donsutherland1

Some quick thoughts as I am still out of town: 1. Over the next 10 days, variability will remain the theme with alternating periods of warmth and cold. No exceptional cold appears likely. 2. Precipitation should remain above average with New York City again reaching 50" annual precipitation and Allentown perhaps reaching 60" for a record second consecutive year. 3. The AO looks to remain predominantly positive through the next 10-14 days with perhaps a 5-7-day dip near the December 20 +/- a few days. 4. During this period, the potential for at least some snowfall exists. 5. The EPS suggests that there is a risk that the coldest air could shift to the other side of the Northern Hemisphere after Day 10. That would again mitigate the risk of Arctic outbreaks. By mid-month, most of the U.S. except for New England and the northern Mid-Atlantic could have warm monthly anomalies. New York City could have a modest cold anomaly despite a much colder than normal start to the month. How the month finishes will depend on the progression of the MJO within the context of a fading positive Indian Ocean Dipole anomaly, the SOI, and the teleconnections.

000 NOUS41 KOKX 111307 PNSOKX CTZ005>012-NJZ002-004-006-103>108-NYZ067>075-078>081-176>179-120107- PUBLIC INFORMATION STATEMENT SPOTTER REPORTS NATIONAL WEATHER SERVICE NEW YORK NY 807 AM EST WED DEC 11 2019 THE FOLLOWING ARE UNOFFICIAL OBSERVATIONS TAKEN DURING THE PAST 12 HOURS FOR THE STORM THAT HAS BEEN AFFECTING OUR REGION. APPRECIATION IS EXTENDED TO HIGHWAY DEPARTMENTS, COOPERATIVE OBSERVERS, SKYWARN SPOTTERS AND MEDIA FOR THESE REPORTS. THIS SUMMARY ALSO IS AVAILABLE ON OUR HOME PAGE AT WEATHER.GOV/NYC ********************STORM TOTAL SNOWFALL******************** LOCATION STORM TOTAL TIME/DATE COMMENTS SNOWFALL OF /INCHES/ MEASUREMENT CONNECTICUT ...FAIRFIELD COUNTY... DANBURY 3.7 750 AM 12/11 SOCIAL MEDIA BETHEL 3.5 700 AM 12/11 EMERGENCY MANAGER WESTON 2.6 700 AM 12/11 TRAINED SPOTTER BRIDGEPORT AIRPORT 2.2 700 AM 12/11 CO-OP OBSERVER ...MIDDLESEX COUNTY... PORTLAND 2.5 605 AM 12/11 AMATEUR RADIO ...NEW HAVEN COUNTY... WOODBRIDGE 3.5 720 AM 12/11 PUBLIC GUILFORD 3.0 630 AM 12/11 CO-OP OBSERVER HAMDEN 2.7 730 AM 12/11 PUBLIC MILFORD 1.0 605 AM 12/11 AMATEUR RADIO ...NEW LONDON COUNTY... LEDYARD CENTER 2.0 800 AM 12/11 TRAINED SPOTTER NEW JERSEY ...BERGEN COUNTY... OAKLAND 1.5 800 AM 12/11 SOCIAL MEDIA RIDGEWOOD 1.0 700 AM 12/11 TRAINED SPOTTER ...UNION COUNTY... CRANFORD 0.5 630 AM 12/11 TRAINED SPOTTER NEWARK AIRPORT 0.5 700 AM 12/11 FAA OBSERVER NEW YORK ...NASSAU COUNTY... WOODBURY 3.0 730 AM 12/11 BROADCAST MEDIA WEST HEMPSTEAD 2.0 755 AM 12/11 SOCIAL MEDIA MERRICK 1.8 800 AM 12/11 TRAINED SPOTTER MANHASSET HILLS 1.2 745 AM 12/11 SOCIAL MEDIA VALLEY STREAM 1.1 800 AM 12/11 TRAINED SPOTTER NEW HYDE PARK 1.0 540 AM 12/11 TRAINED SPOTTER ...NEW YORK (MANHATTAN) COUNTY... CENTRAL PARK 0.2 700 AM 12/11 PARK CONSERVANCY ...ORANGE COUNTY... NEWBURGH 2.5 745 AM 12/11 TRAINED SPOTTER MONROE 2.3 600 AM 12/11 TRAINED SPOTTER ...PUTNAM COUNTY... MAHOPAC 3.5 700 AM 12/11 TRAINED SPOTTER BREWSTER 3.2 755 AM 12/11 TRAINED SPOTTER ...QUEENS COUNTY... NYC/LAGUARDIA AIRPOR 0.6 700 AM 12/11 FAA OBSERVER NYC/JFK AIRPORT 0.5 700 AM 12/11 FAA OBSERVER ...ROCKLAND COUNTY... STONY POINT 1.3 700 AM 12/11 TRAINED SPOTTER ...SUFFOLK COUNTY... NESCONSET 3.0 700 AM 12/11 SOCIAL MEDIA WEST BABYLON 1.0 720 AM 12/11 SOCIAL MEDIA ISLIP AIRPORT 0.8 700 AM 12/11 FAA OBSERVER ...WESTCHESTER COUNTY... WINDMILL FARM 2.8 730 AM 12/11 PUBLIC SPRING VALLEY 1.9 750 AM 12/11 SOCIAL MEDIA &&

Snow, without question.

Central Park has switched to light snow.

Thanks Jerry. I hope all is well with you and also that the snowfall amounts are underdone.

Tomorrow will be very mild in the Middle Atlantic and southern New England region. Temperatures should top out in the upper 50s in southern New England and lower 60s in much of the Middle Atlantic region. This unseasonable warmth will be short-lived.　 As the front slowly moves eastward, a wave could develop along the front bringing parts of the region a light snowfall late Tuesday into Wednesday morning. New York City, Newark, and Philadelphia could be in line for perhaps an inch or two of slushy snow, especially on grassy surfaces. Outside the cities, a general 2"-4" with locally higher amounts appears possible. Lesser amounts remain possible should the arrival of the cold air be somewhat delayed. The ENSO Region 1+2 anomaly was +0.1°C and the Region 3.4 anomaly was +0.3°C for the week centered around December 4. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.23°C and the ENSO Region 3.4 anomaly has averaged +0.67°C. These recent conditions are consistent with a weak El Niño. Nevertheless, a neutral ENSO remains the base case for Winter 2019-20 and the recent cooling in Region 3.4 suggests that the base case remains viable. The SOI was -4.72 today. Today, the preliminary Arctic Oscillation (AO) figure was +0.922. In the long-range, there is disagreement among the guidance. The GEFS is colder than the EPS. The latest week 2 and 3 forecasts for the CFSv2 have moved dramatically away from the severe cold that prior runs had shown. The progression of the MJO over the next 10 days and the evolution of the AO could provide insight. No significant stratospheric warming event appears likely through December 18. Wave 2 activity is forecast to remain suppressed and the stratosphere is forecast to remain cold past mid-month on the EPS. According to NCEP, the correlation of 16-day 10 mb GFS temperature forecasts is near 0.25 (much worse than flipping a coin). 5 mb forecasts have an even lower correlation. 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 December 1-3 storm occurred with a negative PNA and Central Park received 1.6" snow. During the second half of December, larger snowstorms have occurred with a negative PNA.

Following a mild start to the work week, a cold front will move across the region on Tuesday with additional periods of rain. Ahead of the front, much of the Middle Atlantic and southern New England region could see temperatures top out in the upper 50s and even at or above 60° tomorrow and/or Tuesday. The unseasonable warmth will be short-lived. As the front slowly moves eastward, a wave could develop along the front bringing parts of the region a light snowfall late Tuesday into Wednesday morning. New York City, Newark, and Philadelphia could be in line for perhaps an inch or two of slushy snow, especially on grassy surfaces. Outside the cities, a general 2"-4" with locally higher amounts appears possible. 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 +4.83 today. Today, the preliminary Arctic Oscillation (AO) figure was +1.725. In the long-range, there is considerable disagreement among the guidance. The GEFS is colder than the EPS. The CFSv2 favors much colder than normal conditions during weeks 2 and 3 with widespread two-week anomalies of 5° or more below normal. The forecast teleconnections argue for a less cold outcome, though the kind of warmth shown at the extended range of the EPS is not yet a high probability outcome. The progression of the MJO over the next 10 days and the evolution of the AO could provide insight. No significant stratospheric warming event appears likely through December 17. Wave 2 activity is forecast to remain suppressed and the stratosphere is forecast to remain cold through mid-month on the EPS. According to NCEP, the correlation of 16-day 10 mb GFS temperature forecasts is near 0.25 (much worse than flipping a coin). 5 mb forecasts have an even lower correlation. On December 7, the MJO was in Phase 2 at an amplitude of 0.925 (RMM). The December 6-adjusted amplitude was 0.859. 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 December 1-3 storm occurred with a negative PNA and Central Park received 1.6" snow. During the second half of December, larger snowstorms have occurred with a negative PNA.

Utqiagvik is easily on course for its warmest year on record. It is all but improbable that the record will fall. Further, that city will likely finish with its first annual mean temperature of 20.0 degrees or above.

Following yesterday's mild readings, today saw readings remain well below normal across the region. 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 +7.16 today. Today, the preliminary Arctic Oscillation (AO) figure was +1.496. No significant stratospheric warming appears likely through December 16. Wave 2 activity is forecast to remain suppressed and the stratosphere is forecast to remain cold through mid-month on the EPS. According to NCEP, the correlation of 16-day 10 mb GFS temperature forecasts is near 0.25 (much worse than flipping a coin). 5 mb forecasts have an even lower correlation. On December 6, the MJO was in Phase 2 at an amplitude of 0.854 (RMM). The December 5-adjusted amplitude was 0.631. The first week of December saw readings average more than 4° below normal across the northern Mid-Atlantic and southern New England regions. A more variable pattern is now poised to develop. There is a chance that the coming week 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. Nevertheless, cold shots will continue to occur on a periodic basis. By December 15, the anomaly will likely be 1°-2° below normal. The third week of the month could turn colder and possibly for a more sustained period of time, especially if the EPO goes 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. The December 1-3 storm occurred with a negative PNA and Central Park received 1.6" snow. During the second half of December, larger snowstorms have occurred with a negative PNA.

Despite bright sunshine and a cloudless sky during the mid- and late-afternoon, the temperature in New York City reached a maximum reading of 38°. The snow from earlier in the week had almost completely disappeared from the landscape. At the New York Botanical Garden, the annual train show was underway. At the show were replicas of present and past New York City-area landmarks constructed out of wood and other natural materials. Four photos (three from inside the show for a flavor).

It’s a strong Arctic front. Hopefully, the record will fall.

The week 2-3 forecast on the CFSv2 (-3.5 degree C average anomaly) could be overdone. It’s an outlier relative to the other guidance.

Back on October 30, Social Media contained a forecast for an exceptionally cold pattern to lock in. https://www.americanwx.com/bb/topic/52511-autumn-2019-banter-thread/?do=findComment&comment=5338034 While there is always high uncertainty in the extended range, the probability of extreme patterns locking in for weeks at a time is relatively low (not zero, but low). Some examples include the exceptionally cold February of 2015 and the historically warm December of 2015. In general, one needs strong evidence to make such forecasts. At the time, the forecast state of the teleconnections argued against the outcome. Here's the forecast and the actual outcome: 11/16-30 temperatures for two select sites: NYC: 43.0° (2.3° below normal); ORD: Actual: 38.3° (0.6° above normal).

Ahead of another push of colder air, the temperature reached 50° in Central Park. Over the next 7-10 days, temperatures will exhibit wide variability. 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 +4.00 today. Today, the preliminary Arctic Oscillation (AO) figure was +1.967. No significant stratospheric warming appears likely through December 15. Wave 2 activity is forecast to remain suppressed and the stratosphere is forecast to remain cold through mid-month on the EPS. According to NCEP, the correlation of 16-day 10 mb GFS temperature forecasts is near 0.25 (much worse than flipping a coin). 5 mb forecasts have an even lower correlation. On December 5, the MJO was in Phase 2 at an amplitude of 0.630 (RMM). The December 4-adjusted amplitude was 0.485. 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. Nevertheless, cold shots will continue to occur on a periodic basis. Moreover, the third week of the month could turn colder and possibly for a more sustained period of time, especially if the EPO goes negative. Despite the periodic cold shots and possible longer-duration period of cold, no snowstorms appear likely through at least the next 7-14 days in much of the region. Lake effect regions, upstate New York, and northern New England could see additional accumulations. The possibility could also exist for rain to end as a period of snow or flurries as storms depart and colder air returns. 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 December 1-3 storm occurred with a negative PNA and Central Park received 1.6" snow. During the second half of December, larger snowstorms have occurred with a negative PNA.

He may have misspoke. Fortunately, the 1.6” figure is listed in the climate record.