donsutherland1

Tomorrow and Monday will be fair and pleasantly warm days. Afterward, a cold front could bring some showers or thundershowers to the region on Tuesday. 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 -15.92 today. The preliminary Arctic Oscillation (AO) figure was +0.142 today. On September 23 the MJO was in Phase 4 at an amplitude of 0.946 (RMM). The September 22-adjusted amplitude was 1.305 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 89% 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 pleasantly warm. High temperatures will likely reach the middle and upper 70s in most of the region. A few locations could reach or exceed 80°. Likely high temperatures around the region include: New York City (Central Park): 75° Newark: 79° Philadelphia: 77° Normals: New York City: 30-Year: 72.7°; 15-Year: 73.9° Newark: 30-Year: 74.3°; 15-Year: 75.6° Philadelphia: 30-Year: 75.5°; 15-Year: 76.6° Tomorrow will be another sun-filled day.

17/51 (33%) of the 9/25 0z EPS members now show sufficient rainfall to bring Central Park’s monthly total to 10”. It’s still a reach, but there remains some opportunity.

In the wake of the frontal passage that brought a widespread 1"-2" rainfall into today, clouds and rain shifted eastward and the sun returned. Abundant sunshine occurred near New York City and westward. There, readings soared into the 70s. Tomorrow, the entire region will benefit from abundant sunshine. It will be a warm day with temperatures rising into the middle and upper 70s. A few locations could reach or exceed 80°. Sunday will be a similar but perhaps slightly cooler day. 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. 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". Despite the guidance of a few days ago and a likely cold shot to end the month, 2021 is still 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 -18.18 today. The preliminary Arctic Oscillation (AO) figure was +0.787 today. On September 22 the MJO was in Phase 4 at an amplitude of 1.305 (RMM). The September 21-adjusted amplitude was 1.553 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 86% probability that New York City will have a warmer than normal September (1991-2020 normal). September will likely finish with a mean temperature near 70.5° (1.3° above normal).

New York City's Central Park still needs 0.24" of rain before the end of September to register its 3rd consecutive month with 10" or more of precipitation. The EPS ensembles have grown a little wetter around 9/29-30. The 9/24 0z run saw 10% of members with enough rainfall to reach 10" for the month. The 12z run saw 29% of members with sufficient rainfall to reach 10" for the month. Below is a list showing the percentage of outcomes to month's end from tomorrow and then from each day when no additional rain has fallen. The historic probability for cases when no rain was recorded through 9/28 (as is the case with the EPS) is just a little higher than the current share of EPS members showing sufficient rainfall to reach 10" for September.

Two photos as the front responsible for the rainfall slowly edged eastward.

Yes, that’s correct.

9.76” as 2.03” fell. It will be tough, but a small handful of ensemble members (around 10%) have enough rain.

Morning thoughts… At 7:10 am, the front responsible for the heavy rainfall that commenced yesterday continued to move slowly eastward. Central Park picked up 2.03” of rain bringing its monthly total to 9.76”. 2021 is the first year on record with 3 consecutive months of 9.50” or more rainfall. Annual rainfall in New York City has reached 51.69”. That surpassed the 51.38” that fell in 1871 to make 2021 New York City’s 34th wettest year on record. Today will see rainfall shift slowly eastward on Long Island. Clouds will break, especially west of Suffolk County allowing for some sunshine. Areas to the south and west of Newark could see a lot of sunshine. It will be cool for the season. High temperatures will likely reach the lower and middle 70s in most of the region. Where clouds linger longest, temperatures will hold in the 60s. Likely high temperatures around the region include: New York City (Central Park): 71° Newark: 76° Philadelphia: 74° Normals: New York City: 30-Year: 73.1°; 15-Year: 74.3° Newark: 30-Year: 74.7°; 15-Year: 76.0° Philadelphia: 30-Year: 75.9°; 15-Year: 77.0° A sun-filled weekend lies ahead.

Newark also hit 80 both days.

Ahead of an advancing front, the temperature soared into the lower 80s in much of the region. However, for a record 2nd consecutive day, the temperature at New York City's Central Park failed to reach 80° when all of the following cities reached 80° or above: Bridgeport, Islip, New Haven, New York City-JFK, and New York City-LGA. Through 8 pm rainfall totals included: Allentown: 1.76" Atlantic city: 0.74" Baltimore: 0.69" Binghamton: 1.29" (old record: 1.24", 2003) Harrisburg: 1.33" Mount Pocono, PA: 2.49" New York City-NYC: 0.94" Newark: 0.52" Philadelphia: 1.45" Scranton: 1.39" Washington, DC: 1.30" Additional rainfall is likely overnight into the first part of tomorrow. Behind the front, the sun will return tomorrow and readings will reach the lower 70s. 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. 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". Despite the guidance of a few days ago and a likely cold shot to end the month, 2021 is still 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. Considering that the close of September is still more than 10 days out, the guidance can still reverse. 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. 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 -10.22 today. The preliminary Arctic Oscillation (AO) figure was +1.040 today. On September 21 the MJO was in Phase 4 at an amplitude of 1.554 (RMM). The September 20-adjusted amplitude was 1.530 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 87% probability that New York City will have a warmer than normal September (1991-2020 normal). September will likely finish with a mean temperature near 70.6° (1.4° above normal).

The cooling power of trees? Today’s high temperature was 79 degrees at Central Park. For the first time, Central Park failed to reach 80 degrees on 2 consecutive days where Bridgeport, Islip, JFK, LGA, and New Haven all reached 80 degrees or above.

The ones in New Rochelle are thriving.

There is a home in New Rochelle, NY with palm trees.

Through 4 pm, Binghamton has received 1.29” of rain. That breaks the daily record of 1.24” from 2003.

Newark reached 80 degrees for the 110th day this year. That is the 8th highest number of days in record.

Latest HREF:

Morning thoughts… Today will be mostly cloudy and warm. Showers and thundershowers are possible. Heavier rain could arrive during the afternoon. 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: 82° Philadelphia: 77° Normals: New York City: 30-Year: 73.5°; 15-Year: 74.7° Newark: 30-Year: 75.1°; 15-Year: 76.3° Philadelphia: 30-Year: 76.3°; 15-Year: 77.4° A moderate to perhaps significant rainfall is likely tonight through Friday. A general 1”-2” rainfall with locally higher amounts appears likely. Parts of central Pennsylvania could see 3”-6” of rain.

Today was variably cloudy and unseasonably warm. The temperature rose into the upper 70s and lower 80s across much of the region. In addition, Central Park was poised to record its 50th 70° or above minimum temperature of the year. Even as New York City has had a mature urban footprint, the number of such days has increased in recent decades. The average figures for select 30 year periods are: 1971-00 was 33.7 days; 1981-10: 34.7 days; and, 1991-20: 39.0 days. During 1869-1999, Central Park registered 40 or more such days once every 5.5 years. Since 2000, it has seen 40 or more days every 1.6 years. The change in return time for 50 or more such days is even more dramatic. 1869-1999: Once every 26.2 years; 2000-21: Once every 3.1 years (would be once every 2.8 years if today's low temperature remains at or above 70°). The potential exists for a moderate to perhaps significant rainfall from tonight through Friday. A widespread 0.50"-1.50" rainfall with locally higher amounts is possible. Areas to the north and west of Newark and New York City could see 1"-3" amounts with locally higher figures. Flash flooding is possible. Parts of the region could also experience some severe weather, especially tomorrow afternoon into early Friday. The MJO has 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. 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". Despite the guidance of a few days ago and a likely cold shot to end the month, 2021 is still 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. Considering that the close of September is still more than 10 days out, the guidance can still reverse. 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. 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 +0.12 today. The preliminary Arctic Oscillation (AO) figure was +0.735 today. On September 20 the MJO was in Phase 4 at an amplitude of 1.527 (RMM). The September 19-adjusted amplitude was 1.347 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 85% probability that New York City will have a warmer than normal September (1991-2020 normal). September will likely finish with a mean temperature near 70.6° (1.4° above normal).

Newark has reached 80 degrees for the 109th day this year.

New York City's Central Park is on track to record a low temperature of 70° or above today. The mean last date such a temperature has increased 4 days from September 10 (1951-80) to September 14 (1991-20). The interval from the first and last dates has also widened 9 days to 104 days during that time. Most of that widening has occurred during the most recent 30-year period (104 days vs. 96 days for 1981-2010). Overall, September has been warming to the extent that it is now more an extension of summer than gateway into autumn.

Morning thoughts… Today will be mostly cloudy and 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: 81° Philadelphia: 82° Normals: New York City: 30-Year: 73.9°; 15-Year: 75.0° Newark: 30-Year: 75.5°; 15-Year: 76.7° Philadelphia: 30-Year: 76.7°; 15-Year: 77.7° A moderate to perhaps significant rainfall is possible tonight through Friday. A general 0.50”-1.50” rainfall with locally higher amounts appears likely.

Under mostly sunny skies, temperatures rose into the middle and upper 70s. A few locations reached 80°. Newark reached 80° for the 108th time this year, which ties 1959 for the 8th most such days. The record is 118 days, which was set in 2015. Tomorrow will turn mostly cloudy. It will be unseasonably warm. Temperatures will likely top out in the upper 70s and lower 80s. The potential exists for a moderate to perhaps significant rainfall from tomorrow night through Friday. A widespread 0.50"-1.50" rainfall with locally higher amounts is possible. The MJO has 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. 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". Despite the guidance of a few days ago and a likely cold shot to end the month, 2021 is still 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. Considering that the close of September is still more than 10 days out, the guidance can still reverse. 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. 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 +13.02 today. The preliminary Arctic Oscillation (AO) figure was -0.046 today. On September 19 the MJO was in Phase 3 at an amplitude of 1.344 (RMM). The September 18-adjusted amplitude was 1.466 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 77% 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).

While true, the odds would be greater than climatology. Even indirect effects could produce flooding. Of course, what will likely become Sam could recurve if the pattern is still evolving. But there’s always the possibility of additional storms, as it has been a very active season.

This is the kind of situation that is possible under some of the fairly ominous monthly 500 mb forecasts for October (and weekly forecasts going into October).