donsutherland1

Morning thoughts… Today will start off with overcast skies in parts of the region. Those clouds will yield to sunshine. Elsewhere, it will be partly sunny and unseasonably cool. High temperatures will likely reach the middle and upper 60s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 65° Newark: 70° Philadelphia: 70° Normals: New York City: 30-Year: 70.6°; 15-Year: 71.9° Newark: 30-Year: 72.2°; 15-Year: 73.7° Philadelphia: 30-Year: 73.5°; 15-Year: 74.7° Dry but cool weather will continue through tomorrow.

Tonight will provide a genuine autumn preview. Temperatures will likely fall into the lower 50s in New York City, Newark, and perhaps Philadelphia. Outside the cities, temperatures could fall well into the 40s. Westhampton could see the mercury dip below 40°. Afterward, it will be variably cloudy with the mercury rising into the middle and upper 60s in much of the region. Newark's record-breaking 122-day streak with maximum temperatures of 70° or above will be severely challenged. Most of the modeling shows a high of 68°-70° there. 2021 is virtually certain to become the 6th out of the last 7 years during which September has had a mean temperature of 70° or above in New York City. Prior to 2000, New York City saw such warmth on average once every five years. In short, September has become more an extension of summer than a gateway to autumn in the New York City area. Friday will be another relatively cool day. But warmer temperatures will return and the chance of precipitation will increase as the calendar presses deeper into the first week of October. There is strong consensus on the long-range guidance that October will be an unseasonably warm month. The first half could feature much above normal readings in the Northern Plains into Central Canada. Overall, the Middle Atlantic and southern New England areas appear to be in line with a warmer to much warmer than normal October (a general 2°-4° above normal). 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". Following very wet July-September periods, winter precipitation has typically been near or below normal. The most recent exception was winter 2018-19. The ENSO Region 1+2 anomaly was +0.2°C and the Region 3.4 anomaly was -0.3°C for the week centered around September 22. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.05°C and the ENSO Region 3.4 anomaly has averaged -0.43°C. Neutral ENSO conditions will likely prevail through September. Afterward, La Niña conditions could begin to develop during October. The SOI was +30.49 today. The preliminary Arctic Oscillation (AO) figure was -1.308 today. On September 27 the MJO was in Phase 4 at an amplitude of 1.346 (RMM). The September 26-adjusted amplitude was 1.087 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a warmer than normal September (1991-2020 normal). September will likely finish with a mean temperature near 70.3° (1.1° above normal).

I looked at outcomes following high July-September precipitation on fall (September-November) and winter (December-February) precipitation for New York City. Rather than using the full 1869-2020 data set, I used the 1971-2020 data set for two reasons: 1. There has been an abrupt and sustained increase in precipitation after 1970. 1869-1970 average: 42.89". 1971-2020 average: 50.67". The drier region prior to 1971 may no longer be relevant. 2. The 1971-2020 data set is sufficiently large to produce cases for evaluation. To determine "high precipitation" outcomes, I used 0.5 or more sigma above the July-September 1971-2020 average. There were 8 cases that fit that definition: 1971, 1975, 1989, 1990, 2000, 2004, 2011, and 2018. All but 1990 and 2000 were at least 1 sigma above the average. Fall (September-November): 1971-2020 Average: 12.62" 8-Case Subset: 15.74" All but 2 cases were at least 1 sigma above the fall average. Only 1990 and 2000 were slightly below normal (-0.28 sigma and -0.62 sigma). This supports the continuation of above normal precipitation through much of the fall. Following Winter (December-February): 1971-72 through 2020-21 average: 11.29" 8-Case Subset: 10.44" 5 (63%) were within 0.5 sigma of the average 3 (37%) were more than 0.5 sigma below average (1989-90, 2000-01, 2011-12) 1 (13%) were more than 0.5 sigma above average (2018-19) Precipitation amounts did not necessarily impact seasonal snowfall. 2004-05 had 41.0" snowfall with precipitation +0.04 sigma (near normal). 2000-01 had 35.0" snowfall with precipitation -0.94 sigma (much below normal). Winter 2018-19 had 20.5" (precipitation: +0.61 sigma or above normal). Mean snowfall for the subset: 22.8"; median snowfall: 21.7". Excluding the El Niño cases (2004-05 and 2018-19), the mean snowfall was 20.2" and the median snowfall was 20.1".

Morning thoughts… Today will be partly sunny and cooler. High temperatures will likely reach the upper 60s and lower 70s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 68° Newark: 73° Philadelphia: 71° Normals: New York City: 30-Year: 71.0°; 15-Year: 72.3° Newark: 30-Year: 72.6°; 15-Year: 74.1° Philadelphia: 30-Year: 73.9°; 15-Year: 75.1° Dry but cool weather will continue through Friday.

If I correctly recall the posted message, the letter had been sent and the regional headquarters was going to take a closer look. So far, nothing has changed at the Park.

Rainfall totals increased fairly abruptly after 1970.

That could mean less snowfall in the winter all other variables notwithstanding.

0.27” was the final amount. September will very likely end with 10.03”.

I will have a look tonight or tomorrow. I share your concern about drying out, especially if summer and fall are very wet.

An area of showers and thundershowers moved through the region late this morning and early this afternoon. A total of 0.27" of rain fell in New York City's Central Park pushing the monthly rainfall total to 10.03". As a result, New York City has seen a record 3 consecutive months with 10" or more of rain. Records go back to 1869. In addition, 10" or more of rain each month from July-September is unprecedented this far north. In 1894 and again in 1945, Downtown Charleston, SC (32.78°N) saw 10" or more of rain during this period. In 1946, Wilmington, NC (34.21°N) saw 10" or more of rain during this period. Then, in 2018, Dunn (4 NW), NC (35.31°N) recorded 10" or more during July, August, and September. Year-to-date rainfall in New York City is now 51.96". That ranks 2021 as New York City's 33rd wettest year on record. In the Northern Plains, today witnessed searing heat. The thermometer topped out at 98° at Bismarck, which surpassed the daily mark of 97° from 1905. This is also the latest 98° or above reading on record. This evening, a few isolated showers and thundershowers are possible in parts of the region, but skies will clear. Tomorrow through Friday will feature plentiful sunshine and cool temperatures. 2021 remains on course to become the 6th out of the last 7 years during which September has had a mean temperature of 70° or above in New York City. Prior to 2000, New York City saw such warmth on average once every five years. In short, September has become more an extension of summer than a gateway to autumn in the New York City area. There is strong consensus on the long-range guidance that October will be an unseasonably warm month. The first half could feature much above normal readings in the Northern Plains into Central Canada. Overall, the Middle Atlantic and southern New England areas appear to be in line with a warmer to much warmer than normal October. 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 +0.2°C and the Region 3.4 anomaly was -0.3°C for the week centered around September 22. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.05°C and the ENSO Region 3.4 anomaly has averaged -0.43°C. Neutral ENSO conditions will likely prevail through September. Afterward, La Niña conditions could begin to develop during October. The SOI was +36.90 today. The preliminary Arctic Oscillation (AO) figure was -1.474 today. On September 26 the MJO was in Phase 4 at an amplitude of 1.081 (RMM). The September 25-adjusted amplitude was 0.823 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a warmer than normal September (1991-2020 normal). September will likely finish with a mean temperature near 70.3° (1.1° above normal).

With 0.25" rain through 12:08 pm, New York City's Central Park has now reached 10.01" rain for September.

With 0.25" rain through 12:08 pm, New York City's Central Park has now reached 10.01" rain for September. September is the record-breaking 3rd consecutive month with 10" or more rainfall. Records go back to 1869.

Through September 27, New York City is just 0.24" of rain away from an unprecedented third consecutive month with 10" or more of precipitation. It all comes down to this afternoon and evening as to whether the City will receive enough rainfall to make history or fall agonizingly short. No additional precipitation is likely for the remainder of September. The 9/28 0z run of the EPS ensembles shows 29/51 (59%) members with just enough rain to push the monthly total to 10". The ensemble mean and the 0z ECMWF operational forecast both show enough precipitation. The individual models are about as divided as the U.S. Congress has become. Here's where things currently stand with perhaps a fragile consensus leaning against sufficient rainfall: Yes: 0z ECMWF 6z HRRR 6z RGEM 0z UKMET (0.70"!) No: 6z GFS 0z GGEM 0z HREF 6z NAM/3 km NAM 11z NBM (0.19") And historic experience (1869-2020) is no more decisive. Of the 50 cases that saw measurable precipitation on September 28, 46% reached 0.24" or above. And the SPC discussion: Scattered showers and thunderstorms should be spreading across the central Appalachians vicinity at the start of the period, ahead of a weak/fast-moving mid-level short-wave trough. This convection -- and associated cloud cover -- casts some uncertainty over northern portions of the risk area with respect to subsequent heating/destabilization. In general however, areas from northern Virginia eastward across the Delmarva Peninsula to southern New Jersey should experience ample pre-frontal heating such that -- given rather steep mid-level lapse rates being advected eastward and ample low-level moisture -- a zone of 1000 to 2000 J/kg CAPE is expected by late afternoon. All said, the outcome is going to be a nail-biter. But if a thunderstorm crosses Central Park, we'll probably get the needed rainfall.

Yes. In 2015, the lowest daily high temperature was 72.

Morning thoughts… Today will be partly sunny and warm. A strong cold front could trigger some showers and thunderstorms from late afternoon into the night. High temperatures will likely reach the upper 70s and lower 80s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 75° Newark: 79° Philadelphia: 80° Normals: New York City: 30-Year: 71.5°; 15-Year: 72.8° Newark: 30-Year: 73.0°; 15-Year: 74.5° Philadelphia: 30-Year: 74.3°; 15-Year: 75.5° The remainder of the month will be fair but unseasonably cool.

Tomorrow will be another warm day, but a cold front will push across the region overnight bringing some showers and perhaps thundershowers to parts of the region. It is almost a coin toss as to whether Central Park will pick up the 0.24" of rain that it needs to reach 10" for September. The 12z EPS had 30/51 (59%) of members with sufficient rainfall. Afterward, the coolest air so far this fall will close out the month. The MJO had recently been locked in Phase 3 at a high amplitude, frequently in excess of 1.500. Only 2006 and 2009 saw the MJO in Phase 3 at an amplitude of 1.500 or above for 2 or more days during September 10-20. Both years saw September end with a cold shot that continued into the first days of October. Both days saw Central Park's temperature fall to 49° on September 30. The guidance has now come into better agreement concerning a cool shot to end the month. Afterward, in the MJO cases, a fairly sharp rebound in temperatures followed. October wound up wetter than normal with 7.07" rainfall in 2006 and 5.58" of rainfall in 2009. Normal rainfall (1991-2020) is 4.38". 2021 remains on course to become the 6th out of the last 7 years during which September has had a mean temperature of 70° or above in New York City. Prior to 2000, New York City saw such warmth on average once every five years. In short, September has become more an extension of summer than a gateway to autumn in the New York City area. There is increasing consensus on the long-range guidance that October will be an unseasonably warm month. The first half could feature much above normal readings in the Northern Plains into Central Canada. 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 +0.2°C and the Region 3.4 anomaly was -0.3°C for the week centered around September 22. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.05°C and the ENSO Region 3.4 anomaly has averaged -0.43°C. Neutral ENSO conditions will likely prevail through September. Afterward, La Niña conditions could begin to develop during October. The SOI was +24.25 today. The preliminary Arctic Oscillation (AO) figure was -1.185 today. On September 25 the MJO was in Phase 5 at an amplitude of 0.815 (RMM). The September 24-adjusted amplitude was 0.715 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 98% probability that New York City will have a warmer than normal September (1991-2020 normal). September will likely finish with a mean temperature near 70.4° (1.2° above normal).

Morning thoughts… Today will be mostly sunny and unseasonably warm. High temperatures will likely reach the upper 70s and lower 80s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 78° Newark: 83° Philadelphia: 81° Normals: New York City: 30-Year: 71.9°; 15-Year: 73.1° Newark: 30-Year: 73.4°; 15-Year: 74.9° Philadelphia: 30-Year: 74.7°; 15-Year: 75.9° Tomorrow will be another warm day, but a strong cold front will move across the region tomorrow night.

Yes. That’s where the warmest anomalies will be.

It’s usually quite breezy up there. The views have been great the past few days with the absence of haze.

Tomorrow will be mostly sunny and unseasonably warm. Temperatures will likely reach the upper 70s and lower 80s. Tuesday will also be warm, but a cold front will push across the region overnight bringing some showers and perhaps thundershowers to parts of the region. Afterward, the coolest air so far this fall will close out the month. The MJO had recently been locked in Phase 3 at a high amplitude, frequently in excess of 1.500. Only 2006 and 2009 saw the MJO in Phase 3 at an amplitude of 1.500 or above for 2 or more days during September 10-20. Both years saw September end with a cold shot that continued into the first days of October. Both days saw Central Park's temperature fall to 49° on September 30. The guidance has now come into better agreement concerning a cool shot to end the month. Afterward, in the MJO cases, a fairly sharp rebound in temperatures followed. October wound up wetter than normal with 7.07" rainfall in 2006 and 5.58" of rainfall in 2009. Normal rainfall (1991-2020) is 4.38". 2021 remains on course to become the 6th out of the last 7 years during which September has had a mean temperature of 70° or above in New York City. Prior to 2000, New York City saw such warmth on average once every five years. In short, September has become more an extension of summer than a gateway to autumn in the New York City area. There is increasing consensus on the long-range guidance that October will be an unseasonably warm month. The first half could feature much above normal readings in the Northern Plains into Central Canada. 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 +0.2°C and the Region 3.4 anomaly was -0.4°C for the week centered around September 15. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.03°C and the ENSO Region 3.4 anomaly has averaged -0.45°C. Neutral ENSO conditions will likely prevail through September. Afterward, La Niña conditions could begin to develop. The SOI was -0.24 today. The preliminary Arctic Oscillation (AO) figure was -0.455 today. On September 24 the MJO was in Phase 4 at an amplitude of 0.714 (RMM). The September 23-adjusted amplitude was 0.945 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 94% probability that New York City will have a warmer than normal September (1991-2020 normal). September will likely finish with a mean temperature near 70.4° (1.2° above normal).

The afternoon saw plentiful sunshine, fluffy cumulus clouds, and readings in the 70s. The New York Botanical Garden is transitioning to more of an autumn appearance.

Wonderful capture.

The percentage of EPS members showing sufficient rain to bring Central Park’s monthly total to 10.00” has increased in recent runs. The last three cycles: 9/24 12z: 29% 9/25 0z: 41% 9/25 12z: 57% (ensemble mean: 0.3”)

Morning thoughts… Today will be mostly sunny and pleasantly warm. High temperatures will likely reach the lower and middle 70s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 73° Newark: 77° Philadelphia: 75° Normals: New York City: 30-Year: 72.3°; 15-Year: 73.5° Newark: 30-Year: 73.8°; 15-Year: 75.2° Philadelphia: 30-Year: 75.1°; 15-Year: 76.3° Tomorrow will be a very warm day.

Under partly sunny skies with temperatures in the 70s, it was another fine late September beach day.