CONTEST STATUS - Updated: SUN ... 21-JAN-18 @ 8 PM EST

Winter '17 / '18 - Snowfall Forecast Contests

19th Annual 'Regular Season'

Interim Standings ... as of Snow Storm #3 here

Snow Storm #3
FINAL Results here

Snow Storm #2
FINAL Results here

Snow Storm #1
FINAL Results here

17th Annual 'Season-total'
Deadline for entries has passed
Forecasters' summary here

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Winter '16 / '17 - Snowfall Forecast Contests
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18th Annual 'Regular Season'
FINAL results here
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16th Annual 'Season-total'
FINAL results here

Tuesday, November 28, 2017

Winter '17 / '18 - 17th Annual 'Season-total' Snowfall Forecast Contest - Call for Forecasts!

NEWxSFC Meteorologist-in-Charge
Seasonal Forecasts
NE.Wx/s 17th annual ‘Season-total' Snowfall Forecast Contest is the absolute best ... biggest ... and probably ONLY chance to be recognized for your long-range forecasting acumen ;/

And it's easy.

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

Deadline: THU ... 30-NOV-17 @ 11:59 PM EST

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

Sunday, November 26, 2017

Winter '17 / '18 - The Woolly Bear Caterpillar Guide to Winter Weather Forecasting

BGR
03-JAN-63
Lightly edited re-post from USENET news group ne.weather   11-OCT-03

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In recent weeks ... a spate of news articles have appeared about the woolly bear caterpillar and its legendary ability to foretell the upcoming winter based on the color and width of its black and orange stripes.

With so much good information scattered across so many sources ... there appeared to be a need to compile the forecasting rules.  This handy forecasting guide can be printed and keep inside your coat pocket for easy reference.
 
The Woolly Bear Caterpillars Among Us
There is more than one kind of woolly bear caterpillar.  The one you use when forecasting is the banded woolly caterpillar ... which becomes the Isabella moth (Pyrrharctia Isabella) in the spring.  Pictures of the caterpillar and moth can be seen here: Caterpillar Moth Both
 
Science is Skeptical
It should come as no surprise entomologists pooh-pooh the idea about banded woolly bear caterpillars predicting future events.  These naysayers claim variations in band color and width are evidence of a worm/s age and the fall weather conditions when the worm reached maturity.  Worms exhibiting more black than orange are older and grew in wet conditions.  Worms exhibiting less black than orange are younger and grew in dry conditions.

Thursday, November 23, 2017

Winter '17 / '18 - North Atlantic Oscillation Analog Years


To date ... 1990 is the leading analog year for the North Atlantic Oscillation (NAO) in the run-up to the coming winter.

The average NAO for Winter '17 / '18 would turn out positive should this come to pass.  The analog forecast reaches winter's NAO/s minimum in DEC and its maximum in FEB before declining at the start of meteorological spring.

One problem.
Winter '90 / '91 ENSO/s signal was warm La Nada (+0.4°C ENSO Region 3.4 temperature anomaly) yet a weak La Nina appears in the cards for this year and unlike this year ... the corresponding PDO analog year was negative (this year it's positive; trending negative) and QBO was west-positive (this year it's east-negative and trending same).

And herein lies the problem with analogs.
Analog years don't exist in a vacuum.
'94 / '95 moderate El Nino; cool PDO trending warmer; QBO east trending west [REJECTED]
'54 / '55  moderate La Nina; cool PDO trending cooler; QBO east trending west [REJECTED]
'04 / '05 weak El Nino; PDO cool trending warmer;  QBO west trending west [REJECTED]
/73 / '74 strong La Nina; cool PDO, QBO west [REJECTED]

Other teleconnection indexes frequently confound the potential predictive value of a particular index.

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Other correlation-type analysis techniques can also provide insight into the likely state of important winter teleconnection indexes.

Analysis of the North Atlantic Oscillation (NAO) index's period-of-record reveals a statistically significant association (Chi-square Test for Independence; alpha = 0.05) between its sign for the month of NOV and the sign of the average NAO index during a subsequent meteorological winter (D-J-F).

Period-of-record correlation analysis finds if NOV/s NAO is positive (negative) ... then there's a 73% (54%) probability the winter's average NAO/s sign will also be positive (negative).  The analysis false alarm rate is 27% (46%).

Wednesday, November 22, 2017

Winter '17 / '18 - Fans of cold and snow in the U.S. will love this new winter outlook

Or so reads the headline from Mashable which comes with these nuggets of questionable conventional wisdom:

"Along the East Coast of the U.S., for example, major snowstorms tend to take place when a blocking pattern
is in place over Greenland." which more than explains why the AO index for 16 of the KU 66 storms rated '3' or higher was greater than zero including the Storm of the Century (1996).  The AO was positive for 42 storms in the landmark study.

The claim "When the Arctic Oscillation is negative, cold and snowy conditions are favored (though not guaranteed) in the eastern U.S." is unsupported by the data but why let pesky facts get in the way of a quality click-bait headline.


Don't know why the FB text field doesn't render.  Displays OK in Blogger's editor.
Here's the text ...

"Laying to rest the claim season-total snowfall in the NE and M-A is associated with winter's average Arctic Oscillation index.

"A mere 13% of the variability in NE and M-A season-total snowfall is explained by variability in the D-J-F average Arctic Oscillation."

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What's not to love?

Tuesday, November 21, 2017

Winter '17 / '18 - What about snow during La Niña winters?

From the ENSO blog at Climate.gov

"This La Niña footprint is pretty intuitive.

"Given the northward shift of the storm track, relatively cold and wet conditions are favored over the northern Rockies and northern Plains, resulting in the enhancement of snowfall.

"Warmer and drier winters are more likely during La Niña over more southern states, and this is exactly where seasonal snowfall tends to be reduced (4).

"The more vigorous storm track and slight tilt toward colder temperatures over the northern tier of U.S. during La Niña modestly increases the chance of a relatively snowy winter.

"We can break up the snow pattern further and look at the weakest and strongest La Niña events.  Splitting La Niña events into strength reveals some interesting differences worth investigating further.

"In this preliminary analysis below, there is a suggestion that weaker events are snowier over the Northeast and northern and central Plains on average."

More ...

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NOTE:  the data period ends '09 / '10.  Since then ... there have been two El Ninos (one quite strong) ... two La Ninas ... and three cool La Nadas.

Saturday, November 18, 2017

Winter '17 / '18 - Arctic Oscillation Analog Years


 
To date ... 1973 is the leading analog year for the Arctic Oscillation (AO) in the run-up to the coming winter.

The average AO for Winter '17 / '18 would turn out negative should this come to pass.  The analog forecast has winter's AO/s minimum extent in FEB then continues its decline into meteorological spring and suggests a late-winter stratospheric warming event.

One problem.
Winter '73 / '74 ENSO/s signal was strong La Nina (-1.8°C temperature anomaly) yet a weak La Nina appears in the cards for this year and unlike this year ... the corresponding PDO analog year was negative (this year it's positive; trending negative) and QBO was west-positive (this year it's east-negative and trending same).

And herein lies the problem with analogs.
Analog years don't exist in a vacuum.
'08 / '09 weak La Nina; cool PDO trending warmer; QBO west [REJECTED]
'54 / '55 weak La Nina; cool PDO trending cooling; QBO east trending west [REJECTED]
'95 / '96  weak La Nina; warm PDO trending cooler; QBO west trending east [BEST MATCH]
'94 / '95 moderate El Nino; warm trending cooler;  QBO east trending west [REJECTED]

Other teleconnection indexes frequently confound the potential predictive value of a particular index.

---
Other correlation-type analysis techniques can also provide insight into the likely state of important winter teleconnection indexes.

Analysis of the Arctic Oscillation (AO) index's period-of-record reveals a statistically significant association (Chi-square Test for Independence; alpha = 0.05) between its sign for the month of NOV and the sign of the average AO index during a subsequent meteorological winter (D-J-F).

Period-of-record correlation analysis finds if NOV/s AO is negative (positive) ... then there's a 72% (52%) probability the winter's average AO/s sign will also be negative (positive).  The analysis false alarm rate is 28% (48%).

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Historical note:  this is NEWxSFC web log's 1000th post!

Thursday, November 16, 2017

Winter '17 / '18 - Outlooks

Thread updated periodically as new outlooks and forecasts are issued from a variety of credible sources.
 
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Judah Cohen (AER) via National Science Foundation
"The combination of cold and wet could result in an above normal snow season for parts of the northern U.S., including the large population centers of the northeastern U.S.
 
"... indicators suggest ... the polar vortex will break down later this winter, potentially unleashing an extended period of severe winter weather." (ED:  not necessarily over the Western Hemisphere)
 
 
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Cohen (AER):  DCA 17"; BOS 64"; all large cities in the NE and M-A above normal
Bastardi (WxBell Analytics):  PHL 30"; DCA near normal
Crawford (Wx Co.):  DCA 17"
Rogers (Commodity Wx Group):  DCA below normal
Tolleris (WxRisk):  DCA near normal
Capital Wx Gang:  DCA 11"; IAD 16"; BWI 16"
Accu-Wx:  I-95 corridor near normal; NYC/BOS >=6" above normal
NECN:  New England near normal 
 

Wednesday, November 15, 2017

Winter '17 / '18 - NOV/s Arctic Oscillation: Winter/s Leading Indicator

The sign of NOV/s Arctic Oscillation (AO) index has a statistically significant (Chi-square Test for Independence; p <= 0.05) association with the sign of the average AO index during meteorological winter (D-J-F).

 AO Contingency Table
 p = 0.046 Nov + Nov - Total
 D-J-F + 16 10 26
 D-J-F - 15 26 41
 Total 31 36 67
 True + 52% 28% False -
 False - 48% 72% True +

'True + (-)' indicates a true (false) prediction.

IOW ... if NOV/s AO is negative ... then there's a 72% chance the winter's average AO/s sign will also be negative ...

...and the association between the AO/s negative sign for NOV and D-J-F has a 28% 'false alarm rate' (FAR).

The relationship is nowhere near as strong when NOV/s AO is positive (48% FAR).

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Interesting ... albeit different ... relationship between NOV/s North Atlantic Oscillation (NAO).

Tuesday, November 7, 2017

Winter '17 / '18 - Eurasia Snow Cover - OCT

12,052,000 km2
18% above 52-year P-O-R-N (10,225,000 km2)

Rank: 11th
Lowest in five years

Eight of the last nine October above period-of-record-normal

Analog years for winter '17 / '18
Rank Winter ENSO
1 06-07 W-
2 69-70 W-
3 77-78 W-
4 00-01 C-
5 98-99 C+

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Data courtesy Rutgers University Global Snow Lab
http://climate.rutgers.edu/snowcover/index.php

Sunday, November 5, 2017

Winter '17 / '18 - Eurasia Snow Cover - OCT - Snow Advance Index (SAI)

OCT-17's snow advance index is negative.
Snow Crow suicide watch now in effect.

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AER reports a statistically significant correlation between their 'winter severity index' and how quickly Eurasian snow cover advances during OCT.

They define the 'winter severity index' by the state of the North Atlantic Oscillation / Arctic Oscillation (N/AO) and interpret it as an indicator of 'high latitude' blocking potential during D-J-F.

More blocking.
More winter.
More better.

Here's the model ...
"When snow cover advances rapidly (slowly) across Eurasia in October, this is an indication that the upcoming winter will be more severe (milder) for the Eastern US [sic], Europe and East Asia.


Study period seems surprisingly short seeing how contiguous monthly Eurasian snow cover data begins in 1970.  How well does the SAI correlate with the N/AO index prior to 1988?

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Snow Advance Index (SAI) backgrounder from AER here.
Earlier Eurasia snow cover posts here.