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September 2020 wx discussion


forkyfork
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The strong  WAR without a deep trough in the MW/GL favors the SE and GOM like we are seeing with Sally. Notice how the trough remained up near Hudson Bay and couldn’t dig.We’ll have to see if the Euro stronger WAR verifies later in the week with the northern fringe of the remnant Sally moisture streaming into our area. 

7125AA88-C530-4328-942A-30F704F0E8B8.gif.706bef1be43d655f3c751f147705cd91.gif

 

 


 

 

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4 hours ago, wdrag said:

I don 't think so. Not likely after sundown... and the best way to see is a loop where you can see them moving, best time tends to be near sunrise. 

they are mass migrating at several hundred feet up and it shows on velocity

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1 hour ago, forkyfork said:

they are mass migrating at several hundred feet up and it shows on velocity

I was just in the Adirondacks where autumn is becoming visually apparent and found it eerie how there were virtually no birds chirping. The migration is definitely happening. 

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1 hour ago, bluewave said:

The strong  WAR without a deep trough in the MW/GL favors the SE and GOM like we are seeing with Sally. Notice how the trough remained up near Hudson Bay and couldn’t dig.We’ll have to see if the Euro stronger WAR verifies later in the week with the northern fringe of the remnant Sally moisture streaming into our area. 

7125AA88-C530-4328-942A-30F704F0E8B8.gif.706bef1be43d655f3c751f147705cd91.gif

 

 


 

 

That looks a bit more favorable for winter if that type of pattern were to hold. Maybe more like 16/17. 

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3 hours ago, SnoSki14 said:

That looks a bit more favorable for winter if that type of pattern were to hold. Maybe more like 16/17. 

The NPM is remaining strongly positive even with the developing La Niña and -PDO. At least right now, we are getting more ridging out there than we typically see this time of year with a La Niña. But it’s still too early to know if this is a temporary pattern or can hold on into the fall and winter. Last winter the NPM dropped as the +EPO vortex took over.

B1BDFA3A-5DA5-43A0-97A1-A149FFE472FA.png.7d66a77b88f10fa683e8be6d480fb1f8.png

 

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Under variably cloudy skies, temperatures reached the lower and middle 70s. The season's coolest air mass so far will arrive tomorrow.

Strengthening Tropical Storm Sally brought heavy rain to parts of southwestern Florida today. At Naples: 3.47" fell. The 2-day total was 5.06". At Fort Myers, daily rainfall was 1.84" (old record: 1.33", 1975). Sally will likely continue to strengthen overnight before making landfall along the Louisiana coast on Monday night.

During Monday night, the temperature will fall into the 50s in New York City's Central Park for the first time since June 15. An even cooler air mass could arrive late in the week. Generally below normal readings could persist into at least the last week of September. There is an increasing possibility that September could wind up on the cool side of normal, which would be an uncommon event in recent cases preceding La Niña winters.

The newly-released subseasonal guidance is in strong consensus that a generally cool regime could last through the first week of October. The latest EPS weeklies forecast an end to the cool anomalies near the end of September.

The ENSO Region 1+2 anomaly was -1.6°C and the Region 3.4 anomaly was -0.9°C for the week centered around September 2. 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 -0.72°C. La Niña conditions have developed and will likely prevail through the remainder of autumn.

The SOI was +3.03.

Today, the preliminary Arctic Oscillation (AO) figure was +0.636.

On September 12, the MJO was in Phase 4 at an amplitude of 0.813 (RMM). The September 11-adjusted amplitude was 0.935.

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 50% probability that New York City will have a warmer than normal September. September will likely finish with a mean temperature near 68.5°.

Finally,on September 12, Arctic sea ice extent was 3.564 million square kilometers (JAXA). That was just above the figure of 3.562 million square kilometers reached on September 11. Based on 2010-2019 data, the highest 25% bound was 3.742 million square kilometers. The lowest 25% bound was 3.581 million square kilometers. The lowest 10% bound is 3.465 million square kilometers. 2020 is the second consecutive year with a minimum extent figure below 4.000 million square kilometers and the third such year on record. 2020 also has, by far, the second lowest extent on record.

 

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Good Monday morning everyone,

Sally should pass out to sea well south of our area, per NWS guidance as added below. The only major model uncertainty is the CMC ensemble which biases the NAEFS rather wet up here with southerly flow 850MB moisture contribution and potential mid-level FGEN. Ensemble guidance of 00z/14 EPS/GEFS is also wetter than the 00z/14 operational cycle and seems to have trended slightly north from yesterdays post of 00z/13.  The NAEFS prob for 2" axis is directed into the northeast USA for Thu night-Friday.  So, this is posted not to say Sally will impact our area with moisture contribution but forecaster's considerations that may need blending higher?  QPF is yes/no.  In this case, operational modeling says much more strongly NO, but ensembles suggest another look see is required. Monitor the future trends to see if a somewhat wetter scenario will develop for the I95 corridor of the NYC forum late this workweek.  It's basically our only hope for substantive qpf between the event of this past Wed night-friday morning (9th-11th) and Tuesday Sept 22nd. 648A/14

Screen Shot 2020-09-14 at 6.23.24 AM.png

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Screen Shot 2020-09-14 at 6.16.42 AM.png

Screen Shot 2020-09-14 at 6.11.42 AM.png

Screen Shot 2020-09-14 at 6.18.40 AM.png

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The next 8 days are averaging 67degs.       Make it 62degs., or about -6.

70*(75%RH) here at 6am, thin overcast.     76*(46%RH) by 2pm.         77*(40%RH) by 4pm.

Tropical systems near:   28N, 87W (I can do the Twist) 32.5N, 64.7W(in Bermudan waters Oh! so clear and bulging) 13N 41W,  18N 28W..

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Morning thoughts...

Ahead of the arrival of much cooler air, today will be mostly sunny and mild. Temperatures will likely top out in the middle and upper 70s. Likely high temperatures around the region include:

New York City (Central Park): 77°
Newark: 79°
Philadelphia: 79°

Much of the week will feel like early autumn. An even colder air mass could arrive late in the week.  

 

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On 9/11/2020 at 8:44 PM, uncle W said:

they dont make September cool spells like they used to...NYC has no hot days this month so far and no real cool morning like low 50's or upper 40's like the 1960's had frequently...I forget the date but 1961 set the record low...1964 broke it...then 1966 broke it again...I remember one year 1963 set a record low and 1964 broke it...both set a record high on the same date two months later...45 used to be the average low for September in NYC...now its closer to 50...

Yes, I remember having to wear sweaters quite regularly in late September going back to the 90s, haven't done that in at least a decade or more.

 

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72/ 57 and real nice dry breeze.  Warm and dry today as the front moves through and sun comes out.  Mid / upper 70s.  Tuesday cooler with highs near 70 and lows 50s.  Warmer Wed/ Thu highs near 80 and perhaps low 80s on Thu if we see enough sun.  Friday (9/18) the next front arrives and we cool off to levels not seen since May.  9/19 - 9/24 cooler than normal but lookng mainly dry vert Fall-ish airmass.  30s inland Sunday or next monday?

Longer range looks to end the month on a warm note pushing the overall avg positive.

 

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On 9/12/2020 at 2:44 PM, bluewave said:

 

We have a pretty good idea that this will be the 5th consecutive winter with a La Niña-like base state. The North Pacific Ridge was able to extend NE into Alaska in 16-17 and 17-18 allowing for snowy and warm. The El Niño couldn’t couple in 18-19 due to all the record Niña-like SST warmth in the WPAC. So we had the La Niña ridge north of Hawaii and SE ridge for a mild and nearly snowless DJF. The record WPAC warmth in 19-20 set new records north of Australia. So we got a continuation of record MJO 4-6 amplitude and the Niña-like ridge north of Hawaii and SE Ridge. Warm and even less snowy overall than the previous year since we didn’t get the Nov and Mar snows. This fall we will be looking for clues as to which type of La Niña winter we will have this year. It often comes down to how much snow NYC can pick up in December. All the Niña-like Decembers with under 3.0” of snow in NYC since 1995 featured below normal snowfall seasons. While all above 3.0” finished normal to above normal.

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

Yes all those la nina winters that I remember from the late 80s thru early 90s had very little snow in December, some of them only a T.  I'd be thrilled if we even had an average winter, something like 08-09!

 

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We still see plenty of warm days mixed in with the cool ones. After the cool day tomorrow, we're looking at high temps in the upper 70s to near 80 wednesday and thursday. And after the cool weekend into monday, it warms back up mid next week. Next wednesday and thursday look like a repeat of this week with highs close to 80. Still plenty of 80 degree warmth mixed in the cool days.

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2 minutes ago, winterwx21 said:

We still see plenty of warm days mixed in with the cool ones. After the cool day tomorrow, we're looking at high temps in the upper 70s to near 80 wednesday and thursday. And after the cool weekend into monday, it warms back up mid next week. Next wednesday and thursday look like a repeat of this week with highs close to 80. Still plenty of 80 degree warmth mixed in the cool days.

Yeah its sad what counts as an impressive cool down these days

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2 minutes ago, SACRUS said:

Sat (9/19) - Tue (9/22) do look solidly below avg. -5 to -7 each day.  

I think by next tuesday we're already warming back up to low-mid 70s. No question we have a few solidly below normal days this weekend into monday. But other than that, I see a lot of days with high temps well up into the 70s to near 80. Today, wednesday and thursday this week and most of next week after monday. One cool stretch for a few days but otherwise normal to above normal temps.

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Anything below +2 to +6 is considered cool by recent September standards. We would have to go back to 2013 to 2014 for departures under those levels. A continuation of less warm is the new cool.

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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