OKpowdah

This latest easterly QBO period is on track to become the "strongest" episode on record. Below I have plotted the QBO along with an integrated QBO index which very simply sums the monthly QBO across each full easterly period. So far this current -QBO period has an integrated magnitude of -280.62 ... which falls just short of the 2001 -QBO period with a magnitude of -280.79. The mean is -191.6 and standard deviation is 48.6. Data so far for January 2013 suggests the monthly QBO should come in negative once again. It's possible the recent SSW has helped stunt the descent of the westerlies, and is prolonging the easterly QBO. This will put the -QBO period at 18 months long ... behind only 2001 which was 19 months.

For posterity's sake, here is my final call for snowfall totals for the New England area. Expect maximum accumulations in the Monadnocks region of southwest NH and in a swath from eastern NH through western and central Maine ... where up to 18" could fall.

lol thanks man. I'm glad to have known you too! Keep repping PSU!!

Using 00z NCEP (including 20 ensemble members), let's begin by defining the EOFs describing the greatest amount of variance in the ensemble forecasts: Alright what is this telling us? First of all, note the asymmetry in the mean/spread ... there is a maximum in the spread over E PA and NJ ... to the west-northwest of the mean low. EOF1 -- explains 46.6% of the variance -- describes the depth of the low for the cluster of solutions to the NW of the mean ... in general the average SLP across the domain of the low ... so a positive EOF1 is related to lower SLP. EOF2 -- explains 21.5% of the variance -- describes the west-east position of the low ... positive EOF2 is west of the mean, negative is east of the mean. EOF3 -- explains 18.2% of the variance -- describes the north-south position of the low, but also the amplitude of the system ... notice the maximum is colocated with the mean low ... a negative EOF3 is associated with a stronger low off the delmarva peninsula with higher pressures to the north and northwest. Perhaps as you can tell, a negative EOF3 pattern is actually quite similar to the SLP pattern we might look for in an East Coast winter storm threat. So although it explains less of the variance in the ensemble forecast, I'm personally most interested in this EOF. So now let's use this forecast diagnostic and find the correlation to a variable in the ensemble forecast, such as 500mb height. Here we can see that the greatest correlation (sensitivity of the EOF3 to the 500mb height) is associated with the trough moving through the Northeast and Quebec over the next 48 hours. Lower heights over the northwest Atlantic over the next two days correlates with a negative EOF3 ... and a SLP pattern characteristic of Northeast snowstorms. More later.

Thanks very much! I've been trying to get a little better at writing discussions that can be followed easily while still managing information from all different directions. It's a fantastic challenge in meteorology where there are so many different aspects to be considered in any one given situation!

Let's begin with the state of winter right now. Where is it? Recent reports say Russia has found it (http://rt.com/news/r...emperature-379/). In other news, the planetary reconfiguration that is occurring right now. Major ridging burgeoning from the Aleutians to the Bering Strait and right up over the North Pole by Saturday. The effect? Well at 22/00z that's 125kts at the DT crossing the NP toward the western hemisphere. Clear at this stage the magnitude of nonlinear processes leading to anticyclonic breaking of the ridge over the NP toward Greenland this weekend. Quite a signal for developing negative AO and negative NAO regime. At the same time, we have this blizzard ongoing over the Plains associated with an impressive trough, continuing to amplify tomorrow (around -2.5 to -3SD anomaly at 500mb). The trough breaks over the Northeast into Quebec this weekend, amplifying downstream ridging from the northern Atlantic into the Davis Strait. By Christmas Eve, this ridge is starting to bridge with the NP ridge. By Christmas Day, we're actually on our way to achieving a quasi-stable anticyclone from the Hudson Bay to Baffin Island ... i.e. a west-based negative NAO. This pattern is clearly characterized by a tumble in both the AO and NAO domains as seen on the forecast maps I'm presenting here. Notice also in the above map the disturbance (lowered DT / PV anomaly) over the Davis Strait. Tracking it back in time reveals that it originates over eastern Russia currently and is brought around the Pacific ridge as it is bursting poleward. From the Davis Strait, this disturbance continues westward (south of the anticyclone) into eastern Quebec and Newfoundland and Labrador by the 27th. In the end this disturbance in fact plays a crucial role in the 50N/50W slot, with its miriad relationships in Northeast snowstorms. So I see you perked up at the mention of the word "snowstorm." Yes, I suppose I should get to the actual storm itself. The storm of interest originates as a shortwave from the GOA vortex. The shortwave is ejected into the Pacific Northwest on the 24th. At this time, attention turns back to the North Pacific where a strong shortwave is plowing under the recently broken-off ridging from the Aleutians to the NP. The shortwave continues eastward, amplifies and breaks just off the west coast. This results in the Pacific jet briefly splitting as ridging amplifies downstream over the western U.S. ...can also note a relate spike in the PNA at this time ... so certainly convergence of teleconnections supporting this event. Coinciding with this PNA spike, the shortwave associated with our storm amplifies into the southern Plains by late on the 25th-26th. The general progression of events that I outlined above is supported in the model guidance. But some minor discrepancies leads to large disagreements in the end result for the eastern third of the nation. Some of these disagreements I think can be related to the span of time between the ejection of the shortwave and the PNA spike ... the greater separation there is between these two events, the further east the shortwave will amplify. ...Can be thought of simply as timing of the group energy catching up to the shortwave. By the evening of the 26th, we're watching the development of beautiful dual-jet structure, with excellent upper level mass evacuation over an intensifying low. The ECMWF has tended to want to cut this low inland ... actually track it along the spine of the Appalachians, meanwhile attempting but failing to produce a secondary low along the coastal baroclinic zone. The GFS and CMC both achieve this secondary development with the coastal low taking over. Below I've included some maps from the 20/12z run of the GFS that presents the features I discussed above. It's worth noting on the DT theta map signs of convection wrapping into the system from the central Atlantic --> Meteorology ... helps amplify downstream ridging and the overall system. Modelology... can introduce potential convective feedback errors in the model forecast. Some things to think about for the coming week.

A significant cyclogenesis event in the North Pacific will be the primary catalyst of a pattern change over the next few days. Let's take a look at the evolution over the Pacific into western North America. Notice our N Pac storm gets dual jet support and really goes to town over the Aleutians. Wait isn't that where a massive ridge was last week? ... or for that matter the last three months. Well that's one thing that changes. The ridging once over the Aleutians and Bering Straight retrogrades west, while the N Pac storm breaks cyclonically northward. It's really a beautiful event. Minor flat ridging over the eastern Pacific gets pumped up into the Gulf of Alaska, with an intensifying polar jet streak pushing north into the Yukon. What happens after that? Fantastic classic anticyclonic wave breaking into British Columbia! The result is a 170kt+ northerly jet diving into the Pacific Northwest. So you know the trough and all that energy bottled up over Alaska and the Gulf? Well a lot of that comes pouring southeast on the wings of this jet into the northern Rockies So that's the atmosphere's plans for Saturday.

Ahhh I want to be back up there! Great pics man!

Aurora forecast for this weekend! Too bad we're counting on darkness and clear skies ... both of which may be difficult to come by http://www.gi.alaska.edu/AuroraForecast/Alaska/2012/07/14

11th anniversary of my favorite snowstorm

Good stuff Ryan. Mind blowing. Absolutely incredible

I read a little of it in a coffee shop in Keene. The author went to Keene High School and wrote for the Sentinel (the local paper)

Probably about half of the snow on the ground in Plymouth is from the pre-Thanksgiving storm

Absolutely amazing!! That band is incredible. I can't believe I wasn't home in Keene for it.

12" in Keene, which was a little "disappointing", but significant nonetheless And the model watching was the most excitement I've ever had with a storm I have to say. 20-30" in eastern NY, western MA, and S VT where a few days earlier partly cloudy skies were a justifiable forecast. Absolutely incredible.

February 27, 2008

I hope it comes in January. I want to look out the window at night and see what looks like a thick fog from blinding heavy snow

Living vicariously through a case study of the Dec 2002 storm right now

Nino and +QBO ... Definitely a crappy winter next year.

Also just for fun, here's a total snowfall forecast from the NAM for the 2008 ice storm, in NAM fantasy range...

Here's a snapshot. Will probably has a couple gigs of ice storm 2008 porn saved

If you love it, do it. Pretty darn simple I love meteorology