Winter '10 / '11 - Coastal Teaser #2

Look familiar?

GooFuS has a coastal storm on the 7th as well; however...its genesis is in the northern stream leaving the SW bowling ball behind.

Graphics courtesty Plymouth State Wx Center.

Winter '10 / '11 - Snow Storm #1 - Final Results

1st
Donsutherland1

SUMSQ: 385.44

SUMSQ Z: -1.277

STP: 3.45 (1)

TAE: 81.25 (1)

AAE: 3.01 (1)

2nd
Donald Rosenfeld

SUMSQ: 526.03

SUMSQ Z: -1.033

STP: 12.85 (4)

TAE: 95.85 (3)

AAE: 3.55 (3)

3rd
Mitchel Volk

SUMSQ: 585.48

SUMSQ Z: -0.929

STP: 20.65 (5)

TAE: 97.35 (4)

AAE: 3.61 (4)

Honorable mention
EJBauers
SUMSQ: 614.01
SUMSQ Z: -0.880
STP: 51.45 (8)
TAE: 104.25 (5)
AAE: 3.86 (5)

SUMSQ: sum of square errors
STP: storm total precipitation error
TAE: total absolute error
AAE: average absolute error
(number):  category ranking

Full forecast verification and summary at the Contest web site.

Winter '10 / '11 - Snow Storm #1 - Snow Cover

Image courtesy NASA's Terra satellite.

Close-up of the NE here. 

Winter '10 / '11 - Snow Storm #1 - Teleconnections

Arctic and North Atlantic Oscillations have been below zero...with few exceptions...since mid-NOV thanks to strong hi-latitude blocking over the North Atlantic and Pacific Oceans.

Likewise...the PNA.

Winter '10 / '11 - Snow Storm #1 - Storm Evolution at 500 MB

Short-wave trough comes ashore in southern CA on 23-DEC-10...undercuts the short-wave ridge axis over the Rockies on the 24th...then phases with a northern stream short-wave in over the lower MS River Valley.  Note the strong cold air advection (CAA) driving the northern stream short-wave at 00z on the 26th prior to the phasing which causes the wavelength to shorten and amplify.

The mid-level circulation begins to close off 12 hours later at 12z on the 26th followed by a 12-hour 180 m height-fall between 00z and 12z on the 27th.  Large height-falls at 500 MB indicate strong cooling aloft associated with strong upward vertical motion (UVM).

Stream-phasing was one element behind the flip-flopping of NWP solutions in the run-up to the snow storm.

Graphics courtesy University of Wyoming

Winter '10 / '11 - Snow Storm #1 - Preliminary Verification

Preliminary storm-total snowfalls for Sunday and Monday from CDUS41...CXUS51...and PNS.

No snowfall data in the NWS climate bulletins for SBY.  Verifying storm-total snowfall is the average of two vicinity station reports from AKQPNS.  This station's snowfall reporting fell into a black hole last year and has yet to reappear.

Storm-total snowfall for CON looks suspicious given its relatively low water equivalent; however...vicinity reports carried in BOXPNS suggest the amount is accurate.

Twelve new daily records.

SUN...26-DEC-10
ISP - 11.3" (1"; 2003)
JFK - 10.5" (4.4"; 1969)
ACY - 17.4" (0.2"; 1970)
ORF - 13.4" (5"; 2004)
RDU - 6.7" (T; 2004)

MON....27-DEC-10
CAR - 6.2" (5.4"; 2005)
BGR - 10.3" (4.1"; 1947)
BOS - 8.3" (5.7"; 1894)
BDR - 4" (1.1"; 1963)
BDL - 7" (4.7"; 1944)
JFK - 5.1" (3.2"; 1984)
EWR - 6.5" (4.7"; 1984)

Please report errors and a link to the correct data in Comments.

Final results and storm summary by WED evening.

Winter '10 / '11 - Arctic Oscillation

Beautiful imagery from NASA/s Earth Observatory showing surface air temperature anomalies resulting from persistently negative Arctic Oscillation.  Red (blue) areas are warm (cold) surface air temperature anomalies.  "This image shows the temperature of the land surface for December 3-10, 2010 compared to the average temperature for the same period between 2002 and 2009."

The monthly Arctic Oscillation index has been below zero...15 out of 18 months since JUN-09.  The AO fell to an all time low of -4.266 in FEB-10.  Last winter's D-J-F average was -2.587.

Persistent HIGH pressure...often associated with a weak polar vortex (PV)...over the north pole allows arctic air to drain into low latitudes.  Daily AO values have been negative since mid-NOV.  This goes against type considering the QBO is in its westerly phase where the AO is typically positive...a consequence of a strong...cold PV.

Winter '10 / '11 - Snow Storm #1 - NYC/s NWS MET Fails Blizzard Test

From the NYT...

"But for all its bluster and powder, the monster storm was technically a blizzard only outside of Manhattan. The winds in Central Park topped out at 36 miles per hour but were not sustained over a period of three consecutive hours, nor was the visibility under a quarter of a mile for that period — both requirements to qualify as a blizzard.

“We didn’t quite make the criteria in Central Park,” said Matt Scalora, a meteorologist with the National Weather Service in Central Park. “But we did meet the criteria at J.F.K. Airport and La Guardia,” he added."

Blizzard conditions were observed at JFK but not at LGA where the SFC visibility never went below 1/4SM.

KLGA 262346Z 35024G33KT 1/4SM +SN BLSN VV001
KLGA 262351Z 35026G37KT 1/4SM +SN BLSN VV001
KLGA 270051Z 35023G38KT 1/4SM +SN BLSN VV001
KLGA 270151Z 35026G43KT 1/4SM SN BLSN VV001
KLGA 270251Z 34025G38KT 1/4SM SN BLSN VV001
KLGA 270351Z 34027G40KT 1/4SM SN BLSN VV001
KLGA 270451Z 33031G40KT 1/4SM SN BLSN VV001

Winter '10 / '11 - Snow Storm #1 - NYC-area Blizzard Conditions

03z SFC analysis

JFK and HPN (White Plains) get the brass ring.  Other surrounding stations came close but failed the three-hour restricted visibility criterion.

Blizzards are high-wind storms where falling or blowing snow severely restricts the surface visibility for a period of three hours or more.

The blizzard began at JFK at 0151z (8:51 PM EST). The hour's METAR carries 0SM which is the tower visibility. SFC visibility is reported in the remarks as 1/8SM.

The wind was at or above the 30 kt threshold before and after the visibility condition was met. Blizzard conditions prevailed for three hours until 0451z (11:51 PM EST) when the SFC visibility improved to 1/4SM.

KJFK 270051Z 36029G38KT 1/4SM SN FZFG BLSN VV002
KJFK 270151Z 34034G42KT 0SM SN FZFG BLSN VV001 SFC VIS 1/8
KJFK 270251Z 34037G49KT 0SM SN FZFG BLSN VV001 SFC VSBY 1/8
KJFK 270351Z 34035G49KT 0SM SN FZFG BLSN VV001 SFC VIS 1/8
KJFK 270451Z 33031G44KT 1/8SM SN FZFG BLSN VV004 SFC VIS 1/4
KJFK 270459Z 34029G42KT 1/8SM SN FZFG BLSN VV005 SFC VIS 1/4

Similar story at HPN...
KHPN 270056Z 34024G32KT 1/4SM SN BLSN VV002
KHPN 270156Z 34030G41KT 0SM SN BLSN VV002
KHPN 270256Z 33028G45KT 0SM +SN BLSN VV001
KHPN 270356Z 33032G44KT 0SM +SN BLSN VV001
KHPN 270456Z 33034G48KT 0SM +SN BLSN VV001
KHPN 270556Z 33028G42KT 0SM +SN BLSN VV001
KHPN 270656Z 33030G43KT 3/4SM +SN BLSN VV002

Blizzard conditions began in White Plains at 8:56 PM (0156z) and ended at 1:56 AM (0656z)...lasting two hours longer than JFK.

These was a similar storm sixty-three years ago to the day (requires free Djvu plug-in).

Winter '10 / '11 - Snow Storm #1 - Snow Melt Water

NYC/s 8th Avenue
27-DEC-47

ACY...EWR...and ORF observed not only record-setting snowfalls yesterday but also impressive snow melt water.  Not as generous as the historic 26-DEC-47 storm where 2.53" of melt water was measured in NYC from the 26" snowfall.

ACY - 1.60"
EWR - 1.23" (1.06")
ORF - 1.22"

SN:H2O
ACY - 10.9:1
EWR - 14.2:1 16.7:1
ORF - 11:1


Updated 12/29 to revise EWR data.