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November 2019 General Discussions & Observations Thread
donsutherland1 replied to Rtd208's topic in New York City Metro
Overall, with last night's runs, I think Newark and New York City and their immediate suburbs remain on track for their first measurable snowfall of the season (likely a minor accumulation). A few individual EPS members are big hits (10" or more). The Hudson Valley, northwest New Jersey/northeastern Pennsylvania, and southeastern New York (e.g., Sullivan County) should do well. -
Winter 2019-2020 Idea
donsutherland1 replied to donsutherland1's topic in Weather Forecasting and Discussion
I hope that they are low, too. Personally, I found the snowfall estimates that came up quite dissatisfying. I would prefer a notably snowier winter. -
During September, the ENSO Region 1+2 anomaly fell below -1.00°C for multiple weeks. Since 1950, only a single El Niño winter (2002-03) followed a September with one such week. Therefore, based on a combination of the current guidance and historical ENSO data, the underlying ENSO assumption for winter 2019-2020 is a neutral (warm) ENSO state. There could be periods where the ENSO Region 3.4 anomaly is somewhat above +0.5°C, but the winter average should be neutral. For much of the winter the Region 1+2 anomaly should be negative. The September-October ENSO Region 1+2 anomaly was -0.82°C. Since 1950, 12/16 (75%) cases when the Region 1+2 anomaly averaged -0.99°C to -0.50°C had a predominantly negative PDO. In fact, the PDO fell to -0.45 in October. The last time the PDO was negative for a month was November 2018 when it was -0.05. A negative PDO winter favors a negative PNA. Since 1950, there were five years that saw the AO average -1.000 or below in November and -1.500 or below during the second half of November. Out of the total of 15 months that followed, the AO averaged < 0 during 12 (80%) and -0.500 or below during 10 (67%). This data suggests at least somewhat above average frequency of AO blocking for winter 2019-2020. However, winters during which the AO rises to +3.000 or above in December typically have less frequent blocking. Therefore, the assumption is that there will be periods of blocking and periods where blocking is absent. The NAO appears to have transitioned to a predominantly positive state. A generally positive NAO has also been modeled on the seasonal guidance. The core assumption is a positive NAO. The large pool of warm SSTAs south of Alaska has been cooling gradually in recent weeks. Warm SSTAs in that region have often been a precursor of a predominantly negative Eastern Pacific Oscillation (EPO). Based on this trend, the first half of winter 2019-2020 may see more frequent EPO blocking than the second half. Key Assumptions: 1. Neutral-warm ENSO 2. Generally positive NAO 3. Negative to somewhat positive PDO 4. AO variability 5. EPO variability with a tendency toward more positive values later in the winter. A composite temperature anomaly map is below (DJF 1950-51 through DJF 2018-19): The multi-model (C3S)outlook is below: Additional factors to be considered include the observed ongoing warming occurring in the Arctic region. Based on all of the above factors (including some weight being placed on the seasonal climate models), my estimated December-February temperature thinking is: Colder than normal (1.0° to 2.0° below normal): Eastern Canada (eastern Ontario, Quebec, Labrador, New Brunswick, Newfoundland, Nova Scotia, PEI) Near Normal (0.5° below normal to 0.5° above normal): Desert Southwest, Great Lakes Region, New England Somewhat above normal (0.5° to 1.5° above normal): Middle Atlantic Region, Plains States, West Coast, Canada (except for Eastern Canada and Northwest Canada) Warmer than Normal (1.0° to 3.0° above normal): Southeast Much Warmer than Normal (More than 3.0° above normal): Alaska, Northwest Canada (Yukon) Select seasonal snowfall estimates are below: Albany: 60"-70” Atlanta: 0.5"-2.5" Baltimore: 10”-20” Binghamton: 80”-90” Boston: 30”-40” Buffalo: 100”-110” Burlington: 80”-90” Chicago: 25”-35” Detroit: 30”-40” Nashville: 5”-10” New York City: 20”-30” Newark: 20”-30” Philadelphia: 10”-20” Providence: 25”-35” Richmond: 5”-10” Scranton: 45”-55” Sterling: 10”-20” Washington, DC: 7”-17” What could lead to higher amounts: 1. Prolonged deep blocking (AO of -1.000 or below) 2. The MJO's persistently being in Phases 7, 8, 1, and 2 at a high amplitude 3. The ENSO Region 3.4 anomaly falling to somewhat negative values as the winter progresses 4. A mainly negative NAO What could lead to lesser amounts: 1. The development of a persistently positive AO coupled with a strongly negative SOI 2. The MJO's persistently being in Phases 4, 5, and 6 at a high amplitude 3. Dramatic warming in ENSO Region 1+2
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November 2019 General Discussions & Observations Thread
donsutherland1 replied to Rtd208's topic in New York City Metro
Despite clouds and some widely scattered showers, temperatures again rose into the upper 50s and lower 60s in the Middle Atlantic and southern New England regions. In the wake of a cold front, tomorrow will turn partly sunny, cooler with strong winds that could gust past 40 mph in much of the region. Some areas could experience gusts near 50 mph. Wind advisories may need to be extended to the New York City Metro Area tomorrow. In northern Alaska, Utqiagvik (formerly Barrow) is concluding its warmest autumn on record with what will likely be its second warmest November on record. Based on the latest guidance, Utqiagvik will likely have a September-November mean temperature ranging from 28.4°-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 -7.26 today. Today, the preliminary Arctic Oscillation (AO) figure was -0.754. Daily MJO data was unavailable for November 26. 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. As a milder pattern develops in the CONUS, Europe will likely see the cold give way to the pattern that has predominated in November where Scandinavia is colder than normal while much of Europe is warmer than normal. 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. Should the AO have a sustained period of strongly positive levels, the risk of greater warmth than described above would increase. With December likely to get off to a cool start, the potential for at least some snowfall in the Philadelphia to Boston area could exist. The first such opportunity could occur during the December 1-3 timeframe. Although the season's first measurable snowfall is possible in New York City and Newark, amounts will likely be minor. 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 44.1°. That would make this November the coldest November since 2012 when the monthly mean temperature was 43.9°. -
Occasional Thoughts on Climate Change
donsutherland1 replied to donsutherland1's topic in Climate Change
Mann was accused of manipulating data in an attack on his professional and personal integrity. -
Occasional Thoughts on Climate Change
donsutherland1 replied to donsutherland1's topic in Climate Change
The Supreme Court declined to block Michael Mann’s defamation case from proceeding to trial. IMO, this is good news, as the defendants made harsh allegations for which they had no evidence. Debate is undermined when parties fabricate allegations aimed at diverting discussion from the merits, especially when character is attacked to intimidate others into silence. This latest legal development is good news, both from a legal and debate perspective. -
November 2019 General Discussions & Observations Thread
donsutherland1 replied to Rtd208's topic in New York City Metro
The hemispheric meteorological situation is quite dynamic as November nears a conclusion. Some of the factors that contributed to what is all but certain to be a cold November outcome in the eastern half of the CONUS along with much of eastern Canada, are now abating. The EPO was negative to strongly negative for 14 of the first 15 (93%) days of November. The Arctic Oscillation (AO) was negative to strongly negative on 13/15 (92%) days of November and has been negative every day beginning November 3. However, the EPO has now been fluctuating between weakly negative and weakly positive. The AO is forecast to rise sharply perhaps to +3.000 or above in early December. Indeed, the recent changes in the CFSv2 December forecasts provide a hint of the changing conditions. The CFSv2 is now in the skillful part of its monthly forecasting range. CFSv2 Monthly Forecasts for December: 11/19-11/27: Through December 6, no significant stratospheric warming events are likely (EPS). The recent minor warming will have little impact on the polar vortex. While rumors have been flying on Social Media about an imminent significant or major stratospheric warming event, there remains little credible evidence for such an event through 240 hours. Not suprisingly, the idea that the much hyped event would occur during the opening of December now appears unlikely to verify. As noted in past winters, Social Media is a poor place to obtain stratospheric information. With a handful of exceptions, most of those commenting on such events simply read forecast 10 mb charts. However, the atmosphere is three-dimensional. What happens at 10 mb won't necessarily occur above or below. One needs to look at all the layers of the atmosphere before reaching conclusions. Not surprisingly, there are many more calls for such warmings on Social Media than typically verify. Usually, such events occur once or sometimes twice during an entire winter. They are less frequent early in the winter. Some winters also see none. These are important reminders that readers should be wary of such calls, especially as such events are not well-forecast at long timescales. The strong model consensus for the AO to go positive and then strongly positive is consistent with the state of stratosphere. Were the AO to rise to +4.000 as shown on a few ensemble members, December would be very likely to wind up warmer than normal in the Middle Atlantic region and perhaps much of the East. Such cases are uncommon. Since 1950, there have been three such cases: 1979, 2011, and 2013. Finally, the MJO's progression through Phases 6, 7, and 8 in November at high amplitude have often preceded a mild December in the East. All said, while the first week of December could wind up cooler than normal in the East, with perhaps the first measurable snow of the season in Boston, New York City, and Newark, but not a lot of snow, the idea that warmer conditions could develop after the first week to perhaps 10 days of December seems reasonable. Overall, given the forecast teleconnections, the probability of a somewhat warmer than normal December in the East (New England might be an exception, but that is not assured) has increased. -
An update concerning the issue of extreme ideas being broadcast on Social Media. https://www.americanwx.com/bb/topic/52511-autumn-2019-banter-thread/page/5/?tab=comments#comment-5338034 The cold pattern that was supposed to lock into place after mid-month: The November 16-24 anomalies: Based on the latest guidance, Chicago will likely wind up just below 0.5° above normal for the second half of November and New York City will wind up perhaps a little below 2.0° below normal. In short, the extreme scenario does not appear likely to verify. The conclusion at that time (October 30): In sum, the coldest weather of the season so far is likely to develop beginning in early November with perhaps the strongest shot of cold reaching the East during the second week of the month. However, even allowing for uncertainty, there is little support for the idea that the notable cold shown at the end of the GEFS will lock in. For forecasting purposes, one should be wary of extreme calls without really strong supporting evidence. The teleconnection forecast at the time argued against such an outcome. The final conclusion will be posted following November (probably in early December as it takes a few days for the anomalies maps to be updated).
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Many thanks for tagging me. It was an exciting event for Colorado and it will be interesting to see the storm as it continues to track eastward.
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November 2019 General Discussions & Observations Thread
donsutherland1 replied to Rtd208's topic in New York City Metro
Above normal temperatures prevailed again in much of the region today. Today, New York City reached 61°. That was the highest temperature since November 11 when the thermometer reached 62°. In northern Alaska, Utqiagvik (formerly Barrow) is concluding its warmest autumn on record. Based on the latest guidance, Utqiagvik will likely have a September-November mean temperature ranging from 28.2°-28.4°. 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 -8.34 today. Today, the preliminary Arctic Oscillation (AO) figure was -0.745. Daily MJO data was unavailable for November 25. Recent runs of the GEFS, ECMWF, and EPS all continue to suggest that the AO could go positive during the first week in December. Some of the guidance suggests that the AO will go strongly positive. Based on the consistently-modeled idea of a negative to strongly negative EPO (-2.000 to -1.000) to begin December, the first 7 to perhaps 10 days of December will likely average colder than normal in much of the eastern third to eastern half of the CONUS and southern Canada. Warmer conditions will likely return as Atlantic blocking dissipates for at least a period of time. 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. Should the AO rise to strongly positive levels, the risk of greater warmth than described above would increase. With December likely to get off to a cool start, the potential for at least some snowfall in the Philadelphia to Boston area could exist. The first such opportunity could occur during the December 1-3 timeframe. The risk of measurable snow in parts of this area, including New York City and Newark, has increased in recent days. 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. The latest guidance now suggests that the PNA could be somewhat positive during the December 1-3 period. 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 be the coldest November since 2012 when the monthly mean temperature was 43.9°. -
November 2019 General Discussions & Observations Thread
donsutherland1 replied to Rtd208's topic in New York City Metro
Above normal temperatures prevailed in much of the region today. Tomorrow will likely be even warmer with temperatures topping out in the upper 50s and lower 60s across the Middle Atlantic region. In northern Alaska, Utqiagvik (formerly Barrow) is concluding its warmest autumn on record. Based on the latest guidance, Utqiagvik will likely have a September-November mean temperature ranging from 28.1°-28.5°. 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 -13.62 today. Today, the preliminary Arctic Oscillation (AO) figure was -0.329. Daily MJO data was unavailable for November 24. Even as the recent MJO progression through Phases 6, 7 and into 8 at high amplitude has typically preceded a mild December, there remains uncertainty concerning the longer-term evolution of the teleconnections. However, recent runs of the GEFS, ECMWF, and EPS all suggest that the AO could go positive during the first week in December. Some of the guidance suggests that the AO will go strongly positive. With no significant stratospheric warming events likely through at least December 4, there could be an elevated likelihood that the AO will go positive during the first week in December. Based on the consistently-modeled idea of a negative to strongly negative EPO (-2.000 to -1.000) to begin December, at least the first 7-10 days of December will likely be colder than normal in much of the eastern third to eastern half of the CONUS and southern Canada. Warmer conditions could return should Atlantic blocking dissipate. Unseasonable warmth will likely prevail in much of Alaska, including areas that are experiencing their warmest autumn on record. The base case remains a somewhat warmer than normal December as a whole, though New England and the Great Lakes region could be cooler than normal. With December likely to get off to a cold start, the potential for at least some snowfall in the Philadelphia to Boston area could exist. The first such opportunity could occur during the December 1-3 timeframe. 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 be the coldest November since 2012 when the monthly mean temperature was 43.9°. -
November 2019 General Discussions & Observations Thread
donsutherland1 replied to Rtd208's topic in New York City Metro
The storm that brought a soaking rain to much of the region, along with some snow is now departing. In its wake, milder weather will follow. Precipitation amounts through 7 pm included: Allentown: 1.06"; Boston: 1.49"; Bridgeport: 0.46"; Islip: 0.74"; New York City: 0.93"; Newark: 0.74"; Philadelphia: 0.88"; Poughkeepsie: 1.28"; and, Providence: 1.43". A few locations also saw some snow today. Snowfall amounts included: Albany: 0.2"; Binghamton: 2.6"; Harrisburg: Trace; and, Philadelphia: Trace. In northern Alaska, Utqiagvik (formerly Barrow) is concluding its warmest autumn on record. Based on the latest guidance, Utqiagvik will likely have a September-November mean temperature ranging from 28.0°-28.5°. The current record is 26.0°, which was set in 2016. The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was +0.8°C for the week centered around November 13. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.68°C and the ENSO Region 3.4 anomaly has averaged +0.63°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 -10.88 today. Today, the preliminary Arctic Oscillation (AO) figure was -0.731. Daily MJO data was unavailable for November 23. Even as the recent MJO progression through Phases 6, 7 and into 8 at high amplitude has typically preceded a mild December, there remains uncertainty concerning the longer-term evolution of the teleconnections. However, recent runs of the GEFS, ECMWF, and EPS all suggest that the AO could go positive during the first week in December. Some of the guidance suggests that the AO will go strongly positive. With no stratospheric warming events likely through at least December 3, there could be an elevated likelihood that the AO will go positive during the first week in December. Based on the consistently-modeled idea of a negative to strongly negative EPO (-2.000 to -1.000) to begin December, at least the first 7-10 days of December will likely be colder than normal in much of the eastern third to eastern half of the CONUS and southern Canada. Warmer conditions could return should Atlantic blocking dissipate. Unseasonable warmth will likely prevail in much of Alaska, including areas that are experiencing their warmest autumn on record. The base case remains a somewhat warmer than normal December as a whole, though New England and the Great Lakes region could be cooler than normal. With December likely to get off to a cold start, the potential for at least some snowfall in the Philadelphia to Boston area could exist. The first such opportunity could occur during the December 1-3 timeframe. The PNA is forecast to be somewhat negative. 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 be the coldest November since 1996 when the monthly mean temperature was 43.0°. -
November 2019 General Discussions & Observations Thread
donsutherland1 replied to Rtd208's topic in New York City Metro
Persistence of blocking is often key. The first half of November saw an EPO-/AO- combination and November has had 17/24 days with a negative EPO and 22/24 days with a negative AO. Since 1950, just over 70% of December cases with an AO average of +1.000 or above were warmer than normal in much or all of the East. Finally, as seems to be almost a perennial occurrence each winter, Social Media was filled with chatter of an imminent significant stratospheric warming event. In fact, none appears likely through December 3 (EPS). -
November 2019 General Discussions & Observations Thread
donsutherland1 replied to Rtd208's topic in New York City Metro
Some photos from this morning near high tide on the Long Island Sound. The temperature was 46° with drizzle. -
November 2019 General Discussions & Observations Thread
donsutherland1 replied to Rtd208's topic in New York City Metro
At 10 pm, areas of light rain were moving through the region from the south and west. Areas of moderate to heavy rain were located over Virginia and the Carolinas. As the approaching system strengthens and tracks through the region tomorrow, the areas of rain will likely consolidate. By the time the rain ends, much of the region will see 0.50" to 1.50" rain. Some locally higher amounts near or just above 2.00" are possible. Ahead of the storm, New York City had picked up 44.97" precipitation (72nd highest annual amount) and Newark had seen 51.32" (14th highest annual amount). Rankings for New York City and Newark for select precipitation amounts are below: -
November 2019 General Discussions & Observations Thread
donsutherland1 replied to Rtd208's topic in New York City Metro
A moderate to significant rainfall will affect the big cities of the northern Middle Atlantic and southern New England areas late tonight into tomorrow. Cities such as New York, Newark, Providence, and Boston will likely pick up 0.50"-1.50" precipitation with some locally higher amounts near 2.00". In northern Alaska, Utqiagvik (formerly Barrow) is now concluding its warmest autumn on record. Based on the latest guidance, Utqiagvik will likely have a September-November mean temperature ranging from 28.0°-28.5°. The current record is 26.0°, which was set in 2016. The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was +0.8°C for the week centered around November 13. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.68°C and the ENSO Region 3.4 anomaly has averaged +0.63°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 -4.08 today. Today, the preliminary Arctic Oscillation (AO) figure was -1.723. Daily MJO data was unavailable for November 22. Even as the recent MJO progression through Phases 6, 7 and into 8 at high amplitude has typically preceded a mild December, there remains uncertainty concerning the longer-term evolution of the teleconnections. However, recent runs of the GEFS, ECMWF, and EPS all suggest that the AO could go positive during the first week in December. Based on the consistently-modeled idea of a negative to strongly negative EPO (-2.000 to -1.000) to begin December, at least the first 7-10 days of December will likely be colder than normal in much of the eastern third to eastern half of the CONUS and southern Canada. Warmer conditions could return should Atlantic blocking dissipate. Unseasonable warmth will likely prevail in much of Alaska, including areas that will see their warmest autumn on record. With December likely to get off to a cold start, the potential for at least some snowfall in the Philadelphia to Boston area could exist. The first such opportunity could exist during the December 1-3 timeframe. 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 99% probability of experiencing a colder than normal November. November 2019 will likely be the coldest November since 1996 when the monthly mean temperature was 43.0°. -
November 2019 General Discussions & Observations Thread
donsutherland1 replied to Rtd208's topic in New York City Metro
Most of the past cases with high amplitude MJO passages through Phases 6, 7, 8 in November eventually reached the warmer phases in December. Long-range MJO forecasting skill isn’t great. Compounding things, there remains a strong positive Indian Ocean Dipole. I think there will be greater clarity in about a week. -
November 2019 General Discussions & Observations Thread
donsutherland1 replied to Rtd208's topic in New York City Metro
I still think the overall idea that December will finish somewhat warmer than normal despite a cold start. But we’ll see how the teleconnections are evolving as we get closer. Lately, the extended range of such forecasts has fared badly. -
November 2019 General Discussions & Observations Thread
donsutherland1 replied to Rtd208's topic in New York City Metro
Their lead December analog is 1995. -
November 2019 General Discussions & Observations Thread
donsutherland1 replied to Rtd208's topic in New York City Metro
The breakdown of Atlantic blocking is part of the reason the EPO- cold to start December (noted above) often gave way to warmer conditions within 10-12 days. -
November 2019 General Discussions & Observations Thread
donsutherland1 replied to Rtd208's topic in New York City Metro
The EPO is forecast to fall to between -2.000 and -1.000 as November concludes. Such a development has typically seen colder than normal temperatures move into the East. Below are the composite temperature anomalies for all EPO cases from -2.000 to -1.000 (December 1-7, 1981-2018)+ 3 days: Should Atlantic blocking break down and/or the EPO- regime collapse, there would be an increased probability that the cold could be replaced by a warmer regime. From the above composite, the typical cold period lasted 10-14 days. -
November 2019 General Discussions & Observations Thread
donsutherland1 replied to Rtd208's topic in New York City Metro
A moderate to significant rainfall will affect the big cities of the northern Middle Atlantic and southern New England areas late tomorrow into Sunday. Cities such as New York, Newark, Providence, and Boston will likely pick up 0.50"-1.50" precipitation with some locally higher amounts near 2.00". In northern Alaska, Utqiagvik (formerly Barrow) is now concluding its warmest autumn on record. Based on the latest guidance, Utqiagvik will likely have a September-November mean temperature ranging from 27.8°-28.3°. The current record is 26.0°, which was set in 2016. The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was +0.8°C for the week centered around November 13. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.68°C and the ENSO Region 3.4 anomaly has averaged +0.63°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 -2.42 today. An SOI reading of -30 or below, as occurred on November 4-5, also occurred during three prior years in the November 1-10 timeframe. All three cases featured a warmer than normal December. The average temperature for those three cases was 2 degrees warmer than normal. Today, the preliminary Arctic Oscillation (AO) figure was -2.258. Daily MJO data for November 21 was unavailable. Even as the recent MJO progression through Phases 6, 7 and into 8 at high amplitude has typically preceded a mild December, there remains considerable uncertainty concerning the longer-term evolution of the teleconnections. Based on sensitivity analysis applied to the latest guidance, New York City has an implied 99% probability of experiencing a colder than normal November. November 2019 will likely be the coldest November since 1996 when the monthly mean temperature was 43.0°.