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September 2020 wx discussion


forkyfork
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Morning thoughts...

This morning, the temperature fell below 50° in Central Park. The last time the temperature fell in the 40s in September was September 24, 2013 when the temperature fell to 47°. Today will be partly sunny and still very cool for the season. The temperature will likely top out in the lower and middle 60s across the region. Likely high temperatures around the region include:

New York City (Central Park): 64°
Newark: 66°
Philadelphia: 66°

Starting tomorrow, a warmer pattern will develop.

In terms of verification, here's how last evening's estimates worked out:

Albany: 33°; Actual: 32°
Allentown: 37°; Actual: 33°
Boston: 47°; Actual: 45°
Bridgeport: 48°; Actual: 44°
Harrisburg: 42°; Actual: 43°
Hartford: 36°; Actual: 34°
Islip: 48°; Actual: 44°
New York City: 49°; Actual: 49°
Newark: 47°; Actual: 45°
Philadelphia: 48°; Actual: 47°
Poughkeepsie: 36°; Actual: 31°
Providence: 44°; Actual: 43°
White Plains: 43°; Actual: 41°

Average Error: 2.2°

 

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Just now, Cfa said:

Later on I’ll fiddle with my weather radio to see if it gets a stronger connection from Manhattan or Riverhead (weak).

Signal is strong enough in Syosset.  I doubt you’ll hear it from Riverhead with this transmitter now at only 1000w. Old transmitter was 1500w as I recall.

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51/37 off a low of 40 (no frost again). Coldest temps now past us till at least Oct 5th.  Wam-rup underway slowly today and more pronounced Wed (9/23) - Tue (9/29). Max temps likely  in the mid / upper 70s most days but 80 - 85 range best chance Thu (9/24) and more sneaky warmth Mon (9/28 and Tue 9/29).  Lots of Southerly and onshore in the period then clouds may limit warmth later this weekend and early next week.

West coast ridge builds in the 9/26 - 10/2 period and forces a trough into the Plains, Mid West, GL coldest staying west of the area in this period.  The trough does look to split into the southeast and a piece swings through the east coast 9/30 - 10/2 which could see the first meaningful rain since 9/10.  

Way beyond West Coast has dibs on ridging with troughing into the mid section could mean a wetter forst week or two of next month but overall near or warmer than normal.  Going from a 3 week dry period to very wet seems a logical progression for us,

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September is still likely to end up AN but it'll be a departure from the crazy warm Septembers of recent years. 

Things def look a lot weather to end the month if the pattern shown is correct.

GFS overplayed its hand with the ridging though so a late season 90F looks very unlikely right now and probably done till next Spring.

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41 minutes ago, uofmiami said:

Signal is strong enough in Syosset.  I doubt you’ll hear it from Riverhead with this transmitter now at only 1000w. Old transmitter was 1500w as I recall.

I thought this return to full power happened some time ago.    I have had a good locked signal for months in CI.     There was a period where my own position/antenna made a difference.

Concerning the range, the antenna height and its gain is what counts.   Nearby structures and those along signal path play a role too---thus all the testing.   Theoretically, power must increase by 4X to make a significant difference---to 4,000 watts here.

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42 minutes ago, psv88 said:

40.1 this morning. Radiated extremely well here

Same out here.  I am a native LIer and can tell you that there was an early season Arctic air mass that impacted the area back around 1974/1975.  This event produced high temperatures in the 40s and lows of about 30 on the north shore of LI during mid October at that time.  For the time of year it was impressive.  In any case  I have personally never seen frost anywhere this early in the season until today.

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1 hour ago, bluewave said:

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

Yep. Any warm up that comes this week will be short lived 

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1 hour ago, donsutherland1 said:

Morning thoughts...

This morning, the temperature fell below 50° in Central Park. The last time the temperature fell in the 40s in September was September 24, 2013 when the temperature fell to 47°. Today will be partly sunny and still very cool for the season. The temperature will likely top out in the lower and middle 60s across the region. Likely high temperatures around the region include:

New York City (Central Park): 64°
Newark: 66°
Philadelphia: 66°

Starting tomorrow, a warmer pattern will develop.

In terms of verification, here's how last evening's estimates worked out:

Albany: 33°; Actual: 32°
Allentown: 37°; Actual: 33°
Boston: 47°; Actual: 45°
Bridgeport: 48°; Actual: 44°
Harrisburg: 42°; Actual: 43°
Hartford: 36°; Actual: 34°
Islip: 48°; Actual: 44°
New York City: 49°; Actual: 49°
Newark: 47°; Actual: 45°
Philadelphia: 48°; Actual: 47°
Poughkeepsie: 36°; Actual: 31°
Providence: 44°; Actual: 43°
White Plains: 43°; Actual: 41°

Average Error: 2.2°

 

Thanks Don, do you have the lows for JFK and LGA too?

 

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46 minutes ago, SnoSki14 said:

September is still likely to end up AN but it'll be a departure from the crazy warm Septembers of recent years. 

Things def look a lot weather to end the month if the pattern shown is correct.

GFS overplayed its hand with the ridging though so a late season 90F looks very unlikely right now and probably done till next Spring.

With all this cold, what is causing it to end up above normal?  We should just go by the last 10 years, 30 years ago is ancient history and not representative of our current climate.

 

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30 minutes ago, Tatamy said:

Same out here.  I am a native LIer and can tell you that there was an early season Arctic air mass that impacted the area back around 1974/1975.  This event produced high temperatures in the 40s and lows of about 30 on the north shore of LI during mid October at that time.  For the time of year it was impressive.  In any case  I have personally never seen frost anywhere this early in the season until today.

we had upper 20s in mid October a few years ago on the South Shore.  I dont remember what year it was but it was after 2014 and RJay was quite excited about it heh.

 

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1 hour ago, psv88 said:

40.1 this morning. Radiated extremely well here

Looks like Muttontown was down around 37.  Anyone have any numbers out of FOK?  Did they get below freezing for the first time this season?

I'm still in NE PA (coming back tomorrow) we had a frost here, low was 28 degrees at Blakeslee, which is the closest station I could find to my location.

 

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1 hour ago, CIK62 said:

I thought this return to full power happened some time ago.    I have had a good locked signal for months in CI.     There was a period where my own position/antenna made a difference.

Concerning the range, the antenna height and its gain is what counts.   Nearby structures and those along signal path play a role too---thus all the testing.   Theoretically, power must increase by 4X to make a significant difference---to 4,000 watts here.


It has been at 1000w for months, but it’s not at its old transmission power before this whole debacle happened years ago.

 

edit: according to NWS normal power is 1000w. Not sure if that’s always been the case or more recently. Could have sworn KWO35 transmitted at 1250 or so, but perhaps I’m wrong.

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2 hours ago, LibertyBell said:

Thanks Don, do you have the lows for JFK and LGA too?

 

This was the 6th earliest 46° on record at JFK. We haven’t seen a 46° this early since the 1970s.

 

First/Last Summary for JFK INTERNATIONAL AIRPORT, NY
Each section contains date and year of occurrence, value on that date.
Click column heading to sort ascending, click again to sort descending.
Year
Last
Value
First
Value
Difference
1965 05-08 (1965) 45 08-31 (1965) 46 114
1967 06-01 (1967) 45 09-12 (1967) 46 102
1975 05-03 (1975) 46 09-15 (1975) 45 134
1961 05-28 (1961) 44 09-18 (1961) 46 112
1979 04-22 (1979) 45 09-20 (1979) 41 150
1962 05-13 (1962) 42 09-21 (1962) 42 130
1973 05-19 (1973) 44 09-21 (1973) 46 124

 

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New York City's Central Park saw the temperature dip below 50° for the first time in September since September 24, 2013. At Saranac Lake, NY, the thermometer fell to 21°. That broke the previous daily record low temperature of 25°, which was set in 1962 and tied in 1993.

Warmer readings will arrive starting tomorrow afternoon. Afterward, temperatures will likely remain at above normal levels for much of the remainder of September.

Phoenix has an implied 74% 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 -0.4°C and the Region 3.4 anomaly was -0.8°C for the week centered around September 16. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.93°C and the ENSO Region 3.4 anomaly has averaged -0.68°C. La Niña conditions have developed and will likely prevail through the remainder of autumn.

The SOI was +14.32.

Today, the preliminary Arctic Oscillation (AO) figure was +2.225. That is the highest AO figure since March 25, 2020 when the AO was +3.174.

On September 20, the MJO was in Phase 5 at an amplitude of 0.879 (RMM). The September 19-adjusted amplitude was 0.912.

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 64% 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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6 hours ago, bluewave said:

This was the 6th earliest 46° on record at JFK. We haven’t seen a 46° this early since the 1970s.

 

First/Last Summary for JFK INTERNATIONAL AIRPORT, NY
Each section contains date and year of occurrence, value on that date.
Click column heading to sort ascending, click again to sort descending.
Year
Last
Value
First
Value
Difference
1965 05-08 (1965) 45 08-31 (1965) 46 114
1967 06-01 (1967) 45 09-12 (1967) 46 102
1975 05-03 (1975) 46 09-15 (1975) 45 134
1961 05-28 (1961) 44 09-18 (1961) 46 112
1979 04-22 (1979) 45 09-20 (1979) 41 150
1962 05-13 (1962) 42 09-21 (1962) 42 130
1973 05-19 (1973) 44 09-21 (1973) 46 124

 

NYC has three days in a row with a morning low temp of 50 or lower...the last time that happened was 2000?

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