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February 2021


snowman19
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In response to the Arctic Oscillation's having gone positive, a pattern change is now imminent. The advance of the milder air will be preceded by a storm that could bring snow changing to rain to most parts of the region tomorrow. From the Jersey Shore and across Long Island, little or no snow is likely this time around.

New York City and Newark will likely pick up near 1" of snow. Across northeastern Pennsylvania and northwestern New Jersey, including Allentown, 2"-4" with local amounts of 6" is likely.  

A warmup will likely follow the storm. Tuesday will likely see the temperature top out in the lower and middle 40s. Parts of the area could reach or exceed 50° on Wednesday before somewhat cooler air arrives.

Overall, a period of warmer than normal temperatures is likely in the Middle Atlantic and southern New England areas into the first week of March and possibly beyond that. There could be some short-lived shots of cooler air.

The ENSO Region 1+2 anomaly was -0.5°C and the Region 3.4 anomaly was -1.2°C for the week centered around February 10. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.50°C and the ENSO Region 3.4 anomaly has averaged -1.00°C. La Niña conditions will likely prevail at least through mid-March.

The SOI was +19.79 today.

The preliminary Arctic Oscillation (AO) figure was +0.454 today

On February 20 the MJO was in Phase 7 at an amplitude of 1.204 (RMM). The February 19-adjusted amplitude was 1.285.

Based on the latest guidance, no significant stratospheric warming event is likely into the first week of March.  

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. Since January 1, New York City has picked up 27.7" snow.

Winters that saw December receive 10" or more snow, less than 10" in January, and then 10" or more in February in New York City, saw measurable snowfall in March or April in 83% of cases. Winter 2009-2010 was the exception where only a trace of snow was recorded. This group of winters saw 6" or more snow during the March-April period in 50% of the cases. All said, it is more likely than not that there will be measurable snowfall after February.  

Based on sensitivity analysis applied to the latest guidance, there is an implied 97% probability that New York City will have a colder than normal February. February will likely finish with a mean temperature near 32.9° (2.4° below normal).

 

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12 hours ago, bluewave said:

The core of the cold was focused over a smaller geographic region around the Plains during this extreme -AO episode. Notice how much more real estate the winter cold anomalies covered in 09-10, 76-77, and 69-70. So relative to other extreme -AO patterns, this was the warmest for our area.

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hey just for fun, can you post what 1899 looked like? since many want to compare this arctic outbreak to that one

 

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6 hours ago, donsutherland1 said:

A very snowy February is nearing its conclusion. There could be some additional snowfall tomorrow in Central Park. Areas to the west of New York City should pick up 1"-3" snow with 2"-4" and localized higher amounts running across northeastern Pennsylvania and northwestern New Jersey.

How March fares in terms of snowfall will depend, at least in part, on the monthly mean temperature. The monthly mean temperature explains nearly 30% of the City's March snowfall.

March Temperatures and Snowfall (New York City):

March-Snowfall-NYC-1869-2020.jpg

March-Snowfall-NYC-1869-2020-2.jpg

my favorite March was 2015, which continued the amazing backside of winter that started in February.

 

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7 hours ago, bluewave said:

The record AO rise and more -PNA are allowing a Niña-like pattern to finally emerge.

4C81080C-766F-4018-8725-FFAAFECD8030.thumb.jpeg.87da4dc6278d88d5afc9f58df21a3d33.jpeg


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but is that a nina pattern emerging or the fact that we had a -AO for so long it simply had to go positive at some point?  Seems like AO drives our patterns more than any of these other indices do.  So this might be a +AO pattern emerging not a nina pattern emerging.

 

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The last 7 days of February are averaging 37degs.(30/43), or Normal.

Month to date is 31.6[-3.0].         February should end at 33.0[-2.3].

Other than today's fail, No Snow showing.      The start of March looks hotter every run, but for the 2nd.        Averaging 46degs. for first 10 days.     S.E. Canada  is +50F in 15 days.            12Z  GFS pulls  the Switch-er-Rooni  and now says the  first 10 days of March will average, not 46degs., but 38*(31/44)

Spring according to the JMA is:    March AN T,  April,May  Near Normal T.    Spring apparently Wetter Than Normal as it shows BN Sea Level P throughout.

32*(67%RH) here at 6am.        34* by 7am.     35* by 8am.       37* by 9am.       39* by 10am.      35*(88%RH)by Noon---snowing.       36* at 1pm,  snow stopped.   

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Morning thoughts...

At 7:50 am, an area of heavy snow (likely 1”-1.5” per hour) was moving eastward across central Pennsylvania. That snow will continue to advance rapidly eastward.

A period of rain or snow changing to rain will break out during the morning. New York City, Newark, and Philadelphia will likely pick up near 1” of snow. An area extending across northeastern Pennsylvania, northwestern New Jersey and adjacent New York State, including Allentown, will likely see 2”-4” with local amounts of 6”. Temperatures will likely top out in the middle and upper 30s in most of the region. Likely high temperatures around the region include:

New York City (Central Park): 39°

Newark: 39°

Philadelphia: 39°

Following today’s precipitation, most of the remainder of February will likely see temperatures average somewhat above normal. There may still be some opportunity for snowfall despite the milder regime.

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4 hours ago, bluewave said:

Yeah, this was the first time we had such a rapid AO rise following a -5 or lower reading. So we got the biggest snowstorm of the winter before the lowest value instead of after. Usually, the -AO lingers for weeks to a month after it drops so low. The heaviest snowstorm usually occurs at the date or after instead of more than a week before this time. 

looking at the ao forecast its going to stay positive for a while...1974 had a negative ao value but not as great as this year was...Feb 1974 went negative to positive around the 21st and stayed there for two weeks or so...March 74 saw the ao go negative again by mid March...there was a late season snowfall in late March 74 and a little snow and cold in April...If the ao remains positive throughout March it probably will end up as one of the warmest...at this point with twice as much snow as 1973-74 bring on the warmth...

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12 hours ago, bluewave said:

The La Niña was there in the background all winter. But the -AO and +PNA were a stronger influence on our pattern. Now that the AO and PNA are reversing, models forecasts are reverting to more of a La Niña-like look. Ridge near the Aleutians, more -PNA, and SE Ridge. La Niña can still have an effect even if the expected 500 mb patterns and temperature progression didn’t manifest for us.
 

 

If we have a neutral next winter, do you think it will be a 89-90 type winter?

 

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11 hours ago, Brett said:

It looks like all the models break the pattern down next week and it goes mild we had a great run the last 4 weeks

hey today's snow was nice, rather unexpected here for a few hours around mid day and it stuck to everything.

Next week might be mild but it looks yucky and rainy all week- definitely NOT what I want

 

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