Winter '18 / '19 - 18th Annual 'Season-total' Snowfall Forecast Contest - Call for Forecasts!

NEWxSFC Meteorologist-in-Charge
Seasonal Forecasts

Here comes winter with its oscillating Arctic and North Atlantic indexes ... suddenly warming stratosphere ... and an endless parade of coastal teasers.

NE.Wx/s 18th 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 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!

Deadline: FRI ... 30-NOV-18 @ 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.'

1st place prize (delivered post-paid right to your front door):
"The Snow Booklet" by Nolan J. Doesken and Arthur Judson (paperback) and
"Snow in America" by Bernard Mergan (hardcover)

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

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Forecast element: sum-total season snowfall @ each station
Forecast period: 01-DEC-18 through 31-MAR-19

Verification: NWS preliminary climate reports (CLM or CF6)
Error statistic: total absolute error [Σ abs(forecast - observed)]

Read more »

Winter '18 / '19 - ENSO ... Arctic Oscillation ... & Season-total Snowfall @NEWxSFC Stations (Wonkish)

Roosting snow crows rooting for bonus snows thanks to expected weak-to-moderate El Niño conditions.

Typical analysis ignores influence of other controlling factors ... such as the Arctic Oscillation (AO).

BLUF:  ENSO state does not provide robust guidance for season-total snowfall (STP) outcomes @NEWxSFC stations unless AO is considered.

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Analysis period:  '66 / '67 to '17 / '18 (D-J-F-M)
n = 52

For all winter ENSO states ... if AVG D-J-F-M AO < 0 … then STP @NEWxSFC stations > AVG
Weak correlation:  R = -0.311

Correlation (R) >= +/- 0.6 considered generally to have useful predictive power

ONI = Oceanic Niño Index

Read more »

Winter '18 / '19 - Snow Storm #1: FINAL Results

Forecasters' station verifications and the storm summary at NEWxSFC/s home page.
http://www.newx-forecasts.com/

1st - donsutherland1
SUMSQ:	38
SUMSQ Z:	-1.400
STP:	7.1	(1)
TAE:	18.9	(1)
AAE:	0.95	(1)
2nd - Brad Yehl
SUMSQ:	54
SUMSQ Z:	-1.215
STP:	9.2	(2)
TAE:	21.2	(2)
AAE:	1.06	(2)
3rd - WeatherT
SUMSQ:	85
SUMSQ Z:	-0.860
STP:	16.2	(4)
TAE:	33.4	(5)
AAE:	1.52	(3)
HM - Donald Rosenfeld
SUMSQ:	113
SUMSQ Z:	-0.541
STP:	20.3	(8)
TAE:	33.0	(3)
AAE:	1.57	(4)

SUMSQ:  sum of square error (")
SUMSQ Z:  Z-score
STP:  storm total precipitation error (")
TAE:  total absolute error (")
AAE:  average absolute error (")
(#):  category rank

Forecast by Observed Snowfall Scatterplots for Top Forecasts
Dotted blue line below (above) solid red line ==> under (over) forecast

Station by Station Comparison of Top Forecasters

Winter '18 / '19 - Snow Storm #1: Preliminary STP Verification

Table of preliminary storm-total snowfall by station for THU and FRI from CDUS41 (CLI) ... CXUS51 (CF6) and ... SAUS41 (METAR) bulletins.

Exceptions:
BDR - daily snowfall reports missing.
STP estimated from METAR 6/nnnn group @ SLR 10:1

SLR not reported for some stations with measurable snowfall b/c liquid and / or freezing precipitation also occurred during the verification period.

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Stations observing at least Trace - 20 (74%)

Given a forecast station observed measurable snowfall ... stations observing at least:
4" - 10 (50%)
6" - 5 (30%)
8" - 3 (15%)
10" - 0

Max snow melt-water
CAR - 0.70"
BTV - 0.62"
CON - 0.60"
JFK - 0.91"

BGM SLR 6:1 (no liquid precipitation reported)

Max precipitation:  ACY - 1.73"

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New daily records:
15-NOV-18 (1)
ORH - 7.8" (5.7"; 1967)

Eleven daily records set this day -- some held since 1906; however ... snow fell on ten stations before the deadline; therefore  ... they are not included.

16-NOV-18 (4)
CAR - 9.3" (5.4"; 1973)
BGM - 4" (1.8"; 1987, 1999)
ABE - 0.7" (0.05"; 1995)
MDT - 0.5" (0.05"; 1985)


SFC analysis:  00z ... 16-NOV-18

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Please report errors in Comments along with a link to the correct data.
FINAL Results post expected SUN evening ... 18-NOV-18

Winter '18 / '19 - Snow Storm #1: The Forecasts

Forecaster class
Rookie 2
Journey 1
Senior 9
TOT 12

- Brad Yelh is NEWxSFC/s reigning 'Chief Forecaster' for 2019 ... having placed 1st in last year's 'Regular' season contest.

- Welcome and Good Luck to our Rookie forecasters NJWeather & Weather Wizard!

- No entry for ER NWS WSOs b/c of snowfall forecasts for many of their stations occurred before the verification period started.

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

CORR:  quagmireweathercentral return to the fray for his third season warrants promotion to 'Journeyman' status. 

Forecast table ranked MIN-to-MAX by their verification period storm-total precipitation (STP).
BLUE = 25th percentile
RED >= 75th percentile
White / Grey- STP and 4cast cells range between the 25th and 75th percentile

Heaviest snowfall (>= 6") consensus expected along and to the right of a line from CAR - CON - ORH - ALB - BGM - BTV - CAR.  Lollipop @ BGM.

Flat PNA ... POS NAO ... Bi-polar AO.

Another NEWxSFC contest-worthy snow storm defies conventional teleconnection wisdom.

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Challenging verifications ahead given some lower latitude forecast stations observed much of their storm-total snowfall prior to the deadline.

Look for the forecast station's  preliminary verifying STPs NLT tomorrow (SAT) evening.

Winter '18 / '19 - Snow Storm #1: RAW Forecasts

Here

Winter '18 / '19 - Snow Storm #1: Call for Forecasts!

Brooklyn ... NY
26-NOV-38

Cyclogenesis along the Mid-Atlantic progged to develop into an early season Nor'easter & poised to advance on a slowly retreating Arctic HIGH ... shows real promise for plowable snowfalls over northern portions of the forecast area.

Contest-worthy snow storms in NOV are quite rare with only two since NEWxSFC started in 1999 (2003 & 2013).

Earlier than usual deadline (8 PM EST) b/c of the expected pre-midnight on-set of accumulating snows.

Deadline: 8:00 PM EST … THU … 15-NOV-18
Verification begins: 8:00 PM EST … THU … 15-NOV-18
Verification ends: 11:59 PM EST … FRI … 16-NOV-18

Enter your forecast at the NEWxSFC/s home page @ http://www.newx-forecasts.com/
Follow the top center-of-page link from 'Enter Storm Forecast.

Read more »

Winter '18 / '19 - Eurasia Snow Cover: OCT

Eurasia/s areal snow cover for OCT-18:  ~10,391,000 km2

Last year:  ~12,052,000 km2

1% above 53-year P-O-R-N (~10,260,000 km2)
Rank: 22nd

Lowest in eight years

Seven of the last ten years above normal

Analog years for winter '18 / '19
Rank Winter ENSO
1 82-83 W+
2 00-01 C-
3 69-70 W-
4 01-02 nada-
5 84-85 C

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

Winter '18 / '19 - Gains and Losses: 10-NOV-18

Minor snow event over extreme northern portions of the forecast area today forced by a lifting 5H LOW centered @12z over SE Canada and 2ndry SFC LOW occluding INVOF the Gulf of ME.

Gains:  Blue
Losses:  Reds

Image courtesy NOHRSC

Winter '18 / '19 - Snow Advance Index and Season-total Snowfall in the NE and Mid-Atlantic

The Snow Advance Index (SAI) measures the mean daily rate-of-change in Eurasia's areal snow cover at latitudes equatorward of 60°N during OCT.  Published research suggests rapid increases in Eurasia/s OCT areal snow cover are associated with increased season-total snowfall (STP) in the eastern U.S.

Does the SAI provide useful guidance for season-total snowfall at NEWxSFC forecast stations?

Meh ... me thinks.

This analysis looks at the relationship between the SAI and NEWxSFC stations' STP for the winters between '70 / '71 and '17' / '18 (n = 48).

PCT increase in areal coverage is proxy for the mean rate of change of snow cover extent (SCE) from daily snow cover data in the above referenced study. (Cohen and Jones 2011).

AVG PCT increase in weekly Eurasian areal snow cover between Week 40 and Week 44 (OCT):  416% (ORANGE LINE)

OCTs ... where SAI > AVG:  20

Accordingly ... if OCT/s SAI is above AVG ... then STP at NEWxSFC forecast station should also be > AVG.

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AVG 'season-total' snowfall (STP) for NEWxSFC forecast stations:  1,042" (GREEN LINE)
Winters ... where STP > AVG:  23

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The question the analysis wants to answer:
Does the SAI-proxy - PCT increase in Eurasia/s OCT snow cover - predict whether NEWxSFC forecast stations' STP > AVG.

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Years ... where SAI > AVG & Years ... where NEWxSFC stations' STP > AVG:  11 (RED DOTS)
Recall ... there were 20 years when OCT/s SAI > AVG which means nine years the STP < AVG.

Probability of  OCT SAI > AVG:  42% (20/48)
For any given OCT ... there's a 42% chance of SAI > AVG.

Probability NEWxSFC stations STP > AVG:  48% (23/48)
For any given year ... there's a 48% chance of STP > AVG.

What's the probability given SAI > AVG ... the STP will also be > AVG?
Cumulative probability for NEWxSFC stations STP > AVG ... given SAI > AVG:  42%

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BOTTOM LINE:  In any given year ... if the SAI > AVG ... there's a 42% chance the 'season-total' snowfall ... for all NEWxSFC forecast stations ... will be above the period of study's AVG 'season-total' snowfall.

Looking at it another way ... there's a 58% chance the 'season-total' snowfall ... for all NEWxSFC forecast stations ... will _not_ be above the period of study's AVG 'season-total' snowfall.  This isn't to say SAI doesn't offer useful guidance for individual NEWxSFC forecast stations.

OCT-18/s PCT snow cover increase is just under 500% or ~80 PCT-points > AVG; therefore ... there/s a mere 42% chance this season the STP from NEWxSFC/s forecast stations will be > AVG.

Winter '18 / '19 - Predictive Value of NW Atlantic Ocean's SST Anomalies for Winter's Phase of the North Atlantic Oscillation

Up until a few years ago ... the UKMET office issued a long-lead forecast for the phase of the upcoming winter's North Atlantic Oscillation (NAO).  The forecast was based on a statistically significant correlation between May's sea-surface temperature anomalies (SSTA) in the western Atlantic ocean (depicted in the image below left) and NAO's future D-J-F phase (as depicted in the Winter Z500 pattern image below right).

To apply this technique for Winter '18 / '19; take note of the SSTA pattern in the NW Atlantic at the end of MAY-18 shown below.

- Positive anomalies off the mid-Atlantic and NE coasts.
- Negative anomalies in the Labrador Sea off Greenland's southern coast.
- Positive anomalies north of Iceland in the Norwegian Sea.

https://www.ospo.noaa.gov/data/sst/anomaly/2018/anomnight.5.31.2018.gif

Compare these anomalies with the 'May SST pattern' map.
See how well they align?

MET Office research concluded if May's SSTA aligns generally with the prediction pattern in the western Atlantic ocean ... then the expected dominant NAO state would be positive during the upcoming winter.

Above normal SST in the offshore waters of the NE coast ... below normal water temperatures SW of Iceland ... and positive anomalies to the northeast point to a +NAO.  When the pattern is reversed a -NAO is forecast.

Based on May-18 SSTA ... the dominant NAO state prediction for Winter '18 / '19 is positive.

There's even empirical evidence the D-J-F NAO will average above zero if NOV's NAO index is greater than zero.

Winter-season forecasters hitching their collective wagons to the +ENSO state might could want to stop-and-consider the effect of the Northern Annual Modes on their outlooks.

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Earlier post about UKMET NAO predictive research here.