donsutherland1

Previously, the forecast state of the teleconnectiions suggested that the upcoming storm's heaviest precipitation would likely miss the Philadelphia to New York City corridor. Instead, areas on Long Island and New England would have a better chance at seeing 1" or more precipitation. https://www.americanwx.com/bb/topic/51583-october-2018-discussions-observations-thread/?do=findComment&comment=5006049 The caveat was that the event was still 9-12 days away and that much could change (as often happens in the guidance). Now that the event is less than 48 hours away, the details are coming into place. The general idea that the heaviest precipitation would wind up in the area suggested by a probabalistic look at the teleconnection indices (parts of Long Island and New England) still looks reasonable. However, a widespread area of 1"-1.5" rain appears likely. That area includes Philadelphia to New York City. However, the region most likely to see 1.5" or more extends from eastern Suffolk County, across eastern Massachusetts and then parts of Maine (10/25 12z GFS). Select GFS figures: Baltimore: 1.7” Bangor: 1.9” Boston: 1.7” Harrisburg: 1.4” Montauk Point: 2.0” New York City: 1.5” Newark: 1.5” Philadelphia: 1.3” Plymouth: 2.9” Washington, DC: 1.7” Select NAM figures: Baltimore: 0.8” Bangor: 0.8” Boston: 1.2” Harrisburg: 0.9” Montauk Point: 1.4” New York City: 0.9” Newark: 0.9” Philadelphia: 0.7” Plymouth: 1.6” Washington, DC: 0.9” Those rainfall totals will add to the excessive precipitation that has fallen across parts of the Middle Atlantic region this year. Select figures through 10/24: Baltimore: 55.72” (7th highest annual figure) Harrisburg: 51.47” (8th highest annual figure) New York City: 50.05” (33rd highest annual figure) Philadelphia: 44.92” (45th highest annual figure) Richmond: 52.50” (16th highest annual figure) Scranton: 50.05” (3rd highest annual figure) Washington, DC: 51.64” (13th highest annual figure) Wilmington, NC: 87.46” (highest annual figure on record)

Over the past two days, the guidance has moved aggressively toward paring back the magnitude of the cold that the models had suggested would predominate during the closing week of October. As a result, the implied probability for an October 16-31 period with a mean temperature of 49° or below has tumbled from 60% to 34%. That period could average within 0.5° of 50°, which is still remarkably cool for cases when the first 15 days of October had a mean temperature of 65° or above. The implied probability for October’s having an above normal monthly anomaly is currently 76% (estimated range: 57.2°-58.6°). Going into November, there are growing indications that the first half of the month could see the pattern turn warmer than normal as the trough retreats to the center of the CONUS and ridging tries to take hold in the East. The EPS weekly forecast favors a continuation of below normal temperatures through most of the first half of November, but the possible rise in the AO, decline in the PNA, and near neutral to somewhat positive EPO favor an evolution toward the kind of milder pattern that has predominated for the most part during the autumn. However, the warmth likely won’t be as extreme relative to normal as it had been. The latest CFSv2 weekly forecast is particularly aggressive with the return to warmer anomalies. Taking into consideration the preponderance of the guidance and teleconnection forecast, the odds likely favor an evolution to a milder pattern during the first half of November. This could favor November’s winding up somewhat warmer than normal as a whole.

Through the first 15 days of October, New York City had a mean temperature of 66.2°, ranking that period the 11th warmest 10/1-15 period on record. Records go back to 1869. Since then, the temperature has averaged 51.0°. Given the latest guidance, it is likely that the 10/16-31 period will rank among the 10 coldest on record. The 10 coldest 10/16-31 periods are: 1. 46.8°, 1940 2. 47.3°, 1886 3. 47.5°, 1925 and 1976 5. 47.7°, 1888 6. 48.1°, 1887 7. 48.6°, 1882 8. 48.7°, 1907 9. 48.8°, 1879 10. 49.0°, 2002 Applying sensitivity analysis to the guidance, the implied probability of a mean 10/16-31 average temperature of 49.0° or below was 60%. The implied probability of a 10/16-31 mean temperature below 46.8° was 36%. Looking at the larger record, 13 years had a mean temperature below 50° for the 10/16-31 period. Select snowfall data for the subsequent winters is below: Mean snowfall: 35.0” Median snowfall: 32.9” Least snowfall: 16.5”, 1888-89 Most snowfall: 60.4”, 1922-23 Frequency of Select Outcomes (13 cases with a 10/16-31 mean temperature < 50°): < 20” snow: 8% (historic frequency: 32%) 30” or more snow: 62% (historic frequency: 41%) 40” or more snow: 31% (historic frequency: 24%)

With 0.01" rain by 3 am today, New York City's 2018 total precipitation reached 50.00" for the 33rd time on record and first time since 2014 when 53.79" precipitation fell. Records go back to 1869. 21 (64%) of those cases occurred after 1970. Number and Frequency of Years with 50.00” or More Precipitation: Historic Period (1869-2018): 33 years; Return time: 4.5 years 1869-1970: 12 years; Return time: 8.5 years 1971-2018: 21 years; Return time: 2.3 years 2000-2018: 10 years; Return time 1.9 years Mean Annual Precipitation: Historic Period: (1869-2017): 45.27” 1869-1970: 42.89” 1971-2017: 50.42” 2000-2017: 50.58” Note: excludes 2018, as 2018 has not ended Implied Probabilities for Annual 2018 Precipitation: Historic Period (1869-2017) Scenario: 55.00” or more: 88% 60.00” or more: 31% 1971-2017 Period: 55.00” or more: 90% 60.00” or more: 47% All of New York City’s years during which 60.00” or more precipitation fell occurred after 1970.The most recent such year was 2011 when 72.81" precipitation fell. October 21-December 31 Precipitation Records: Least precipitation: 2.75", 1998 Most precipitation: 19.53", 1972

At 2:30 pm, an area of rain extended from parts of Arkansas across Missouri, Illinois, Indiana, and Michigan into Ontario. That area of rain and showers was associated with a frontal system that will cross the region tomorrow morning. Even as precipitation amounts should be light, the guidance suggests that Central Park will likely receive the 0.01" it needs in order for 2018 to become New York City's 33rd year on record with 50" or more precipitation. To date, 2018 has seen above to much above normal precipitation in the Middle Atlantic region. 2018's total precipitation was as follows for select sites (the start of their recordkeeping is in parentheses): Asheville (1869): 59.54” (5th wettest year) Baltimore (1871): 55.66” (7th wettest year) Harrisburg (1888): 51.32” (8th wettest year) New York City (1869): 49.99” (33rd wettest year) Oakland (1 SE), MD (1893): 59.46” (6th wettest year) Richmond (1887): 52.42” (16th wettest year) Scranton (1901): 49.69” (3rd wettest year) Washington, DC (1871): 51.55” (13th wettest year) Wilmington, NC (1870): 87.46” (wettest year on record)

There was lots of frost on vehicles and the grass in southern Westchester County this morning.

Islip's monthly low temperature of 36° occurred on October 29. On October 27 (low temperature of 40°), Islip had a trace of snow. New York City's (Central Park) monthly low temperature of 38° occurred on October 26.

This morning, the temperature fell to 42° in New York City’s Central Park. Some of the guidance had suggested that the temperature could fall into the upper 30s. The next shot at such a low would be Monday morning. The GFS MOS currently forecasts a low temperature of 40°. Outside the City, low temperatures fell into the 30s including (as of 8 am): Bridgeport: 39° Danbury: 37° Morristown: 39° Poughkeepsie: 37° White Plains: 39° Tonight, many of those locations will see even colder temperatures on account of radiational cooling. Places such as Danbury, Poughkeepsie, and Westhampton could see readings fall below 30°. New York City has seen an increase in October cases where the temperature has not fallen below 40°. This increase has been occurring after 1950, by which time the City had a mature urban footprint. During the period beginning in 2010, October cases with the lowest temperature of 40° or above have become as likely as those with a monthly minimum temperature below 40°. Return Times for October Cases with a Monthly Minimum Temperature of 40° or Above: Historic (1869-2017): 4.7 years 1869-1950: 5.9 years 1950-2017: 3.8 years 1980-2017: 3.5 years 2000-2017: 3.6 years 2010-2017: 2.0 years At the same time, cases with at least one October temperature of 32° or below have diminished in frequency. Since 1950, there have been 11 such cases. The last such occurrence was October 31, 1988 when the temperature fell to 31°. Given the latest guidance, New York City will likely extend that stretch to 30 years when October concludes. The previous longest such stretch was 25 years and 7 days (from October 22, 1940 to October 29, 1965). Overall, based on sensitivity analysis applied to the guidance, there is an implied 69% probability that October will finish with an above normal monthly temperature despite the cooler second half of the month.

That was October 2016. NYC, though, only got down to 38° and ISP to 36°. In October 2017, both locations had their lowest monthly readings as 42° and 40° respectively.

There have been some heavier snow showers and squalls in parts of the Adirondacks this afternoon. Winter is approaching.

Through October 15, the temperature has averaged 66.2° in New York City’s Central Park. That makes 2018 the 11th warmest October 1-15 period on record. Records go back to 1869. The second half of October looks to be notably cooler than the first half. In fact, it could be among the coolest periods to close October from among the cases where the first 15 days had averaged 65° or above, with a mean temperature of 54° or below for the 10/16-31 period. Select data for 15 prior cases with an October 1-15 mean temperature of 65° or above: October 16-31: Mean temperature: 55.7° Lowest: 49.8°, 1922 Highest: 60.7°, 2007 October Monthly Average Temperature: Mean temperature: 61.1° Lowest: 58.1°: 1922 Highest: 64.1°, 2017 Sensitivity analysis applied to the guidance: Probability of a warmer than normal October: 66% Estimated range for the October 16-31 period: 49.0°-54.0° Estimated range for the October 2018 mean temperature: 56.8° - 59.7° The relatively cool conclusion to October after a very warm start has often coincided with a snowy winter. From among the 15 cases cited above, 6 had a mean temperature below 55° during the October 16-31 period. Four of those cases saw 30” or more snow during the following winter. Even as the GFS has persistently signaled the potential for a significant storm to close October, the forecast state of the teleconnections suggests that such a storm could take a course in which the heaviest precipitation misses the Philadelphia to New York City corridor. Areas on Long Island into New England could have a better chance of seeing 1” or more precipitation. Much can still change, as the period in question is approximately 9-12 days away. Finally, the latest EPS weekly guidance is colder than the CFSv2 for the first week in November. The former maintains a fairly deep trough in the means in the East.

That’s very impressive, as they radiate much better than the City does.

This morning's temperature of 47° was New York City's first reading below 50° this fall. 2018 became only the 8th year on record that New York City had not seen such a temperature through October 12. Despite what is likely to be a cooler than normal stretch, October remains on track to finish warmer than normal in NYC with a mean temperature just under 60°. Normal is 56.9°. In addition, with the 0.04" rain that has fallen so far, New York City's total precipitation for 2018 has reached 49.87". That ranks 2018 as the City's 33rd wettest year, just ahead of 1934 when 49.84" precipitation was recorded for the year.

Some areas around the City have received significantly more precipitation. It has been super wet in parts of the area.

In the wake of the rainfall associated with a passing cold front and tropical storm Michael, New York City's 2018 precipitation has reached 49.83". That figure ties 2018 with 1936 as New York City's 34th wettest year on record. New York City still has more than two-and-a-half months to add to its figure. 2018 is already among the 20 wettest years in numerous cities in the Middle Atlantic, Southeastern, and southern New England regions. Select locations: Baltimore: 55.41" (8th wettest) Bridgeport: 45.52" (21st wettest) Harrisburg: 51.16" (8th wettest) Islip: 47.34" (19th wettest) Richmond: 52.18" (16th wettest) Washington, DC: 51.34" (13th wettest) Wilmington, NC: 87.36" (wettest year on record) The rankings relate to total annual precipitation figures, not year-to-date figures. Based on both the historical climate record (1869-2017) and recent period (1971-2017) when a wetter regime appears to have developed, it appears more likely than not that 2018 will be among New York City's 10 wettest years on record. Some probabilities: Historic Data: 50" or more: >99% 55" or more: 91% 60" or more: 41% 65" or more: 4% 10th wettest (58.42"): 60% 1971-2017 Data: 50" or more: >99% 55" or more: 92% 60" or more: 56% 65" or more: 13% 10th wettest (58.42"): 71% Historic extremes (October 13-December 31): Least precipitation: 3.14", 1998 Most precipitation: 20.37", 1983 Mean precipitation: 9.42" 1971-2017 mean precipitation: 10.78"

As of 5:20 pm, Richmond had picked up 0.41" rain. That brings 2018 precipitation to 49.00". As a result, 2018 now ranks just ahead of 1923 as Richmond's 31st wettest year on record. During 1923, Richmond had 48.96" precipitation. 7 pm update: Richmond's annual precipitation reached 50.00". 2018 is only the 24th year on record with 50.00" or more precipitation in Richmond.

A downpour near 5 pm brought New York City an additional 0.23" rain in just 10 minutes. The 2018 figure has now climbed to 48.97", which ranks 2018 as the City's 38th wettest year on record.

The NHC had been warning that Michael would make landfall as a major hurricane by late Monday. Its discussion Monday night also highlighted unusual behavior in the face of sheer. If the general public were expecting anything less than a major hurricane at landfall, the general public wasn’t paying adequate attention to the NHC. The NHC had been forecasting a major hurricane to make landfall more than 36 hours in advance, which is quite good given intensity forecasting challenges. Any complacency likely would have had more to do with skewed expectations based on the high-visibility weakening of Florence, memories of Opal's rapid weakening ahead of landfall, overconfidence due to the lack of recent major hurricanes making landfall on the Florida Panhandle, and expectations that the storm would shift course. Here are some highlights from select NHC discussions: Monday (10/8) 4 am CDT NHC discussion: An Air Force Reserve Hurricane Hunter aircraft made several passes through the system during the past few hours, and somewhat surprisingly, found that the central pressure has fallen to about 983 mb and maximum winds have increased to near 60 kt. This increase in intensity indicates that despite the shear which has been affecting Michael, the system has, by definition, rapidly intensified during the past 24 hours... This new official forecast brings the intensity to just below major hurricane strength in 48 hours, and since the storm will still be over water for a time between 48 and 72 hours, there is a real possibility that Michael will strengthen to a major hurricane before landfall. Monday (10/8) 4 pm CDT NHC discussion: Forecast 100 kts near landfall -- about 44 hours before landfall Data from an Air Force Reserve hurricane hunter aircraft that was in the storm until about 1700 UTC continued to indicate that the hurricane was deepening. The pressure had fallen to 978 mb on the final fix, but the aircraft was still not able to sample the northeastern portion of the storm due to the close proximity of land. The initial intensity has been increased to 70 kt based on a blend of Dvorak satellite classifications and the continued deepening that was observed… Although the statistical guidance is somewhat lower this cycle, the regional hurricane and global models still favor steady to rapid strengthening… Monday (10/8) 10 pm CDT NHC discussion: Notice that something unusual appeared to be taking place Data from NOAA and Air Force Reserve hurricane hunter aircraft this evening indicate that Michael has continued to strengthen...despite westerly vertical shear of about 20 kt, which is most unusual… Michael's steady intensification over the past 48 hours in the face of 20-kt westerly shear defies traditional logic. Either the shear calculations are unrepresentative or Michael has become more inertially stable due to its large eye and large outer wind field, making it more shear resistant. Having said that, all of the model guidance calls for the shear to decrease to around 10 kt or less by 36 hours, which argues for at least steady intensification during that time given that Michael will be moving over warm SSTs of 28.5C-29C, which are about 1-2 deg C above average for this time of the year. Tuesday (10/9) 10 pm CDT NHC discussion: Category 4 landfall: about 14 hours prior to landfall Michael is now explicitly forecast to become a category 4 hurricane before landfall occurs...

As of 3:10 pm, Washington, DC had received 0.17" rain. That brings 2018's total precipitation to 50.00". 2018 is the 19th year on record that saw 50.00" or more precipitation fall in Washington.

No. Those are year-end figures. With 48.74", 2018 ranks as the 7th wettest January 1- October 12 on record for NYC.

The 10th highest figure is 58.42" from 2003. If NYC receives just the historically-average precipitation for the remainder of 2018 (and no more today, which is unlikely for today), NYC would wind up with 58.27". I believe NYC will finish in the top 10 this year.

With 0.14" rain in the past hour, New York City's 2018 total precipitation has reached 48.70". That surpasses the 48.69" that fell in 1901 and 1998 to make 2018 New York City's 39th wettest year on record.

Andrew's re-analysis can be found here: https://www.nhc.noaa.gov/pdf/04landsea.pdf

Right now, I think the base case is a Category 4 hurricane at landfall. Multiple measurements confirmed Michael's strength as it neared landfall. The area of its most extreme winds was very small. Approximately 40-45 minutes before landfall, Tyndall AFB was registering wind gusts of 129 mph before its instruments failed or were destroyed. It is extremely likely that even stronger winds occurred prior to landfall, but were not measured. Data from some of the storm chasers, particularly Brett Adair who may have been in the storm's most severe winds, might provide further insight (many videos were taken away from the storm's strongest winds, as the area of most intense winds was very small). It will take time to survey the damage. Damage surveys will provide further information on the storm's winds. Until all of that work is complete, I think one has to be cautious about suggesting significant changes regarding the storm's strength at landfall. For now, given the multiple reconnaissance measurements and last instrument measurements prior to landfall, I see little reason to argue that the base case wasn't a landfalling Category 4 hurricane. Given the storm's small size and wind field, one won't see the kind of large-scale devastation from a storm such as Hugo. One will see a much smaller area of extreme wind damage (area) more in line with an Andrew, Charley, or Harvey. More details will probably be available when the National Hurricane Center posts its end-of-season report.

With rainfall from Michael spreading into the region, Baltimore and Washington, DC are again moving higher on their all-time annual precipitation lists. As of 8:20 am, Baltimore's annual precipitation was 54.86". Today's rainfall allowed 2018 to surpass 2009 when 54.71" precipitation fell, for that city's 8th wettest year on record. Washington, DC's 2018 figure had reached 49.96", tying 2018 with 1884 for Washington's 19th wettest year on record.