December Medium/Long Range Discussion

[Ji]

Gfs no storm next Friday for us. South/flat

[SnowenOutThere]

23 minutes ago, SnowenOutThere said:

Here's my quick breakdown as a bit of practice for my upcoming atmosphere and weather test. I am going to start with the negatives before ending with the path to victory I can imagine.  I think the more notable issue is that the high appears to go from helping to hurting before the event even starts. By Friday midday the main surface high pressure is off the coast which promotes flow in from the Atlantic (which as a reminder it is still early December).

 

Additionally, we have no real mechanism for keeping any cold air in place for the layers below 700mb as the surface high is unhelpful. The upper level low and surface low are both in a position to eat away at the remaining cold wedge before precipitation even comes close to our area. Just take a look at this 925mb map. The flow is completely out of the south 12 hours before the event even begins. It should be noted our saving grace here is that the storm is weak so the winds are minimal. 

The better news is that the 850+ level is less affected by the surface high and general weak low that is "attacking" from the south. This means that the flow is firstly, not that strong; secondly, out of the southwest/westsouthwest. 

Once you get above 850mb the flow largely veers to be out of the west as there just isn't enough cyclogenesis to really distort the westerly flow. All of this said, I think that ultimately with currently modeling the event this Friday is not in a good spot. I believe this as in order to get a real plowable snowstorm we need two things to go right. 1. A stronger low pressure center in order to actually get lift into the area 2. A correspondingly stronger/more stubborn high. If we get 1. and not 2. all of the thermal issues I highlighted goes from bad to worse as the southern flow just becomes stronger. Meanwhile, if we get 2. but not 1. then we probably end up suppressing this storm. In the end it seems like another thread the needle event that just seems unlikely to get more than 1-3 inches. Disclaimer is that ofc I would be happy with 1-3 inches but this analysis is from a "how could we get a plowable storm" perspective. 

That said, I think there is room for hope as it is not impossible we get 1. and 2. to align. The 5h pattern isn't horrible after all.

There is clearly a path here. Though as it stands everything is slightly off. We have a some semblance of a 50/50, though we need it to be further southwest if we want to trap the surface high pressure in. Additionally, the shortwave out west isn't in a horrible spot. However, as it stands it seemingly gets both weakened and pulled north by the larger low pressure center over central Canada. I think the path to victory here is quite simply that the low out west doesn't get stuck. Currently, the energy enters the southwest around hour 60 then languishes there through 110 before a secondary shot of energy pulls it along. I think if we're able to have the first ball of energy keep its form and progress eastwards and the second shot of energy enters faster its honestly quite possible we manage to get a stronger, more consolidated, and further south system without as much northern stream interference. Additionally, the 50/50 would naturally be in a better spot which would help offset the WAA from a stronger storm. Thank you for listening to my Ted-Talk and if any met read this through let me know if I am gonna fail my test. 

 

TDLR: As it stands I don't think Friday looks good for anything more than 1-3 inches, however, I think the path to victory for a bigger storm is still there if the energy out west is more progressive

Well the latest GFS run opted for shredding the southern shortwave entirely by moving it out as the northern bowling ball crushed it. So making this an addendum to the og post but it appears that instead we need to have constructive interactions between the northern and southern energy to get a storm. So really I think watching for a stronger piece of energy out of the south which would help pull the northern stream energy souther is needed. Additionally, a stronger but further south piece of the NS diving in would be beneficial. Either way I just don't see a great likely way all of this breaks our way as we have to contend with a southern energy split, northern stream interaction, and trying to keep the 50/50 in a better position. 

 

[Maestrobjwa]

34 minutes ago, SnowenOutThere said:

Here's my quick breakdown as a bit of practice for my upcoming atmosphere and weather test. I am going to start with the negatives before ending with the path to victory I can imagine.  I think the more notable issue is that the high appears to go from helping to hurting before the event even starts. By Friday midday the main surface high pressure is off the coast which promotes flow in from the Atlantic (which as a reminder it is still early December).

 

Additionally, we have no real mechanism for keeping any cold air in place for the layers below 700mb as the surface high is unhelpful. The upper level low and surface low are both in a position to eat away at the remaining cold wedge before precipitation even comes close to our area. Just take a look at this 925mb map. The flow is completely out of the south 12 hours before the event even begins. It should be noted our saving grace here is that the storm is weak so the winds are minimal. 

The better news is that the 850+ level is less affected by the surface high and general weak low that is "attacking" from the south. This means that the flow is firstly, not that strong; secondly, out of the southwest/westsouthwest. 

Once you get above 850mb the flow largely veers to be out of the west as there just isn't enough cyclogenesis to really distort the westerly flow. All of this said, I think that ultimately with currently modeling the event this Friday is not in a good spot. I believe this as in order to get a real plowable snowstorm we need two things to go right. 1. A stronger low pressure center in order to actually get lift into the area 2. A correspondingly stronger/more stubborn high. If we get 1. and not 2. all of the thermal issues I highlighted goes from bad to worse as the southern flow just becomes stronger. Meanwhile, if we get 2. but not 1. then we probably end up suppressing this storm. In the end it seems like another thread the needle event that just seems unlikely to get more than 1-3 inches. Disclaimer is that ofc I would be happy with 1-3 inches but this analysis is from a "how could we get a plowable storm" perspective. 

That said, I think there is room for hope as it is not impossible we get 1. and 2. to align. The 5h pattern isn't horrible after all.

There is clearly a path here. Though as it stands everything is slightly off. We have a some semblance of a 50/50, though we need it to be further southwest if we want to trap the surface high pressure in. Additionally, the shortwave out west isn't in a horrible spot. However, as it stands it seemingly gets both weakened and pulled north by the larger low pressure center over central Canada. I think the path to victory here is quite simply that the low out west doesn't get stuck. Currently, the energy enters the southwest around hour 60 then languishes there through 110 before a secondary shot of energy pulls it along. I think if we're able to have the first ball of energy keep its form and progress eastwards and the second shot of energy enters faster its honestly quite possible we manage to get a stronger, more consolidated, and further south system without as much northern stream interference. Additionally, the 50/50 would naturally be in a better spot which would help offset the WAA from a stronger storm. Thank you for listening to my Ted-Talk and if any met read this through let me know if I am gonna fail my test. 

 

TDLR: As it stands I don't think Friday looks good for anything more than 1-3 inches, however, I think the path to victory for a bigger storm is still there if the energy out west is more progressive

Not that this means much coming from this layman, but...you are going to become a main anchor here very soon 

[WxUSAF]

6 hours ago, Ji said:

Gfs no storm next Friday for us. South/flat

Euro agrees. AI still has a light event though and kinda breaks it into 2 parts, one Friday and then more Saturday as a coastal gets going. 

[Terpeast]

10 minutes ago, WxUSAF said:

Euro agrees. AI still has a light event though and kinda breaks it into 2 parts, one Friday and then more Saturday as a coastal gets going. 

The deamp trend is still alive and well. Maybe we should start looking for "cutters" along with blocking and... "right where we want it at 6 days out"?

[Heisy]

6th event kind of fell off the ledge last night. I dont think the pattern looks bad from 6-12th or so. However, to me it seems like a very Northern Stream dominant pattern, so keep an eye on one of those clipper type waves with enough space to redevelop or at least be strong enough itself to give us some flakes during that time period. Would need a little support from the PNA and too to help amplify any of those waves that flow across the NS.





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