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January 2021

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6" for Jan. my worst yet. surpasses Jan '16 (8") and Jan '12 (10"). also surpases last Jan (7.5")

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On 2/1/2021 at 8:28 AM, SJonesWX said:

6" for Jan. my worst yet. surpasses Jan '16 (8") and Jan '12 (10"). also surpases last Jan (7.5")

I've found January snow to often be a poor predicter of season totals.  Had 24.6", in the top 1/3 of Januarys and 5" AN, in Jan 2006 then only 7.8" total for Feb/Mar/April.  January 2013 had only 5.7", then the lowest here, but finished right at my 90" average.  That low-snow record lasted only a year as January 2014 had just 5.1" - by the 14th I'd had 2" snow and 3" RA with average temp 6° BN, the "impossible trifecta" but that winter had over 100" and excellent pack retention.  This January's 18.2" is only 1.4" BN, the closest to my average of 19.6".  The month's coldest temp thru the 29th was a mere -1, which would've been the least cold month of January minimum in my 23 years here but 30-31 had lows of -7 and -19. 

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January Review and February Preview

January 2020 Recap

What Went Wrong

There were two major flaws with the January forecast.
1) The Pacific pattern was again rather poorly forecast, as the residual + PNA pattern of December carried over through roughly the first 2/3 of the month of January.
 
PNA.png
 
 
This obvious wreaked havoc with the national temperature composite in much the same manner as it in December in that the gradient was inverse of what was forecast. While the anomalies in New England were fairly accurate across at leas the souther portion of the region, it was cooler to the south, and warmer the north, which was opposite of the forecast.
 
"Temperatures should be near normal to 1 degree above across northern New England, 1-3 degrees above normal in central and southern New England, and 2-3 degrees above in the mid atlantic. Any storm activity will entail large precipitation type issues near the coast, with the most snow reserved for northern New England. The RNA pattern should only strengthen, as overall storm activity wanes".
 
-Eastern Mass Weather 11-5-20
 
Here is the forecast temperature anomaly composite:
Screen%2BShot%2B2020-11-03%2Bat%2B1.29.3
vs the the actual:
 
Jan%2B2021%2BTemps.gif
Note that while locally the forecast managed to succeed, it suffered suffered nationally as it did in December, due to the poorly forecasted December PNA that lingered throughout the first 2/3 of January.
 
2) The second main issue with the January portion of the outlook was that high latitude blocking has shown no signs of abating, as forecast. This has likely been protracted by the early January Sudden Stratospheric Warming event.
 
NAO.png
 
 
 
 
AO.png
 
 
It is evident in the forecast composite that while some blocking was forecast to persist into the new year:
 
Screen%2BShot%2B2020-11-03%2Bat%2B1.42.0
It has clearly been more prevalent than forecast, as evidenced by the actual monthly composite:
 
image.gif.bdc78874d378537f7f0bc077689ce079.gif
While this portion of the season outlook was certainly flawed, it was not without its strengths.
 

What Went Right

The month of January was forecast to see lower heights build into the Alaskan region as part of a positive East Pacific Oscillation, and as illustrated in the verification composite above, this was indeed the case. The Aleutian ridge relocated to the southeast, away from Alaska, as forecast. This led to an active Pacific jet, which made it very difficult to time phasing well enough for any major northeast storms, as is often the same in moderate to strong la nina events. In fact, thus mid winter lull was very well forecast.
"A lull in winter for the northeast, especially below the latitude of northern New England and east of New York state, should develop during the month, as storms becomes less frequent and the predominate track shifts inland. Some seasonal cold bouts should be sufficient for some mountain snow, and perhaps some "front end" wintery precipitation further to the south".
 
-Eastern Mass Weather 11-5-20
 
Here was the forecast temperature composite, which depicted a dearth of precipitation along the east coast:
Screen%2BShot%2B2020-11-03%2Bat%2B1.40.2
vs reality:
 
Jan%2B2021%2BPrecip.gif
 
Note that both the active Pacific jet across the Pacific northwest, as well as the fairly quiet conditions along the east coast were both well forecast. The storm track did indeed feature multiple mixed precipitation events and rain events in the area during what was a well below normal month snowfall wise with most location measuring single digit monthly totals. However, the tide has quickly turned to begin what was expected to be a very mild month of February.
 

High Latitude Blocking Likely to Delay February  Forecast Warm up

A major premise of the seasonal forecast was that while the polar vortex would be prone to assaults early on in the season, it would ultimately recover, however, the major Sudden Stratospheric Warming event that occurred in early January proved that particular supposition incorrect. 
 
Note how diffuse and nearly indiscernible the polar vortex remains at present, as the polar stratosphere remains infiltrated with warmth.
Current%2BPV.png
 
 
Clearly the polar domain is still reeling from last months Sudden Stratospheric Warming, which means that, an end to the current high latitude blocking regime is not imminent. While this is in conflict with the timing of the progression laid out in the Winter Outlook, the current data is indisputable and overwhelming. However, as was the case with the development of the RNA, it may be a case of delayed, but not denied.
 
Note the recovery to at least near neutral with respect to the polar fields, as forecasted by the EPS:
 
Feb%2BNAO.png
Feb%2BAO.png
Recovery of Polar domain and consolidation of polar vortex forecast later in February.
 
Likewise, a realignment of the Pacific is also expected to take place toward mid month, as lower heights work in tandem with RNA to induce an active Pacific jet.
 
 
Feb%2BEpo.png
 
Feb%2BPNA.png
Active Pacific Jet Expected for Especially Second Half of February
 
This evolution is well supported by the European weekly product.
 
Depicted below is the major negative NAO and EPO blocks that are expected to persist throughout the early portion of the month:
 
Feb%2B6.png
 
 
Note by mid month, the NAO block has weakened, and the EPO block as retrograded towards a more classic la nina position, in the vicinity of the Aleutians. The latter of which continues lower heights in the west.
 
Feb%2B14.png
 
 
Finally, by the final week of the month, there is a vortex in the vicinity of Alaska, which would flood the CONUS with milder Pacific air, and at least theoretically, make sustaining any residual high latitude blocking more difficult.
 
Feb%2B22.png
 
This is congruent with a the longer range forecast for a more consolidated polar vortex, which is more fixed near the pole.
 
pv%2B2%2B13.png
 
In summary, while the month of February is certain to feature more high latitude blocking than forecast due in large part to the early January Sudden Stratospheric Warming, there remains ample opportunity for the original forecast monthly departure of +2 to +4F to verify due to anticipated second half warming. Regardless, the month does not appear to be void of opportunities for winter storms, nor was it ever anticipated to.

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