September 2021

[LibertyBell]

52 minutes ago, KEITH L.I said:

Looks like we are finished with the heatwaves. Not saying it could not hit 90..although most models don't show any through the middle of the month..But typical September weather takes over with 70's and the warmest low 80's

Could have an isolated 1 or 2 90 degree days here and there but probably no heatwaves

[forkyfork]

people have been posting that since july

[bluewave]

Ida will be the first storm this summer that finally begins a break in the 90° heat potential. Very strong blocking for early September will develop. Long range guidance is hinting at a resurgence of the WAR by mid to late September.

 

 

[Stormlover74]

Weather should be spectacular behind Ida. Sunny and mid 70s with a brisk northerly breeze Thursday afternoon and nice right through Sunday at least

[nycwinter]

19 minutes ago, Stormlover74 said:

Weather should be spectacular behind Ida. Sunny and mid 70s with a brisk northerly breeze Thursday afternoon and nice right through Sunday at least

nyc will not have another 90 degree day until next spring..

[Rjay]

5 minutes ago, nycwinter said:

nyc will not have another 90 degree day until next spring..

I'll take the under.  Central Park doesn't count.  

[LibertyBell]

27 minutes ago, Stormlover74 said:

Weather should be spectacular behind Ida. Sunny and mid 70s with a brisk northerly breeze Thursday afternoon and nice right through Sunday at least

hello early fall!  I see it'll get into the 50s Thursday night even in the city?  I think Thursday could be a really nice day with the rain ending early and the sun coming out.  Might even be in the upper 60s during the day.

 

 

[LibertyBell]

2 minutes ago, Rjay said:

I'll take the under.  Central Park doesn't count.  

For us only Long Island counts and not the north shore.

 

[etudiant]

3 minutes ago, Rjay said:

I'll take the under.  Central Park doesn't count.  

Does too, us Manhattanites build our world around it.

[LibertyBell]

2 minutes ago, etudiant said:

Does too, us Manhattanites build our world around it.

I'm looking forward to the goal of NYC having 30% tree coverage by 2035.  

 

[Rjay]

1 minute ago, etudiant said:

Does too, us Manhattanites build our world around it.

Midtown is at least 5 degrees warmer on days after it rains in Central Park.  

[donsutherland1]

Clouds will increase overnight. Some periods of light rain are possible during the morning.

Tomorrow into Thursday will be cloudy with heavy rain likely. Much of the region will see a general 3"-6" of rain with local amounts at or above 8". Flash flooding is likely on account of the saturated ground from excessive August rainfall.

High PWAT values in excess of 2" and strong frontogenic forcing, particularly tomorrow night, should produce a very intense period of rainfall in and around New York City. The latest National Model Blend guidance suggests that 3.50" of rain will fall in Central Park from 9/2 0z through 9/2 12z. It also suggests a storm total of around 5.00". Thus, it appears that Central Park will further extend its 15-day record for the 8/21-9/4 period.

Based on 1971-2020 data, there is an implied 97% probability that New York City will pick up 50" or more precipitation this year. There is also an implied 40% probability that the City could pick up 60" or more precipitation. Since 1869, New York City has had 34 years with 50" or more precipitation (65% of which have occurred after 1970) and 8 years with 60" or more precipitation (all of which have occurred after 1970). Records go back to 1869.

Despite a cooler than normal first 7-10 days, September will likely feature near normal to somewhat warmer than normal temperatures in much of the region.

Fall 2021 will likely be wetter to much wetter than normal in the northern Middle Atlantic region. Since 1869, there have been 9 August cases where New York City picked up 20.00" or more rainfall during the summer. Two thirds of those cases (and 4/5 of those with summer mean temperatures of 73.0° or above) had 17.00" or more fall precipitation in New York City. 2011 is probably the closest match in terms of precipitation and a nearly identical summer mean temperature. Mean fall precipitation for those 9 cases was 14.86". The median was 17.35". The 1991-2020 normal value is 12.27".

The ENSO Region 1+2 anomaly was 0.0°C and the Region 3.4 anomaly was -0.3°C for the week centered around August 25. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.35°C and the ENSO Region 3.4 anomaly has averaged -0.47°C. Neutral ENSO conditions will likely prevail into at least mid-September. Afterward, La Niña conditions could begin to develop.

The SOI was +25.43 today.

The preliminary Arctic Oscillation (AO) figure was -1.752 today.

On August 29 the MJO was in Phase 2 at an amplitude of 1.332 (RMM). The August 28-adjusted amplitude was 1.340 (RMM).

 

[LibertyBell]

9 hours ago, forkyfork said:

people have been posting that since july

I was mostly going by climatological records for JFK.  I've found that 1 or 2 90 degrees do typically happen there in September, but not more than that except for the amazing summer of 1983 when they had 5.

[LibertyBell]

8 hours ago, bluewave said:

Ida will be the first storm this summer that finally begins a break in the 90° heat potential. Very strong blocking for early September will develop. Long range guidance is hinting at a resurgence of the WAR by mid to late September.

 

 

We're going to have lows in the 50s!  We also had that in July lol

 

[Santa Claus]

some fantastic weather coming behind Ida for the long weekend--thank you based god

[larrye]

A question on Thunderstorms in the greater NYC metro.

I think I grasp the concept that T-Storms, when they approach the coast, often encounter marine air and lose their intensity. We also know that T-Storms normally lose their intensity later in the evening when daytime heating is lost. 

But this doesn't always hold true. Sometimes, T-Storms do not lose their intensity as they move from west to east closer to the Atlantic or Long Island Sound. And sometimes (albeit rarely), they do not lose their intensity diurnally. Can someone explain in both cases, why? What are the dynamics responsible for situations where T-Storms don't lose their intensity as they approach the coast or during the night?

Thanks in advance.

[SI Mailman]

Has there ever been 3 consecutive months of 10+ inch rainfall? Or could tomorrow put us on a good path to history?

[donsutherland1]

3 hours ago, SI Mailman said:

Has there ever been 3 consecutive months of 10+ inch rainfall? Or could tomorrow put us on a good path to history?

Not for NYC.

[CIK62]

The first 8 days of September are averaging 72degs.(65/80), or about Normal.

August ended at  77.5[+1.4].

In a switcheroo, the CMC =7", EURO =3", GFS =2" for the IDA remnants today and tomorrow.      Strong S winds, say 9pm-3am.

74*(88%RH) here at 6am, gloomy.     72*{P=1010mb} at 8am.          73*{P=1000.0mb} at 8pm.          66* at 11pm.   P has started back up.

[donsutherland1]

Morning thoughts...

The remnants of Hurrican Ida will bring a soaking rain to much of the region today. A general 3"-6" rainfall (perhaps lower amounts in New York City and higher amounts north of the City) with locally higher amounts of 8" or more. Parts of eastern Pennsylvania to southern New Jersey could see a pronounced severe weather threat. Temperatures will likely the middle and upper 70s across much of the region. Likely high temperatures include:

New York City (Central Park): 73°
Newark: 76°
Philadelphia: 82°

Tomorrow will become partly sunny pleasant.

Normals:
New York City: 30-Year: 80.9°; 15-Year: 80.8°
Newark: 30-Year: 82.3°; 15-Year: 82.3°
Philadelphia: 30-Year: 83.5°; 15-Year: 83.2°

30-Day Verification:

New York City (Central Park):
Average daily forecast: 83.4°
Average temperature: 83.9°
Average error: 1.2°

Newark:
Average daily forecast: 87.7°
Average temperature: 87.7°
Average error: 1.6°

Philadelphia:
Average daily forecast: 87.2°
Average temperature: 87.5°
Average error: 1.7°

 

[SACRUS]

 

[SACRUS]

71/67 and 0.20 in the bucket.  Rain aimed more north for now but storms could catchup southern areas in a hurry tonight.  September morning in with rain then a more California style long weekend with highs near below 80 Fri, near 80/low 80s Sat and Sun and perhaps low/mid 80s on Monday.  Beyond there more rain/storms with front next week.  Tropica look to miss wide right then warmer return similarly fashion to the late July to transition to August warmth.  

[SACRUS]

https://cdn.star.nesdis.noaa.gov//GOES16/ABI/SECTOR/EUS/GEOCOLOR/GOES16-EUS-GEOCOLOR-1000x1000.gif

 

 

[Dark Star]

12 hours ago, larrye said:

A question on Thunderstorms in the greater NYC metro.

I think I grasp the concept that T-Storms, when they approach the coast, often encounter marine air and lose their intensity. We also know that T-Storms normally lose their intensity later in the evening when daytime heating is lost. 

But this doesn't always hold true. Sometimes, T-Storms do not lose their intensity as they move from west to east closer to the Atlantic or Long Island Sound. And sometimes (albeit rarely), they do not lose their intensity diurnally. Can someone explain in both cases, why? What are the dynamics responsible for situations where T-Storms don't lose their intensity as they approach the coast or during the night?

Thanks in advance.

Imagine the ordinary ridge or trough passing through is like one big bicycle tire, with asymmetrical spokes.  Each spoke represents a “wrinkle” in the atmosphere or Positive Vorticity Advection (PVC).  The ridge or trough will rotate the various PVC areas through your area.

On a hot dry day, with no PVC, a thunderstorm can still form due to hot rising air, but will normally be localized and short lived.  On a hot humid day, a thunderstorm can form, but will still likely be localized and short lived.  When a “spoke” of PVC rotates through, this can spark several scattered thunderstorms, as it feeds more upper level dynamics.  Of course a larger area of PVC has the potential to set off widespread areas of thunderstorms.  And if the you get enough crossing/merging of different layers of various pressures, temperatures, etc. (in the atmosphere) you can get the severe types of supercells.  The more upper level support, the less likely the lack of sun or marine air will affect the thunderstorm development.

[larrye]

9 minutes ago, Dark Star said:

Imagine the ordinary ridge or trough passing through is like one big bicycle tire, with asymmetrical spokes.  Each spoke represents a “wrinkle” in the atmosphere or Positive Vorticity Advection (PVC).  The ridge or trough will rotate the various PVC areas through your area.

On a hot dry day, with no PVC, a thunderstorm can still form due to hot rising air, but will normally be localized and short lived.  On a hot humid day, a thunderstorm can form, but will still likely be localized and short lived.  When a “spoke” of PVC rotates through, this can spark several scattered thunderstorms, as it feeds more upper level dynamics.  Of course a larger area of PVC has the potential to set off widespread areas of thunderstorms.  And if the you get enough crossing/merging of different layers of various pressures, temperatures, etc. (in the atmosphere) you can get the severe types of supercells.  The more upper level support, the less likely the lack of sun or marine air will affect the thunderstorm development.

Thank you.

So is PVC an upper level feature? Mid-level feature? Talking ridges and troughs makes me think upper level.

[Rtd208]

Picked up 0.22" of rain so far today. 

[donsutherland1]

Through 8 pm, Ida's remnants have already produced September 1 daily record rainfall totals in a number of locations including:

Harrisburg: 6.52" (old record: 3.60", 1952)
Hartford: 1.38" (old record: 0.91", 1952)
Mount Pocono: 4.72" (old record: 4.54", 1952)
New York City-JFK: 0.68" (old record: 0.63", 2002)
Philadelphia: 2.00" (old record: 1.80", 1952)
Poughkeepsie: 2.76" (old record: 2.50", 1952)
Scranton: 4.86" (old record: 2.59", 2003)
York, PA: 6.51" (old record: 2.01", 2003)

Unofficially, Newark picked up 1.36" rain in the past hour. The last time Newark picked up 1.00" or more in an hour was June 26, 2020. This was also Newark's largest hourly rainfall since May 28, 2013 when 1.84" was measured.

Ida will bring heavy rain and possible tornadoes to the region overnight into early tomorrow. Much of the region will see a general 3"-6" of rain with local amounts at or above 8". Flash flooding is likely on account of the saturated ground from excessive August rainfall.

Based on 1971-2020 data, there is an implied 97% probability that New York City will pick up 50" or more precipitation this year. There is also an implied 40% probability that the City could pick up 60" or more precipitation. Since 1869, New York City has had 34 years with 50" or more precipitation (65% of which have occurred after 1970) and 8 years with 60" or more precipitation (all of which have occurred after 1970). Records go back to 1869.

Despite a cooler than normal first 7-10 days, September will likely feature near normal to somewhat warmer than normal temperatures in much of the region.

Fall 2021 will likely be wetter to much wetter than normal in the northern Middle Atlantic region. Since 1869, there have been 9 August cases where New York City picked up 20.00" or more rainfall during the summer. Two thirds of those cases (and 4/5 of those with summer mean temperatures of 73.0° or above) had 17.00" or more fall precipitation in New York City. 2011 is probably the closest match in terms of precipitation and a nearly identical summer mean temperature. Mean fall precipitation for those 9 cases was 14.86". The median was 17.35". The 1991-2020 normal value is 12.27".

The ENSO Region 1+2 anomaly was 0.0°C and the Region 3.4 anomaly was -0.3°C for the week centered around August 25. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.35°C and the ENSO Region 3.4 anomaly has averaged -0.47°C. Neutral ENSO conditions will likely prevail into at least mid-September. Afterward, La Niña conditions could begin to develop.

The SOI was +9.03 today.

The preliminary Arctic Oscillation (AO) figure was -1.846 today.

On August 30 the MJO was in Phase 2 at an amplitude of 1.481 (RMM). The August 29-adjusted amplitude was 1.331 (RMM).

 

 

[LibertyBell]

4 minutes ago, donsutherland1 said:

Through 8 pm, Ida's remnants have already produced September 1 daily record rainfall totals in a number of locations including:

Harrisburg: 6.52" (old record: 3.60", 1952)
Hartford: 1.38" (old record: 0.91", 1952)
Mount Pocono: 4.72" (old record: 4.54", 1952)
New York City-JFK: 0.68" (old record: 0.63", 2002)
Philadelphia: 2.00" (old record: 1.80", 1952)
Poughkeepsie: 2.76" (old record: 2.50", 1952)
Scranton: 4.86" (old record: 2.59", 2003)
York, PA: 6.51" (old record: 2.01", 2003)

Unofficially, Newark picked up 1.36" rain in the past hour. The last time Newark picked up 1.00" or more in an hour was June 26, 2020. This was also Newark's largest hourly rainfall since May 28, 2013 when 1.84" was measured.

Ida will bring heavy rain and possible tornadoes to the region overnight into early tomorrow. Much of the region will see a general 3"-6" of rain with local amounts at or above 8". Flash flooding is likely on account of the saturated ground from excessive August rainfall.

Based on 1971-2020 data, there is an implied 97% probability that New York City will pick up 50" or more precipitation this year. There is also an implied 40% probability that the City could pick up 60" or more precipitation. Since 1869, New York City has had 34 years with 50" or more precipitation (65% of which have occurred after 1970) and 8 years with 60" or more precipitation (all of which have occurred after 1970). Records go back to 1869.

Despite a cooler than normal first 7-10 days, September will likely feature near normal to somewhat warmer than normal temperatures in much of the region.

Fall 2021 will likely be wetter to much wetter than normal in the northern Middle Atlantic region. Since 1869, there have been 9 August cases where New York City picked up 20.00" or more rainfall during the summer. Two thirds of those cases (and 4/5 of those with summer mean temperatures of 73.0° or above) had 17.00" or more fall precipitation in New York City. 2011 is probably the closest match in terms of precipitation and a nearly identical summer mean temperature. Mean fall precipitation for those 9 cases was 14.86". The median was 17.35". The 1991-2020 normal value is 12.27".

The ENSO Region 1+2 anomaly was 0.0°C and the Region 3.4 anomaly was -0.3°C for the week centered around August 25. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.35°C and the ENSO Region 3.4 anomaly has averaged -0.47°C. Neutral ENSO conditions will likely prevail into at least mid-September. Afterward, La Niña conditions could begin to develop.

The SOI was +9.03 today.

The preliminary Arctic Oscillation (AO) figure was -1.846 today.

On August 30 the MJO was in Phase 2 at an amplitude of 1.481 (RMM). The August 29-adjusted amplitude was 1.331 (RMM).

 

 

JFK has to have over 3 inches now lol

I saw a report of nearly 8" near Allentown, have you seen figures like that, Don?

 

[donsutherland1]

13 minutes ago, LibertyBell said:

JFK has to have over 3 inches now lol

I saw a report of nearly 8" near Allentown, have you seen figures like that, Don?

 

I haven’t reviewed local storm reports.

[Stormlover74]

Temp down to 62