Winter '12 / '13 - Storm #2: RAW Forecasts

NYC - 5th Avenue
1905

RAW forecasts here.

# Forecasters: 12
Two fresh Rookies.

Marginal event but what the hay.  Best case scenario...the plows will be out on the road.

In hindsight...should have left the verification period open ended.  When the 'Call for Forecasts' was issued on THU...NWP indicated most of the snow would have fallen by 11:59 PM SAT.  Later guidance suggested otherwise.

Storm #2 forecast summary and all individual forecasts will be posted to the Contest/s web log and / or web site by Saturday evening.

Winter '12 / '13 - Storm #2: Call for Forecasts!

NYC
27-DEC-47


Another Miller A-B hybrid storm heading toward the forecast area.

Southern stream LOW forms in the Gulf of Mexico.  Second decaying LOW INVOF the Great Lakes drifting east in the northern stream.

Stronger GOM LOW captures the Lake's LOW over the western M-A.  Rapid deepening near the 40/70 benchmark late in the period as the storm kicks out to sea.  Mainly a rain event over the water and contest-worthy snows over the northern M-A and SNE.

Storm #2 potential appears marginal at post time where the best case scenario produces widespread plowable snowfall; however...there are equal chances for widespread nuisance amounts.

The forecast contest for Storm #2 may be canceled prior to deadline if NWP indicates a fizzling event.

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Forecast element: storm-total snowfall
Deadline for entries: 10:30 PM EST FRI...28-DEC-12

Verification period begins: 12:01 AM SAT...29-DEC-12
Verification period ends: 11:59 PM SAT...29-DEC-12

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 the 'Call for Forecast' is issued?
Send requests to 'newx at newx-forecasts dot com'.

Winter '12 / '13 - Storm # 1: The Forecasts

Consensus for this season/s inaugural event has bonus snows for New England/s northern stations and crumbs for most inland locations along the mid-Atlantic.  The eight to 10 stations in play makes this a decent synoptic-scale winter storm despite rain for major cities along the I-95 corridor.



13 forecasters
11 veterans and 2 Rookies



Forecasts are ranked by their storm-total precipitation (STP).
BLUE ==> 25th percentile.
RED ==> 75th percentile.
STP cells without color are between the 25th and 75th percentile.

Everyone/s station-by-station forecast at the Contest/s web site.

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Roger Smith is promoted to Senior forecaster this year.
Brad Yehl is now a Journeyman forecaster.
Dryslot is an Intern.

Forecaster status - Years Experience
Rookie - 0
Intern - 1
Journeyman - 2
Senior - 3
Chief - last year/s 'Regular' season contest winner.

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PNA at long last comes out of its long coma and a good looking AO although a fair case can be made the state of these indices played a relatively minor role.

Winter '12 / '13 - Storm #1: RAW Forecasts

Maine mill pond
12-28-1951

RAW forecasts posted at NEWxSFC/s GoogleGroup here.

# Forecasters: ~13
Welcome back Vets and welcome aboard to the one or two Rookies.

Where a forecaster issued more than one forecast...only the last one is verified.

Storm #1 forecast summary and all individual forecasts will be posted to the Contest/s web log and / or web site sometime Wednesday.

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Progs suggest an active period over the next week or two...so keep them pencils sharp!

Winter '12 / '13 - January 2013: Week One Outlook

From today/s PSD GFS ensembles...Week 2 anomaly forecasts (VT centered on 05-JAN-13).

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Area 1 depicts the Pacific/s polar jet at 250 mb riding up and over PNA ridge.

Area 2 is the sub-tropical jet (STJ) phasing with the polar jet over the upper MIssissippi river valley.

Area 3 is the negative height anomaly at 500 mb located over New Foundland...CN

Area 4 shows the 850 mb temperature anomaly drawing high-latitude cold air into the NE on the backside of the Newfoundland LOW and the warm advection onto the Greenland ice sheet which in turn would induce or strengthen a blocking HIGH and negative northern annular oscillation indexes (AO; NAO).

Area 5 highlights precipitation anomalies from Mexico to the mid-Atlantic states aligned with the STJ axis.  Note the northern edge of the anomaly coincides with negative 850 mb temperature anomalies.

Amplified flow + short wave energy + cold air + moisture = forecast for snow

Winter '12 / '13 - Storm #1: Call for Forecasts!

NYC
14-JAN-1915


Today/s 12z GFS progs indicate a fair number forecast stations across the mid-Atlantic and southern New England are in line to get more than nuisance snows making this season/s premiere event a contest-worthy storm.

Miller A-B hybrid storm expected to spawn in the Gulf of Mexico INVOF KBRO on Christmas Day...then move into western TN beneath the eastern extension of a 1033 HIGH over James Bay.

Weak re-development on the southern mid-Atlantic coast coast near the VA Capes late Wednesday followed by a track up the NE coast.  Poor upper-level support suggested by the open wave at 5H and little if any height falls throughout the forecast period.

Mainly a rain event with snow on the northern edge of the cloud shield and a broad transition zone of mixed precipitation.

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

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Forecast element: storm-total snowfall
Deadline for entries: 10:30 PM EST TUE...25-DEC-12

Verification period begins: 12:01 AM WED...26-DEC-12
Verification period ends: 11:59 PM FRI...28-DEC-12

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

---
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 requests to 'newx at newx-forecasts dot com'.

Winter '12 / '13 - Coastal Teaser #1

UPDATE:
Today/s 12z precip-type prog @VT90 trending 'NO GO'.
Blocking HIGH is keeping the storm close to shore.

No longer a weakness up the coast indicated @VT132.



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Signs of life at 132 hours from today/s 12z GFS...

 

Storm originates in the Gulf of Mexico Tuesday then moves NE along the western slopes of the Applachain mountains and re-develops off the Delmarva coast on Wednesday.

Should this come to pass...the 'Call for Forecasts' would be issued Monday evening with a deadline for entries Tuesday evening at 10:30 PM.

Winter '12 / '13 - The Change

A pattern change appears to be finally in the works as a stable...four wave flow regime with an anti-cyclone parked over the Pole sets up by D+10.

Initial state starts with the 'never-say die' blocking ridge over the Bering Sea and a deep trof in the Gulf of Alaska where SSTAs are below normal thanks to the PDO.

These two persistent teleconnection features have kept the PNA underwater for months...wasting the cold air potential of a negative AO and its sister index..the NAO.

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All that is forecast to change in 10 days as the Bering Sea HIGH becomes pinched off and shoved to a position directly over the Pole...where its circulation is re-enforced by the flow around four trofs at lower latitudes.

 The Gulf of Alaska LOW is replaced by the PNA ridge....achored by a cut-off LOW offshore of SOCAL.  The ridge delivers cold air and short-wave energy embedded in the Polar jet stream into the Lower 48 where it has opportunities to phase with short-wave energy ejecting from the cut-off LOW and moisture transport y the sub-tropical jet stream.

This scenario was more-or-less forecast by PSD's GFS '8-14 day' ensembles earlier in the month altho the model had the change in place about ten days too soon.

Even the GFS shows large chunks of arctic air reaching the Gulf of Mexico and Miller 'A' storms moving along the east coast.

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Images courtesy Plymouth State Wx

Winter '12 / '13 - Arctic Oscillation: Meteorological Winter - Day 15

Not sure what if anything it means but here's the state of the AO on Day 15 of meteorological winter during its 63 year period-of-record.

Blue line is the observed AO on 15-DEC.

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

The 15-DEC-12 AO ranks 19th (25th percentile).

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

The 15-DEC-12 NAO ranks 36th (57th percentile).

Winter '12 / '13 - Mid-DEC Snow Scenes

Times Sq
13-DEC-33



NYC

13-DEC-60







Haverhill...MA
12/13-DEC-1890



Haverhill...MA

14-DEC-1890