Winter '17 / '18 - Snow Storm #2: Call for Forecasts

High-amplitude flow regime with shortening wavelength poised to excite cyclogenesis off the SE coast on WED then deepen rapidly along the VA / NC coast early THU as it heads toward the M-A and SNE coast.

Accumulating snows may be observed at southern forecast stations before the verification period begins; therefore ... forecasters should EXCLUDE these amounts from their forecasts.

Contest may be cancelled before deadline if storm appears not to be contest-worthy.

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Forecast element: station total snowfall

Deadline for entries:  WED ... 03-JAN-18 @10:30 PM EST
Verification begins:  THU ... 04-JAN-18 @ 12:01 AM EST
Verification ends:  FRI ... 05-JAN-18 @ 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

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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.

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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 - Temperature Departure From Normal: Progress Report - December

Winter '17 / '18 - Coastal Teaser #1

Snow Storm #2 may be in the cards later this week as an Arctic air mass in a high amplitude flow regime excites cyclogenesis along the SE coast where SST are anomalously warm.

Latest progs suggest nuisance snow amounts may begin accumulating over extreme southern forecast stations around sundown on WED ... several hours before the deadline.

Don't see any reason to set the deadline for entries TUE evening to ensure these stations are in the mix when this system/s main event will likely play out farther north on THU.

Should the present trend in NWP output continue ...
Call for Forecasts:  TUE ... 02-JAN-18
Deadline for entries:  10:30 PM EST ... WED ... 03-JAN-18
Verification period begins:  12:01 AM EST ... THU ... 04-JAN-18
Verification period ends:  11:59 PM EST ... FRI ... 05-JAN-18

Winter '17 / '18 - Snow Storm #1: FINAL Results

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

	1st - JessicaCain
	SUMSQ:	17
	SUMSQ Z:	-0.991
	STP:	4.3	(4)
	TAE:	12.0	(1)
	AAE:	0.63	(1)
	2nd - TQ
	SUMSQ:	24
	SUMSQ Z:	-0.858
	STP:	4.7	(5)
	TAE:	14.3	(2)
	AAE:	0.75	(2)
	3rd - Shillelagh
	SUMSQ:	25
	SUMSQ Z:	-0.847
	STP:	3.6	(3)
	TAE:	14.4	(3)
	AAE:	0.76	(3)
	HM - WeatherT
	SUMSQ:	33
	SUMSQ Z:	-0.685
	STP:	0.4	(2)
	TAE:	17.4	(5)
	AAE:	0.92	(5)

SUMSQ:  sum of square errors (")

STP:  storm total precipitation (")

TAE:  total absolute error (")
AAE:  average absolute error (")

(#): rank

Forecast by Observed Snowfall Scatter Plots of Top Forecasters 

 

Station Verification Comparison of Top Forecasters

 

Snowfall Distribution and Magnitude by Station (Power Map - Excel 2013)

 

 

Winter '17 / '18 - Snow Storm #1: Preliminary STP Verification

Table of preliminary storm-total snowfalls by station for MON from CDUS41 and CXUS51 bulletins.

Exceptions:
PWM and CON
25-DEC/s daily CLI and CF6 bulletins carry 'MM' as daily snowfall at post-time. 
Preliminary verification STP from latest PNSGYX and METARs.
Values subject to change pending updates to CDUS41 ... CXUS51 ... or PNS bulletins.

HYA
Storm-total snowfall report based on METARs

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Stations observing at least:
Trace - 19
4" - 6
6" - 1
8" - 1
10" - 0

Max melt-water at BGR (0.46")
Snow-Liquid Ratios (SLR) for areas with mixed precipitation ... such as BDR and BOS ... are not reported.

12z 12-25-17

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Please report any errors in Comments along with a link to the correct data.
Final results expected NLT WED evening.

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

Rookie 0
Intern 1
Journey 0
Senior 11
TOT 12 (+ 1 for GOVT / NWS)

Forecasts at the Contest/s web site.
Direct link:  http://www.newx-forecasts.com/NEWxSFC_19/storms/storm1_forecasts_25Dec17.htm

Forecasts are ranked by their storm-total precipitation (STP).

BLUE ==> 25th percentile

RED ==> 75th percentile
White STP and 4cast cells range between the 25th and 75th percentile

NWS forecasts derived from current issuances at the deadline.

 

Heaviest snowfall (>= 6") consensus along and the right of CAR - BGR - PWM - CON - CAR.

Lollypop expected at CAR.

 

 

AO/s dead-cat bounce cushioned by NAO and PNA bank shot.

Winter '17 / '18 - Snow Storm #1: RAW FORECASTS

Here

Winter '17 / '18 - Ignorosphere Tonight

Polar vortex centered over Barents Sea.
Anticyclonic circulation over NOAM

10 mb circulation

The HIGH made a strong attempt to displace the PV but will lose out shortly.

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Image courtesy Earth

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.

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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.

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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.