donsutherland1

East Grenville had 25.2” as of the last PNS.

A storm continues to bring some snow to the region this evening. Storm total accumulations include: Albany: 17.3"; Binghamton: 10.6"; Bridgeport: 0.7"; East Glenville, NY: 25.2"; Hartford: 5.5"; Highland Lakes, NJ: 10.5"; Islip: 0.2"; New York City: 1.0"; and, Newark: 1.4". The ENSO Region 1+2 anomaly was +0.4°C and the Region 3.4 anomaly was +0.4°C for the week centered around November 27. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.43°C and the ENSO Region 3.4 anomaly has averaged +0.62°C. These recent conditions are consistent with a weak El Niño. Nevertheless, a neutral ENSO remains the base case for Winter 2019-20. The SOI was +6.80 today. Today, the preliminary Arctic Oscillation (AO) figure was +1.749. The preliminary PNA value was -0.108. Daily MJO data was unavailable. Outgoing long-wave radiation is currently unavailable according to Australia's Bureau of Meteorology (BOM). The BOM is working on the issue. After a generally cold first week of December, warmer conditions will likely return. There is a chance that the second week of December could see one or more days with much above normal readings topping out in the 50s and perhaps even near 60° in the northern Mid-Atlantic region. Overall, December will likely finish somewhat warmer than normal to warmer than normal across the region. When it comes to New York City's 4" or greater snowstorms the PNA is more important than the AO during the first half of December. Since 1950, December 1-15 has seen 10 storms bring 4.0" or more snow to New York City. 50% occurred with an AO- or AO+. However, 80% occurred when the PNA was positive. All 6" or greater snowstorms during this timeframe occurred when the PNA was positive. During the second half of December, larger snowstorms have occurred with a negative PNA.

Taking into consideration the recent guidance and the observed data, my thinking is that NYC remains on track for a solid 3"-6" snowfall (EWR closer to 6"). Parts of northern New Jersey could see 6"-12". To put this into perspective, NYC has had only four snowfalls of 3" or more during the first week of December since 1950. Three of those winters went on to have 40" or more snow.

Yesterday saw daily record snowfall in a number of locations. Records included: Albany: 13.3" (old record: 3.7", 1969) Boston: 1.2" (old record: 1.0", 1940) Providence: 1.6" (old record: 0.5", 1907) Worcester: 8.9" (old record: 4.2", 1917) Based on the overnight guidance and early observations, it still appears that New York City is in line for 3"-6" snow with 1"-3" in Islip. Newark should also pick up closer to 6" and the potential.

Large flakes of snow are now falling in the Bronx.

A complex, long-duration, two-part winter storm is now affecting the region. Just outside New York City, the first snowfall of the season whitened the ground. Storm total snowfall amounts so far include: Albany: 2.8" Allentown: Trace Binghamton: 0.2" Bridgeport: Trace Hartford: 1.4" New York City: Trace Newark: 0.1" More significant snow could develop later tomorrow as the vigorous upper-level low associated with the system swings eastward and rapidly develops. The guidance has been in good agreement with the development of an intense band of snow. Model disagreement persists with the exact placement of the band. New York City (Central Park) and Newark continue to appear in line for a general 3"-6" snowfall. On account of the aforementioned band of intense snowfall, either or both locations could see notably less or notably more snow. The exact amounts might not become clear with a high degree of confidence until overnight. The following storm total amounts are likely for select cities in the Middle Atlantic and southern New England regions: Albany: 12"-18" Allentown: 4"-8" Binghamton: 8"-16" Boston: 5"-10" Bridgeport: 2"-4" (high uncertainty) Hartford: 6"-12" Islip: 1"-3" Philadelphia: 3"-6" (high uncertainty) Providence: 4"-8" Worcester: 8"-16"　 Following its warmest autumn by far, Utqiagvik (formerly Barrow) is currently on course to register its first annual mean temperature of 20.0° or above. That city's warmest year on record was 2016 with an annual average temperature of 18.9°. The ENSO Region 1+2 anomaly was -0.1°C and the Region 3.4 anomaly was +0.7°C for the week centered around November 20. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.63°C and the ENSO Region 3.4 anomaly has averaged +0.68°C. These recent conditions are consistent with a weak El Niño. Nevertheless, a neutral ENSO remains the base case for Winter 2019-20. The SOI was +4.10 today. Today, the preliminary Arctic Oscillation (AO) figure was -0.109. Daily MJO data was unavailable. Outgoing long-wave radiation is currently unavailable according to Australia's Bureau of Meteorology (BOM). The BOM is working on the issue. After a generally cold first week of December, warmer conditions will likely return. There is a chance that the second week of December could see one or more days with much above normal readings topping out in the 50s and perhaps even near 60° in the northern Mid-Atlantic region. Overall, December will likely finish somewhat warmer than normal to warmer than normal across the region. When it comes to New York City's 4" or greater snowstorms the PNA is more important than the AO during the first half of December. Since 1950, December 1-15 has seen 10 storms bring 4.0" or more snow to New York City. 50% occurred with an AO- or AO+. However, 80% occurred when the PNA was positive. All 6" or greater snowstorms during this timeframe occurred when the PNA was positive. During the second half of December, larger snowstorms have occurred with a negative PNA.

This afternoon the sleet turned to a burst of snow in Larchmont, NY in southern Westchester County. As of 2:30 pm, the snow had yielded to sleet.

Light freezing rain has changed to sleet in White Plains.

Sleet has started falling in parts of southern Westchester County.

For now, I am. I will review tonight’s and tomorrow’s guidance for any changes given the differences that still exist among the models.

The 12/1/2019 0z RGEM:

That's the GGEM. The RGEM comes out earlier.

Another nice run by the RGEM. More model runs to come later this evening.

New York City finished November with a monthly mean temperature of 43.9°. That made 2019 the coldest November since 2012 when the average temperature was also 43.9°. A significant long-duration, two-part winter storm will impact the region Sunday into Tuesday morning. While some snow and sleet could fall in the New York City area on Sunday (with accumulating snow well to the north and west of the City), a larger-impact snowfall is possible Monday into late Monday night as the vigorous upper-level low associated with the system swings eastward and rapidly develops. The 18z GFS did not develop this low along the lines of the other guidance and is likely providing a bad solution for both coastal and interior regions of New York State and southern New England. New York City (Central Park) and Newark continue to appear in line for a general 3"-6" snowfall. While model solutions have varied widely for NYC, 40/51 (78%) EPS members show 3" or more snow for New York City. Therefore, the above range still appears reasonable. Locations such as Binghamton, Poughkeepsie and Albany could see 8"-16". Utqiagvik (formerly Barrow) experienced its warmest autumn on record by far with an estimated seasonal mean temperature of 28.7°. There remains a chance that the final figure could be 28.8° depending on today's minimum temperature, which could occur near midnight Alaska time. The previous record was 26.0°, which was set in 2016. The ENSO Region 1+2 anomaly was -0.1°C and the Region 3.4 anomaly was +0.7°C for the week centered around November 20. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.63°C and the ENSO Region 3.4 anomaly has averaged +0.68°C. These recent conditions are consistent with a weak El Niño. Nevertheless, a neutral ENSO remains the base case for Winter 2019-20. The SOI was +0.38 today. Today, the preliminary Arctic Oscillation (AO) figure was -0.491. Daily MJO data was unavailable. Outgoing long-wave radiation is currently unavailable according to Australia's Bureau of Meteorology (BOM). The BOM is working on the issue. Based on the consistently-modeled idea of a negative to strongly negative EPO (-2.000 to -1.000) to begin December, the first 7 days of December will likely average colder than normal in much of the eastern third to eastern half of the CONUS and southern Canada. However, the EPO will likely go positive and the AO could go strongly positive during the first week of December. As a result, warmer conditions will likely return after the first week in December. Overall, December will likely finish somewhat warmer than normal to warmer than normal across the region. When it comes to New York City's 4" or greater snowstorms the PNA is more important than the AO during the first half of December. Since 1950, December 1-15 has seen 10 storms bring 4.0" or more snow to New York City. 50% occurred with an AO- or AO+. However, 80% occurred when the PNA was positive. All 6" or greater snowstorms during this timeframe occurred when the PNA was positive. During the second half of December, larger snowstorms have occurred with a negative PNA.

It will soon initialize.

Big differences in outcomes among the guidance illustrate the considerable uncertainty that still exists.

Here are some quick instructions. Also, the "Local" feature isn't available for all models.

DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA 1.5 0.8 0.5 1.5 2.0 2.2 1.2 0.5 0.2

The 0z NAM did little to undermine my initial thoughts posted earlier that New York City (Central Park) and Newark appear to be in line for a general 3"-6" snowfall. Locations such as Poughkeepsie and Albany could see 8"-16". The NAM exceeds those amounts, especially in and around Albany. The rest of the guidance will be interesting. It's still a high-risk storm as a relatively small shift in track and or evolution of the upper level low could make a large difference in and around NYC and probably in nearby Nassau County.

A significant long-duration, two-part winter storm will impact the region Sunday into Tuesday morning. While some snow and sleet could fall in the New York City area on Sunday (with accumulating snow well to the north and west of the City), a larger-impact snowfall is possible Monday into late Monday night as the vigorous upper-level low associated with the system swings eastward and rapidly develops. The forecast 500 mb pattern for December 2 bears similarities to that of December 24, 2002. The key difference is that the trough on the East Coast is forecast to be south of where it was in 2002. For now, New York City (Central Park) and Newark appear to be in line for a general 3"-6" snowfall. Locations such as Poughkeepsie and Albany could see 8"-16". In northern Alaska, Utqiagvik (formerly Barrow) is concluding its warmest autumn on record with what will likely be its second warmest November on record with a mean temperature near 16.0°. Based on the latest guidance, Utqiagvik will likely have a September-November mean temperature ranging of 28.6°. The current record is 26.0°, which was set in 2016. The ENSO Region 1+2 anomaly was -0.1°C and the Region 3.4 anomaly was +0.7°C for the week centered around November 20. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.63°C and the ENSO Region 3.4 anomaly has averaged +0.68°C. These recent conditions are consistent with a weak El Niño. Nevertheless, a neutral ENSO remains the base case for Winter 2019-20. The SOI was -3.38 today. Today, the preliminary Arctic Oscillation (AO) figure was -0.408. Daily MJO data was unavailable. Outgoing long-wave radiation is currently unavailable according to Australia's Bureau of Meteorology (BOM). The BOM is working on the issue. Based on the consistently-modeled idea of a negative to strongly negative EPO (-2.000 to -1.000) to begin December, the first 7 days of December will likely average colder than normal in much of the eastern third to eastern half of the CONUS and southern Canada. However, the EPO will likely go positive and the AO could go strongly positive during the first week of December. As a result, warmer conditions will likely return after the first week in December. At present, the warmth does not appear to be too impressive. Transient shots of cooler air will remain possible. Should the AO remain elevated at strongly positive levels, the probability of a warmer than normal second half of December would increase. Overall, the base case remains a somewhat warmer than normal December as a whole, though New England and the Great Lakes region could still wind up cooler than normal. With December likely to get off to a cool start, Newark, New York City, and Boston will likely see their first measurable snowfall of the season during December 1-3. Philadelphia could also pick up its first measurable snowfall. When it comes to New York City's 4" or greater snowstorms the PNA is more important than the AO during the first half of December. Since 1950, December 1-15 has seen 10 storms bring 4.0" or more snow to New York City. 50% occurred with an AO- or AO+. However, 80% occurred when the PNA was positive. All 6" or greater snowstorms during this timeframe occurred when the PNA was positive. During the second half of December, larger snowstorms have occurred with a negative PNA. Based on sensitivity analysis applied to the latest guidance, New York City has an implied near 100% probability of experiencing a colder than normal November. November 2019 will likely finish with a mean temperature near 43.9°. That would make this November the coldest November since 2012 when the monthly mean temperature also was 43.9°. There is a chance that the mean temperature could come in at 43.8°. If so, November 2019 would be the coldest November since 1996 when the monthly average temperature was 43.0°. 　

Albany also picked up 21”.

I took regional snowfall to date as one piece of information for some context, which added a degree of confidence to my thinking. That suggested that the numbers could be plausible. The major assumptions largely drove the forecast.

Prospects for an appreciable snowfall in and around the New York City Metro Area increased overnight. The single teleconnections fly in the ointment remains the forecast of a negative PNA. Most of the early December snowstorms that dumped 4" or more snow in the New York City area occurred when the PNA was positive. Nevertheless, such a snowfall remains among the plausible scenarios. The last time New York City received 2" or more snow was March 3-4, 2019 when 5.0" fell. Following the snowfall, several days of below to much below normal temperatures are likely before warmer air returns following the first week in December. Some of the latest guidance has grown warmer in the extended range.

Thanksgiving Day featured a bountiful harvest of winds that buffeted much of the Middle Atlantic and southern New England regions. The 12z ECMWF gave much of the region a lot to be thankful for with its forecast of a major snowfall early next week. While the ECMWF might be overdone, the pattern is conducive for at least some snowfall, even in the big cities, especially from late Monday into Tuesday morning. In northern Alaska, Utqiagvik (formerly Barrow) is concluding its warmest autumn on record with what will likely be its second warmest November on record. Through 5 pm Alaska time, Utqiagvik had a daily high temperature of 27°, which was just short of the daily record of 28° from 1995. Based on the latest guidance, Utqiagvik will likely have a September-November mean temperature ranging from 28.5°-28.6°. The current record is 26.0°, which was set in 2016. The ENSO Region 1+2 anomaly was -0.1°C and the Region 3.4 anomaly was +0.7°C for the week centered around November 20. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.63°C and the ENSO Region 3.4 anomaly has averaged +0.68°C. These recent conditions are consistent with a weak El Niño. Nevertheless, a neutral ENSO remains the base case for Winter 2019-20. The SOI was -9.23 today. Today, the preliminary Arctic Oscillation (AO) figure was -0.754. Daily MJO data was unavailable for November 27. Outgoing long-wave radiation is currently unavailable according to Australia's Bureau of Meteorology (BOM). The BOM is working on the issue. Based on the consistently-modeled idea of a negative to strongly negative EPO (-2.000 to -1.000) to begin December, the first 7 days of December will likely average colder than normal in much of the eastern third to eastern half of the CONUS and southern Canada. However, the EPO will likely go positive and the AO could go strongly positive during the first week of December. As a result, warmer conditions will likely return after the first week in December. At present, the warmth does not appear to be too impressive. Transient shots of cooler air will remain possible. Should the AO remain elevated at strongly positive levels, the probability of a warmer than normal second half of December would increase. Overall, the base case remains a somewhat warmer than normal December as a whole, though New England and the Great Lakes region could still wind up cooler than normal. With December likely to get off to a cool start, Newark, New York City, and Boston will likely see their first measurable snowfall of the season during December 1-3. Philadelphia could also pick up its first measurable snowfall. When it comes to New York City's 4" or greater snowstorms the PNA is more important than the AO during the first half of December. Since 1950, December 1-15 has seen 10 storms bring 4.0" or more snow to New York City. 50% occurred with an AO- or AO+. However, 80% occurred when the PNA was positive. All 6" or greater snowstorms during this timeframe occurred when the PNA was positive. Based on sensitivity analysis applied to the latest guidance, New York City has an implied near 100% probability of experiencing a colder than normal November. November 2019 will likely finish with a mean temperature near 44.0°. That would make this November the coldest November since 2012 when the monthly mean temperature was 43.9°.

For those who are interested, recent shifting forecasts on the CFSv2. First, November CFSv2 forecasts and the November 1-25 temperature anomalies: The December 2019 forecasts: