Winter '10 / '11 - Snow Storm #5 - Preliminary Verification

Preliminary storm-total snowfalls for Wednesday and Thursday from CDUS41...CXUS51...and PNS...as of noon Friday.

No updated snowfall report was carried in the NWS PNSBOX bulletin for HYA. Verifying storm-total snowfall of 3.5" was estimated from vicinity reports.

SBY/s Daily Climate Bulletin did not carry a snowfall report.  Verifiying storm-total snowfall came from PNSAKQ.

PHL/s record-setting snowfall on Wednesday piled-up over the course of six hours!

Many stations in the data table do not have SN:H2O reported b/c their totals included mixed precipitation.
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Fourteen new daily records!

Wednesday...26-JAN-11
PHL - 14.2" (4.4"; 1963)
ABE - 11.3" (5.3"; 1994)
EWR - 11" (5.8"; 1994)
BWI - 7.8" (6.9"; 1966)
MDT - 6.4" (6.1"; 1904)
BDR - 6" (3.6"; 1949)
JFK - 6" (3.3"; 1994)

Thursday...27-JAN-11
ORH - 11" (6.1"; 1963)
ISP - 9.6" (1.1"; 2004)
BDL - 9.1" (5.2"; 1963)
BOS - 8.8" (8"; 1894)
BDR - 7" (3.8"; 1963)
PVD - 6.7" (3"; 1963)
JFK - 4.3" (2.7"; 2004)

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Please report any errors and drop a link to the correct data in Comments.
Final results and storm summary Saturday evening.

Winter '10 / '11 - Snow Storm #5 - Snow Gun

(Updated below)

Tonight's 00z rawindsonde flight launched from OKX observed some major-league instability atop deep low-level moisture.

- Note the strong deep-layer iso-thermal WAA through ~600 mb beneath a layer of CAA near 500mb.
- Snow is indicated b/c the entire column is below zero.
- Specific gravity peaks close to 5g/kg near 750 mb.
- Baroclinic instability indicated with strong increase in wind speed with height.

More importantly is the observed instability AOA 700 mb as indicated by the theta-E plot shown below.  Strong instability is indicated when the trace goes straight up as it does ~700 mb and in the layer between 650 and 500 mb.

Snowfall rates at IAD earlier this evening were quite intense...where less instability was observed.  If I'm the duty forecaster at OKX this evening...I'd be preparing for snowfall rates in excess of 2"/HR over my CWA.

Sounding images courtesy SPC.

UPDATE:

METAR KISP 270656Z 02025KT 1/4SM R06/1800V2200FT +SN BLSN BKN003 OVC008 M01/M03 A2950 RMK AO2 SLP988 SNINCR 5/019

5" / hour!

Winter '10 / '11 - Snow Storm #5 - TSSN

SPECI KIAD 262021Z 34007KT 1SM -TSSN BR BKN004 OVC010CB 01/M01

METAR KFDK 262051Z AUTO 35010KT 1SM -TSSN OVC009 01/01

METAR KBWI 270154Z 34009KT 3/4SM R10/3500V4500FT -TSSN BR OVC003 01/00

Winter '10 / '11 - Snow Storm #5 - The Forecasts

EDIT:  a double-entry for Roger Smith was removed.  The forecast data table at the Contest's web site has been updated.

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14 13 entries

1 Rookie
4 2 Intern forecasters
1 Journeyman forecasters
7 Senior forecasters including Chief forecaster Ira Libov.

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All forecasts have been posted to the Contest's home page.
Follow the link from Storm #5.

Entries are ranked in ascending order by 'storm-total' snowfall.
Please check you entry for accuracy.

Larger than usual range of expected storm-total snowfall...
Min: 56" (Roger Smith) Min: 67" (Donald Rosenfeld)
Max: 188" (iralibov)
Avg: 120" Avg: 125"
Median: 123" Median: 124"
STD: 35" STD: 31"

Heaviest snowfall axis expected to fall inside ORH - BOS - PVD - ISP -EWR - ORH

Winter '10 / '11 - Snow Storm #5 - Raw Forecasts

Raw forecasts here (ne_wx GoogleGroup).

Winter '10 / '11 - Interim Standings - #2

After four snow storms...

Under the 'two-thirds' rule...the best 'two out of three' z-scores are used to compute the interim standings. After Snow Storm #4...your top three z-scores were used to calculate these standings.  Data used to compute the standings are posted at the Contest web site here.

Z-scores are used to standardize / normalize forecast errors for each snow storm so at the end of the season...the 'equalized' scores can be averaged.

An expanded data table with additional measures of forecaster skill at the Contest's home page.

Winter '10 / '11 - Snow Storm #5 - Call for Forecasts

East Side...NYC
24-JAN-1908

Large-scale disagreement between today/s 12z NAM and GooFuS runs. HPC discounted the NAM solution as a 'slow outlier' in its afternoon discussion.

GooFuS keeps the LOW closer to the coast putting enough stations in play for a contest-worthy event.

The contest may be canceled prior to the deadline if NWP indicates a fizzling event.








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Deadline for entries:  10:30 PM EST TUE...25-JAN-11
Forecast element: storm-total snowfall

Verification period begins:  12:01 AM WED...26-JAN-11
Verification period ends:  11:59 PM THU...27-JAN-11

Enter your forecast at the Contest's home page here.
Follow the link from 'Enter Storm Forecast.'

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As always...there/s no cost...or fee...or advertising...or annoying requests for personal information to enter a forecast. It's just a fun exercise among 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).

Want to be notified via e-mail when a 'Call for Forecasts' is issued?
Send your request to newx at newx-forecasts dot com.

Winter '10 / '11 - WSI Expects Warm FEB

"“The end of the recent long-lived and extreme North Atlantic blocking episode, along with a return to more dateline blocking typical of late winter La Nina regimes, should result in a return of colder weather to the western half of the US in February while the eastern US finally experiences more moderate temperatures,” said WSI Chief Meteorologist Dr. Todd Crawford."

FEB - warmer
MAR - colder
APR - colder
More...

Winter's seasonal forecast for the northeast from WSI...
DEC - colder
JAN - warmer
FEB - warmer

"“The recent behavior of the North Atlantic Oscillation, along with the fact that current and recent atmospheric/oceanic patterns have closely resembled those from the 1950s-1970s period, has reinforced our hypothesis that there may have been a fundamental climate shift in 2008 that will result in weather patterns more similar to those found 40-60 years ago,” Dr. Crawford added."

Crawford/s reference to the NAO's recent behavior may be related to the index's 5-year moving average falling below zero for the first time in more than two decades. This chart shows the historical tendency for the NAO's moving average for meteorological winter (D-J-F) to remain positive or negative once the shift occurs.

Winter '10 / '11 - Stratospheric Warming - Take 4

Meant to post this over the weekend. Subsequent runs of the ECMWF have continued with the idea of a weakening polar vortex by month/s end suggesting a warming in the stratosphere with implications for cold temperatures toward the end of meteorological winter.

Note how the strong 85 m/s (~170 kts) PV in the left panel weakens to 35 m/s (~70 kts) by D+10 where the deep-layer blue highlights near 90°N indicates an east wind.  Favorable conditions are indicated for the Arctic Oscillation to fall well below zero in late February.

Not that significant warmth is expected anytime soon as the NAO ridge retrogrades toward Greenland and PNA remains positive with the most northern extension of the ridge reaching well above the Arctic Circle.  Short-wave energy migrating from this hi-latitude into the base of a deep eastern trough brings great potential to spin-up strong coastal storms off the SE CONUS.

Winter '10 / '11 - Snow Storm #4 - Final Results - UPDATED

The final results for Snow Storm #4 have been updated to include a forecast issued after the deadline.  Technical difficulties with the Contest's web site were experienced by Senior forecaster Mitch Volk Friday evening around 9:30 PM.  These difficulties prevented him from issuing a forecast before the deadline.

When I learned of this problem...I asked Mitch to send me the forecast he tried unsuccessfully to enter.  His forecast was included and verified along with the other forecasts.  Forecaster skill scores have been re-computed and posted to the Contest's web site.

Mitch has participated in the NEWxSFC every winter since its inception in 1999...issuing a timely forecast for almost every snow storm and every season-total contest.  Under the circumstances...accepting his forecast after the deadline is the right thing to do.
 
1st - Brad Yehl
SUMSQ: 75.76
SUMSQ Z: -1.032
STP: 7.50 (4)
TAE: 26.50 (2)
AAE: 1.10 (3)

Bride's Maid - Shillelagh
SUMSQ: 79.91
SUMSQ Z: -0.976
STP: 0.80 (2)
TAE: 26.90 (3)
AAE: 1.08 (2)

3rd - TQ
SUMSQ: 95.25
SUMSQ Z: -0.770
STP: 11.50 (7)
TAE: 27.90 (4)
AAE: 1.16 (4)

Honorable Mention - donsutherland1
SUMSQ: 100.19
SUMSQ Z: -0.703
STP: 17.60 (9)
TAE: 24.50 (1)
AAE: 1.07 (1)

SUMSQ: sum of square errors
STP: storm-total precipitation error
TAE: total absolute error
AAE: average absolute error
(rank)