates include:

Albany: 33°
Allentown: 37°
Boston: 47°
Bridgeport: 48°
Harrisburg: 42°
Hartford: 36°
Islip: 48°
New York City: 49°
Newark: 47°
Philadelphia: 48°
Poughkeepsie: 36°
Providence: 44°
White Plains: 43°

Warmer readings will arrive toward mid-week. Afterward, temperatures will likely remain at above normal levels for much of the remainder of September.

Phoenix has an implied 69% probability of recording just its 13th September on record with a mean temperature of 90° or above. The most recent such occurrence was 2018 with a mean temperature of 91.8°. Phoenix will very likely record its hottest June-September period on record with a four-month mean temperature of 95.1°-95.3°. The existing record is 93.9°, which was set in 2011.

The ENSO Region 1+2 anomaly was -1.0°C and the Region 3.4 anomaly was -1.0°C for the week centered around September 9. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.08°C and the ENSO Region 3.4 anomaly has averaged -0.75°C. La Niña conditions have developed and will likely prevail through the remainder of autumn.

The SOI was +13.73.

Today, the preliminary Arctic Oscillation (AO) figure was +1.521.

On September 19, the MJO was in Phase 4 at an amplitude of 0.915 (RMM). The September 18-adjusted amplitude was 1.284.

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°.

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 60% probability that New York City will have a warmer than normal September. September will likely finish with a mean temperature near 68.4°.

 

Weird how difficult it is to get a below normal September....even if we have an above normal rest of the month after Monday, there isn't much left in the month;  October will start in 10 days.

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15 minutes ago, LibertyBell said:

Weird how difficult it is to get a below normal September....even if we have an above normal rest of the month after Monday, there isn't much left in the month;  October will start in 10 days.

In many parts of the U.S., including the New York City area, September has become an extension of summer. 

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11 minutes ago, wdrag said:

Wantage NJ 629A: Frosty roofs etc    and everyone should  be noticing smoke in this mornings sunrise...not as dense as last week, but that's coming by Wednesday. Yesterday's predictive smoke post still reasonable.

 

First official frost here and down to 31 now a couple miles south of KMGJ

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First 47° low in September at JFK since 1997. This is also the first September freeze at Sussex, NJ since the records began in 2001 on xmacis2.

Kennedy Intl   PTCLDY    47  39  74 NE6    
Sussex         CLEAR     31  29  92 CALM      30.58R

 

 

Time Series Summary for JFK INTERNATIONAL AIRPORT, NY - Month of Sep
Click column heading to sort ascending, click again to sort descending.
Year
Lowest Min Temperature 
Missing Count
2020 47 10
2019 49 0
2018 54 0
2017 54 0
2016 51 0
2015 56 0
2014 51 0
2013 48 0
2012 52 0
2011 50 0
2010 53 0
2009 50 0
2008 52 0
2007 50 0
2006 49 0
2005 50 0
2004 51 0
2003 52 0
2002 54 0
2001 50 0
2000 44 0
1999 51 0
1998 46 0
1997 47 0

 

Time Series Summary for SUSSEX AIRPORT, NJ - Month of Sep
Click column heading to sort ascending, click again to sort descending.
Year
Lowest Min Temperature 
Missing Count
2020 31 10
2019 36 0
2018 44 0
2017 38 0
2016 36 8
2015 42 0
2014 39 0
2013 33 0
2012 37 1
2011 39 0
2010 38 0
2009 37 0
2008 37 0
2007 36 0
2006 34 0
2005 36 0
2004 40 0
2003 39 0
2002 38 0
2001 37 0


 

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29 minutes ago, Allsnow said:

September in September this year which has become a rarity 

These days we need some type of record 500 MB blocking ridge to get cold. Looks like the ridge will build again to close out the month. Probably our best chance for rain in a while as the trough really digs into the GL.

98C09DD6-FD6C-4BA8-AC99-D9B06795C3DE.thumb.png.f2871e34d79b6646ddbf95c59658186b.png

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