donsutherland1

At 3 pm, TEB was reporting an 82° reading. That figure is suspect, as it is notably warmer than the temperature at any other nearby location.

With today's 76°-57° split and the latest MOS guidance, the implied probability that October 2017 will become the warmest October on record has increased to about 2-in-3. The implied probability that October 2017 will become the first October to register a monthly mean temperature of 64° or above has increased to about 3-in-5. On account of the warm sunshine, large amounts of Monarchs were continuing to migrate southward across the New York area.

With yet another morning of warm sunshine and readings in the lower 60s by mid-morning, the Monarch migration remained underway.

With today’s 73°-57° temperature range in Central Park, that station has a mean monthly temperature of 65.8°. If one incorporates the MOS MEX values and operational GFS forecast for the remainder of the month (with errors as high as 10° per day, which are unlikely in the near-term), there would be an implied probability of 51% for October 2017's surpassing Octobers 1947 and 2007 as the warmest on record. Implied probabilities for select October monthly mean temperatures are below: 61°: 88% 62°: 76% 63°: 62% 64°: 45% 65°: 29% Taking into consideration the 12z ECMWF, a monthly mean temperature of around 64° remains plausible.

What happens in December will likely provide strong insight. Since 1869-70, NYC had seen 17 cases when October had a mean temperature of 60° or above and November had a mean temperature of 45° or above (one of which was 2007). Mean snowfall for the following winter was 21.6" (median: 18.1"). 53% of those winters had less than 20" snow; 41% had less than 15" snow; 47% had 20" or more snow; 24% had 30" or more snow. The subset that saw less than 4" snowfall in December wound up with a mean seasonal total of 15.2" (median: 11.9"). 73% of those winters had less than 20" snowfall and 64% less than 15". The most recent winter in that group was 2007-08 with 11.9" snow. The subset that saw 4" or more snowfall in December wound up with a mean seasonal total of 33.2" (median: 27.6"). 83% of those winters saw 20" or more snow and 50% saw 30" or more snowfall. The most recent winter in that group was 2013-14 with 57.4" snow.

The MJO was in Phase 5 with an amplitude of 3.479 on October 18. That is a new October record for Phase 5. 2017 set the record on October 16 with an amplitude of 3.421. Similar extreme events have seen the seasonal winter temperature anomaly in the eastern U.S. (including the Midwest) wind up warmer than normal if November was warmer than normal or colder than normal if November was colder than normal. Aside from a possible cold shot during the first half of November from the impact of Lan's recurvature on the jet stream, odds lean toward a warmer than normal November right now. It should also be noted that Lan does not appear likely to rival Nuri's (2014) intensity as it recurves and passes north of the Aleutian Islands in the extended range.

There's a lot of guidance suggesting it could happen. Taking into consideration uncertainty and modeling error, even as the outcome is not yet assured, it's plausible. Taking the ECMWF through the 30th and then assuming the 31st finished with a normal daily mean temperature, the monthly mean would wind up near 64°. So, we'll see what happens. If this month winds up the warmest October on record, the outcome will represent another case where persistent warmth rather than extreme warmth during a short period of time was the driving factor.

Not yet. It's currently the 4th warmest October through the 19th with a mean temperature of 65.8°. If the mean temperature for the October 20-31 period is 60.2°, October 2017 would surpass October 1947's and 2007's monthly record high mean temperature of 63.6°,

Eduardo, I believe it is a short-term effect. The November cold shot can be attributed to it. The extreme February probably can't. The EPO can't be predicted at long timeframes with a great deal of accuracy, though there is some correlation between SSTAs and the EPO.

So far, it looks like a warmer than normal November could be on tap. A wildcard might be concern the possibility of a strong Pacific typhoon's recurvature. Much as happened with Nuri (2014), there might be the risk of a strong shot of cold sometime in the first half of November. For now, that's highly speculative.

Yesterday saw the temperature fall below 50° for the first time this fall in Central Park. 2017 is only the fourth year on record that the first sub-50° reading occurred so late in the season. The other three years are: 1955: October 16 1995: October 16 2005: October 20 In addition, on October 15, the MJO was in Phase 5 with an amplitude of 3.293. That was the 3rd highest figure on record for October in Phase 5. Only October 4, 1979 (Amplitude: 3.311) and October 1, 1979 (Amplitude: 3.298) had a higher amplitude. The highest October amplitude on record occurred during Phase 1 of the MJO on October 18, 2011 (3.602). The following years saw the MJO reach amplitudes of 2.000 or above during Phase 5 in October: 1979, 1988, 1998, 2006, 2008, and 2010. Typically November’s temperature anomalies in the East (from the MJO sample and late sub-50° sample) provided a good idea of the predominant temperature anomalies during meteorological winter in the East. Therefore, as goes November in the East, so might the winter go, so to speak when it comes to temperature anomalies.

38° at sunrise, along with unusually great visibility.

For the first time, the International Monetary Fund's (IMF) semiannual World Economic Outlook report contains a chapter devoted to climate change. The chapter discusses, among other things, the relationship between temperature and precipitation shocks on economic activity, how countries can cope with such shocks, the issue of mitigation, and how low-income countries might be impacted by expected temperature increases through the end of the 21st century. This report provides further evidence that there is deepening understanding that climate change has impacts beyond changes in temperature, precipitation, and other weather-related extremes. The chapter can be found at: http://www.imf.org/en/Publications/WEO/Issues/2017/09/19/~/media/Files/Publications/WEO/2017/October/pdf/analytical-chapters/c3.ashx

At 5 am, now post-tropical Hurrican Ophelia was centered near 51.3°N 11.4°W. Ophelia still had a large area of 75-knot (85 mph) winds as it headed north-northeast and was poised to turn somewhat more to the northeast toward Ireland. At 6 am, Cork Airport was reporting sustained winds of 41 knots (47 mph) with gusts to 67 knots (77 mph). Roches Point had sustained winds of 50 knots (58 mph) with gusts to 70 knots (81 mph). Based on the EPS, ECWMF, and GEFS, later today, Ophelia will likely pass near or over the Beara and Dingle Peninsulas and then likely somewhere between Clifden and Galway as it tracks northeastward. Ophelia should remain at hurricane strength as it passes over those areas.

Thin squall line (let's see if it holds together for later tonight):