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Pattern Fabulous February

My interest level in this event on a scale from a 0 to 10 is low, around a 2 & will remain pretty low until we can actually get this system inside about day 5-6, every day we can inch closer to verification it'll come up about a point or so as long as most models still have the storm.
 
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Gefs through day 10
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Serious question, the 6z GFS shows absolutely 0 snow or ice East of the apps!? How do the ensembles show those crazy amounts of snow and ice???
 
This certainly isn't the classic way to get a cold air damming event at a planetary-scale but it's easy to see why this might become a legitimate threat in 2-3 days and how we've gotten into this position. We're also getting to that time of the winter (usually around mid Feb & beyond or so) where the wavelengths become short s.t. we're apt to see more "quirky" looks at 500mb produce winter storms (cut-off ULLs for ex), so I'll give the non-traditional planetary look w/ this event a pass.

Increasing confluence and cold air advection in the wake of the trough over Newfoundland raises surface pressures over Quebec, Ontario, & New England creating the big CAD high that's often needed in a setup like this. Furthermore, notice how the upstream ridge over the gulf of Alaska has become suppressed in more recent runs, allowing for more progressive flow over the CONUS, which means the western US/Rockies trough slides eastward more quickly and is beginning to more properly time the confluence and CAA underneath the Newfoundland trough s.t. we stand a better chance of seeing wintry precip before we warmed up too much at the surface. We need the blocking high over the Baffin Bay/northern Canada to not only induce a pattern that deposits colder air into our part of the world, but also create at least a minor upper tropospheric traffic jam to hold the Newfoundland trough back just a little longer and afford us a larger window to fit a storm into.

We're still about 2 ish days away from me being legitimately interested in this event but we've taken massive strides in the right direction of late & if we continue these trends mentioned above going forward, a large section of the board could get involved w/ a winter storm here
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Webberweather53 said:
This certainly isn't the classic way to get a cold air damming event at a planetary-scale but it's easy to see why this might become a legitimate threat in 2-3 days and how we've gotten into this position. We're also getting to that time of the winter (usually around mid Feb & beyond or so) where the wavelengths become short s.t. we're apt to see more "quirky" looks at 500mb produce winter storms (cut-off ULLs for ex), so I'll give the non-traditional planetary look w/ this event a pass.

Increasing confluence and cold air advection in the wake of the trough over Newfoundland raises surface pressures over Quebec, Ontario, & New England creating the big CAD high that's often needed in a setup like this. Furthermore, notice how the upstream ridge over the gulf of Alaska has become suppressed in more recent runs, allowing for more progressive flow over the CONUS, which means the western US/Rockies trough slides eastward more quickly and is beginning to more properly time the confluence and CAA underneath the Newfoundland trough s.t. we stand a better chance of seeing wintry precip before we warmed up too much at the surface. We need the blocking high over the Baffin Bay/northern Canada to not only induce a pattern that deposits colder air into our part of the world, but also create at least a minor upper tropospheric traffic jam to hold the Newfoundland trough back just a little longer and afford us a larger window to fit a storm into.

We're still about 2 ish days away from me being legitimately interested in this event but we've taken massive strides in the right direction of late & if we continue these trends mentioned above going forward, a large section of the board could get involved w/ a winter storm here
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One thing that definitely sticks out which probably foretold of favorable changes especially upstream over the North Pacific is the descent of this big high over Mongolian and China this past weekend that also triggered a positive mountain torque event over the Himalayas. This positive mountain torque event through global angular momentum conservation extends the Pacific jet in the following week which effectively squashes the Gulf of Alaska ridge creating more progressive flow over the CONUS, forcing the Rockies trough eastward.

I've highlighted this area over Eastern Asia where this big high descended into China/east of the Himalayas last weekend

gfs_mslpaNorm_global_1.png

Positive Mountain Torque Diagram.png
 
Tarheel1 said:
Serious question, the 6z GFS shows absolutely 0 snow or ice East of the apps!? How do the ensembles show those crazy amounts of snow and ice???
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I'm with you there, I've got no clue how its spitting out those numbers
 
Tarheel1 said:
Serious question, the 6z GFS shows absolutely 0 snow or ice East of the apps!? How do the ensembles show those crazy amounts of snow and ice???
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Probably has to be due to the fact the run is close to being a storm, and a few small adjustments and there would be a storm. I think ensembles were explained earlier this winter as being the same run with different events occurring than the OP produces. Those events aren't implausible ones either most of the time. If there is agreement between most ensembles there is a good chance as you would know of the event occurring. Of course you have to look at all of them to check for a skew in the mean, but we already know that. Main point is that the OP has been coming around to a possible solution, and the op doesn't have to agree with the ensembles this far out as the window of possible solutions is large.
 
May be a few spin ups tommorow and gusty winds, lots of wind energy and dry air entrainment/DCAPE May even support a few shelfies ? but instability is lackin 55A407D5-E1F8-4C8D-82A6-F7CB93A832ED.png13264758-7D40-4116-9C5E-1B436A2AE3F1.png
 
ForsythSnow said:
Probably has to be due to the fact the run is close to being a storm, and a few small adjustments and there would be a storm. I think ensembles were explained earlier this winter as being the same run with different events occurring than the OP produces. Those events aren't implausible ones either most of the time. If there is agreement between most ensembles there is a good chance as you would know of the event occurring. Of course you have to look at all of them to check for a skew in the mean, but we already know that. Main point is that the OP has been coming around to a possible solution, and the op doesn't have to agree with the ensembles this far out as the window of possible solutions is large.
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There is still quite a bit of misuse and misunderstanding of the ensemble system as a tool. Your explanation is really good. Ensembles essentially help define probability.

If you look at the EPS, for example, you have the main Euro Op run that is fed an initial set of conditions and run at a high resolution out to 240 hours. For the ensembles, they rerun the model with the same set of initial conditions at a lower resolution out to 360 hours (I believe it's 360). That solution is the Control. They then, using the control, repeat that same process 50 times, altering the initial conditions slightly each time. So essentially, for the Euro Ensemble system, you have 51 model runs, each with slightly different initial conditions. The mean (which is commonly shown on weather boards) is the blend of all 51 members.

The Euro Op run through 240 would seem to have the best skill over that time frame, as it has the higher resolution. But we know that the atmosphere is in a constant state of flux/chaos. The EPS kind of measures the degree of the chaos by illustrating the sensitivity of the atmosphere to small tweaks in the initial environment. If the EPS shows very diverse solutions across its member set, then you have an atmosphere that is quite chaotic and highly sensitive to changes in the initial observed state (keeping in mind, we don't have the ability to measure the entire atmosphere -- just points within the domain), which should lower your confidence in model output, especially at longer time frames. However, if you have more agreement between members and agreement of the EPS with the Op, then your confidence in the general pattern, and also storm signals, should increase.

Regarding individual storms, Forsyth hit it. If the pattern supports a storm, i.e. the pieces are there, but the Op shows no storm, the chances are, with small tweaks in the initial conditions, rerunning the model 50 times is probably going to produce a storm across at least some of the members. None of this guarantees a storm. But you can see in this type of an example how the EPS can be used the right way to identify a period of interest. Conversely, if the Op shows a storm, and you get very little support across the EPS members, your confidence should be lower. And like Forsyth said, the blend can often be skewed by one or two robust members. What you really want to see is many members with a storm signal which show some amount of snow over your house...not necessarily just a big pink area on a mean snowfall map.
 
I've been thinking about the ensembles like a cooking show where each contestant is given the same ingredients and they have to create a specific dish. The outcomes vary from one contestant to another.
 
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