Thursday, December 02, 2021

Winter '21 / '22 - 21st Annual 'Season-total' Snowfall Forecasting Contest: The Forecasts!

 Forecasters:  28

Welcome back all the veterans of winters' past.
Welcome Rookie forecasters!
TimB84
bdocdog1
JoeMartWx
Tullioz
BOSWIZARD

MillVilleWx ... having made the best season-total forecast for Winter '20 / '21 ... is back this year to defend his 'Chief Season-total Forecaster' title.

Forecasters also compete against the Period-of-Record-Normal (P-O-R-N) and CONSENSUS.


Forecaster table below ranked by descending season-total snowfall.



BLUE - 25th percentile
RED - >= 75th percentile
ORANGE - Chief 'Season-total' Forecaster
P-O-R-N - Period-Of-Record-Normal
CONSENSUS - average of each station's forecasts

Forecasts issued with decimal values have been recorded as such for verification purposes;  however ... rounding was applied for display purposes only.

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Total station forecasts:  702 (includes P-O-R-N & CONSENSUS)

Station forecasts for snowfall ...
BELOW average - 372 (53%)
AVERAGE - 26 (4%)
ABOVE average - 302 (43%)



Likely confidence (>= 65% of all forecasts) for stations with ...
- ABOVE average snowfall:  7
CAR ... BGR ... CON ... BTV ... BDR ... ALB ... BGM

- BELOW average snowfall:  10
BDL ... MDT ... ACY ... BWI ... IAD ... DCA ... SBY ... RIC ... ORF ... RDU

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All Contest entries posted to the Contest/s web site here (direct link to forecasts here).

Sunday, November 07, 2021

Winter '21 / '22 - Pacific Decadal Oscillation (PDO): OCT-21

 -3.06 (~2.25-sigma below the monthly mean)

PDO/s cool phase continues apace.  22 continuous months with an index value < 0 (JAN-20 - present).

Leading analog years
Winter / ENSO (MEI) / QBO
99-00 / C / W
08-09 / C- / W
62-63 / C- / E
75-76 / C / W
55-56 / C / -

All PDO analog years happened during a La Nina; however ... only one winter ('62 / '63) had QBO-E (D-J-F AVG:  ~ -16).

Winter '62 / '63
D-J-F Index Averages
NAO: -1.467
AO:  -1.914

Select season-total snowfalls  / P-O-R-N (inches)
RIC - 16.9 / 12.5
RNK - 29.7 / 19.5
DCA - 21.4 / 15.6
PHL - 20.5 / 22.1
NYC - 16.3 / 28.7
BGM - 95.3 / 83.7
BTV - 72.6 / 80.8
BOS - 30.9 / 43.7
CAR - 147.5 / 115.6

PDO < 0 (cool water along NOAM/s west coast) is associated with a longwave trof over NOAM/s west coast + above normal 500 mb geopotential heights over the SE CONUS + mild eastern U.S. winters.  La Nina is also associated with 500 mb ridging over SE CONUS.

These conditions more often than not mean a warmer than normal winter with below normal snowfall over at least the southern half of the forecast area but there have been notable exceptions to those rules.


Friday, November 05, 2021

Winter '21 / '22 - Quasi-Biennial Oscillation (QBO): OCT-21

-19.14 (just inside 1-sigma from the mean)

OCT is now the 5th month with a QBO index below zero having flipped in JUN following its 14 month run in positive territory.  The 30mb flow over the Equator oscillates from east to west every 14 months; therefore ... the current easterly state of the QBO is expected to last throughout Winter '21 / '22.

Leading analog years
Winter / ENSO (MEI)
72-73 / W+
00-01 / C-
09-10 / W
91-92 / W+
58-59 / W-

With La Nina temperature anomalies in ENSO Region 3.4 expected to persist through at least late winter ... all QBO analog years are rejected except Winter 00/01.

- Winter '00 / '01
The sum-total of the season-total snowfall for all Contest forecast stations was 1,312".  (~21% above the 1968 - 2021 period-of-record average 1,085".

Eurasia/s OCT areal snow cover slightly below normal.

D-J-F Index Averages
AO:  -1.312
NAO:  +0.040

"The QBO determines the character of the early winter, leading to a colder and more stable polar vortex in December and January during the west phase of the QBO and a more disturbed and warmer Arctic during the east phase of the QBO." [1]

In years with low solar activity (solar cycle 25 is just beginning) ... the polar winter vortex tends to be disturbed and weak when the QBO is easterly.  Positive geopotential height anomalies over high latitudes ... i.e., blocking ... are also correlated with QBO-E and solar minimums.
 
Antecedent odds currently favor a weak and disturbed stratospheric polar vortex and SSW (sudden stratospheric warming) leading to a long-lasting negative Arctic Oscillation (AO) and well-below normal temperatures periodically in eastern North America ... northern Europe ... or eastern Asia.


Tuesday, November 02, 2021

Winter '21 / '22 - Eurasia Snow Cover: OCT-21

Observed:  10,671,792 km^2
Average:  10,310,000 km^2
Median:  10,130,000 km^2

3.5% (5.3%) above normal (median)
Rank:  19 (n = 54)

Above average snow cover observed in 10 of the past 10 OCTs.
At least 1 standard deviation above normal snow cover in 5 of the last 10 OCTs.

Top Analog Winters (weight) / ENSO state / QBO state
1 - 2009/10 (2x) / W / E
2 - 2001/02 (2x) / nada- / W
3 - 2020/21 (1x) / C / W
4 - 2019/20 (1x) / nada+ / E
5 - 2015/16 (1x) / W+ / W

These analog winters have questionable predictive value b/c a moderate La Nina (C) and QBO-E are expected to prevail during Winter '21 / '22.

Blue markers located between the inner and outer circle have a weak yet statistically significant (p <= 0.05) positive correlation between Eurasia/s OCT areal snow cover and a forecast station/s season-total snowfall.  Strongest correlations found in New England where correlations range between 0.269 (BTV) and 0.376 (ORH).

A paultry ~16% of the variability (R2 = 0.158) in combined season-total snowfall from all forecast stations is explained by Eurasia/s OCT areal snow cover. 

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Period-of-Record:  1967 - 2021 (1969:  no data)
Data courtesy Rutgers Global Snow Lab

Previous posts about Eurasia's OCT areal snow cover here

Sunday, October 31, 2021

Winter '21 / '22 - 21st Annual 'Season-total' Snowfall Forecast Contest: Call for Forecasts!

NEWxSFC/s Director of Season-total Snowfall Forecasting
Here comes winter with its oscillating Arctic and North Atlantic indexes ... sudden stratosphere warmings ... so-so ENSO ... and if we get lucky ... a seemingly endless parade of 'Miller A' LOWs raking the eastern seaboard.

NE.Wx/s 21st Annual ‘Season-total' Snowfall Forecast Contest is the absolute best ... biggest ... and possibly ONLY chance to be recognized for your astute long-range forecasting acumen ;/

And it's s-o-o easy.
Cool prizes ... too!

All you have to do is issue the best forecast for the 'season-total' snowfall at 25 east coast stations between RDU and CAR!

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Forecast element:
season-total snowfall @ each station

Forecast period:
01-DEC-21 through 31-MAR-22

Error statistic: total absolute error
[Σ abs(forecast - observed)]

Verification:
NWS climate reports (CLM or CF6)

Low. Score. Wins.

Deadline for entries: TUE ... 30-NOV-21 @ 11:59 PM EST (01-DEC-21 @ 4:59 UTC)

Visit the Contest's website to enter your forecast.
Follow the link at the top right corner of the page to 'Enter Season-total Forecast.'

Update your forecast as often as you want prior to the deadline.
Only the last entry gets verified.

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1st place prize (delivered post-paid right to your front door):
... choice of a book from NEWxSFC library
... the august and coveted title 'Chief Season-total Snowfall Forecaster' for Winter '22 / '23 and
... a well-deserved place of high esteem and honor with past winners.

2nd place prize (delivered post-paid right to your front door):
... choice of a book from NEWxSFC library

3rd place prize (delivered post-paid right to your front door):
... choice of a book from NEWxSFC library

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The reigning NE.Wx ‘Season-Total’ Snowfall Forecasting Champ-een is MillVillWx
Last winter's 'Season-total' forecast summary ... verification ... and final results at our website here.

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As always; NO cost ... NO fees ... NO advertising ... NO annoying requests for personal information to enter the contest.  NEWxSFC is a just-for-fun exercise for winter wx enthusiasts to see who can make the best 'season-total' snowfall forecast.

The Contest is open to all including amateur and professional forecasters; broadcasters with or without trained Seals; any and all weather-biz types and / or wanna-bees; wish-casters ... astrologers ... along with any other universally recognized classes of dreamers; Pollyannas or Cassandras ... registered Nostradamuses ... non-violent megalomaniacs ... woolly-bear caterpillars or their agents ... pest detectives ... ne.weather USENET veterans and lurkers ... riders on the StormVista ... refugees from AmericanWx ... US Weather survivors ... including self-imposed exiles from Eastern Wx ... and of course ... meteorologists.

In honor of USENET/s ne.weather patron saint Mr. Joseph Bartlo's final request (RIP); trolls ... goats ... hat3-lsiters ... and psests need not apply.