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donsutherland1

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  1. Flagstaff finished with an all-time daily snowfall record of 35.9" yesterday and daily record precipitation of 1.44". Phoenix also picked up a daily record precipitation amount of 1.01". There is a strong correlation between precipitation in the Southwest and a negative SOI.
  2. While parts of the region have seen very little snowfall this winter, Flagstaff has set a new one-day snowfall record. As of 5 pm MST, Flagstaff had picked up 31.6" snow today. The previous one-day record was 31.0", which was set on December 30, 1915. So far, Flagstaff has picked up a storm total of 33.1" over two days. The two-day record is 51.0", which was established during December 30-31, 1915. The three-day record is 54.0", which was set during December 29-31, 1915.
  3. Basin-wide neutral-warm ENSO conditions persist. The ENSO Region 1+2 anomaly was +0.60°C and the Region 3.4 anomaly was +0.60°C for the week centered around February 13. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.58°C and the ENSO Region 3.4 anomaly has averaged +0.48°C. Basin-wide, neutral-warm/very weak El Niño conditions are not conducive for large snowstorms in northern Mid-Atlantic cities including New York and Philadelphia during February.   There have been just 3 snowstorms of 4" or more in Boston during February when the ENSO 1+2 anomaly was > 0.00°C and the ENSO 3.4 anomaly ranged from 0.00°C to 0.69°C since 1950. In New York City, there was just one such storm and in Philadelphia there were two. The biggest snowstorms during such ENSO conditions were as follows: Boston: 9.7"; New York City: 4.3"; and, Philadelphia: 4.7". Those three figures might represent the upper bound of what's possible in terms of accumulations in the current pattern unless there is strong modeling consensus for a larger snowfall. During the most recent storm, all three cities had accumulations that fell short of 4.0".   Such ENSO conditions will likely persist through February with some possible fluctuations to levels consistent with weak El Niño events. Under such a scenario, the probability of a significant snowfall (6" or more) will be well below climatology for the northern Mid-Atlantic region.   The SOI was -27.27 today. That is the 11th consecutive day during which the SOI was -10.00 or below. The last time the SOI was at or below -10.00 for at least 11 consecutive days was April 12-23, 2016.   Today's preliminary value of the Arctic Oscillation (AO) was +2.486. The preliminary average for meteorological winter is -0.005. Should the AO average +0.068 for the remainder of February, it would finish with a meteorological winter average +0.001.   On February 20, the MJO was in Phase 8 at an amplitude of 2.156 (RMM). The amplitude rose from the February 19-adjusted figure of 1.833. The MJO could spend an extended duration in Phase 8 before moving slowly into Phase 1 during the closing week of February. Late February high amplitude MJO Phase 8 cases have not always led to a snowy March. March 1978 saw 6.8" snow fall in New York City. March 1988 saw no measurable snowfall in New York City.   The SOI remains at very negative levels. The SOI has a correlation to precipitation in the southern tier of the United States. As a result, precipitation will likely be above to much above normal in both the Southwestern United States (including California) and Southeastern United States.   Another storm could bring moderate to potentially heavy rainfall to parts of the East this weekend. Afterward, the pattern could evolve toward a colder one. Unlike with February when neutral-warm to very weak El Niño conditions are not conducive to significant snows in the Middle Atlantic region, the frequency of such snowfalls during such ENSO conditions increases in March courtesy of shortening wave lengths. Since 1950, 43% of New York City's 6" or greater snowstorms during March 1-15 occurred with an AO+/PNA- pattern and 27% occurred with an AO-/PNA+ pattern.   Based on historic data following similar ENSO conditions to those of February 2019, March 1-15 could provide perhaps the final window of opportunity for a moderate or significant snowstorm in the New York City area. Afterward, pronounced warming could limit opportunities for snowfall.
  4. That's exactly what one would expect from the recent severely negative SOI. The big storm affecting the Southwest (with nearly 2 feet of snow in Flagstaff) is consistent with a severely negative SOI (correlation of southern tier precipitation with the SOI).
  5. Ice accretion from the recent storm: New Rochelle, New York
  6. I’m not sure. Maybe they thought it would warm more quickly at the surface than it has. It was a challenging forecast. Unfortunately, this time around there was more ice than had been forecast.
  7. Much of the area, including Central Park has picked up 0.10”-0.20” freezing rain.
  8. Basin-wide neutral-warm ENSO conditions persist. The ENSO Region 1+2 anomaly was +0.60°C and the Region 3.4 anomaly was +0.60°C for the week centered around February 13. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.58°C and the ENSO Region 3.4 anomaly has averaged +0.48°C. Basin-wide, neutral-warm/very weak El Niño conditions are not conducive for large snowstorms in northern Mid-Atlantic cities including New York and Philadelphia during February. Today's storm proved consistent with historic experience.   Such ENSO conditions will likely persist through February with some possible fluctuations to levels consistent with weak El Niño events. Under such a scenario, the probability of a significant snowfall (6" or more) will be well below climatology for the northern Mid-Atlantic region.   The SOI was -38.91 today. That is the 10th consecutive day during which the SOI was -10.00 or below. The last time the SOI was at or below -10.00 for at least 10 consecutive days was April 12-23, 2016.   Today's preliminary value of the Arctic Oscillation (AO) was +3.112. The preliminary average for meteorological winter is -0.035. Should the AO average +0.371 for the remainder of February, it would finish with a meteorological winter average +0.001.   On February 19, the MJO was in Phase 8 at an amplitude of 1.839 (RMM). The amplitude rose from the February 18-adjusted figure of 1.550. The MJO could spend an extended duration in Phase 8 before moving slowly into Phase 1 during the closing week of February.   The SOI remains at very negative levels. The SOI has a correlation to precipitation in the southern tier of the United States. As a result, precipitation will likely be above to much above normal in both the Southwestern United States (including California) and Southeastern United States.   Another storm could bring moderate to potentially heavy rainfall to parts of the East this weekend. Afterward, the pattern could evolve toward a colder one. Unlike with February when neutral-warm to very weak El Niño conditions are not conducive to significant snows in the Middle Atlantic region, the frequency of such snowfalls during such ENSO conditions increases in March courtesy of shortening wave lengths.   Based on historic data following similar ENSO conditions to those of February 2019, March 1-15 could provide perhaps the final window of opportunity for a moderate or significant snowstorm in the New York City area. Afterward, pronounced warming could limit opportunities for snowfall.
  9. Basin-wide neutral-warm ENSO conditions persist. The ENSO Region 1+2 anomaly was +0.60°C and the Region 3.4 anomaly was +0.60°C for the week centered around February 13. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.58°C and the ENSO Region 3.4 anomaly has averaged +0.48°C. Basin-wide, neutral-warm/very weak El Niño conditions are not conducive for large snowstorms in northern Mid-Atlantic cities including New York and Philadelphia during February.   Such ENSO conditions will likely persist through February with some possible fluctuations to levels consistent with weak El Niño events. Under such a scenario, the probability of a significant snowfall (6" or more) will be well below climatology for the northern Mid-Atlantic region.   The SOI was -43.61 today. That's the lowest figure since the SOI was at -51.97 on February 18, 2017. That's also the ninth consecutive day during which the SOI was -10.00 or below. The last time the SOI was at or below -10.00 for at least nine consecutive days was February 1-9, 2018.   Today's preliminary value of the Arctic Oscillation (AO) was +3.481. That is highest AO reading since March 14, 2017 when the AO was +3.548. The preliminary average for meteorological winter is -0.074. Should the AO average +0.675 for the remainder of February, it would finish with a meteorological winter average +0.001.   Based on historic experience (1950-2018) when the AO reached +3.000 or above during the February 1-15 period, the AO will likely remain predominantly positive through most of the second half of February. The probability of the AO's reaching negative levels during the last week of February has declined.   On February 18, the MJO was in Phase 8 at an amplitude of 1.554 (RMM). The amplitude was little changed from the February 17-adjusted figure of 1.523. The MJO could spend an extended duration in Phase 8.   The combination of a neutral-warm ENSO and a powerful polar vortex responsible for the strongly positive AO remain the dominant factors driving the pattern evolution. They will likely continue to predominate over the next week. As a result, MJO convection will have little meaningful impact on the larger pattern during that time.   The SOI remains at very negative levels. The SOI has a correlation to precipitation in the southern tier of the United States. As a result, precipitation will likely be above to much above normal in both the Southwestern United States (including California) and Southeastern United States.   There could be several opportunities for snowfall in the East in coming days, the first of which is tonight into tomorrow. However, the probability of significant snowfall events (6" or more) is well below climatology (but not zero) for the Middle Atlantic region. Central/Upstate New York across central and northern New England have a greater probability of seeing significant snow events.   Given this context, the probabilities remain weighted against a large-scale snowstorm The next storm could bring a moderate snowfall (a general 3"-6") to an area focused on Baltimore, Philadelphia, and Washington on Wednesday into Thursday, but lesser snowfall from New York City into southern New England (probably 1"-3" in such cities as Bridgeport, Islip, New York City, and Newark) with lesser amounts up the Hudson Valley.   Based on historic data following similar ENSO conditions to those of February 2019, March 1-15 could provide perhaps the final window of opportunity for a moderate or significant snowstorm in the New York City area. Afterward, pronounced warming could limit opportunities for snowfall.
  10. In the wake of the most recent storm, Boston's seasonal snowfall has increased to 8.2". That figure remains far below normal for this point in the season.   Basin-wide neutral-warm ENSO conditions persist. The ENSO Region 1+2 anomaly was +0.60°C and the Region 3.4 anomaly was +0.60°C for the week centered around February 13. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.58°C and the ENSO Region 3.4 anomaly has averaged +0.48°C. Basin-wide, neutral-warm/very weak El Niño conditions are not conducive for large snowstorms in northern Mid-Atlantic cities including New York and Philadelphia during February.   Such ENSO conditions will likely persist through February with some possible fluctuations to levels consistent with weak El Niño events. Under such a scenario, the probability of a significant snowfall (6" or more) will be well below climatology for the northern Mid-Atlantic region.   The SOI was -35.88 today. That's the lowest figure since the SOI was at -40.30 on February 18, 2017. That's also the eighth consecutive day during which the SOI was -10.00 or below. The last time the SOI was at or below -10.00 for at least eight consecutive days was February 1-9, 2018.   Today's preliminary value of the Arctic Oscillation (AO) was +2.165. The preliminary average for meteorological winter is -0.118. Should the AO average +0.956 for the remainder of February, it would finish with a meteorological winter average +0.001.   Based on historic experience (1950-2018) when the AO reached +3.000 or above during the February 1-15 period, the AO will likely remain predominantly positive through most of the second half of February. There still remains a possibility that the AO could head toward neutral or negative levels during the last week of the month, but probably not until after the AO again rises toward +3.000 or above.   On February 17, the MJO was in Phase 8 at an amplitude of 1.524 (RMM). The amplitude was above the February 16-adjusted figure of 1.283. The MJO could spend an extended duration in Phase 8.   The combination of a neutral-warm ENSO and a powerful polar vortex responsible for the strongly positive AO remain the dominant factors driving the pattern evolution. They will likely continue to predominate over the next week. As a result, MJO convection will have little meaningful impact on the larger pattern during that time.   The SOI remains at very negative levels. The SOI has a correlation to precipitation in the southern tier of the United States. As a result, precipitation will likely be above to much above normal in both the Southwestern United States (including California) and Southeastern United States.   There could be several opportunities for snowfall in the East in coming days, the first of which is tonight into tomorrow. However, the probability of significant snowfall events (6" or more) is well below climatology (but not zero) for the Middle Atlantic region. Central/Upstate New York across central and northern New England have a greater probability of seeing significant snow events.   Given this context, the probabilities remain weighted against a large-scale snowstorm The next storm could bring a moderate snowfall (a general 3"-6") to an area focused on Baltimore, Philadelphia, and Washington on Wednesday into Thursday, but lesser snowfall from New York City into southern New England.   The forecast 500 mb pattern for the upcoming storm has some similarities to the composite 500 mb anomalies of February 17-18, 1967 and February 27-28, 2003, but with the ridging penetrating farther north. Such a pattern would see the most meaningful snows fall from central New Jersey southward.   Based on historic data following similar ENSO conditions to those of February 2019, March 1-15 could provide perhaps the final window of opportunity for a moderate or significant snowstorm in the New York City area. Afterward, pronounced warming could limit opportunities for snowfall.  
  11. donsutherland1

    Southwest Flow Event Potential 2-17/2-18

    Back to sleet in southern Westchester County.
  12. donsutherland1

    Southwest Flow Event Potential 2-17/2-18

    Light rain now in southern Westchester County.
  13. donsutherland1

    Southwest Flow Event Potential 2-17/2-18

    It has now begun to sleet in southern Westchester County.
  14. Basin-wide neutral-warm ENSO conditions persist. The ENSO Region 1+2 anomaly was +0.30°C and the Region 3.4 anomaly was +0.40°C for the week centered around February 6. For the past five weeks, the ENSO Region 1+2 anomaly has averaged +0.73°C and the ENSO Region 3.4 anomaly has averaged +0.40°C. Basin-wide, neutral-warm ENSO conditions are not conducive for large snowstorms in northern Mid-Atlantic cities including New York and Philadelphia during February.   Such ENSO conditions will likely persist through February with some possible fluctuations to levels consistent with weak El Niño events. Under such a scenario, the probability of a significant snowfall (6" or more) will be well below climatology for the northern Mid-Atlantic region.   The SOI was -29.88 today. That's the lowest figure since the SOI was at -30.78 on September 8, 2018. That's also the seventh consecutive day during which the SOI was -10.00 or below. The last time the SOI was at or below -10.00 for seven consecutive days was August 9-16, 2018.   Today's preliminary value of the Arctic Oscillation (AO) was +1.556. The preliminary average for meteorological winter is -0.147. Should the AO average +1.066 or above for the remainder of February, it would finish with a meteorological winter average +0.001.   Based on historic experience (1950-2018) when the AO reached +3.000 or above during the February 1-15 period, the AO will likely remain predominantly positive through most of the second half of February. There still remains a possibility that the AO could head toward neutral or negative levels during the last week of the month, but probably not until after the AO again rises toward +3.000 or above.   On February 16, the MJO was in Phase 8 at an amplitude of 1.281 (RMM). The amplitude was above the February 15-adjusted figure of 1.023. The MJO could spend an extended duration in Phase 8.   The combination of a neutral-warm ENSO and a powerful polar vortex responsible for the strongly positive AO remain the dominant factors driving the pattern evolution. They will likely continue to predominate over the next week. As a result, MJO convection will have little meaningful impact on the larger pattern during that time.   The SOI remains at very negative levels. The SOI has a correlation to precipitation in the southern tier of the United States. As a result, precipitation will likely be above to much above normal in both the Southwestern United States (including California) and Southeastern United States.   There could be several opportunities for snowfall in the East in coming days, the first of which is tonight into tomorrow. However, the probability of significant snowfall events (6" or more) is well below climatology (but not zero) for the Middle Atlantic region. Central/Upstate New York across central and northern New England have a greater probability of seeing significant snow events.   Given this context, it is likely that the snow event for parts of the region later today into tomorrow will be largely unimpressive. Central Park will likely pick up 1" or less of snow. Meanwhile, snow-starved Boston (where just 4.8" snow has fallen to date) could pick up 2"-4" snow. The next storm could bring a moderate snowfall (a general 3"-6") to an area focused on Baltimore, Philadelphia, and Washington on Wednesday into Thursday, but lesser snowfall from New York City into southern New England.   Based on historic data following similar ENSO conditions to those of February 2019, March 1-15 could provide perhaps the final window of opportunity for a moderate or significant snowstorm in the New York City area. Afterward, pronounced warming could limit opportunities for snowfall.
  15. donsutherland1

    Southwest Flow Event Potential 2-17/2-18

    Based on the latest guidance through 18z, I have little changes to my thinking from yesterday. My final estimates are as follows: Albany: 3"-6" Binghamton: 2"-4" Boston: 2"-4" Bridgeport: 1"-3" Concord: 1"-3" Hartford: 2"-4" Islip: 1" or less (initial estimate was 1"-2") New City: 1"-3" New York City: 1" or less Newark: 1" or less Portland: 1" or less Poughkeepsie: 2"-4" Providence" 3"-6" Scranton: 2"-4" White Plains: 1"-3" Worcester: 3"-6"
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