September 2020 wx discussion

[SACRUS]

72/69 / .95 in the bucket.  9/11 - 9/18 overall warmer than normal but no heat and some cooler days.Clouds breaking a bit as winds are more out of the NE.  We dry things out later this morning and afternoon and yet another beautiful Saturday on tap dry and warm  California-like minus the fires and reddish skies.  Sunday - Tue  flow comes around from the SW and likely coming with some clouds with more sun and warmer on Monday (9/14).  Cooler and drier Tue and part of Wed before warmer weather arrives Thu (9/17) and Fri (9/18).  Looks mainly dry this period.

9/19 - 9/23  :cooler air brings the coolest readings since  May / 40s inland cooler spots at night?  Way beyond looks to warm things up the end and close the month above normal. Lets see how models trend with this.  

Tropics watch 9/20 - 9/24 : overnight guidance has mostly in the Atlantic but WAR has been consistently under forecast and plenty of time to watch as prior guidance had a FL threat in the timeframe.

[Brian5671]

35 minutes ago, SACRUS said:

72/69 / .95 in the bucket.  9/11 - 9/18 overall warmer than normal but no heat and some cooler days.Clouds breaking a bit as winds are more out of the NE.  We dry things out later this morning and afternoon and yet another beautiful Saturday on tap dry and warm  California-like minus the fires and reddish skies.  Sunday - Tue  flow comes around from the SW and likely coming with some clouds with more sun and warmer on Monday (9/14).  Cooler and drier Tue and part of Wed before warmer weather arrives Thu (9/17) and Fri (9/18).  Looks mainly dry this period.

9/19 - 9/23  :cooler air brings the coolest readings since  May / 40s inland cooler spots at night?  Way beyond looks to warm things up the end and close the month above normal. Lets see how models trend with this.  

Tropics watch 9/20 - 9/24 : overnight guidance has mostly in the Atlantic but WAR has been consistently under forecast and plenty of time to watch as prior guidance had a FL threat in the timeframe.

Euro has highs in the upper 50's a week from Saturday (overcast)  Would be one of the colder September days in recent memory if that verified

[ForestHillWx]

Noticed the progged low temps down here in the upper 40s for 9/14-15; sign me up. 

[bluewave]

15 minutes ago, ForestHillWx said:

Noticed the progged low temps down here in the upper 40s for 9/14-15; sign me up. 

This is one of those times that a firehose Pacific Jet can help bring a series of cold fronts across the country.

 

[KEITH L.I]

19 minutes ago, bluewave said:

This is one of those times that a firehose Pacific Jet can help bring a series of cold fronts across the country.

 

12 GFS shows below normal,with no 90's maybe a day or 2 in the  80's and the rest in the 60's to low 70's.Haven't seen a September that cool in a while

[SnoSki14]

9 minutes ago, KEITH L.I said:

12 GFS shows below normal,with no 90's maybe a day or 2 in the  80's and the rest in the 60's to low 70's.Haven't seen a September that cool in a while

It'll still likely average AN but it'll certainly feel much cooler than we're used to with actual BN days. 

Looks like the heat will stay in the west and northern plains for now. 

[bluewave]

1 hour ago, KEITH L.I said:

12 GFS shows below normal,with no 90's maybe a day or 2 in the  80's and the rest in the 60's to low 70's.Haven't seen a September that cool in a while

The record breaking ridge centered near the Pacific Northwest Is a big change from the recent September decadal pattern. That area has usually experienced a trough during September. So it will be interesting to see if this temporary or has lasting potential through the fall and winter. This pattern keeps generating very strong highs that roll across the Northern US. 
 

 

 

[LibertyBell]

2 hours ago, bluewave said:

The record breaking ridge centered near the Pacific Northwest Is a big change from the recent September decadal pattern. That area has usually experienced a trough during September. So it will be interesting to see if this temporary or has lasting potential through the fall and winter. This pattern keeps generating very strong highs that roll across the Northern US. 
 

 

 

I was wondering about the winter implications of this sudden switch

[LibertyBell]

3 hours ago, bluewave said:

This is one of those times that a firehose Pacific Jet can help bring a series of cold fronts across the country.

 

meh if thats the reason then it wont stop us from having another mild winter.  I remember a few years in the late 80s and early 90s were like this (cold falls, mild winters).....

 

[LibertyBell]

is the 99 record high for today from 1983 the latest any of the NYC reporting stations (NYC, EWR, JFK, LGA) have recorded 99+ and did any of them record triple digits?

 

[uncle W]

1 minute ago, LibertyBell said:

is the 99 record high for today from 1983 the latest any of the NYC reporting stations (NYC, EWR, JFK, LGA) have recorded 99+ and did any of them record triple digits?

 

yes for NYC...I went to a wedding in a tuxedo that day...it was brutal being outside...

[donsutherland1]

Sunshine and cool conditions are likely for the start of the weekend. The season's coolest air mass so far could arrive next week. Generally below normal readings could persist into the last week of September.

Beyond that, some of the guidance is hinting at a possible dramatic and sharp decline in the PNA. Such a pattern, should it develop, would favor a return to warmer and perhaps much warmer than normal conditions late in the month.

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 +1.25.

Today, the preliminary Arctic Oscillation (AO) figure was +1.599.

On September 10, the MJO was in Phase 4 at an amplitude of 0.901 (RMM). The September 9-adjusted amplitude was 0.689.

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 55% probability that New York City will have a warmer than normal September. September will likely finish with a mean temperature near 69.1°.

Finally,on September 10, Arctic sea ice extent was 3.571 million square kilometers (JAXA). 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 figure on record.

 

[SACRUS]

Clouds held tough

9/11

LGA: 79
ACY: 79
PHL: 79
EWR: 78
ISP: 78
TEB: 77
JFK: 76
NYC: 76
TTN: 76
New Brnswck: 76
BLM: 75

[uncle W]

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...

[mweisenfeld]

Anyone have any idea what's happening with the radar tonight?

[donsutherland1]

52 minutes ago, 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...

The combination of rising minimum temperatures and decreasing low temperature variability in recent decades, with the warming especially pronounced for the 30-year period ending 2010 or later, has diminished the probability of September minimum temperatures below 50°. Moreover, the recent warming has been occurring during a time when New York City has had a mature urban footprint.

New York City's September Minimum Temperatures:

[forkyfork]

2 minutes ago, mweisenfeld said:

Anyone have any idea what's happening with the radar tonight?

bird migration

[hudsonvalley21]

27 minutes ago, forkyfork said:

bird migration

I’m glad I’m not under one of those flocks.

[rclab]

2 hours ago, 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...

I don’t remember the 64 date either. It was my first day in college. 48 degree number seems to stick with me. No biggie, even today, for the  NNE folks but a shock, even then, to us UHI citizens. As always .....

[CIK62]

The next 8 days are averaging 71degs.        Make it 66degs., or -3.

64*(72%RH) here at 6am, 63* at 6:30am-m. clear.        69* by Noon.        72* by 3pm.

In the Tropics: 25N 82W (new) and getting meaner,   27N 57W,    22N 44W-being absorbed-u r Not of the Body,    12N 31W.

Trough far enough east to protect us from any TS harm the next 16 days?    No rain till the 22nd?      Every model says so.   So it looks that way.

[ForestHillWx]

56 currently. Looks like a glorious stretch of weather coming up. 

[Rtd208]

Overnight low of 60 here.

Current temp 61/DP 54/RH 78%

[wdrag]

Forgot to add the radar appearance quote from mweisenfeld. 

 

Not Birds:  AP with temperature inversion developing near or after sunset. Shows some nearby non-moving targets near radar and not too distant hills. Here is more information below. Extracted from sensAgent.com

 

The position of the radar echoes depend heavily on the standard decrease of temperature hypothesis. However, the real atmosphere can vary greatly from the norm. Anomalous Propagation (AP) refers to false radar echoes usually observed when calm, stable atmospheric conditions, often associated with super refraction in a temperature inversion, direct the radar beam toward the ground. The processing program will then wrongly place the return echoes at the height and distance it would have been in normal conditions.^[2]

This type of false return is relatively easy to spot on a time loop if it is due to night cooling or marine inversion as one sees very strong echoes developing over an area, spreading in size laterally, not moving but varying greatly in intensity with time. After sunrise, the inversion disappears gradually and the area diminishes correspondingly. Inversion of temperature exists too ahead of warm fronts, and around thunderstorms' cold pool. Since precipitation exists in those circumstances, the abnormal propagation echoes are then mixed with real rain and/or targets of interest, which make them more difficult to separate.

Anomalous Propagation is different from ground clutter, ocean reflections (sea clutter), biological returns from birds and insects, debris, chaff, sand storms, volcanic eruption plumes, and other non-precipitation meteorological phenomena. Ground and sea clutters are permanent reflection from fixed areas on the surface with stable reflective characteristics. Biological scatterer gives weak echoes over a large surface. These can vary in size with time but not much in intensity. Debris and chaff are transient and move in height with time. They are all indicating something actually there and either relevant to the radar operator and/or readily explicable and theoretically able to be reproduced. AP in the sense of radar is colloquially known as "garbish" and ground clutter as "rubbage".

Doppler radars and Pulse-Doppler radars are extracting the velocities of the targets. Since AP comes from stables targets, it is possible to subtract the reflectivity data having a null speed and clean the radar images. Ground, sea clutter and the energy spike from the sun setting can be distinguished the same way but not other artifacts.^[2][3] This method is used in most modern radars, including air traffic control and weather radars.

[wdrag]

Regarding the probable development of (TD19 as of 12z/12) Sally in GOMEX. Has a currently UNLIKELY but small chance of contributing moisture ahead of an approaching cold front moving into our area late this coming week (Thu-Fri 17th-18th?) Here's the 00z/12 EPS... 00z/12 GEFS does not have it for us (furthest north is dark brown track), but a few from the EC ensemble attempt a newd drift toward PA. No topic planned for this for at least another day or two, to monitor overall 500MB pattern. 821A/12

[donsutherland1]

Morning thoughts...

Today will be partly to mostly sunny, but quite cool. Temperatures will likely top out in the lower and middle 70s across much of the region. Likely high temperatures around the region include:

New York City (Central Park): 72°
Newark: 73°
Philadelphia: 74°

Much of next week will feel like early autumn as the coolest air so far this season moves into the region.

 

[lee59]

57 degrees here for a low last night.

[bluewave]

Today was the 4th latest that HPN dropped below 55° after August 1st. Looks like NYC is on track for a 2nd latest first drop below 60 in a couple of days. 

HPN

12 Sep 7:56 am

57

50

77

ENE

6

10.00

CLR

29.92

1026.6

30.32

59

54

 

First/Last Summary for WESTCHESTER CO AP, 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
2005	06-23 (2005)	53	09-24 (2005)	51	92
2015	06-07 (2015)	51	09-21 (2015)	54	105
2011	06-15 (2011)	54	09-15 (2011)	50	91
1959	06-20 (1959)	50	09-12 (1959)	50	83

 

First/Last Summary for NY CITY CENTRAL PARK, 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
2016	06-14 (2016)	58	09-17 (2016)	59	94
1947	06-25 (1947)	58	09-17 (1947)	58	83
1966	06-13 (1966)	58	09-15 (1966)	51	93
2015	06-27 (2015)	58	09-14 (2015)	59	78
1996	06-03 (1996)	54	09-14 (1996)	57	102

[SACRUS]

71/55 partly cloudy NE winds.  Looks to be a gorgeous day but it may stay partly and at times mostly cloudy low to mid 70s..  Thicker clouds into PA  Tomorrow a bit warmer but more clouds will keep temps in the 70s.  Warmup Monday into the 80s before a 36 - 48 hour cooldown Tue and Wed with temps back into the 70s.  Warmer Thu (9/17) and Fri (9/18) with chance for low to perhaps mid 80s in the warmer spots.  Dry week on tap unless tropical remnants push this way later in the week.

9/19 - 9/24 - coolest readings since may but looking overall dry.  Warmer times look to arrive to close the month on the warm side overall.

 

[SACRUS]

Lots of clouds

 

 

[lee59]

As many named storms as we have had this season, so far, it really has not been as bad as it could have been. Many of the storms were weak and fortunately we have had only a few hurricanes and one major. It is now mid September and in a few weeks we will be past peak, very active right now and even though the waters are warm, wind shear has been helping to keep many of the storms this season at bay. Of course things can change fast.