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  1. donsutherland1

    [Eastern US] December 2018: Consolidated Discussion / Obs

    Congratulations and best wishes for your studies.
  2. donsutherland1

    [Eastern US] December 2018: Consolidated Discussion / Obs

    In the wake of yesterday’s snowstorm in the Southeast and lower Middle Atlantic region, Raleigh has 7.0” snow and Richmond has 11.5” snow to date. To date, New York City has picked up 6.4”. Through winter 2017-18, there were 15 cases where seasonal snowfall in Raleigh or Richmond exceeded seasonal snowfall in New York City, including 6 cases where seasonal snowfall in both Raleigh and Richmond exceeded New York City’s seasonal snowfall. The 6 shared cases were: 1954-55: New York City: 11.5”; Raleigh: 16.8”; Richmond: 12.9” 1958-59: New York City: 13.0”; Raleigh: 13.5”; Richmond: 14.9” 1972-73: New York City: 2.8”; Raleigh: 11.3”; Richmond: 6.7” 1979-80: New York City: 12.8”; Raleigh: 18.3”; Richmond: 38.6” 1988-89: New York City: 8.1”; Raleigh: 12.0”; Richmond: 15.4” 2001-02: New York City: 3.5”; Raleigh: 10.8”; Richmond: 8.7” In all 6 of the above cases, New York City’s December snowfall was less than 4”. To date, New York City has received no snowfall during December. Further, none appears likely through at least the next 7 days, as two pulses of warmer than normal weather are likely to roll into the East. Winter cancel? Below is the January-February composite 500 mb anomaly map for the above 6 cases: That’s a composite for winters that featured frequent EPO+/AO+ combinations. Winter 2018-19 remains on track to feature an EPO-/AO-. The latest ensemble guidance shows the EPO+ peaking in coming days and then trending lower for the next two weeks to neutral. The warm SSTAs in the Gulf of Alaska favor a predominantly negative EPO. Further, the kind of deep Atlantic blocking (AO and NAO) that occurred in November has often preceded a winter with a predominantly negative AO. Second, none of the 15 cases cited above, including the 6 common cases, had measurable snowfall in November. This leaves a final question: Is a “super winter” where New York City receives 40” or more snow, Raleigh picks up 10” or more, and Richmond receives 20” or more possible? There are 5 such cases: 1898-99: New York City: 55.9”; Raleigh: 29.2”; Richmond: 34.0” 1913-14: New York City: 40.5”; Raleigh: 17.2”; Richmond: 26.8” 1947-48: New York City: 63.2”; Raleigh: 24.9”; Richmond: 25.2” 1966-67: New York City: 51.5”; Raleigh: 10.6”; Richmond: 31.8” 1995-96: New York City: 75.6”; Raleigh: 14.6”; Richmond: 37.2” Additional winters came close to meeting these criteria, including winter 2002-03. In sum, even as some might still be haunted by the Ghost of 2011-12 following that winter’s October snowstorm, one should not take this weekend’s snowstorm as proof that winter 2018-19 will feature little snowfall in the New York City and the larger surrounding region. At this stage, I continue to expect that consistent with El Niño/EPO-/AO- winters, winter 2018-19 will prove to be colder than normal and snowier to much snowier than normal in the New York City region. Finally, there continue to be growing indications that the pattern could be evolving toward the more dominant winter pattern during the last week of December. That timeframe +/- a few days could well offer the possibility of accumulating snow in the region.
  3. donsutherland1

    Don Sutherland

  4. donsutherland1

    [Eastern US] December 2018: Consolidated Discussion / Obs

    FWIW, my thinking from earlier this afternoon (prior to the 18z guidance) was as follows:
  5. donsutherland1

    [Eastern US] December 2018: Consolidated Discussion / Obs

    Good luck with the forecast.
  6. donsutherland1

    [Eastern US] December 2018: Consolidated Discussion / Obs

    I like his assessment, as my focus has been on and remains on the last week of the month for the renewed risk of snow events.
  7. donsutherland1

    Introducing the 33andrain Gallery!

    Thanks. I will gradually add some photos to the gallery.
  8. donsutherland1

    [Eastern US] December 2018: Consolidated Discussion / Obs

    Act 1 winter 2018-19 will conclude after this weekend's major Lower Middle Atlantic/Southeast snowstorm. The scenario painted by the return of a generally positive EPO and periodically positive Arctic Oscillation (AO) has shown up for some time on the ensembles. A look at where we have been is helpful. Scene 1 saw a historic November snowstorm in parts of the East. Cities such as Newark and New York had their biggest ever snowfall so early in the season. Heavy snow blankets the New York City area (November 15) Scene 2 featured an exceptional Arctic blast for Thanksgiving Day and the day after. Central Park's 15° temperature was New York City's lowest November temperature since the mercury fell to 12° on November 27, 1932. Select record-breaking and record-tying low temperatures for November 22: Albany: 8° (old record: 9°, 1969) Allentown: 14° (old record: 15°, 2014) Bangor: 5° (old record: 11°, 1978) Binghamton: 3° (old record: 10°, 1989) ***Tied November Record set on 11/30/1976*** Bridgeport: 16° (old record: 18°, 1987) ***Tied November Record set on 11/28/1951 and tied on 11/23/1972*** Hartford: 9° (old record: 14°, 1969) Islip: 18° (old record: 20°, 1987) Manchester: 9° (old record: 12°, 1969) Mount Washington: -26° (old record: -11° set in 1969 and tied in 1987) ***Broke November Record (old monthly record: -20°, 11/30/1958)*** New York City-JFK: 18° (old record: 20°, 1987) ***Broke November Record (old monthly record: 19°, set on 11/30/1976 and tied on 11/21/1987)*** New York City-LGA: 19° (old record: 21°, 1987) Newark: 17° (old record: 19°, 1987) Portland: 6° (old record: 11°, 1888) Poughkeepsie: 10° (old record: 14° set in 1972 and tied in 1984) Providence: 15° (old record: 16° set in 1969 and tied in 1987) Saranac Lake: -19° (old record: -2° set in 1972 and tied in 1987) ***Broke November Record (Old monthly record: -14°, set 11/26/1938 and tied on 11/28/1951)*** Scranton: 9° (old record: 15° set in 1969 and tied in 1987 and 2014) Worcester: 7° (old record: 11°, 1987) Record-breaking and record-tying low temperatures for November 23: Albany: 4° (old record: 5°, 1972) Allentown: 11° (old record: 16°, 1964 and 2000) Binghamton: 0° (old record: 12°, 1989 and 2008) ***Broke November Record (old record: 3°, set on 11/30/1976 and tied on 11/22/2018)*** Bridgeport: 13° (old record: 16°, 1972) ***Broke November Record (old record: 16°, set on 11/28/1951 and tied on 11/23/1972 and 11/22/2018)*** Burlington: -1° (old record: 2°, 1888 and 1972) Hartford: 5° (old record: 12°, 1972) Mount Washington: -13° (tied record set in 1994) New York City-JFK: 15° (old record: 25°, set in 1949 and tied in 1964, 1972, 2000, and 2008) ***Broke November Record (old record: 18°, 11/22/2018)*** New York City-LGA: 17° (old record: 23°, 1972) ***Tied November Record set on 11/29/1955*** Newark: 13° (old record: 21°, 1932) Portland: 4° (old record: 7°, 1888 and 1978) Poughkeepsie: 6° (old record: 9°, 1989) Providence: 13° (old record: 14°, 1972) Saranac Lake: -17° (old record: -11°, 1932) Scranton: 5° (old record: 13°, 1972) ***Broke November Record (old record: 6°, set 11/29/1929 and tied on 11/26/1938) Trenton: 13° (old record: 16°, 1880) Westhampton: 6° (old record: 14°, 1964 and 2000) ***Broke November Record (old record: 9°, 11/24/2000)*** Worcester: 7° (old record: 9°, 1929, 1972, and 1989) Scene 3 featured a blizzard on November 25-26 that brought heavy snow from Kansas to the Great Lakes Region. That storm dumped 8.4" snow at Chicago and 11.7" at Rockford. Scene 4 saw an inverted trough bring a localized 3"-6" snowfall (with some higher amounts) to a portion of New Jersey, including Atlantic City where 4.8" fell. Scene 5 will star a major early December Lower Mid-Atlantic/Southeast snowstorm. There had been a window of opportunity during the first two weeks of December. By the time that period ends, Scenes 4 and 5 will have been put into the weather records books. That the northern Mid-Atlantic and southern New England regions will very likely miss out given the 500 mb pattern (which, in this case provided above normal lead time for the area at greatest risk of significant snow) does not mean that the potential did not exist. It did. Act 2, courtesy of the onset of a positive EPO, variable Arctic Oscillation (including positive values), and the MJO's move into milder phases will be defined by a pause. Typically, such pauses last 2 and sometimes 3 weeks. Unlike some recent Decembers, it does not appear that this pause will see exceptional warmth. It will likely see above normal readings in the means. Act 2 is not the closing Act of December, much less winter. Unlike such "non-winters" as 2011-12, the SSTAs in the Pacific favor a negative EPO. Those SSTAs are remarkably similar to those that were present during winter 2002-03. During that winter, the EPO went positive and remained predominantly positive into the first week of January. Afterward, it went negative and was largely negative through the remainder of what proved to be a very snowy meteorological winter. Already, some of the guidance suggests an end to the positive EPO that will likely develop in coming days. Whether the EPO will go negative toward the end of the December or start of January remains to be seen, as there remains uncertainty concerning the timing of such an evolution. Nevertheless, my guess has been and remains that the last week of December could feature a growing risk of wintry weather. First, the trough will begin to redevelop. The weekly guidance strongly suggests the development of a sustained trough in the East in the longer-term. As that happens, colder air will return and opportunities for snow will increase. The last week of December could be volatile as the pattern evolves toward a stable colder pattern--the kind of pattern that defined such winters as 1977-78, 2002-03, and 2009-10. During that last week of December, I believe it is more likely than not that New York City will see accumulating snow. Waiting might be challenging, but I believe the patience will be rewarded so to speak. At present, there remains no meaningful indication that the promising start to Winter 2018-19 will end in heartbreak. Overall, things remain on track for a very widespread winter with cold anomalies and greater than normal snowfall. The coming pause does not change things. It is part of a larger transition that will see the winter increasingly gain the attributes one has seen in past Central Pacific-based El Niño winters during which both Atlantic and Pacific blocking predominated.
  9. donsutherland1

    [Eastern US] December 2018: Consolidated Discussion / Obs

    My latest thoughts on the weekend storm... A moisture-laden storm will bring heavy precipitation to parts of the Southeast and Lower Middle Atlantic region during the December 9-11 period. Cities such as Atlanta, Charleston, Pensacola, and Tallahassee could pick up 2" or more precipitation. As a result, 2018 would rank among the 15 wettest years on record for a number of those cities. Farther north, the pattern remains consistent with the composite 500 mb patterns that have seen significant accumulations of snow in parts of the Carolinas and Virginia. Further, the guidance has gradually moved into increasing consensus for a moderate to possibly significant snowfall in such cities as Asheville, Charlotte, Greenville-Spartanburg, Raleigh, and Roanoke. With cold air damming likely to precede the storm and a strong ridge likely to block it from turning sharply up the Coast, my confidence in a track favorable to the Lower Middle Atlantic region and parts of the Southeast has continued to increase. Consistent with many of the notable snowstorms to affect this region, accumulating snow will likely remain south of the Mason-Dixon Line. There is also a possibility that the accumulating snow remains south of Washington, DC and its nearby Virginia suburbs.
  10. donsutherland1

    [Eastern US] December 2018: Consolidated Discussion / Obs

    The RGEM had a small area with 8”.
  11. donsutherland1

    [Eastern US] December 2018: Consolidated Discussion / Obs

    0.25 mile visibility at ACY.
  12. donsutherland1

    [Eastern US] December 2018: Consolidated Discussion / Obs

    IMO, there were no appreciable changes in the upper air (500 mb) pattern on the EPS (mean) from the 0z run. With the 12z GGEM moving toward the broader model consensus, my confidence that this will primarily be a lower Mid-Atlantic/Southeast storm is increasing. There still remains some possibility that the precipitation could reach parts of the NYC region (especially central New Jersey southward), but the low (or lows depending on the guidance one is examining) will likely head east-northeastward out to sea and make a turn that is too wide to do more than brush the region. The storm's precipitation shield could miss altogether. Among the cities that could be in line for a moderate and possibly significant snowfall from the 12/9-11 storm(s) are Asheville, Charlotte, Danville, Greensboro, Greenville-Spartanburg, Raleigh, Richmond, and Roanoke. There remains a reasonable possibility that cities such as Baltimore, Hagerstown, and Washington could also pick up some accumulations, but this remains uncertain. Note: The lead time involved still provides latitude for changes.
  13. donsutherland1

    [Eastern US] December 2018: Consolidated Discussion / Obs

    One run, there was no snow at all. The next run there was 14". The former was a bleak nightmare. The latter was a wonderful dream. The city in question was Richmond. The model in question was the GFS. The runs were the 12/3/2018 12z and 18z runs. Run-to-run continuity was lacking. At this stage, it continues to appear that a storm will likely bring accumulating snow to portions of the Carolinas and Virginia. Cities such as Richmond and Raleigh will likely see accumulations. Whether the storm comes far enough north to bring at least light accumulations north of the Mason-Dixon line remains to be seen. However, even if it does not, winter 2018-19 still appears to be in line for above to much above normal snowfall across the Middle Atlantic, southern New England, and parts of the Great Lakes region. There still remains a window of opportunity for additional snow in the above region during the last week of December as the pattern becomes more volatile in the latter stages of a milder regime. Winter 2002-03 continues to provide insight. Much as happened then, the EPO is forecast to go positive. The latest EPS weekly forecast takes the EPO back to negative levels (ensemble mean) by around December 21. Afterward, it stays negative through mid-January (the end of the forecast period). In addition, during much of the time, the same guidance favors a negative AO. The EPO-/AO- combination was an important assumption in my expectation that winter 2018-19 will be very snowy in the Northeast. That such a combination is showing up on the EPS weekly guidance is an encouraging development.
  14. donsutherland1

    [Eastern US] December 2018: Consolidated Discussion / Obs

    As of 7 pm, total annual precipitation and 2018's rank among the wettest years is provided for select cities: During Friday into Saturday, low pressure will be developing and gaining moisture as it tracks near the Gulf Coast. Afterward, it will gradually turn east-northeast and move off either the Georgia or South Carolina coasts. Given repeated cycles of the guidance, this idea is one in which I have high confidence. Afterward, questions begin to emerge. The storm could continue to track generally east-northeastward while making a wide turn more to the north. A second possibility is that it could turn more sharply northward. The latter situation would present a greater risk of accumulating snowfall, potentially a moderate accumulation, in much of the northern Middle Atlantic region. However, issues concern weak low pressure that will be tracking eastward from Quebec and a vorticity maximum that could be present well off the South Carolina-Georgia border. The presence of both those factors increases the risk of the former scenario. The forecast 500 mb anomalies (especially those on the EPS) would strongly favor the former scenario. After another 24-30 hours of unseasonably mild readings, colder air will return to the eastern United States. By the next weekend, the focus of attention could be a large storm that is moving off the Southeast coast. Right now, the EPS is forecasting 500 mb anomalies that are reasonably similar to the composite for significant snowstorms (prior to 12/20) in parts of North Carolina. Such storms typically result in little or no snowfall north of the Mason-Dixon Line. The best match for the forecast 500 mb height anomalies is the December 2-3, 1896 snowstorm. The following snowstorms dumped 6" or more snow at Raleigh prior to December 20: December 2-3, 1896: 7.5" December 12-13, 1917: 7.1" December 17, 1930: 7.0" December 11, 1958: 9.1" Snowfall for select cities from those storms was as follows: December 2-3, 1896: Greenville-Spartanburg, SC: 10.5" New York City: None Philadelphia: None Washington, DC: None December 12-13, 1917: Greenville-Spartanburg, SC: 5.7" New York City: 8.1" Philadelphia: 2.3" Washington, DC: 3.0" December 17, 1930: Greenville-Spartanburg, SC: 14.4" New York City: None Philadelphia: None Washington, DC: 2.0" December 11, 1958: Greenville-Spartanburg, SC: 0.1" New York City: Trace Philadelphia: None Washington, DC: Trace Taking into consideration the EPS anomalies and the historical data, I have moderate confidence that the storm will eventually make a wide turn. As a result, at least from this point in time, a glancing blow might be possible, but the odds of a moderate to possibly significant snowfall in the New York City area could be low. Nevertheless, at these large lead times, significant changes remain possible. Thus, higher confidence in the details won't likely begin to emerge until the middle of the week. Therefore, even as the early data and historical experience with the currently forecast 500 mb maps suggest much greater prospects of a lower Mid-Atlantic, the lead time leaves some opportunity for changes in the forecast 500 mb pattern. Regardless of the outcome, winter 2018-19 still appears to be in line for much above average snowfall.
  15. donsutherland1

    [Eastern US] December 2018: Consolidated Discussion / Obs

    Last year was a close call. 0.4" fell in Bridgeport and 2.9" fell in Boston. The last measurable snowfall in NYC (Central Park) on Christmas Day occurred in 2002 when 5.0" fell. Interior sections received much greater amounts. For example, Port Jervis received 14.9" and Albany had 21.0".