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February 2019 General Discussion and Observation Thread


Stormlover74

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Weak El Niño conditions have redeveloped. The ENSO Region 1+2 anomaly was +0.20°C and the Region 3.4 anomaly was +0.70°C for the week centered around February 20. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.53°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. Conditions can be somewhat more favorable during the first half of March.

Such ENSO conditions will likely persist into at least the first half of March with some possible fluctuations to levels consistent with weak El Niño events. The warm SSTAs will likely remain basin-wide.

The SOI was -9.99 today. The 30-day SOI average is -12.50.

Today's preliminary value of the Arctic Oscillation (AO) was +1.620. The preliminary average for meteorological winter is +0.074. Should the AO average -2.129 for the remainder of February, it would finish with a meteorological winter average +0.001. Therefore, given the latest ensemble forecast, the AO will very likely finish with a positive average for winter 2018-19. Further, consistent with cases where the AO peaked at +3.000 or above during the February 20-28 period, the odds of a return to negative AO values is low. Almost half of such cases actually had no AO- readings through March 15.

On February 24, the MJO was in Phase 1 at an amplitude of 2.125 (RMM). The amplitude was somewhat lower than the February 23-adjusted figure of 2.172.

The SOI remains at 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.

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. That the MJO will likely enter March at a high amplitude is consistent with a colder start to the month. Due to shorter wave lengths, the state of the AO has little impact on the probability of such storms.

Afterward, pronounced warming could limit opportunities for snowfall. The odds of such warming would be particularly high should the PDO be negative, as has been the case in both December and January.

The 12z ECMWF was most aggressive with the idea of a Middle Atlantic and New England snowstorm during the first week in March. Both the latest CFSv2 and EPS weekly forecasts favor a warm-up near mid-month. Cold could linger in the Central and Northern Plains through much of March.

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Last three days of Feb. averaging 30degs., or 6degs. BN.

Month to date is +2.1[37.0].    Should end Feb. at +1.0[36.2].

All 8 days averaging 33degs., or 4degs. BN.

EURO is 8" for the next 10 days.   The GEFS is 5" on the next 10 days.

Concerning the mid-month warming in two weeks mentioned in previous entry, the RRWT is BN till 3/15, then Normal for a week and BN again 3/23---04/01.   Then it is AN.

The next 30 days are BN for the northeast and most of western Europe.

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The two primary issues that delayed the FV3's implementation:

-The snow depth and the water equivalent of snow depth at the surface have unrealistically large values when precipitation occurs in environments with low-level temperature profiles close to freezing. Techniques that use either of these variables for deriving snowfall will exhibit excessive snowfall values.

-The model forecasts exhibit a cold bias in the lower atmosphere that became more prominent after late September 2018.

https://www.weather.gov/media/notification/scn19-12gfsv15.pdf

 

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1 hour ago, donsutherland1 said:

The two primary issues that delayed the FV3's implementation:

<i>-The snow depth and the water equivalent of snow depth at the surface have unrealistically large values when precipitation occurs in environments with low-level temperature profiles close to freezing. Techniques that use either of these variables for deriving snowfall will exhibit excessive snowfall values.

-The model forecasts exhibit a cold bias in the lower atmosphere that became more prominent after late September 2018.</i>

https://www.weather.gov/media/notification/scn19-12gfsv15.pdf

 

That’s a good move. If all the FV3 virtual snow verified, then we might have had more snow than 95-96.;)

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26 minutes ago, yoda said:

UKMET is coastal rain storm for you and me... you get a lil snow before the 850 line moves north

850 line is way too detailed. ‘Storm in vicinity with some snow potential’ is really all we can say this far out which is what snow88 was saying I think.

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1 hour ago, Snow88 said:

Euro shows several inches for the area

4-6" Wilmington-New Brunswick and 6-8" New Brunswick through NYC and beyond (and a bit more NE of NYC in New England) on the Euro, as modeled.  Between that and 6-10" on the CMC and 3-5" on the GFS-FV3, we have a legitimate snowstorm threat for Sunday night into Monday.  Sure it's still 5+ days out, but it's better than tracking warm rain.  

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The ENSO Region 1+2 anomaly was +0.20°C and the Region 3.4 anomaly was +0.70°C for the week centered around February 20. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.53°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. Conditions can be somewhat more favorable during the first half of March, but based on historic data, the recent warming of ENSO Region 3.4 may not be a positive development for the first half of March.

Similar ENSO conditions will likely persist through at least the first half of March with some possible fluctuations to just below weak El Niño levels. Some guidance suggests the potential for further warming of ENSO Region 3.4.

The SOI was -15.32 today. The 30-day SOI average is -12.90.

Today's preliminary value of the Arctic Oscillation (AO) was +1.997. The preliminary average for meteorological winter is +0.096. Should the AO average -4.192 for the remainder of February, it would finish with a meteorological winter average +0.001. Therefore, given the latest ensemble forecast, the AO is virtually certain to finish with a positive average for winter 2018-19. Further, consistent with cases where the AO peaked at +3.000 or above during the February 20-28 period, the odds of a return to negative AO values is low. Almost half of such cases actually had no AO- readings through March 15.

On February 25, the MJO was in Phase 1 at an amplitude of 2.157 (RMM). The amplitude was somewhat higher than the February 24-adjusted figure of 2.126. Over the next 1-3 days, the MJO will likely move into Phase 2. Afterward, it could move into Phase 3 near the start of the second week of March.

The SOI remains at 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.

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. That the MJO will likely enter March at a high amplitude is consistent with a colder start to the month. Due to shorter wave lengths, the state of the AO has little impact on the probability of such storms.

Afterward, pronounced warming could limit opportunities for snowfall. The odds of such warming would be particularly high should the PDO be negative, as has been the case in both December and January.

During the March 1-15 period, the frequency of a widespread moderate or significant snowstorm (a storm that brings 4" or more snow to two or more of the following cities--Boston, New York City, and/or Philadelphia) has been limited when the March ENSO Region 3.4 anomaly has been at or above the El Niño threshold. Since 1950, 18/21 (86%) of such snowstorms occurred when the ENSO region 3.4 anomaly was below +0.50°C. The biggest snowstorms when the March Region 3.4 anomaly was at or above +0.50°C were as follows: Boston: 5.8"; New York City: 7.5"; and, Philadelphia: 7.5". In terms of 6" or greater snowstorms during March 1-15, 1950-2018, 0/19 (0%) in Boston, 1/7 (14%) in New York City, and 1/13 (8%) in Philadelphia have occurred when the March ENSO Region 3.4 anomaly was +0.50°C or above. However, March 1958 saw a major snowstorm during the second half of the month during El Niño conditions, so some probability of such a storm would exist even if current ENSO Region 3.4 anomalies persist.

March could finish with an ENSO Region 3.4 anomaly above +0.50°C if some of the recent ENSO forecasts are reasonably accurate and earlier today the World Meteorological Organization indicated that there is a 50%-60% chance that a weak El Niño could develop by May.

https://public.wmo.int/en/media/press-release/wmo-update-50-60-chance-of-el-ni%C3%B1o-within-next-3-months

Therefore, one should wait for good run-to-run continuity and strong model consensus before embracing high-impact snow scenarios for the Philadelphia-Boston region that may appear from time to time on the guidance. Put another way, even as a moderate or significant snowfall remains possible, confidence in such an outcome could be fairly low until the possible event is 48-96 hours away.

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41 minutes ago, ILoveWinter said:

lol so the NYC area is just too far south for this one? man we cant catch a break!

Meanwhile my niece just moved back from Minnesota she said you can have all the snow and cold you want there but she's had it. Came back here where the winters are " more reasonable."

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