Winter '12 / '13 - Storm #3: The Forecasts!

15 forecasters
10 Senior
1 Journeyman
1 Intern
3 Rookies...including 1 'first-timer'.  Welcome flame_boy!

Entries ranked by STP.
336 station forecasts.

Consensus heavy snowfall axis from CAR-BGR-PWM-BOS-HYA-PVD-ISP-JFK-EWR-BGM-ALB-BTV-CAR.  At least 20" expected at PWM...CON...BOS...ORH...and PVD.  Biggest losers in the M-A this go'round.



NAO sitting it out...again.

Everyone/s station-by-station forecast has been posted on the Contest/s web site.

Winter '12 / '13 - Storm #3: Snow Cover

Winter '12 / '13 - Storm #3: RAW Forecasts

Raw forecasts here.

Chances are...the posting of forecasts and forecast summary on the Contest/s web page and web log will be delayed until Saturday.

Winter '12 / '13 - PD III ?

Winter '12 / '13 - Storm #3: Call for Forecasts!

Route 128
Danvers...MA
10-FEB-69

The last 'Call for Forecasts' came 41 days ago.  What a crappy winter!

NWP offering up another odd Miller A / B hybrid with explosive development along the SNE coast...near-blizzard conditions...and a track over the famed' benchmark' at 40°N / 70°W.

This go-round it's an actual real-live snowstorm and not some poser LOW with a thin strip of snow on the northwestern edge of the precipitation shield.

The forecast contest for Storm #3 may be canceled prior to deadline if NWP indicates a fizzling event altho that seems unlikely.

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Forecast element: storm-total snowfall
Deadline for entries: 10:30 PM EST THU...07-FEB-13

Verification period begins: 12:01 AM FRI...08-FEB-13
Verification period ends:  when the snow stops*

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 for 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).

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

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* Current NWP suggests accumulating snows coming to an end Saturday evening.
Verification period may end 11:59 PM SAT...09-FEB-13 even if light snowfall is occurring over a station or two.  No reason to hold up the preliminary verification report to count 12 extra snowflakes somewhere.

Winter '12 / '13 - 12th Annual 'Season-Total' Forecast Contest: DEC / JAN Totals

DEC/s snowfall totals got the season off to a promising start with nine stations measuring above normal snowfall and 103% above normal for the entire forecast area where northern stations got the best of it.  Total departure was +5.7".



All stations measured below normal snowfall totals in JAN for a total departure of -139.5".  Three southern stations made it into the Top Ten.

As of the end of JAN...season-total snowfall over the entire forecast area was 28% below normal.

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GREEN - 75th percentile and above
RED - 25th percentile and below

Winter '12 / '13 - VCP32: Late for Work

Winter '12 / '13 - Storm #3: MR Teaser

Long-range progs continue to offer a contest-worthy storm toward week's end for the northern M-A and SNE.



UL:  500 mb Z and PMSL
UR:  500 mb Z and vorticity
LL:  PMSL and precipitation type
LR:  PMSL and 2m Td

Today/s 108-hour solutions from the 12z GFS suggest initial forcing from-low level warm air advection followed by a modest measure of mid-level intensification as the system approaches the SNE coast.

Should this scenario come to pass...
Call for Forecasts:  Wed evening...23-JAN-13
Deadline:  10:30 PM EST Thu...24-JAN-13

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Images courtesy Meteocentre.com

Winter '12 / '13 - Arctic Oscillation: Meteorological Winter/s Mid-point

Not sure what if anything it means but here's the state of the AO at the mid-point of meteorological winter during its 64 year period-of-record.



Blue line is the observed AO on 15-JAN.

Red line is a 9-point binomial filter.  The filter removes noise from the signal to highlight trends.

Yellow line is an 11-year moving average.

The 15-JAN-13 AO (-0.646) ranks 26th (41th percentile).

Same idea for AO/s sister...the North Atlantic Oscillation (NAO).

The 15-JAN-13 NAO (0.011) ranks 26th (41th percentile).

Three things to note...
1)  The highly variable AO index on D+45 compared to its sister index...then NAO.
2)  The 11-year moving average between 1960 and1980 is negative...followed by a 30-year period were the average is above zero.
3)  This season/s mid-winter AO and NAO values are slightly below normal for all mid-winter values during the period-of-record (Z = -0.207 and Z = -0.045, respectively).

Winter '12 / '13 - Stratospheric Sudden Warming: Watch #2

UPDATE #3
Current SSW event can now be classified as a major warming.  Temperatures have increased ~50°C in less than seven days AND zonally averaged winds @60°N have turned easterly.



Max 10 mb (31,242m; ~50K') temperature @12z today was -22°C (-7.6°F) over Viljujsk...Russia (map).

Why is SSW matters...

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.

http://www.nwra.com/resumes/baldwin/pubs/Thompsonetal_2002.pdf

Pronounced weakening of the PV (cool colors) as it splits in two bya strong anticyclone advancing on 90°N...



10 mg height analysis courtesy JMA.



Warm colors indicate east wind.  Polar wind field along left edge of frame.  Anticyclonic circulation is strongest above 10 mb and extends to surface.  Blue action center near 30N @ 200 mb is the sub-tropical jet.

Height-Latitude Cross Section of Zonally Averaged Zonal Wind image courtesy JMA.

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UPDATE #2 (7-JAN-13 @ 7:08 PM EST)

North- South 0° - 180W°
East - West 90°E - 90°W

Minor warming under way...evidenced by the sharp increase in temperature at 10 mb (> 25K) over the Pole in less than a week's time.  A 'major' warming classification requires the same rapid temperature increase and the PV to become easterly at 60°N at 10 mb or below.



Just a hint of the warming down to ~30 mb along seen on the right edge of the above image.



Not the wave flux above 100 mb...especially in the final frame...where the 'hot' colored vectors veer toward the pole indicating energy propagating from the troposphere into the poleward Ignorosphere.

ECMWF forecasts the PV to bifurcate and maintain that state through D+10 as anticyclone builds over 90N.  CW has it the anticyclone propagates to the surface in a few weeks where -AO becomes established.  Some unknown location in the mid-latitudes can probably expect a Mother lode of cold toward the end of January.

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UPDATE #1 (30-DEC-12 @ 1:58 PM EST)
Strong anticyclone forecast at D+10 (blue region in upper right of frame).

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