Winter '17 / '18 - Snow Storm #1: Call for Forecasts Redux

Court St. Keene ... NH
c.1870
 

Sharp short wave diving into the base of a high-amplitude long wave trof centered nicely near 85W progged to spawn a meek area of LOW pressure over the OH river valley then transfer its energy to the SNE coast.

Bare minimum number of stations appear candidates for more than nuisance snowfall for this season/s inaugural event.  Contest may be cancelled before deadline if storm appears not to be contest-worthy.

---
Forecast element: station total snowfall

Deadline:  SUN ... 24-DEC-2017 @10:30 PM EST
Verification begins:  MON ... 25-DEC-2017 @ 12:01 AM EST
Verification ends:  MON ... 25-DEC-2017 @ 11:59 PM EST

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

----
As always ... there/s no cost ... no fee ... no advertising ... or annoying requests for personal information to enter a forecast.  It's just a fun exercise for winter wx enthusiasts to see who can make the best synoptic-scale snowfall forecast.

---
If you are issuing your first forecast this winter ... or you entered the 'season-total' forecast contest ... you/ll need to create an account (user name / password / valid e-mail ... if you want a copy of your forecast sent to your Inbox.

Winter '17 / '18 - Snow Storm #1: White Christmas

Time Square - NYC
26-DEC-47

Today/s American NWP output continued their collective tease for a potentially contest-worthy snow storm over northern portions of the forecast area on Christmas day.

Little comfort in store for true believers in sacred tele-connections for NE / M-A snows ... such as -AO ... -NAO ... +PNA ... despite plenty of evidence the conventional wisdom is largely unsupported empirically ... but I digress.

----
Should the stars finally align for this winter/s inaugural snowfall forecasting contest ... the 'Call for Forecasts' will be issued late tomorrow (SAT) afternoon / early evening with the deadline for entries NLT 10:30 PM EST on SUN.

Winter '17 / '18 - VCP 32: Anything Yet?

Winter '17 / '18 - Snow Storm #1: Call for Forecasts!

Broadway - NYC
19-DEC-32

CANCELLED CANCELLED CANCELLED
Areal snowfall coverage not expected to meet minimum standards for a contest-worthy event.

---
Promising Clipper system swings into the northern forecast area TUE deepening nicely over the Lakes before slowly exiting on WED.

Forecast element: station total snowfall

Deadline:  MON ... 11-DEC-2017 @10:30 PM EST
Verification begins:  TUE ... 12-DEC-2017 @ 12:01 AM EST
Verification ends:  when snow stops accumulating over the forecast area

Enter your forecast at the NEWxSFC/s home page @ http://www.newx-forecasts.com/

Follow the top-of-page link from 'Enter Storm Forecast.'

----
As always ... there/s no cost ... no fee ... no advertising ... or annoying requests for personal information to enter a forecast.  It's just a fun exercise for winter wx enthusiasts to see who can make the best synoptic-scale snowfall forecast.

---
If you are issuing your first forecast this winter ... or you entered the 'season-total' forecast contest ... you/ll need to create an account (user name / password / valid e-mail ... if you want a copy of your forecast sent to your Inbox.

---
Contest may be cancelled before deadline if storm appears to fizzle.

Winter '17 / '18 - Snow Storm #1: Close Call

Valley Forge ... PA
16-DEC-70

Some winter storms ... like the one affecting a large swath of the M-A and SNE coastal plain this weekend ... have a sneaky way of not playing its 'snow card' until it's too late to issue a 'Call for Forecasts' and a contest-worthy storm ends up slipping through the cracks.

This has been especially true over the years for primarily rain events featuring a ribbon of accumulating snows along the NW edge of the precipitation shield.

---
Call it a failure of numerical weather prediction.
Call it a failure of operational weather forecasters.
Call it Banana-Bana ... BO-Bana ... FE-FI ... FO-fanna ...

Either way ... the 19th Annual NEWxSFC awaits its inaugural event for Winter '17 / '18.

---
But did anyone ... anywhere ... get it right three days out?

Why ... yes.  'Someone' did get it right.
The 06/12z NAM ... of all things ... kinda nailed it (GFS was all along ... all in on all liquid).


Image courtesy MeteoCentre

---
Logistically ... the deadline for this storm would have been FRI evening given snow was expected to begin over the forecast area by early SAT AM.  With a FRI deadline ... the 'Call for Forecasts' would have been issued THU evening.  The NCEP forecast at that time called for 10% chance for at least 4" over interior VA stations and a 10% chance for at least 4" along the coasts of NJ continuing into SNE.

As outlined in this post from 2016 ... issuing a 'Call for Forecasts' is not a trivial matter.

---
Had this been the Day3 NCEP prog ... there would have been more than enough lead time to issue the call and the season would be up and running.

Instead ... the call ended up being too close.

Winter '17 / '18 - Arctic Oscillation - NOV

NOV/s Arctic Oscillation (AO) Index:  -0.078

Given NOV-17/s negative AO ... the 2x2 contingency table predicts a 72% likelihood the three-month average AO will be negative this winter.  The results says nothing about the magnitude of the winter/s AO or which months will be negative ... only its sign.

NOTE:
True + ==> correct prediction
False + ==> incorrect prediction


Scatterplot of the 67-year AO period of record (1950 - 2016)

Lower left quad:  NOV -AO and DJF -AO
Lower right quad:  NOV +AO and DJF -AO

Upper left quad:  NOV -AO and DJF +AO
Upper right quad:  NOV +AO and DJF +AO

Related posts by NEWxSFC ...
Winter '17 / '18 - NOV/s Arctic Oscillation: Winter/s Leading Indicator
http://newxsfc.blogspot.com/search?q=arctic+oscillation

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

17 forecasters + P-O-R-N + CONSENSUS

Two first-time forecasters
Welcome Any.wx and 33andrain

475 station forecasts
Entries ranked by STP

BLUE - <= 25th percentile
RED - >= 75th percentile
ORANGE - Winter '16 / '17 Top 'Season-total' forecaster
P-O-R-N - period of record normal
CONSENSUS - average of individual forecasts by station

 ---
Station forecasts for ...
BELOW average snowfall - 189 (40%)
AVERAGE snowfall - 26 (5%)
ABOVE average snowfall - 260 (55%)

NOTE:  Label should read '17 / '18

Consensus (at least 67% of forecasts) for stations with ...
BELOW average snowfall @ ACY ... IAD ... RIC ... ORF ... RDU
ABOVE average snowfall @ CAR ... BGR ... CON ... BTV ... PWM ... ORH ... PVD ... BDL ... BGM ... BDR
Forecasters are all in for above average snows @ BDR

---
See all forecasters' entries at the Contest/s web site here.

The regular 'snow storm' forecasting contests begin when the flakes start a-flyin'.
'Call for Forecasts' are issued at NEWxSFC/s web site and blog (you are here) ... via e-mail ... and Facebook.

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

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

Read more »

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.

---

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%).

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."

---
What's not to love?