CONTEST STATUS - Updated: FRI ... 30-JAN-15 @ 9:35 PM EST

Winter '14 / '15 - Snowfall Forecast Contests

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16th Annual 'Regular Season'

STORM #3
'Call for Forecasts'
Deadline for entries: 10:30 PM EST ... SAT ... 31-JAN-15
Details here

STORM #2
FINAL results here.

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14th Annual 'Season-total'
Forecasts here.
.

Friday, January 30, 2015

Winter '14 / '15 - Storm #2: FINAL Results

Full forecast verifications and summary for Storm #1 at the Contest/s web site.

     
 1st - Donald Rosenfeld 
 SUMSQ:654.05  
 SUMSQ Z:-1.375  
 STP:12.7 (2) 
 TAE:96.1 (1) 
 AAE:3.56 (1) 
     
 2nd - donsutherland1 
 SUMSQ:1116.14  
 SUMSQ Z:-0.873  
 STP:56.4 (5) 
 TAE:129.8 (3) 
 AAE:4.81 (3) 
     
 3rd - shillelagh 
 SUMSQ:1409.4  
 SUMSQ Z:-0.555  
 STP:89.6 (9) 
 TAE:117.0 (2) 
 AAE:4.34 (2) 
     
 HM - WeatherT 
 SUMSQ:1456.6  
 SUMSQ Z:-0.504  
 STP:41.1 (3) 
 TAE:138.7 (4) 
 AAE:5.14 (4) 
     

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SUMSQ: sum of square errors
STP: storm-total precipitation error
TAE: total absolute error
AAE: average absolute error
(number): category rank
Click on images for higher resolution.
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Click images to enlarge.

Winter '14 / '15 - Storm #3: Call for Forecasts!

NYC
02-FEB-1969
This weekend/s storm comes courtesy of an upper level LOW positioned off the Baja coast of Mexico on 25-JAN. 

The western long wave ridge rolled over the LOW as it moved inland.  The advancing ridge in turn amplified the full-latitude trof over the east ... the same trof responsible for record snowfalls for Storm #2 ... and pulled the remnants of the upper LOW into the 4-corners region today.

As the trof shears out to the east on SAT .. surface LOW pressure begins to develop in the lee of the southern Rockies and starts organizing INVOF the Arklatex early SUN morning. 


Over-running frozen precipitation expected in the Arctic air north of the warm front attending the LOW and along the backside of the system as it moves up the M-A and NE coast.

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Forecast element: storm-total snowfall
Deadline for entries:  10:30 PM EST ... SAT ... 31-JAN-15

Verification begins:  12:01 AM EST ... SUN ... 01-FEB-15
Verification ends:  when the snow stops falling

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Enter your forecast at the NEWxSFC/s home page here.
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.

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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).

Thursday, January 29, 2015

Winter '14 / '15 - Storm #2: Preliminary Verification

Preliminary storm-total snowfalls for Storm #2 (26/28-JAN-15) from CDUS41 and CXUS51 bulletins.

Fairly good coverage and reporting.

Suspect observations
 - PWM/s 2.37" liquid on the 27th works out to an SLR slightly less than 10:1.
The 7-group @ 12z/28th is much lower.
Estimated liquid:  0.95"

- BTV/s 0.03" liquid on the 27th ==> 120:1 SLR.

- PNSBOX carried 27" @HYA; however ... vicinity reports averaged 22".

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One new daily snowfall record on 26-JAN-15
ISP - 7.5" (4.5"; 1987)

Eight new daily snowfall records on 27-JAN-15
ORH - 31.9" (11"; 2011)
PWM - 22.8" (8.3"; 1963)
BOS - 22.1" (8.8"; 2011)
ISP - 17.3" (9.6"; 2011)
PVD - 16" (6.7"; 2011)
BGR - 14.9" (10.8"; 1963)
CON - 12.8" (6.2"; 1963)
JFK - 5.6" (4.3"; 2011)

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

Monday, January 26, 2015

Winter '14 / '15 - Public Service Announcement: Blizzard Defined

NYC - Brooklyn Bridge
"4.2 Blizzard.
A blizzard means ... the following conditions are expected to prevail for ... 3 hours or longer.
 
"(1)  Sustained wind or frequent gusts to 35 miles an hour (30 knots) or greater; and
 
"(2)  considerable falling and/or blowing snow (... reducing visibility frequently to less than 1/4 mile).
 
"Although there is no set temperature requirement for blizzard conditions, the life-threatening nature of the low temperatures in combination with the other hazardous conditions of wind, snow, and poor visibility increases dramatically when the temperature falls below 20°."
 
REF:  National Weather Service Operations Manual
 
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Blizzards have high winds?
Yes!
 
Blizzards have low visibilities?
Yes!
 
Blizzards have heavy snow?
Not so much.
 
Note the National Weather Service's (NWS) o-fookin'ficial blizzard definition has no explicit or implicit reference to snowfall amounts.
 
Note also the snow responsible for restricting the visibility does not even have to be falling from clouds.
The snow responsible for restricting the visibility just has to be blowin'around!
 
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Blizzards are wind storms.
Blizzards are not necessarily snow storms
 
Blizzard is a meteorological phenomenon where the forward visibility at the surface is severely restricted by the combination of high wind speed and falling or blowing snow.
 
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Yo ... morans.
Stop the Stupid
It burns.

Winter '14 / '15 - Storm #2: The Forecasts!

Rookies 0
Interns 0
Journeymen 2
Senior 12
TOT 14

Total station forecasts: 357


Forecasts are ranked by their storm-total precipitation (STP).
BLUE ==> 25th percentile.
RED ==> 75th percentile.
STP cells without color are between the 25th and 75th percentile.

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Heaviest snowfall (+20") consensus along a line from BOS - PVD - ISP - BDR - BDL - ORH - BOS.
 
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CPC/s tele-connection data file is FUBAR today ... so there/s no trend analysis graphic.
 
NEWxSFC can report the AO is and has been positive and trending up ... the NAO is and has been positive and trending up ... and the PNA is and has been positive and trending down.
 
How is it even remotely possible to have an historic snow storm along the east coast when all the supposedly important tele-connections indices are upside-down?
 
IDK.
The so-called '93 'Storm of the Century' had the same issues.
 
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Forecaster/s station-by-station entries for Storm #2 available at the Contest/s web site.

Saturday, January 24, 2015

Winter '14 / '15 - Storm #2: Call for Forecasts!

NYC
27-JAN-1937
Garden-variety Alberta clipper sliding out of Canada at post time progged to dig into the coastal waters off the Carolina then morph into a Sutcliffe-Petterssen 'self-development'* coastal bomb INVOF the famed 40°N / 70°W benchmark.

* - http://fas.org/spp/military/docops/afwa/atmos-U3.htm
Scroll to "Self-development/intensification of a baroclinic low"

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Forecast element: storm-total snowfall
Deadline for entries:  10:30 PM EST ... SUN ... 25-JAN-15

Verification period begins:  12:01 AM EST ... MON ... 26-JAN-15
Verification period ends:  11:59 PM EST ... WED ... 28-JAN-15

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Enter your forecast at the NEWxSFC/s home page here.
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.

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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).

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Hard to believe the last 'Call for Forecasts' was issued two months ago ... all the way back on 25-NOV-14

Only three years (2000, 2007, 2012) where there no contest-worthy storms in DEC.
Only two years (2007, 2013) where there no contest-worthy storms in JAN.

Even FEB is not immune to no-hitters (2002, 2009).
The good news is early FEB looks quite promising.

Probably get two in APR (h/t snowman).
Last and only time that happened was 2002.

Monday, January 5, 2015

Winter '14 / '15 - Weakening Polar Vortex ==> Sudden Stratospheric Warming: UPDATE 6

OBS
The current sudden stratospheric warming (SSW) event has likely peaked as evidenced by
1)   the deep layer wind reversal of the polar vortex (PV) and
2)  a dipole of hi-latitude warming maximized INVOF eastern Greenland.

Image:  10-hPa temperature change in a week in the Northern Hemisphere (courtesy Tokyo Climate Center, Climate Prediction Division).  The contour interval is 5 °C. The pink and light blue shadings indicate warming and cooling, respectively. The red shading denotes warming for values higher than 25 °C.

Upper air analysis courtesy University of Wyoming, College of Engineering, Department of Atmospheric Science

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Deep-layer hi-latitude easterlies ~30 KTs.

 
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Arctic Oscillation (AO) poised to tank by mid-month.
 
 
D+11 prog of a near-perfect AO tri-pole and a stationary... four-wave pattern.
 
 
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Bonus OB:  DEC QBO dipped to -25.35.
 

Wednesday, December 31, 2014

Winter '14 / '15 - Weakening Polar Vortex ==> Sudden Stratospheric Warming: UPDATE 5

"Overall, the easterly winds descending into the lower tropical stratosphere is continually favorable for redirecting tropospheric waves anomalously poleward, which increases the odds of interaction with the stratospheric polar vortex and hence increases the chances of a SSW event this winter. (AER)

OBS



CPC - Stratosphere-Troposphere Monitoring

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First sign of sudden warming at 30 mb

30-hPa temperature change in a week in the Northern Hemisphere
The contour interval is 5 °C. The pink and light blue shadings indicate warming and cooling, respectively. The red shading denotes warming for values higher than 25 °C.
 
Tokyo Climate Center, Climate Prediction Division
 
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PROGS
NWP projecting a return to above-normal temperatures around mid-JAN.
Have they accounted for the effects from this SSW event?

Tuesday, December 30, 2014

Winter '14 / '15 - Weakening Polar Vortex ==> Sudden Stratospheric Warming: UPDATE 4

OBS
Expanding area at 10 mb over Siberia (red shading) where the one-week temperature change exceeds 25°C.
 
10-hPa temperature change in a week in the Northern Hemisphere

The contour interval is 5 °C. The pink and light blue shadings indicate warming and cooling, respectively. The red shading denotes warming for values higher than 25 °C.
 
Imagery courtesy Tokyo Climate Center, Climate Prediction Division
 
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PROGS
The 12z / 29-DEC-14 ECMWF suggests the 'split-vortices' SSW portion of the current event will peak between 03 / 06-JAN-15 followed by displacement. on D+10.


Deep-layer easterlies depicted on 03-JAN.
Short-lived daughter vortices appear briefly at the 475K level on 06-JAN.

Displacement
 
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SSW TYPES