Winter '17 / '18 - Season-total Snowfall Forecast Contest: JAN totals

Station snowfall summary for JAN-18.
Rank ordered by percent of monthly normal.

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Green ==> 75th - 100th percentile
White ==> Less than 75th and greater than 25th percentile
Red ==> 0 - 25th percentile

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Teleconnection indexes and month-over trend (updated as they become available)
AO:  -0.281⇩
NAO:  1.44⇧
PDO:  0.70⇧
QBO:  -19.02⇩
SOI:  8.9⇧

Winter '17 / '18 - Temperature Departure From Normal: Progress Report - January

Winter '17 / '18 - Snow Storm #4: The Forecasts!

Rookie   -
Intern   1
Journey  -
Senior   10
GOVT    1
PWSP    1
TOT  13

All forecasts posted to the Contest/s web site.
Direct link:  http://www.newx-forecasts.com/NEWxSFC_19/storms/storm4_forecasts_07Feb18.htm
Forecasts ranked by their verification period storm-total precipitation (STP).

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

NWS ER WFOs (GOVT) and PWSP (Private Weather Service Provider) forecasts derived from public issuances current at the deadline.

Heaviest snowfall (>= 7") consensus along and to the right of CAR - BGR - PWM - CON - BTV - CAR with an isolated action center INVOF BGM.   Snow cone expected at BGR.  Mainly a SNE event with nuisance amounts near much of its coast.

Tele-connection indexes floating high above the fray.  NAO still wandering alone in the wilderness.

 
Median station forecasts (Excel 2013 - Power Map)

Winter '17 / '18 - Snow Storm #4: RAW FORECASTS

Here

Apologies to those who did not receive a copy of their forecast.

Forecast confirmation emails sent from the Contest/s web site are being blocked by more ISPs such as Hotmail ... Yahoo ... Comcast ... and Mindspring.

Winter '17 / '18 - Snow Storm #4: Call for Forecasts

Mass General Hospital
Boston ... MA
06-FEB-61
 

Less than perfect storm track may end up short-changing some SNE coastal stations but more than enough snowfall expected over the interior for a contest-worthy snow storm.

The forecast contest for Snow Storm #4 may be cancelled prior to the deadline if fewer than six stations are likely to observe at least a 4" snowfall.

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Forecast element:  each station's verification period snowfall
Deadline for entries:  10:30 PM EST ... TUE ... 06-FEB-18
Verification period begins:  12:01 AM EST ... WED ... 07-FEB-18
Verification period ends:  11:59 PM EST ... THU ... 08-FEB-18

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

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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.  See how well your forecast stacks up against NWS Eastern Region Weather Forecast Offices.

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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 - Sudden Stratospheric Warming: Watch #1

Something worth keeping an eye on ...

 

D+10/s polar vortex splits in two with action centers over northern Canada along ~90W and ~45E INVOF the Black Sea.

 

Deep layer ... high latitude flow reversal (negative / blue values into the board i.e., east wind / anticyclonic circulation) would provide highly favorable conditions for a negative Arctic Oscillation index over an extended period toward meteorological winter's end.

Winter '17 / '18 - Season-total Snowfall Forecast Contest: DEC totals

Station snowfall summary for DEC-17.
Rank ordered by percent of monthly normal.



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Green ==> 75th percentile
White ==> Less than 75th and greater than 25th percentile
Red ==> 25th percentile

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Teleconnection indexes and month-over trend (updated as they become available)
AO:  -0.059⇧
NAO:  0.88⇧
PDO:  0.50⇧
QBO:  -18.12⇩
SOI:  -1.4⇩

Winter '17 / '18 - Regular Season Interim Standings: 1

Under the ‘two-thirds’ rule … forecasters who have entered at least TWO forecasts are included in the interim standings.

Complete interim statistics table and charts at the Contest/s web site here. (fixed)
Forecaster statistics for Winter '17 / '18 contest snow storms here.

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SUMSQ errors for each contest snow storm are normalized with a 'Z-score' ... then averaged to compute the standings. If a forecaster has issued forecasts for more than two-thirds of all snow storm contests ... then Z-scores from their 'best two-thirds' forecasts are used to calculate the Interim and Final standings.

Same idea as dropping the lowest quiz score before computing the final grade.

Winter '17 / '18 - Snow Storm #3: FINAL Results

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

	1st - donsutherland1
	SUMSQ:	28
	SUMSQ Z:	-1.085
	STP:	5.9	(4)
	TAE:	22.5	(1)
	AAE:	0.83	(1)
	2nd - TQ
	SUMSQ:	37
	SUMSQ Z:	-0.841
	STP:	2.3	(3)
	TAE:	23.0	(3)
	AAE:	0.85	(3)
	3rd - Herb @MAWS
	SUMSQ:	39
	SUMSQ Z:	-0.803
	STP:	0.8	(1)
	TAE:	25.1	(4)
	AAE:	0.93	(4)
	HM - Brad Yehl
	SUMSQ:	41
	SUMSQ Z:	-0.739
	STP:	6.9	(6)
	TAE:	23.0	(2)
	AAE:	0.85	(2)

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

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

Station Verification Comparison of Top Forecasters

Winter '17 / '18 - Snow Storm #3: Preliminary STP Verifications

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

Exceptions:
SBY
17-JAN CLI and CF6 bulletins carried 'MM' as daily snowfall at post-time.  Intermittent light snow reported during the day between 1029 and 1527 ... twice reducing VSBY briefly to 2 1/2 SM for a total of 34 minutes.  Tipping bucket data unhelpful.  STP entered as Trace.

HYA
Estimated storm-total snowfall based on inverse distance weighting technique using vicinity STP reports from Barnstable county carried in PNSBOX.

BOS
All frozen precipitation.  Low SLR due likely to 2M temperatures > 0°C.

PWM and CON
17-JAN CLI and CF6 bulletins carried 'MM' as daily snowfall at post-time.  STPs from PNSGYX.

UPDATE 19-JAN-18 @ 3:15 PM EST
PWM/CON CLI and CF6 carry 5.9" and 2.5" ... respectively.

UPDATE 19-JAN-18 @ 10:15 PM EST
CON
The 17-JAN CLI snowfall report issued by GYX for CON is clearly in error given VCNTY PNSGYX
reports.

Inverse distance weighting using all VCNTY PNSGYX reports from Merrimack county in NH results in
a derived two-day STP of 4.3". The closest public report of 4.2" came from CoCoRaHS 1.7 MI SE of
CON.

The derived two-day STP of 4.3" was reduced for verification to 3.5" after applying an SLR of 13.6 to the 0.06"
liquid reported by ASOS prior to contest deadline.  CON/s SLR was derived by inverse distance
weighting of SLRs from 'neighboring' NEWxSFC forecast stations (ORH [12.7] and PWM [14.6]).

Bottom line:  Changing CON/s preliminary STP (5.6") to the verifying STP (3.5") flipped
forecaster rankings in the 4th / 5th and 8th / 9th slots along with changes to all Z-scores
(some better; some worse).

CON ... along with SBY ... have long been a troublesome stations.

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Stations observing at least:
Trace - 27
4" - 5 (19%)
6" - 1 (4%)
8" - 0

Max melt-water at RDU (0.49")
PWM - 0.41"
BGR - 0.37"

New daily records:  2
RDU - 5.9" (4"; 1946)
ORF - 2.5" (1.8"; 1911) [corrected station ID:  h/t Roger Smith / Peter O'Donnell in Comments]

Surface analysis:  15z ... 17-JAN-18
 
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Please report any errors in Comments along with a link to the correct data.
Final results for Snow Storm #3 delayed one day (conducting fermentation experiment FRI evening)
Expected post time: NLT SAT evening.