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...
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.
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
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.
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.
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.
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.
(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)
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.
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.
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
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:
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.
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.
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.
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.
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.
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.
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.
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.
The short-wave progged to affect the forecast area Saturday appears well south of the Aleutian Islands on GOES-W this evening. It/s heading for shore in the PAC NW THU afternoon. GooFuS phases / amplifies this feature on Friday over the Great Lakes with remnants of a weakening upper LOW currently atop AK.
Saturday is still aways away; however...this storm...as currently depicted...has good upper air support (PVA; left exit-region of lifting jet max) for dynamic cooling and strong warm-air advection at 85H. The omega equation couldn/t be happier.
Monday/s 00z NAM is dangling dendrites over the forecast area on Wednesday.
CON f-sounding ==>
Model predicts 18 hours of precipitation over southern NH...where the moist column depth is below 0°C and nine 'stellar' hours where the cloud top temperature is ~15°C.
First flakes are still aways out; however...even some interior mid-Atlantic stations may be in play for this storm.
A notably...nay brutally...cold December was heralded for the eastern CONUS by many well-known LR wx forecasters as meteorological winter approached.
Offered for your consideration...a cumulative temperature departure animation for NOAM here.
Northeastern CONUS temperatures never did observe negative anomalies...nor did the mid-Atlantic region except for a brief period centered around the 8th. The negative anomaly centroid was over the SE for much of the month before retrograding into the upper Plains.
End-of-month snapshot of precipitation departures.
Note main storm track running NE through MO - IL - MI and secondary axis from MS - TN - WV continuing into New England.
The primary storm track is at odds with the statistical correlation between 'NAO - precipitation.' The map below indicates when NAO is positive the storm track runs from MO - IL - MI...as observed during December. Problem is...the daily average NAO for December was -0.281.
The ten-year NAO precipitation correlation time period was selected b/c it excludes the +PDO / +ENSO years that dominated the late 80s and early 90s. The correlation coefficient must be at least +/- 0.6 to be statistically significant.
December/s storm track was quite favorable for southern New England stations where Bridgeport (BDR) and Boston (BOS) observed more than triple their normal monthly snowfall.
Four other stations (Providence...Bangor... Worcester...and Burlington) measured at least twice their long-term average.
December snowfall at five stations was more than 50% of their normal season-total (D-J-F-M) snowfall.
Biggest losers were in the mid-Atlantic region...as was the case last season.
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