donsutherland1

A relatively quiet weather pattern remains in place. Through Friday, partly sunny and somewhat milder than normal conditions will likely prevail. The likely continuation of Arctic blocking through at least January 15 would typically provide a higher than climatological probability for above normal snowfall. Ideally, an expansive block would be anchored across the Baffin Bay or Greenland, not south of the Davis Strait. Blocks that are anchored near Newfoundland and Labrador can inhibit opportunities for snowfall and result in warmer to much warmer than normal conditions in the Middle Atlantic and southern New England regions. This is now the most likely scenario for much of the first half of January. Under this scenario, the first 10-15 days of January will likely be generally warmer to perhaps much warmer than normal across the northeastern United States, Quebec, and much of eastern Canada. After January 10, the EPS continues to shows a transition during which a trough will move into the East. The operational ECMWF has persistently shown an opportunity for snowfall during or near the end of the transitional period. Arctic air will likely shift mainly to Eurasia. However, the evolving pattern could be sufficiently cold to afford opportunities for snowfall if the pattern evolves as currently shown on the EPS. It remains possible that the pattern evolution could lead to a multiweek period with higher than climatological potential for snowfall. The ENSO Region 1+2 anomaly was -1.3°C and the Region 3.4 anomaly was -1.2°C for the week centered around December 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.80°C and the ENSO Region 3.4 anomaly has averaged -1.10°C. La Niña conditions will likely prevail at least through the winter. The SOI was +26.62 today. Today, the preliminary Arctic Oscillation (AO) figure was -3.510. That is the lowest AO figure since November 26, 2018 when the AO was -3.629. On January 5 the MJO was in Phase 3 at an amplitude of 1.048 (RMM). The January 4-adjusted amplitude was 0.908. A significant stratospheric warming event is continuing to evolve. The temperature has now peaked at 1 mb, but was still rising at 10 mb and 30 mb. Temperatures at those levels of the stratosphere should peak and begin falling in coming days. The mean zonal winds have reversed at 1 mb and 10 mb. They could reverse 30 mb. In the wake of this warming event, the polar vortex will likely split. The dominant piece will, as is typical with such events, migrate to Eurasia. The significant December 16-17 snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. For now, blocking appears likely to continue through at least the first half of January.

Perhaps the recent short-term strengthening of the La Nina has contributed to this modeled outcome this time around. A gradual weakening remains far more likely than a collapse. The canonical La Nina evolution has a lot to do with the tropical forcing. But there are numerous pieces that could impact the outcome this time around, including but not limited to the evolving stratospheric warming event.

That’s far enough away that there remain alternative scenarios. The ongoing stratospheric warming event provides additional long-range uncertainty.

It’s too soon to tell. The polar vortex should remain weak through much of the month. Nevertheless, the EPS weeklies are forecasting the development of an EPO+/AO+/PNA- pattern for late January. At this point, that’s beyond their skillful range.

Morning thoughts... Today will become partly to mostly sunny. Temperatures will likely reach the lower 40s in much of the region. Likely high temperatures around the region include: New York City (Central Park): 42° Newark: 43° Philadelphia: 43° Mainly fair and somewhat milder than normal temperatures will prevail through much of the week.

A relatively quiet weather pattern is in place. Through Friday, partly to mostly sunny and milder than normal conditions will likely prevail. The likely continuation of Arctic blocking through at least January 15 would typically provide a higher than climatological probability for above normal snowfall. Ideally, an expansive block would be anchored across the Baffin Bay or Greenland, not south of the Davis Strait. Blocks that are anchored near Newfoundland and Labrador can inhibit opportunities for snowfall and result in warmer to much warmer than normal conditions in the Middle Atlantic and southern New England regions. This is now the most likely scenario for much of the first half of January. Under this scenario, the first 10-15 days of January will likely be generally warmer to perhaps much warmer than normal across the northeastern United States, Quebec, and much of eastern Canada. After January 10, the EPS continues to shows a transition during which a trough will move into the East. Arctic air will likely shift mainly to Eurasia. However, the evolving pattern could be sufficiently cold to afford opportunities for snowfall if the pattern evolves as currently shown on the EPS. It remains possible that the pattern evolution could lead to a multiweek period with higher than climatological potential for snowfall. The ENSO Region 1+2 anomaly was -1.3°C and the Region 3.4 anomaly was -1.2°C for the week centered around December 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.80°C and the ENSO Region 3.4 anomaly has averaged -1.10°C. La Niña conditions will likely prevail at least through the winter. The SOI was +20.07 today. Today, the preliminary Arctic Oscillation (AO) figure was -3.430. On January 4 the MJO was in Phase 3 at an amplitude of 0.910 (RMM). The January 3-adjusted amplitude was 0.762. A significant stratospheric warming event is underway. The mean zonal winds has reversed at 1 mb and will likely reverse at 10 mb and possibly 30 mb. In the wake of this warming event, the polar vortex will likely split. The dominant piece will, as is typical with such events, migrate to Eurasia. The significant December 16-17 snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. For now, blocking appears likely to continue through at least the first half of January.

That system has been in the ECMWF for 3 if the last 5 0z/12z runs. Details have differed, but there’s some potential.

The pattern transition should occur during January 10-15. It would be nice to get something during that timeframe, but it isn't assured. Then, there could be 2 to maybe 4 weeks where there is potential. Patterns with potential don't always produce, though, but we'll see how things unfold.

The 1983 data was ultimately validated. I had emailed on this topic in the past. Here’s the response: Back in late 2011 when we had a very wet year around here, WFO OKX, Eastern Region Headquarters and what was then NCDC held a teleconference to discuss the 1983 total for Central Park since it was left as a cliffhanger since 1983. It was decided after that call to accept the values as initially reported based on some additional data quality analysis and comparisons conducted with surrounding stations based on trends over many years before and since 1983. There never was any further follow up done by NCDC on those initial 1983 until this call took place in 2011 as was initially mentioned back in the mid 1980s.

Morning thoughts... Today will become partly sunny. It will be milder than normal. Temperatures will likely reach the lower 40s across much of the region. Likely high temperatures include: New York City (Central Park): 41° Newark: 42° Philadelphia: 43° The quiet weather pattern will continue at least through Friday.

Following yesterday's system that brought rain and snow to parts of the region, a quieter pattern has now settled in. Through Friday, partly to mostly sunny and milder than normal conditions will likely prevail. The likely continuation of Arctic blocking through at least January 15 would typically provide a higher than climatological probability for above normal snowfall. Ideally, an expansive block would be anchored across the Baffin Bay or Greenland, not south of the Davis Strait. Blocks that are anchored near Newfoundland and Labrador can inhibit opportunities for snowfall and result in warmer to much warmer than normal conditions in the Middle Atlantic and southern New England regions. This is now the most likely scenario for much of the first half of January. Under this scenario, the first 10-15 days of January will likely be much warmer than normal across the northeastern United States, Quebec, and much of eastern Canada. After January 10, the EPS continues to show a possible transition that could lead to a trough's moving into the East. Arctic air will likely shift mainly to Eurasia. However, the evolving pattern could be sufficiently cold to afford opportunities for snowfall if the pattern evolves as currently shown on the EPS. It remains possible that the pattern evolution could lead to a multiweek period with higher than climatological potential for snowfall. The ENSO Region 1+2 anomaly was -1.3°C and the Region 3.4 anomaly was -1.2°C for the week centered around December 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.80°C and the ENSO Region 3.4 anomaly has averaged -1.10°C. La Niña conditions will likely prevail at least through the winter. The SOI was +25.40 today. Today, the preliminary Arctic Oscillation (AO) figure was -2.711. On January 3 the MJO was in Phase 3 at an amplitude of 0.754 (RMM). The January 2-adjusted amplitude was 0.692. A significant stratospheric warming event is underway. The mean zonal winds has reversed at 1 mb and will likely reverse at 10 mb and possibly 30 mb. In the wake of this warming event, the polar vortex will likely split. The dominant piece will, as is typical with such events, migrate to Eurasia. The significant December 16-17 snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. For now, blocking appears likely to continue through at least the first half of January.

000 NOUS41 KOKX 041623 PNSOKX CTZ005>012-NJZ002-004-006-103>108-NYZ067>075-078>081-176>179-050422- Public Information Statement Spotter Reports National Weather Service New York NY 1122 AM EST Mon Jan 04 2021 The following are unofficial observations taken during the past 24 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 (AT LEAST 2.0 INCH)********** LOCATION TOTAL TIME/DATE COMMENTS SNOWFALL MEASURED (inches) CONNECTICUT ...Fairfield County... Danbury 3.4 800 AM 1/04 Trained Spotter Newtown 3.2 1145 PM 1/03 Public New Fairfield 2.6 600 AM 1/04 Trained Spotter ...New Haven County... Southbury 2.0 750 AM 1/04 Public NEW JERSEY ...Passaic County... West Milford 2.6 600 AM 1/04 Public NEW YORK ...Orange County... Newburgh 3.9 530 AM 1/04 Trained Spotter 1 N Orange Lake 3.3 1045 PM 1/03 Trained Spotter 1 S Walden 3.1 930 PM 1/03 CoCoRaHS Gardnertown 3.0 947 PM 1/03 Trained Spotter 1 SW Pine Bush 2.8 820 PM 1/03 Social Media ************STORM TOTAL ICE (AT LEAST 0.00 INCH)************ LOCATION TOTAL TIME/DATE COMMENTS ICE MEASURED (inches) CONNECTICUT ...Fairfield County... Redding T 500 PM 1/03 Trace of freezing rain NEW YORK ...Orange County... 1 NNW Berea 0.03 221 PM 1/03 CoCoRaHS &&

True, but nothing severely cold.

Unfortunately, this is very consistent with splitting polar vortexes. A less cold but snowy pattern is still possible, though.

000 NOUS41 KBOX 041054 PNSBOX CTZ002>004-MAZ002>024-026-RIZ001>008-042254- Public Information Statement Spotter Reports National Weather Service Boston/Norton MA 554 AM EST Mon Jan 04 2021 The following are unofficial observations taken during the past 23 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/boston ********************STORM TOTAL SNOWFALL******************** LOCATION STORM TOTAL TIME/DATE COMMENTS SNOWFALL OF /INCHES/ MEASUREMENT CONNECTICUT ...Hartford County... Burlington 3.5 519 AM 1/04 Trained Spotter Bradley AP 1.7 1200 AM 1/04 CWOP ...Windham County... East Killingly 1.2 509 AM 1/04 NONE MASSACHUSETTS ...Essex County... Saugus 1.0 952 PM 1/03 Trained Spotter ...Hampden County... Longmeadow 2.0 1138 PM 1/03 Trained Spotter Westfield 1.3 933 PM 1/03 CWO West Springfield 1.0 821 PM 1/03 Ham Radio Agawam 1.0 1037 PM 1/03 Ham Radio ...Hampshire County... Easthampton 1.3 1035 PM 1/03 Ham Radio ...Middlesex County... Hopkinton 1.5 446 AM 1/04 Trained Spotter Lexington 1.3 1155 PM 1/03 Public ...Norfolk County... Medway 1.9 919 PM 1/03 Ham Radio Millis 1.2 1030 PM 1/03 Trained Spotter ...Worcester County... Grafton 1.8 1200 AM 1/04 Trained Spotter Westborough 1.7 949 PM 1/03 NWS Employee Milford 1.6 932 PM 1/03 Trained Spotter Leominster 1.5 1200 AM 1/04 Public Boylston 1.3 1041 PM 1/03 Trained Spotter Worcester 1.1 1144 PM 1/03 CWO Holden 1.0 841 PM 1/03 Ham Radio &&

000 NOUS41 KBGM 041149 PNSBGM NYZ009-015>018-022>025-036-037-044>046-055>057-062-PAZ038>040-043-044-047- 048-072-042349- Public Information Statement National Weather Service Binghamton NY 649 AM EST Mon Jan 4 2021 ...SNOWFALL REPORTS... Location Amount Time/Date Lat/Lon ...New York... ...Broome County... 2 E Vestal 6.0 in 1212 AM 01/04 42.08N/76.01W 2 SW Vestal Center 5.8 in 1015 PM 01/03 42.01N/76.05W 2 N Johnson City 5.7 in 0646 AM 01/04 42.15N/75.96W 1 S Nineveh 5.5 in 1220 AM 01/04 42.19N/75.60W Port Crane 5.1 in 0830 PM 01/03 42.17N/75.84W 4 SE Nineveh 5.0 in 1105 PM 01/03 42.17N/75.54W 3 SSW Sanitaria Spgs 4.2 in 0830 PM 01/03 42.13N/75.79W 2 E Whitney Point 4.0 in 0754 PM 01/03 42.33N/75.93W Vestal 4.0 in 0717 PM 01/03 42.08N/76.05W Nws Binghamton 3.8 in 1219 AM 01/04 42.21N/75.99W 1 SW Endwell 2.7 in 1015 PM 01/03 42.11N/76.03W Whitney Point 2.5 in 0511 PM 01/03 42.33N/75.97W Port Dickinson 2.2 in 0845 PM 01/03 42.14N/75.89W Endwell 2.0 in 0621 PM 01/03 42.12N/76.02W ...Chemung County... Van Etten 2.3 in 0432 PM 01/03 42.20N/76.55W Elmira 1.5 in 0736 PM 01/03 42.09N/76.81W ...Chenango County... 3 SW Greene 4.8 in 1010 PM 01/03 42.30N/75.81W Nineveh 4.0 in 0637 PM 01/03 42.20N/75.60W ...Delaware County... Hobart 4.0 in 0755 PM 01/03 42.37N/74.67W Delhi 2.5 in 0600 PM 01/03 42.28N/74.91W East Meredith 2.0 in 0234 PM 01/03 42.42N/74.88W ...Oneida County... 1 NNW Utica 0.5 in 0632 PM 01/03 43.11N/75.24W ...Onondaga County... 2 SSE North Syracuse 1.5 in 1100 PM 01/03 43.11N/76.11W Syracuse 1.0 in 0500 PM 01/03 43.04N/76.14W Marcellus 0.8 in 0700 PM 01/03 42.98N/76.34W ...Otsego County... Hartwick 6.0 in 1200 AM 01/04 42.65N/75.05W Milford 4.5 in 0900 PM 01/03 42.59N/74.95W 1 NNE Oneonta 4.0 in 0900 PM 01/03 42.47N/75.06W Unadilla 3.5 in 0950 PM 01/03 42.33N/75.32W 1 WSW Emmons 3.3 in 0900 PM 01/03 42.46N/75.04W 1 N Oaksville 3.1 in 0845 PM 01/03 42.75N/75.00W Edmeston 3.0 in 0930 PM 01/03 42.70N/75.24W ...Sullivan County... 1 ENE Callicoon Center 7.0 in 0620 AM 01/04 41.84N/74.95W Callicoon Center 6.0 in 1030 PM 01/03 41.83N/74.97W 1 ESE Callicoon Center 1.0 in 1045 AM 01/03 41.83N/74.95W ...Pennsylvania... ...Bradford County... New Albany 14.0 in 1100 PM 01/03 41.60N/76.44W 4 WSW South Branch 11.0 in 0945 PM 01/03 41.64N/76.50W 3 SSW West Burlington 7.1 in 1045 PM 01/03 41.72N/76.69W 3 ENE Alba 4.2 in 0845 PM 01/03 41.72N/76.77W Alba 4.0 in 1000 PM 01/03 41.71N/76.83W 1 SSE Towanda 4.0 in 0930 PM 01/03 41.76N/76.44W Litchfield 3.0 in 0730 PM 01/03 41.97N/76.43W ...Lackawanna County... Clarks Summit 6.2 in 0900 PM 01/03 41.49N/75.70W 1 SSE Clarks Summit 5.7 in 0800 PM 01/03 41.48N/75.70W Taylor 5.5 in 0845 PM 01/03 41.40N/75.72W 1 NW Throop 4.5 in 0800 PM 01/03 41.45N/75.61W 1 S Blakely 4.0 in 0800 PM 01/03 41.47N/75.60W Scranton 3.5 in 0718 PM 01/03 41.40N/75.67W 1 NE Moosic 3.2 in 1100 PM 01/03 41.37N/75.68W Richmondale 2.0 in 0511 PM 01/03 41.63N/75.50W ...Luzerne County... Edwardsville 5.0 in 0945 PM 01/03 41.26N/75.91W 2 WNW Harveys Lake 3.8 in 0900 PM 01/03 41.37N/76.06W 1 S Exeter 3.8 in 0800 PM 01/03 41.32N/75.82W Harveys Lake 2.5 in 0724 PM 01/03 41.36N/76.03W ...Susquehanna County... Dimock 4.0 in 0638 PM 01/03 41.75N/75.90W Harford 4.0 in 0559 PM 01/03 41.78N/75.70W Susquehanna 3.0 in 0744 PM 01/03 41.93N/75.60W Forest City 2.6 in 0600 PM 01/03 41.65N/75.47W ...Wayne County... Beach Lake 6.0 in 0541 AM 01/04 41.60N/75.15W 1 WNW Hawley 1.0 in 0954 AM 01/03 41.48N/75.19W 2 ESE Beach Lake 1.0 in 0950 AM 01/03 41.59N/75.11W ...Wyoming County... 1 NNW Factoryville 6.5 in 1015 PM 01/03 41.57N/75.79W &&

000 NOUS41 KPHI 041022 PNSPHI DEZ001>004-MDZ012-015-019-020-NJZ001-007>010-012>027-PAZ054-055-060>062-070- 071-101>106-042222- Public Information Statement National Weather Service Mount Holly NJ 522 AM EST Mon Jan 4 2021 ...SNOWFALL REPORTS... Location Amount Time/Date Provider ...New Jersey... ...Hunterdon County... Tewksbury Twp 0.5 in 0954 AM 01/03 Trained Spotter Lebanon 0.4 in 0953 AM 01/03 Trained Spotter ...Morris County... Ledgewood 1.5 in 1032 AM 01/03 Trained Spotter 1 NE Rockaway 1.5 in 1100 AM 01/03 Cocorahs Lake Hopatcong 1.5 in 1000 PM 01/03 Public 2 NNE Brookside 1.2 in 1030 AM 01/03 Trained Spotter Budd Lake 1.2 in 1140 AM 01/03 Public 2 ESE Randolph 0.9 in 1045 AM 01/03 Cocorahs Long Valley 0.8 in 0955 AM 01/03 Public Denville 0.6 in 1109 AM 01/03 Trained Spotter Montville 0.4 in 1205 PM 01/03 Trained Spotter ...Somerset County... Bridgewater 0.6 in 0925 PM 01/03 Trained Spotter Branchburg Twp 0.5 in 1005 AM 01/03 Public ...Sussex County... Wantage Twp 3.5 in 1041 PM 01/03 Public 4 SW Wantage 2.3 in 0245 AM 01/04 Trained Spotter ...Warren County... 1 NNW Stewartsville 1.6 in 0942 AM 01/03 Public 1 ENE Pohatcong Twp 1.6 in 1100 AM 01/03 Cocorahs Blairstown 1.1 in 1000 AM 01/03 Public 2 NW Hope 1.0 in 0926 AM 01/03 Trained Spotter ...Pennsylvania... ...Berks County... 2 W Colebrookdale Twp 1.4 in 0850 AM 01/03 Trained Spotter 1 N Huffs Church 1.1 in 1000 AM 01/03 Trained Spotter Douglassville 0.5 in 0830 AM 01/03 Trained Spotter ...Bucks County... Chalfont 0.5 in 0921 AM 01/03 Trained Spotter Furlong 0.5 in 0955 AM 01/03 Trained Spotter New Hope 0.4 in 0915 AM 01/03 Trained Spotter ...Carbon County... 2 ENE Palmerton 1.0 in 1100 AM 01/03 Trained Spotter ...Chester County... Elverson 1.0 in 0811 AM 01/03 Public East Nantmeal Twp 1.0 in 0838 AM 01/03 Trained Spotter East Coventry Twp 1.0 in 0900 AM 01/03 Trained Spotter 1 ENE Modena 0.5 in 0929 AM 01/03 Public 1 WNW Chesterbrook 0.5 in 0208 PM 01/03 Trained Spotter 2 SE Exton 0.4 in 0858 AM 01/03 Cocorahs ...Delaware County... 1 WNW Wayne 0.3 in 0916 AM 01/03 Trained Spotter ...Lehigh County... Macungie 2.0 in 0910 AM 01/03 Public Whitehall Twp 1.5 in 1138 AM 01/03 Public 1 W Hokendauqua 1.4 in 0935 AM 01/03 Public Center Valley 1.3 in 0930 AM 01/03 Trained Spotter 2 NE Emmaus 1.2 in 1100 AM 01/03 Trained Spotter 2 SSE Zionsville 1.0 in 0903 AM 01/03 Public 1 E Allentown 1.0 in 0922 AM 01/03 Public Coopersburg 1.0 in 1014 AM 01/03 Public Lehigh Valley International 1.0 in 0100 PM 01/03 ASOS North Whitehall Twp 0.8 in 0841 AM 01/03 Public ...Monroe County... Coolbaugh Twp 4.2 in 0930 PM 01/03 Trained Spotter Mount Pocono 4.0 in 0915 PM 01/03 Trained Spotter Bossardsville 3.5 in 1030 PM 01/03 Public ...Montgomery County... 1 SSE Trappe 1.0 in 0900 AM 01/03 Trained Spotter Gilbertsville 1.0 in 0916 AM 01/03 Trained Spotter New Hanover Twp 1.0 in 0918 AM 01/03 Public Pottstown 0.5 in 0850 AM 01/03 Public ...Northampton County... Eastlawn Gardens 1.5 in 1001 AM 01/03 Trained Spotter Bushkill Twp 1.5 in 1005 AM 01/03 Trained Spotter Bethlehem 1.4 in 1139 AM 01/03 Public Forks Twp 1.3 in 1020 AM 01/03 Trained Spotter Hellertown 1.1 in 0920 AM 01/03 Trained Spotter Palmer Heights 1.1 in 0957 AM 01/03 Public 1 NNW Danielsville 1.1 in 1020 AM 01/03 Trained Spotter Lower Mount Bethel Twp 1.0 in 0915 AM 01/03 Trained Spotter &&

Morning thoughts... Today will be partly sunny and milder than yesterday. Temperatures will likely reach the lower and middle 40s in much of the region. Likely high temperatures around the region include: New York City (Central Park): 42° Newark: 44° Philadelphia: 44° Mainly fair and somewhat milder than normal temperatures will prevail through much of the week.

Two photos from Armonk, NY from this evening: A short video clip:

A developing storm was bringing rain and snow to parts of the region this evening. Tomorrow will be drier, milder, with partly sunny skies. The likely continuation of Arctic blocking through at least the first 10 days of January would typically provide a higher than climatological probability for above normal snowfall. Ideally, an expansive block would be anchored across the Baffin Bay or Greenland, not south of the Davis Strait. Blocks that are anchored near Newfoundland and Labrador can inhibit opportunities for snowfall and result in warmer to much warmer than normal conditions in the Middle Atlantic and southern New England regions. This is now the most likely scenario for much of the first half of January. Under this scenario, the first 10-15 days of January will likely be much warmer than normal across the northeastern United States, Quebec, and much of eastern Canada. After January 10, the EPO continues to show a possible transition that could lead to a trough's moving into the East. Arctic air will likely shift mainly to Eurasia. However, the evolving pattern could be sufficiently cold to afford opportunities for snowfall if the pattern evolves as currently shown on the EPS. The ENSO Region 1+2 anomaly was -1.1°C and the Region 3.4 anomaly was -0.9°C for the week centered around December 23. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.70°C and the ENSO Region 3.4 anomaly has averaged -1.15°C. La Niña conditions will likely prevail at least through the winter. The SOI was +23.42 today. Today, the preliminary Arctic Oscillation (AO) figure was -2.437. On January 2 the MJO was in Phase 3 at an amplitude of 0.691 (RMM). The January 1-adjusted amplitude was 0.640. A significant stratospheric warming event is now in its early stages. The highest levels of the stratosphere will continue to warm through the first half of the first week of January. The mean zonal winds will likely reverse at 1 mb, 10 mb, and 30 mb making this a major warming event. Toward the end of the first week in January, the top layers of the stratosphere will likely begin to cool. The significant December 16-17 snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. For now, blocking appears likely to continue through at least the first half of January.

Sleet has resumed falling.

At around 11 am, there was a burst of large snowflakes and sleet in and around Larchmont, NY. The precipitation quickly transitioned to all sleet and a mixture of sleet and rain. Before then, it produced some scattered coatings on colder surfaces. The large flakes of snow melted almost on contact with the pavement.

Morning thoughts... At 8 am, precipitation was advancing north and eastward through eastern Pennsylvania and central New Jersey. Rain was falling at such locations as Atlantic City and Philadelphia. Snow was falling just south of Allentown. Rain and sleet will move into Newark and New York City this morning and continue into the evening. Well north and west of those cities, there will be accumulating snow with 2”-4” and some locally higher amounts likely. Temperatures will likely reach the upper 30s and perhaps lower 40s in much of the region. Likely high temperatures around the region include: New York City (Central Park): 39° Newark: 40° Philadelphia: 42° Drier weather will return tomorrow.

Colder weather will return tonight into tomorrow. Tomorrow will see increasing clouds. A cold rain will overspread the Philadelphia, Newark, and New York City. Some sleet or wet snow is possible at the onset. North and west of the cities, there could be some accumulations. Poughkeepsie and Hartford could see 2"-4" snow. Boston could pick up 1"-2". Afterward, a generally mild regime will likely prevail. The likely continuation of Arctic blocking through at least the first 10 days of January would typically provide a higher than climatological probability for above normal snowfall. Ideally, an expansive block would be anchored across the Baffin Bay or Greenland, not south of the Davis Strait. Blocks that are anchored near Newfoundland and Labrador can inhibit opportunities for snowfall and result in warmer to much warmer than normal conditions in the Middle Atlantic and southern New England regions. This is now the most likely scenario for much of the first half of January. Under this scenario, the first 10-15 days of January will likely be much warmer than normal across the northeastern United States, Quebec, and much of eastern Canada. After January 10, the EPO continues to show a possible transition that could lead to a trough's moving into the East. Arctic air will likely shift mainly to Eurasia. However, the evolving pattern could be sufficiently cold to afford opportunities for snowfall if the pattern evolves as currently shown on the EPS. The ENSO Region 1+2 anomaly was -1.1°C and the Region 3.4 anomaly was -0.9°C for the week centered around December 23. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.70°C and the ENSO Region 3.4 anomaly has averaged -1.15°C. La Niña conditions will likely prevail at least through the winter. The SOI was +18.05 today. Today, the preliminary Arctic Oscillation (AO) figure was -2.910. On January 1 the MJO was in Phase 3 at an amplitude of 0.640 (RMM). The December 31-adjusted amplitude was 0.568. A significant stratospheric warming event is now in its early stages. The highest levels of the stratosphere will continue to warm through the first half of the first week of January. The mean zonal winds will likely reverse at 1 mb, 10 mb, and 30 mb making this a major warming event. Toward the end of the first week in January, the top layers of the stratosphere will likely begin to cool. The significant December 16-17 snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. For now, blocking appears likely to continue through at least the first half of January.

I added the NAO, along with ISP.