donsutherland1

After a few additional showers or thundershowers tonight, tomorrow will be another warm day with temperatures rising to near or somewhat above normal levels. Afterward, cooler air will be bleeding into the region. The week could end with unseasonably cool temperatures. Developments in ENSO Region 1+2 could have implications for October's temperature anomalies. A decline in the anomaly to -1.0°C or below would likely mean a warmer than normal outcome. Since 1950, 11/13 (85%) of cases where the ENSO Region 1+2 anomaly was -1.0°C or below were warmer than normal in the northern Mid-Atlantic region. In New York City, the mean monthly temperature for those cases was 59.3° (the current normal is 57.9°). Of the two cooler cases, 1967 was slightly below normal while 1988 was much cooler than normal. Later this week, Cuba will face a potential major hurricane threat and the Gulf Coast of Florida could face a hurricane threat. In part due to Merbok's impact on the jet stream, September will likely end with cooler than normal conditions. The cool weather could continue into the start of October. In the 6 past cases when the June AO averaged +0.750 or above (1950-2021), 67% of the following August and September cases featured above normal temperatures. The August ECMWF forecast shows a warmer than normal September in the Northeast. This warmth would be consistent with the ongoing warming that has been occurring in September. The ENSO Region 1+2 anomaly was -0.9°C and the Region 3.4 anomaly was -1.0°C for the week centered around September 6. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.62°C and the ENSO Region 3.4 anomaly has averaged -1.00°C. La Niña conditions will likely persist through the fall. The SOI was +24.07 today. The preliminary Arctic Oscillation (AO) was -0.108 today. On September 23 the MJO was in Phase 5 at an amplitude of 0.478 (RMM). The September 22-adjusted amplitude was 0.500 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 70% probability that New York City will have a warmer than normal September (1991-2020 normal). September will likely finish with a mean temperature near 69.7° (0.5° above normal).

Morning thoughts… Today will be mostly cloudy and warmer. A strong or perhaps severe thunderstorm is possible, especially during the afternoon or evening hours. High temperatures will 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: 76° Philadelphia: 78° The mild weather will continue tomorrow. 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°

The surf was lower than had been forecast at Robert Moses, too. The waves had been forecast to be around 10’ but were generally 4’-5’.

This morning, New York City saw the temperature dip into the 40s in September for the first time since September 22, 2020 when the thermometer registered 48°. Early this morning, Hurricane Fiona made landfall in Nova Scotia as a Category 1 hurricane. The storm set a Canadian national low pressure record with a reading of 931.6 mb (27.51") on Hart Island. Next week, Cuba and Florida could face a potential major hurricane threat. Tomorrow and Monday will see readings return to near to somewhat above normal levels. In part due to Merbok's impact on the jet stream, September will likely end with cooler than normal conditions. The cool weather could continue into the start of October. In the 6 past cases when the June AO averaged +0.750 or above (1950-2021), 67% of the following August and September cases featured above normal temperatures. The August ECMWF forecast shows a warmer than normal September in the Northeast. This warmth would be consistent with the ongoing warming that has been occurring in September. The ENSO Region 1+2 anomaly was -0.9°C and the Region 3.4 anomaly was -1.0°C for the week centered around September 6. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.62°C and the ENSO Region 3.4 anomaly has averaged -1.00°C. La Niña conditions will likely persist through the fall. The SOI was +17.06 today. The preliminary Arctic Oscillation (AO) was -0.217 today. On September 22 the MJO was in Phase 3 at an amplitude of 0.482 (RMM). The September 21-adjusted amplitude was 0.478 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 75% probability that New York City will have a warmer than normal September (1991-2020 normal). September will likely finish with a mean temperature near 69.9° (0.7° above normal).

Some scenes from Robert Moses State Park this morning with waves rolling in from Hurricane Fiona, which made landfall in Nova Scotia very early this morning.

It used to be common. Not any more. This morrning’s low, so far, has been 49.

Morning thoughts… This morning, the temperature fell into the 40s in New York City for the first such September reading since September 22, 2020. Today will be mostly sunny and milder. High temperatures will reach the upper 60s and lower 70s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 70° Newark: 72° Philadelphia: 73° Tomorrow will be warmer. 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°

I believe Environment Canada issued those warnings. https://www.canada.ca/en/environment-climate-change/services/hurricane-forecasts-facts.html

There’s a real chance. I suspect that Fiona’s expanding circulation will help drive cool air into the region. 40s in September have become infrequent. Since 2000, only 2006, 2009, 2013, and 2020 have seen the temperature dip below 50.

In many parts of the region, today was the coolest day since late Spring. In New York City's Central Park, the mercury topped out at 63°. The last time the high temperature was at least as cool was May 8th when the temperature reached 58°. Newark's high temperature of 64° was the lowest since May 8th when the high was just 62°. Select low temperatures from this morning included: Boston: 50° (coolest since May 26: 50°) New York City: 51° (coolest since May 10: 51°) Newark: 50° (coolest since May 10: 50°) Philadelphia: 56° (coolest since May 26: 54°) After another very cool start, tomorrow will be somewhat warmer with readings reaching the upper 60s and lower 70s. Sunday and Monday will see readings return to near to somewhat above normal levels. In part due to Merbok's impact on the jet stream, September will likely end with cooler than normal conditions. The cool weather could continue into the start of October. In southern Florida, near record and record heat prevailed. Miami reached 95°, which broke the daily mark of 94° from 1943. Today's 95° temperature was the second latest on record. It was also the second such temperature in September, which tied the monthly record set in 1989 and tied in 2019 and 2021. Florida faces a hurricane risk next week. Hurricane Fiona will make landfall in Atlantic Canada tomorrow. With a contribution from the ongoing marine heatwave, Fiona will likely do so as a category 2 hurricane. Canada's lowest barometric pressure on record could be challenged. The powerful storm could also sweep a surge of warm air northward along Greenland's west coast sending temperatures in some areas up to near 50°. In the 6 past cases when the June AO averaged +0.750 or above (1950-2021), 67% of the following August and September cases featured above normal temperatures. The August ECMWF forecast shows a warmer than normal September in the Northeast. This warmth would be consistent with the ongoing warming that has been occurring in September. The ENSO Region 1+2 anomaly was -0.9°C and the Region 3.4 anomaly was -1.0°C for the week centered around September 6. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.62°C and the ENSO Region 3.4 anomaly has averaged -1.00°C. La Niña conditions will likely persist through the fall. The SOI was +14.80 today. The preliminary Arctic Oscillation (AO) was +0.341 today. On September 21 the MJO was in Phase 3 at an amplitude of 0.476 (RMM). The September 20-adjusted amplitude was 0.336 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 70% probability that New York City will have a warmer than normal September (1991-2020 normal). September will likely finish with a mean temperature near 69.9° (0.7° above normal).

Almost certainly, the ongoing marine heatwave has put a category 3 scenario on the table for Nova Scotia. Without it, one would see a weaker but still potent storm.

Morning thoughts… Today sunny but unseasonably cool. High temperatures will reach the middle 60s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 64° Newark: 66° Philadelphia: 67° Tomorrow will be another cool day. 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°

Through September 22, Galveston has 100 days on which the low temperature was 80°F or above. That is well above the old mark of 91 days, which was set in 2011. Very few locations in the mainland U.S. have ever seen 100 or more such days.

A strong cold front moved across the region during the morning and early afternoon bringing showers and thundershowers. In response, temperatures began falling even as the sun returned. Tomorrow, many parts of the region will experience their coldest temperatures so far this season. Temperatures will warm up during the second half of the weekend. However, in part due to Merbok's impact on the jet stream, September will likely end with cooler than normal conditions. During Saturday, Hurricane Fiona will likely make landfall in Atlantic Canada. With a contribution from the ongoing marine heatwave, Fiona will likely do so as a category 2 hurricane. Canada's lowest barometric pressure on record could be challenged. In the 6 past cases when the June AO averaged +0.750 or above (1950-2021), 67% of the following August and September cases featured above normal temperatures. The August ECMWF forecast shows a warmer than normal September in the Northeast. This warmth would be consistent with the ongoing warming that has been occurring in September. The ENSO Region 1+2 anomaly was -0.9°C and the Region 3.4 anomaly was -1.0°C for the week centered around September 6. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.62°C and the ENSO Region 3.4 anomaly has averaged -1.00°C. La Niña conditions will likely persist through the fall. The SOI was +12.72 today. The preliminary Arctic Oscillation (AO) was +0.341 today. On September 20 the MJO was in Phase 3 at an amplitude of 0.336 (RMM). The September 19-adjusted amplitude was 0.365 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 61% probability that New York City will have a warmer than normal September (1991-2020 normal). September will likely finish with a mean temperature near 69.9° (0.7° above normal).

The temperature reached 95°F today in Galveston, which tied the daily record set in 2005. Today's 90° or above reading further extended this year's record for such days to 105. That number has increased as Galveston's climate has warmed.