Snow Storm #8: Preview

(updated below - Update II - Update III)

Wowser!

Storm 8 being loaded into the chamber with at least six weeks of winter to go! Could easily be 12+ contest-worthy storms this season...a NEWxSFC record.

Storm 8/s 'Call for Forecasts' may be issued SUN evening...if current model solutions and trends continue. Interesting event unfolding with a number of stations poised to measure wrap-around / comma head accumulations.

Long-wave amplitude forecast to increase rapidly along with shortening wave-lenght...but the flow regime is progressive. HPC decidedly cool to the idea in this afternoon/s 'Heavy snow / Icing' discussion of a winter storm for the east coast...but what do they know?

Today/s 12z NAM and GooFuS flock southern forecast stations beginning late in the day on MON and over most stations on into TUE.

A '2 to 3' hour earlier than usual 'deadline for entries' on MON is being considered to capture snowfall expected over southern forecast stations MON evening. Otherwise...the deadline would have to be SUN evening...which is a long 'a-double scribble' leadtime...given the main event looks to be TUE.

Image: MAR 1888 Blizzard...Newburgh...NY

UPDATE
02/01/00z progs are manna from heaven. NWP puts PHL underneath the crystal factory for 24-hours. Not that it/ll actually happen. Just saying.

UPDATE II
02/01/12z progs presenting quite a conundrum. NAM solutions still GO for Storm 8 even though the heaviest precipitation axis has shifted east.

GooFuS puts the storm several hundred miles farther east with no snow depicted for the east coast. 12z GooFuS a significant departure from its 00z and 06z solutions.

Will evaluate 18z runs and proceed from there. A 'Call for Forecasts' is still expected later today with the standard 10:30 PM deadline; although Contest #8 could be canceled on MON if 02/02/00z/12z model runs push the system well offshore.

Cancellation announcement...if required...will be made on the web log and StormVista...not via e-mail.

UPDATE III
18z runs of NAM and GFS in good agreement that Storm 8 will not happen TUE / WED.

VCP 32 - Call It A Single

Snow Storm #7: Results

Senior forecaster Donald Rosenfeld makes it two in a row having issued the best synoptic-scale forecast for NEWxSFC/s seventh snow storm. His 25 station forecasts verified with 56.4 SUMSQ error points (Z-Score = -1.318)...which was a 47% improvement over the average error of 106".

He hit the trifecta...placing first in Total Absolute Error and Average Absolute Error.
Total Absolute Error: 28" (29% better than average)
Average Absolute Error: 1.12" (29% better than average)

Donald Rosenfeld/s forecast had the lowest station errors @ PWM BDR ALB BGM MDT BWI and perfect forecast @ BDR.

Congratulations Donald Rosenfeld!

Donald Rosenfeld wins one FREE month of StormVista GOLD for his forecasting acumen.

2nd Place: skiGirl (57.7"; -1.283)
3rd Place: shanabe (60.6"; -1.205)
Honorable Mention: Raven (68.2"; -1.003)

Full forecast verification and results summary here.

Snow Storm #7: Preliminary Verification

Preliminary storm-total snowfalls for Tuesday and Wednesday from CDUS41...PNS...and CF6 bulletins.

Two new daily records.
BTV: 9.1" (5.3"; 1958)
BGM: 5.9" (5.1"; 2004)

HYA STP estimated from METAR 6-group data @ 10:1 in good agreement with vicinity reports carried in BOSPNS.

Please report errors in Remarks.
Final results and storm summary Friday evening.

Sudden Stratospheric Warming - Full On

Full-blown SSW underway with a reversal of the 10 mb wind extending below 60°N.

Broke through 50 and 70 mb...heading for 100.

Sudden Stratospheric Warming - Close @ Hand

Defined as a complete disruption / reversal of the polar vortex @ 60°N... a well-forecast MAJOR stratospheric warming appears close-at-hand.

The vortex has bifrucated @ 10 mb on JAN 24...30 mb on JAN 27...and is poised to reach 50 mb level in a few days.

The event gets a quick mention in WSI/s latest winter update...

""An incipient stratospheric warming event, which appears to be historic in magnitude, may continue to favor more Arctic air masses in mid-latitudes and increases confidence in the widespread cold forecast of the US these upcoming few months.""

Upper air plots courtesy Univeristy of Wyoming/s Department of Atmospheric Science





Wowzer!

Snow Storm #7: The Forecasts

14 forecasters...including 3 rookies...for the season/s seventh storm. Forecasters in the table above are ranked in ascending order by expected storm-total snowfall.

Station forecasts here.



Mid-Atlantic region gets a bone tossed its way. Best snows expected over northern stations...a season-long trend.



Teleconnections celebrating Opposite Day.



LOW pressure over Mississippi River on tonight/s surface chart expected to morph into...

Snow Storm #7: Raw Forecasts

Here.

13 entries...including 11 veterans and 2 rookies.

Formatted forecasts will be available at the Contest web site early tomorrow evening.

Overview and some summary charts will go up on the web blog around the same time...too.

WSI - JAN Update - Winter '08 / '09

NE...
Feb - colder than normal
March - colder than normal
April - colder than normal

""The general pattern of cold-north and warm-south observed during the winter so far will generally continue into early spring. The warmest temperatures, relative to normal, will be in the south-central and southeastern states while the coldest temperatures will continue to be observed in the north-central states.

"The cold Pacific Ocean suggests that the upcoming aggregate three-month period will be relatively cold nationwide, relative to normal, especially in March and April.

"An incipient stratospheric warming event, which appears to be historic in magnitude, may continue to favor more Arctic air masses in mid-latitudes and increases confidence in the widespread cold forecast of the US these upcoming few months.""

(updated to include full forecast discussion)

Full press release here.

Snow Storm #7: Call for Forecasts

Large-scale...two-day event expected over the forecast area on Tuesday and Wednesday as the long-wave trof currently over the west coast comes east.

HPC discounted today/s 12z solutions for widespread heavy snow from GooFuS as an outlier; however...long-range NWP models have been flip-flopping for days on the evolution of the western trof...so here/s hoping they/ve missed the boat.

Deadline: 10:30 PM EST Monday...26 January 2009

Forecast element: storm-total snowfall
Verification begins: 12:01 AM EST Tuesday...27 January 2009
Verification ends: 11:59 PM EST Wednesday...28 January 2009

Enter your forecast here.
Follow the link from 'Enter Storm Forecast.'

Make the best forecast and you/ll win one month of FREE access to StormVista GOLD.
Details here.

More prizes will be awarded at the end of winter for the best over-all forecaster.
Details here.

As always...there/s no cost...or fee...or annoying requests for personal information to enter.

If you are making your first forecast this year 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) before entering a forecast.

Image: Niagra Falls 2/9/1908

VCP 32 - What/s Wrong With Your Snowman?

Sudden Stratospheric Warming

Welcome to our visitors from The Wx Outlook - TWO Community Wx Forum...NetWx...and UKWxWorld. Good discussions and information about this unusual event.

(updated below)

240-hr ECMWF: complete disruption / reversal of the polar vortex ==> MAJOR stratospheric warming.



Major winter stratospheric warmings preferentially occur during the easterly phase of the QBO (Holton and Tan (1980))...so this event is notable since QBO is currently west ~10 m/sec...as seen on the latitide-height x-section in the 30 - 50 mb layer over the Equator.



As would be expected...AO tanks...too.



All a consequence of the huge mid-month +PNA / Rossby wave propagating into the ignore-o-sphere?



Sig wx ahead?

UPDATE

Chart below shows just how unusual SSW is during QBO-west and solar minima.



(h/t TWO Community Weather Forum from across the pond)

Tropospheric after-effects of SSW lag by ~4 weeks and can last for many weeks afterward. A warm stratosphere means the tropopause has lowered which in turn means lower heights in the troposphere and low trope heights mean cold conditions at the surface.

"Pronounced weakenings of the NH wintertime stratospheric polar vortex tend to be followed by episodes of anomalously low surface air temperatures and increased frequency of occurrence of extreme cold events throughout densely populated regions such as eastern North America, northern Europe, and eastern Asia that persist for ~2 months." (Thompson et. al. - 2002)

EDIT: corrected reference to present QBO phase.

Interim Standings

Plenty-o-new faces in the latest Interim Summary with four more forecasters eligible for ranking.

After six snow storms... donsutherland1 retains his lead... anthony appears out of nowhere into second...a mere 0.0004 points ahead of shanabe...who slips to third.

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

Full interim forecaster error statistics table and charts here.

Forecaster storm summary data here.

SUMSQ errors for each contest snow storm are normalized with a 'Z-score'...then averaged to compute the standings. Forecasters who have entered at least 2/3 of all snow storm contests are included in the standings.

If a forecaster has participated in more than two-thirds of all snow storm contests...then Z-scores from two-thirds of their best forecasts are used to calculate Interim and Final standings. Same idea as dropping the lowest quiz score before the final grade is computed.

Previous Interim summary here.

Snow Storm #6: Results

Senior forecaster Donald Rosenfeld made the best synoptic-scale forecast for NEWxSFC/s sixth snow storm. His 24 station forecasts verified with 84 SUMSQ error points (Z-Score = -1.285)...which was a 54% improvement over the average error of 183".

He placed first in all other forecast skill categories...as well.
Total Absolute Error: 32.15" (27% better than average)
Average Absolute Error: 1.34" (31% better than average)
STP: 14.35" (54% better than average)
R-SQ: 78% (24% better than average)

Donald Rosenfeld/s forecast had the lowest station errors @ CAR ISP SBY ORF.

Congratulations Donald Rosenfeld!

Donald Rosenfeld wins one FREE month of StormVista GOLD for his forecasting acumen.

2nd Place: Raven (117.9"; -0.846)
3rd Place: Newa (122.2"; -0.791)
Honorable Mention: Mitchel Volk (123.4"; -0.774)

Full forecast verification and results summary here.

Snow Storm #6: Preliminary Verification

(updated below - Update II - Update III)

Preliminary storm-total snowfalls from CDUS41...PNS...and CF6 bulletins for Sunday.

Four new daily records.
PWM - 11.5" (11.2"; 1979)
CON - 10.3" (7.7"; 1994)
ORH - 8.2" (6.5"; 1948)
BGM - 3.8" (2.5"; 1978)

One daily record tied.
PVD - 7.5" (7.5"; 1948)

CAR SN:H2O was the only suspect report...given the low densities reported by most other stations. Storm-total snowfall amount looks reasonable in comparison to vicinity reports carried in the PNS; therefore...no adjustments indicated.

Please report errors in Remarks.
Final results and storm summary Tuesday evening.

UPDATE
Regarding PNS snowfall totals referenced in Remarks; The Local Climate Bulletin (CDUS41) is the primary source for snowfall verification data. The snowfall reports in the PNS do not always reflect the official data in the CDUS41.

The BOS PNS issued today @ 1:15 PM EST carries a 3.2" snowfall report for PVD valid @6:50 AM EST SUN...18 JAN. METARs show snow continued for another six hours 41 minutes. The 1751z METAR 6-group reported 0.52" liquid. The 4-group...which rounds to the nearest inch...increased from 3" to 7" between 12z and 18z.

The same holds true for BOS (PNS report time was 7:00 AM EST...18 JAN)...ORH (6:50 AM...EST 18 JAN) and BDL (6:50 AM EST...18 JAN).

Thanks to the poster 'Anonymous' for taking the time to eagle-eye the verifications.

UPDATE II
In Remarks...poster 'Anonymous' links to a WFO CAR summary report where BGR/s FSS reported a two-day snowfall of 11.2" @ 8:00 AM EST MON...JAN 19 and questions whether preliminary verification value of 4.4" is accurate.

The two-day storm-total liquid precipitation...as reported in METAR 6- and 7-groups... totaled 0.43"...of which 0.32" fell before the end of the verification period (11:59 PM EST SUN...18 JAN).

The density of 11.2" frozen precipitation from 0.43" of liquid precipitation is 26:1. If the same SN:H2O is applied to the 0.32" liquid observed during the verification period...an adjusted BGR snowfall total of 8.3" seems reasonable.

UPDATE III
Daily record tied @ MDT - 1.5" (1.5"; 1958)

Going Coastal

SPC weighed in on Storm 6 this afternoon...

"MAXIMUM SURFACE PRESSURE FALLS HAVE BECOME CENTERED ALONG WARM FRONT ACROSS COASTAL ME...DOWNSTREAM OF INTENSIFYING CYCLONE OVER MA BAY AT 16Z. AN INTENSE BAROCLINIC ZONE / CHARACTERIZED BY A SURFACE TEMPERATURE GRADIENT OF 45 F OVER 200 NM ACROSS ERN ME/ HAS RESULTED IN SUBSTANTIAL LOW-LEVEL WAA /INFERRED BY LARGE CYCLONIC HODOGRAPHS IN GRAY AND CARIBOU VAD PROFILERS/ AND SNOWFALL RATES REACHING 1 IN/HR /PER 16Z METARS IN BRUNSWICK ME AND PROVIDENCE RI/.

WAA WILL STRENGTHEN AS THE LLJ INTENSIFIES THIS AFTERNOON WITH APPROACH OF SHORT WAVE TROUGH /CURRENTLY ROUNDING BASE OF LARGER-SCALE TROUGH OVER TN VALLEY/.

MORNING MODEL GUIDANCE QPF CORRESPONDINGLY INCREASE WITH BOTH GFS/NAM INDICATING PEAK AMOUNTS AROUND 0.50 IN FROM 21-00Z. ALTHOUGH SURFACE TEMPERATURES MAY WARM ABOVE FREEZING ACROSS IMMEDIATE COASTAL AREAS S OF THE US-1 CORRIDOR EAST OF ROCKLAND...HIGH SNOW TO LIQUID RATIOS FARTHER INLAND SHOULD RESULT IN SNOWFALL RATES OF 1 TO 2 IN/HR BECOMING PREVALENT."

..GRAMS/DARROW.. 01/18/2009

Graphic and discussion courtesy SPC.

Stellar Dendrites

High SN:H2O were observed in this morning early snowfall reports.

ORH - 23:1
CON - 24:1
BDL - 25:1

Ratios are well above normal.



Image courtesy Cooperative Institute for Precipitation Systems



12z Skew-T from GYX shows cloud-top ~-18°C...the cold edge of favored stellar dendrite growth region. Note the strong warm-air advection near 700 mb acting on the elevated moist layer where mixing ratios reach their maximum value.

Skew-T courtesy SPC.



Snowflake morphology courtesy SnowCrystals.com

Snow Storm #6: The Forecasts

13 forecasters...including 2 rookies...for the season/s sixth storm. Forecasts in the table above are ranked by expected storm-total snowfall.

Station forecasts here.



Typical Winter '08 / '09 snowfall distribution favoring northern forecast stations.



+PNA delivering the cold.



Evolution of coastal front is a key element in the forecast.

Snow Storm #6: Call for Forecasts

Poor consensus today between NAM and GooFuS concerning Sunday's snow storm over the forecast area.

GooFuS solutions depict more mid-level energy digging deeper into the eastern trof...which excites cyclogenesis along the southeast coast and a second snow storm on Monday.

NAM is more progressive as it shunts the bulk of its impulse into New England.

Given the present uncertainty...the verification period for this event will be be restricted to 12:01 AM EST to 11:59 PM EST on Sunday. This leaves the door open for a 'Call for Forecasts' on Saturday for Snow Storm #7.

Make the best forecast and you/ll win one month of FREE access to StormVista GOLD. Details here.

Deadline: 10:30 PM EST Saturday...17 January 2009

Forecast element: storm-total snowfall
Verification period begins: 12:01 AM EST Sunday...18 January 2009
Verification period ends: 11:59 PM EST Sunday...18 January 2009

Enter your forecast here.
Follow the link from 'Enter Storm Forecast.'

More prizes will be awarded at the end of winter for the best over-all forecaster. Details here.

As always...there/s no cost...or fee...or annoying requests for personal information to enter.

If you are making your first forecast this year 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) before entering a forecast.

Image: March 1888 Blizzard - NYC

Interim Standings

After five snow storms... donsutherland1 holds the lead... shanabe holds onto second...and Donald Rosenfeld lunges from sixth into third.

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

Forecasters who will be eligible for Interim Standings ranking...if they enter a forecast for Snow Storm #6:

• anthony
  
• dmcuriman
  
• emoran
  
• Mitchel Volk
  
• Newa
  
• Raven
  
• skiGirl
  

Full interim forecaster error statistics table and charts here.

Forecaster storm summary data here.

SUMSQ errors for each contest snow storm are normalized with a 'Z-score'...then averaged to compute the standings. Forecasters who have entered at least 2/3 of all snow storm contests are included in the standings.

If a forecaster has participated in more than two-thirds of all snow storm contests...then Z-scores from two-thirds of their best forecasts are used to calculate Interim and Final standings. Same idea as dropping the lowest quiz score before the final grade is computed.

Previous Interim summaries here and here.

Snow Storm #5: Results

Senior forecaster emoran made the best synoptic-scale forecast for NEWxSFC/s fifth snow storm. His 23 station forecast verified with 68.8 SUMSQ error points (Z-Score = -1.352)...which was a 66% improvement over the average error of 205".

He hit the trifecta with lowest Total Absolute Error (29.9") and Average Absolute Error (1.3"). His 63% R-SQ score...a measure of how well a forecast captures the variability of the observed snowfall... ranked second.

This is emoran/s second...first place finish this season.

Emoran had the lowest station errors @ HYA PVD BDR ALB MDT DCA.

Congratulations emoran!

Emoran wins one FREE month of StormVista GOLD for his forecasting acumen.

2nd Place: anthony (75.1"; -1.290)
3rd Place: donsutherland1 (96"; -1.082)

Donald Rosenfeld...TrekkerCC...and skiGirl came within 5% of the 58.1" storm-total snowfall. skiGirl missed by a mere 0.65"!

Full forecast verification and results summary here.

Snow Storm #5: Preliminary Verification

Preliminary storm-total snowfalls from CDUS41...PNS...and CF6 bulletins for Saturday and Sunday.

One new daily record.
BGM - 5.5" (5.3"; 1957)

ORH/s 3.1" value is suspect and should be rejected based on vicinity SN:H2O and spotter report, and empirically-derived SN:H2O estimates.

Vicinity SN:H2O calculations were ~14:1...which suggests ORH storm-total snowfall was 4.6".

A Worcester ham radio spotter reported 4.8".

KORH/s SN:H2O...based on 0.33" liquid precipitation...is 9.4". Surface temperatures during the storm ranged between 16° and 19°...which supports a SN:H20...based on empirical evidence...of 20:1 or 6.5".

KORH is notorious for underreporting snowfall b/c their SN:H2O is always 10:1.

Recommend KORH/s STP be adjusted to 4.6" for this event.

Please report errors in Remarks.
Final results and storm summary Tuesday evening.

Interim Standings

After four snow storms...donsutherland1 moves into the lead...trailed by shanabe...who moved up from 5th and dmcguriman holding in third.

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

Full interim forecaster statistics table and charts here.

Forecaster storm summary data here.

SUMSQ errors for each contest snow storm are normalized with a 'Z-score'...then averaged to compute the standings. Forecasters who have entered at least 2/3 of all snow storm contests are included in the standings.

If a forecaster has participated in more than two-thirds of all snow storm contests...then Z-scores from two-thirds of their best forecasts are used to calculate Interim and Final standings. Same idea as dropping the lowest quiz score before the final grade is computed.

Previous Interim summary here.

Snow Storm #4: Results

Senior forecaster 'shanabe' made the best synoptic-scale forecast for NEWxSFC/s fourth snow storm. His forecast verified with 36.7 'SUMSQ error' points (Z-Score = -1.201) which was a 60% improvement over the average of all forecasters 'SUMSQ errors' of 91.

He completed the trifecta with a tie for the lowest 'Total Absolute Error' (13.4") and 'Average Absolute Error' (1.03"). His 'storm-total precipitation (STP) forecast for 31" had an error of 1.6".

Shanabe had the lowest station errors @ PWM CON BDR ALB EWR DCA and made a perfect forecast @ BDL.

Congratulations shanabe!
Shanabe wins one FREE month of StormVista GOLD for his efforts.

2nd Place: donsutherland1 (40.9"; -1.107)
3rd Place: nynjpaweather (43.0"; -1.061)

Shanabe and donsutherland1 tied for 'Total Absolute Error' (13.4"); however...Shanabe had a lower 'Average Absolute Error' b/c he made 13 station forecasts and donsutherland1 made 11.

Full forecast verification and results summary here.

It/s Official - WX GO for SNOW

Snow Storm #5: The Forecasts

19 forecasters...including 5 rookies...for the season/s fifth storm.

Station forecasts here.



First time in a while the distribution of heaviest snowfall has shifted toward southern New England and mid-Atlantic forecast stations.



Preferred teleconnection states still nowhere to be found.



Verification began last night at 12:01 AM EST. Snowfall is expected to continue into Sunday afternoon over extreme northeastern stations. Preliminary storm-total snowfalls may be available for posting Sunday evening. Final results could be available on the web site as early as Monday evening but maybe not until Tuesday evening should final storm-total snowfall data be delayed.

Snow Storm #4: Preliminary Verification

Preliminary storm-total snowfalls from CDUS41...PNS...and CF6 bulletins for Wednesday and Thursday.

No new daily records.

Please report errors in Remarks.
Final results and storm summary Saturday.

Snow Storm #5: Call for Forecasts

A genuine snow storm appears in the offing this weekend. Not the 'some snow on the northern edge of the precipitation shield' that has been so common so far this season. After the way Snow Storm #4 fizzled...the atmosphere owes us one.

Make the best forecast and you/ll win one month of FREE access to StormVista GOLD. Details here.

Deadline: Friday...09 January...2009 @ 10:30 PM EST

Forecast element: storm-total snowfall
Verification period begins: 12:01 AM EST Saturday...10 January 2009

Enter your forecast here.
Follow the link from 'Enter Storm Forecast.'

More prizes will be awarded at the end of winter for the best over-all forecaster. Details here.

As always...there/s no cost...or fee...or annoying requests for personal information to enter.

If you are making your first forecast this year 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) before entering a forecast.

Snow Storm #4: The Forecasts

16 forecasters...including 4 rookies...for the season/s fourth storm.

Station forecasts here.



Northern stations continue to get the best of it again this winter.



-NAO pulling its weight...again.



Verification began last night at 12:01 AM EST. Snowfall continues over the forecast area at post time and is expected to continue into early Thursday afternoon. Preliminary storm-total snowfalls will be posted Thursday evening with the final results available on the web site Friday evening.