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February 2019 General Discussion and Observation Thread


Stormlover74
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10 minutes ago, bluewave said:

This is the strongest early February -PNA outside of a cold ENSO state in a long time. Just the latest in a string of oddities this winter.

 

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EPS continues the RNA right through the last week of this month. It would appear the CanSIPS wasn’t so crazy after all with its prediction for February a couple of weeks ago

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25 minutes ago, bluewave said:

This is the strongest early February -PNA outside of a cold ENSO state in a long time. Just the latest in a string of oddities this winter.

These strange oddities have worked in our favor in past winters.

I think last year winter had well AN temps but AN snowfalls. 

Unfortunately the reverse happened this time.

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2 hours ago, Snow88 said:

Why do you think people went snowy this winter ?

Even majority of forecasters said they went snowy because of the forecasted weak EL Nino.

Go ahead and nitpick by post

I can't speak for others, but my base assumptions were:

1. Central Pacific-based weak El Niño event

Actual: Neutral-warm to very weak basin-wide El Niño event. The outcomes between the two situations differ substantially in terms of probabilities e.g., the frequency of measurable snow events is about half of climatology in NYC and Philadelphia for the ENSO conditions that prevailed.

It's difficult to be sure, but I suspect a big part of the reason the EPS weeklies so persistently showed a classic winter pattern developing at the two week and later timeframe was because the EPS was unable to distinguish what was actually taking place with respect to ENSO. To some extent, that issue likely led to its missing the MJO's high amplitude in December and early January.

At least this winter, the CFSv2 weeklies have essentially been vastly superior at weeks 3 and 4 than the EPS. A big part of the reason might be that by November, the CFSv2 correctly recognized that the El Niño event would be a basin-wide event. Even then, it was too strong with the magnitude e.g., it forecast a DJF ENSO Region 3.4 anomaly of just over +1.00°C.  The December-January average is +0.74°C, but the latest weekly figure is down to +0.30°C. Three of the last four weeks have had anomalies < 0.50°C. By the time meteorological winter concludes, Winter 2018-19 will be in the books as a weak basin-wide El Niño event.

2. Predominantly negative AO

Actual: On track. 61% days have seen an AO < 0; 30% have had an AO of -1.000 or below; Winter average: -0.433. But no single variable determines the overall outcome. They all contribute. The AO- was present during the most severe Arctic outbreaks.

3. Predominantly negative EPO

46% of days this winter have had an EPO < 0. It is forecast to remain negative for the next 15 days.

Another thing that has happened is that the PDO has remained predominantly negative this winter. That's likely the result of the weaker ENSO event than had been anticipated. That outcome has led to reduced PNA ridging which has increased opportunities for snowfall in the Pacific Northwest. There were clusters of winters during the late 1940s-early 1950s and late 1960s-early 1970s that were characterized by a strongly negative PDO during which Seattle frequently received more snowfall than New York City.

All said, my error concerning the ENSO can't be overstated. It has played a large role, particularly as it relates to seasonal snowfall.

I do believe we'll see more snowfall in New York City before the winter is finished (probably bringing the seasonal total to 15"-25"). I also expect Boston to see enough snowfall to avert setting a record low figure for the winter (current figure is 2.3", which ranks just above the 1.8" that had been recorded during 2006-07 to date).

In sum, seasonal forecasting remains challenging. Missing critical details, especially those related to ENSO, can lead to a very bad forecast. That's what happened for me.

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27 minutes ago, SnoSki14 said:

These strange oddities have worked in our favor in past winters.

I think last year winter had well AN temps but AN snowfalls. 

Unfortunately the reverse happened this time.

It may be the interference created by all the competing influences that resulted in the unusually low snowfall since December 1st. Hopefully, we see at least one classic benchmark snowstorm or KU before we get to the end of March.

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13 minutes ago, Brian5671 said:

The point and click for seattle looks like something out of Alaska....a week of snow and blowing snow...

Also check out the unusually intense storm set to impact Hawaii in this pattern.

https://weather.com/forecast/regional/news/2019-02-08-hawaii-storm-high-winds-coastal-flooding

Unusually Strong Hawaii Storm This Weekend May Bring Damaging Winds, Unprecedented Coastal Flooding, NWS Says

The surface low will quickly intensify into the 980s millibars, a central pressure on par with some typical intense Northeast U.S. coastal storms known as nor'easters

"This is the strongest forecast kona low that I have witnessed near Hawaii in my 25-plus years living on Oahu," said Dr. Steven Businger, an expert on kona storms and atmospheric scientist at the University of Hawaii. 

The upper-level core of this storm may be among the coldest for this part of the central Pacific in the last 40 years, according to analysis from Tomer Burg, an atmospheric science graduate student at SUNY Albany.

 

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9 minutes ago, purduewx80 said:

It's interesting that Seattle typically sees 2x as much snow during La Nina and neutral years vs El Nino. No surprise they're cashing in during this -PNA, Nina-like pattern.

They’ve done poorly in general though the last few La Ninas.  I believe 98-99 was their last decent La Niña winter 

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15 minutes ago, Snow88 said:

For everyone. That's what it shows.

Let's see if we can get one storm to deliver for us before we go off half-cocked again. Expectations need to be modest. A 2-4 front end would be something to celebrate at this point. I know you're not saying it will happen, but we've all been burned this winter so far.

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6 hours ago, jr461 said:

Why is it a "nice highlight" to get a few inches only to be shortly washed away?  I don't get that even for a snow lover.  That only serves to make travel difficult, snarl traffic and cause transit delays with no lasting effect ...

Because when it's snowing, it's snowing.  Crass analogy, but think of it as spending time with a dying relative.  It ends soon but she's here now and that's what matters.

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26 minutes ago, NorthShoreWx said:

Because when it's snowing, it's snowing.  Crass analogy, but think of it as spending time with a dying relative.  It ends soon but she's here now and that's what matters.

I think you nailed it. Snow is transient. Think of the Tibetan Monks who made elaborate sculptures from butter; they understood it would melt, like life itself. If you lived in a part of the world where it snowed for 7 months out of the year, you might not miss it if you moved....and in fact when I talk to people in FL who lived in Buffalo or upper Michigan or Syracuse they say they moved specifically to get away from snow and cold. Likewise, many people who have grown up in the heat don't miss it when they move to a milder climate. We like snow precisely because it is temporary and transient.

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The February 1-7 average temperature in New York City was 38.8°. That was the 14th warmest first week on record for February. New York City's records go back to 1869.

There are prior cases when the temperature averaged 38.0° or above during the first week in February. Just 2 (13%) saw February wind up with a below normal monthly temperature. Based on sensitivity analysis applied to the latest guidance, there is an implied 71% probability that February will wind up warmer than normal.

In terms of snowfall February-March-April snowfall, 40% of those cases saw 10" or more. 27% of those cases saw 20" or more.

The SOI was -10.33 today. This figure is the lowest reading since January 5 when the SOI was -18.60.

The Arctic Oscillation (AO) is now on the brink of going positive. Today's preliminary value was -0.051. The preliminary average for meteorological winter is -0.431.

On February 7, the MJO was in Phase 6 at an amplitude of 1.303 (RMM). The amplitude was little changed from the February 6-adjusted figure of 1.337.

After spending another 1-3 days in Phase 6, the MJO should return to Phase 7. Upon reaching Phase 7, it should slowly advance toward Phase 8. It could approach or reach Phase 8 within a few days of mid-month.

After that, there is considerable uncertainty. Even as some of the dynamical models show the MJO's pushing into Phase 1, the historical risks are somewhat weighted in favor of a possible return to Phase 7. Right now, none of the operational guidance shows such an outcome, but the guidance has not fared well in the extended range.

The risks of a delayed return to Atlantic blocking have recently increased. During neutral-warm ENSO conditions, the MJO's being in Phase 7 at a high amplitude has often coincided with a positive AO. The latest GEFS guidance has suggested that the AO+, once it develops, could persist beyond mid-month.

However, as the MJO moves into Phase 8, the AO should return to negative values. Were the AO to peak at or above +3.000, the probability of that outcome could decline. A period of sustained colder readings could develop afterward.

Finally, the pattern remains on track to become stormy after the 10th. Details for potential storms will need to be resolved as the possible events draw closer. However, the probability of a light snow event in the region (moderate snowfall in northwest NJ, northeast Pennsylvania, and southeast New York to the north and west of New York City) sometime in the next 3-6 days and potentially a light to perhaps moderate event in the snow-starved Boston area has increased.

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