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January 2020 Discussion


Torch Tiger
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15 minutes ago, Ginx snewx said:

Good call I think, hard to find that amongst the 100 page outlook. 

There is a seasonal progression section near the end....if you go to the thread, I have posted select excrepts. You seemed to get the gist when you posted last fall that "I hope you are wrong"...lol

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On 11/14/2019 at 5:27 PM, Ginx snewx said:

So basically a 15/16 winter, meh

 

On 11/15/2019 at 8:09 AM, Ginx snewx said:

Similar snowfall distribution.  Hope you are wrong, no offense 

 

On 12/31/2019 at 2:54 AM, 40/70 Benchmark said:

December Review

 

The month of December has largely evolved as anticipated, with a very active storm track and near normal to slightly negative monthly temperature departures throughout most of New England. These departures should not change much over the final few days given the current forecast.

 

Dec.png

Note our thoughts in relation to December that were expressed in the 11/13/19 Eastern Mass Weather Winter Outlook:

 

"The month of December should be both active and variable. A robust PNA should be the primary driver of the pattern, thus central and northern New England should see the most robust snowfall anomalies. While the PV may encounter some disruptions, it should recover, which may ultimately prove more inimical to the development of early season blocking, which is not climatologically favored, regardless. The NAO should have some increased moduality, and a transient negative phase could link with the PNA to create a major early season storm. Favored period being from 12-5 to 12-19.

-1 to -2 departures north of Concord, NH, around normal down to 40N, and up to +1 points southward". 

-Eastern Mass Weather 11-13-19

 

Dec%2B2019.png

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Obviously the month did not verify as cold as the composite across the Eastern half of the nation, nor was it supposed to, as the normal to -2 departure that was explicitly mentioned implied. The potential for a major winter storm did indeed come to fruition, however it occurred two days prior to the outlined two week window.  This system likely contributed to one slight discrepancy with regard to the monthly snowfall departures, as the heaviest snowfall anomalies ended up verifying over south central New England, as opposed to north central New England, as forecast. However the real proverbial "fly in the ointment" was the PNA forecast, which was predicted to be robust and was merely modestly positive, as evidenced by the cooler anomalies over the Pacific northwest than implied in the composite. .

 

MEH.gif

 

 

The polar domain behaved largely as anticipated, with increased variability that manifested in an active storm track.

 

Variable.gif

 

Although the polar vortex did endure some minor assaults early on in the month of December, as suggested in the winter outlook, it has also proven every bit as resilient as anticipated. Thus the notion that the first half of December would be biased cold, followed by a mild second half of the month that would herald in a rather protracted winter reprieve has also come to fruition.

Here is a review of the expressed thoughts from 11-13-19 in relation to the behavior of the polar fields.

 

"The seemingly favorable antecedent conditions for the disruption of the PV in conjunction with both the observed north atlantic tripole over the summer, as well as the anticipated favorable Hadley cell configuration in association with the ongoing modestly warm ENSO event all favor increased blocking. However they are interpreted as being suggestive of perhaps one month during the coming period featuring one or more major and sustained blocking episodes. This will likely occur later in the season because conditions should be hostile for the development of sustained blocking during the first half of boreal winter 2019-2020 due to the considerable initial intensity of the PV, in conjunction with the delayed descent of the easterly QBO phase. This does not preclude intervals of negative NAO and bouts of wintery early season weather, owed to the elongation of the PV that is conducive to periodic and transient cold intrusions, as well expected volatility of the NAO modality. It is also important to note that while conditions appear favorable for at least minor disruptions to the PV,  its recovery from any such occurrence is expected to be both proficient and timely. This is due in part to climatology favoring only minor assaults early in the season, as well as the anticipated resiliency of a potent PV denoted by +AO conditions presently observed within the polar stratosphere. Such a recovery period after any potential assault would likely lead to a protracted mid winter thawing period as the vortex reconsolidates and possibly becomes more circular in nature.

 

Sure enough, the polar vortex is fairly stout, though elongated, and well centered in the vicinity of the pole at present, which is indicative of a positive AO.

 

Current%2BPV.png

 

And there are signs that it remain as such for a rather extended period of time.

 

 

January Preview

There are not significant changes to the though process regarding the month of January.

 

 

"January remains fairly active, at least throughout the first half. The PNA ridge begins to erode, however the PV may be undergoing some dysregulation, so the PNA relaxation may be offset to a degree. Departures normal to -1 NNE, normal to +1 for SNE and the mid atlantic." Eastern Mass Weather- 11-13-19

 

Jan%2B2020.png

 

However it does now appear increasingly likely that the polar fields will remain fairy hostile to extended periods of cold and snow, as the latest forecasts have confirmed the Eastern Mass Weather notion of the polar vortex continuing to grow more consolidated and circular throughout the first third of January.

 

Day%2B10%2BPV.png

 

Jan%2BNAO.png

Predominately +NAO Indicative of Strong Polar Vortex Throughout January

 

Jan%2BAO.png

Predominately +AO Indicative of Strong Polar Vortex Throughout January

 

In addition to the hostile polar domain, the expected development of an RNA has already ensued and is expected to remain prevalent through at least the month of January, all but ensuring a relatively mild month for the northeast.

 

Jan%2BPNA.png

RNA Favors Southeast US Ridge this January

 

The correction vector with regard to the slightly above normal January forecast issued this past fall would seem to be pointed in the milder direction. Snowfall in southern New England will likely be below normal this month, with normal snowfall across central New England and perhaps above normal in norther New England. This stratification of the monthly snowfall gradient will be owed to a strong polar vortex and RNA favoring a mean southeast US ridge in conjunction with an eventual relaxation of the deep trough currently positioned in the vicinity of Alaska. This abatement should allow cold to remain entrenched in Canada, thus providing a reservoir of cold to be tapped by storm systems for at least northern areas.

 

Jan%2BEPO.png

Relaxation of Alaskan Trough Reflected by More variable EPO

 

This progression is also favored by the MJO, which is forecasted to flirt with phase 7, before relaxing and remerging in phased 4 and 5 about a week into January.

 

 

MJO.gif

 

Phase 4:

 

 

 

PHASE%2B4.png

And Phase 5 of the MJO in the second week of January also teleconnect to the aforementioned pattern, which features a predominate west coast troughs and southeast ridge:

 

 

Phase%2B5.png

 

 

Finally, seasonal guidance confirms:

 

Both the Canadian SIPS:

 

SIPS%2BJan.png

 

 

 

And the European monthly guidance confirm:

 

Euro.png

 

 

Conclusions

 

The month of January looks fairly mild, and should not produce very much in the way of significant snows or severe cold for southern New England. However much like last season, what opportunities do present themselves should favor the interior and central/northern New England, as the cold will enter through the western US, and only methodically bleed eastward  near the Canadian border in a modified state. The best chance for the foreseeable future appears to be with a system approaching around January 5th, as heights in the vicinity of Alaska and the polar domain appear to relax as much as they appear that they will for most of the next month. The interior and northern areas are of course still favored, but the system may feature some mixed precipitation for coastal southern New England.

 

Ensemble consensus for this system exists amongst the European ensemble suite:

 

 

EPS.png

 

The GFS ensemble package:

 

GEFS.png

 

 

 

And the Canadian product:

 

CEPS.png

 

 

Second Half Revival of Winter Likely

 

While it does appear that January may perhaps verify even milder than originally anticipated, the forecast for the balance of winter remains unchanged, as a more favorable polar field should negate what may remain a hostile Pacific. This is supported by the notion that the QBO (+5.07 as of November) should be neutralizing in February, the Eastern Mass Weather analog composite from the winter outlook, as well as some of the current seasonal guidance.

 

For February:

CANFEB.png

 

 

 

 

 

And especially March:

CFSMAR.png

 

 

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44 minutes ago, Ginx snewx said:

Been a disaster for you guys. I  have been pretty much skunked since right before Christmas.  It is what it is. 

4.5 here so far and none of it has stuck to the pavement. I have thrown out any hope of a good winter as we basically punted a month and half so far. I just hope to get to avg and have a solid 2nd half. Tropical forcing should get into the colder phases by the end of the month  and the Pv should start taking some hits. 
 

Obviously is sne you guys have more room for error being further north.

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21 minutes ago, CoastalWx said:

Oh that was updated late December. In that case, yeah writing on the wall for Jan first half at least.

No, the call was made in November...I just updated in late December. The protracted thaw was always expected, but I increased the magnitude with the shorter lead time.

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Things are definitely looking more favorable after about 1/15...and especially the final 10 days of the month. But even as early as 1/14-15 or so, we get some intense press of cold into central canada and that could leak out way....so we can't rule out an overrunning event just after mid-month. Could obviously be a cutter too...that's how these things go....we start to actually build a western ridge a little bit after that though which will tend to reduce the cutter risk some.

Cutters will always be on the table considering how awful the ATL is....the ATL was favorable in the first half of December which really helped us.

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1 minute ago, ORH_wxman said:


Things are definitely looking more favorable after about 1/15...and especially the final 10 days of the month. But even as early as 1/14-15 or so, we get some intense press of cold into central canada and that could leak out way....so we can't rule out an overrunning event just after mid-month. Could obviously be a cutter too...that's how these things go....we start to actually build a western ridge a little bit after that though which will tend to reduce the cutter risk some.

Cutters will always be on the table considering how awful the ATL is....the ATL was favorable in the first half of December which really helped us.

Cutters will be heavy with a crap west as well. Until the RNA is fixed, razor blades remain on standby

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