January 24th-26th Winter Storm Potential

[ArmyGreens]

I wish I understood things more...so what would the ramifications of this be?

of the the sref model?

Basically, closer to a phase.

[Stevo6899]

Has anyone seen DT's write up from Jan. 19th on his web site? It talks about this very same thing and that without blocking it favors a phase happening west of the mississippi river. Interesting......maybe some hope afterall?

Regardless if there is a block or not, I don't think it causes phasing to happen sooner or later. It will allow a storm to come north once it does phase but I don't know if it aids or hampers the phasing

[Harry]

Regardless if there is a block or not, I don't think it causes phasing to happen sooner or later. It will allow a storm to come north once it does phase but I don't know if it aids or hampers the phasing

The blocking IF there typically results in the phasing happening later and thus along the eastcoast.

[Hoosier]

Regardless if there is a block or not, I don't think it causes phasing to happen sooner or later. It will allow a storm to come north once it does phase but I don't know if it aids or hampers the phasing

I'd say it plays an indirect role if there's a wave that gets forced around a block and goes on to phase.

[Stevo6899]

I'd say it plays an indirect role if there's a wave that gets forced around a block and goes on to phase.

Bingo. I can see how with no block the northern stream could take a more direct route to the southern energy. This is exactly where we were 5 days out with the dec 12 storm. Models showing a low in the southeast. I hate to keep bringing the dec 12 storm up but I would have to laugh if this turns out similar. I dont know if the teleconnections or pattern are similar though.

[baroclinic_instability]

Phasing is not the key here--it is height field amplification. It is pretty clear this will be dominated by the southern stream wave--and the only way this things tracks up the Apps or nearly straight N in this configuration is that it A) Digs deep near the GOM or into the GOM, B)Does not directly phase with the northern stream in any way as it ejects NE.

First, the GOM is needed for sufficient warming of the low levels for height field amplification to occur. What folks here want is a big rainstorm for the EC. Why? A mass amount of GOM moist air is going to be needed to advect N in the warm sector to amplify the height field aloft and develop a large upstream ridge. Only way this scenario happens is a nearly complete cutoff solution. The CMC now is close to that with a very strong southern S/W pivoting near the base of the trough. Second--if this trough "phases" too early with the northern stream--height field amplification will not penetrate inland into the CONUS far enough W to take the trough up the Apps or nearly due N and the storm will be shunted well E. The 12Z CMC is close but has too much northern stream interaction.

Compare these notes to the best runs such as the 0Z ECMWF and the 0Z CMC and notice the northern stream played no part in those storms. Note in the latest runs both the upstream height field and WAA is shunted too far E--and also note the deformation done (due to the interaction of the northern stream) is also displaced farther E and is essentially "blocked" from developing farther W. Phasing is not a desired solution in this scenario.

[buckeye]

Bingo. I can see how with no block the northern stream could take a more direct route to the southern energy. This is exactly where we were 5 days out with the dec 12 storm. Models showing a low in the southeast. I hate to keep bringing the dec 12 storm up but I would have to laugh if this turns out similar. I dont know if the teleconnections or pattern are similar though.

wasn't that storm ALL northern stream ? I thought it cut thru michigan

[snowstormcanuck]

Has anyone seen DT's write up from Jan. 19th on his web site? It talks about this very same thing and that without blocking it favors a phase happening west of the mississippi river. Interesting......maybe some hope afterall?

Do you have a link to DT's article?

[buckeye]

Phasing is not the key here--it is height field amplification. It is pretty clear this will be dominated by the southern stream wave--and the only way this things tracks up the Apps or nearly straight N in this configuration is that it A) Digs deep near the GOM or into the GOM, B)Does not directly phase with the northern stream in any way as it ejects NE.

First, the GOM is needed for sufficient warming of the low levels for height field amplification to occur. What folks here want is a big rainstorm for the EC. Why? A mass amount of GOM moist air is going to be needed to advect N in the warm sector to amplify the height field aloft and develop a large upstream ridge. Only way this scenario happens is a nearly complete cutoff solution. The CMC now is close to that with a very strong southern S/W pivoting near the base of the trough. Second--if this trough "phases" to early with the northern stream--height field amplification will not penetrate inland into the CONUS enough to take the trough up the Apps or nearly due N and the storm will be shunted well E. The 12Z CMC is clsoe but has too much northern stream interaction.

Compare these notes to the best runs such as the 0Z ECMWF and the 0Z CMC.

Baro, why's that? (bold red)

[baroclinic_instability]

Baro, why's that? (bold red)

I added a few notes to the previous post at the end.

"Compare these notes to the best runs such as the 0Z ECMWF and the 0Z CMC and notice the northern stream played no part in those storms. Note in the latest runs both the upstream height field and WAA is shunted too far E--and also note the deformation done (due to the interaction of the northern stream) is also displaced farther E and is essentially "blocked" from developing farther W. Phasing is not a desired solution in this scenario."

[Hoosier]

Phasing is not the key here--it is height field amplification. It is pretty clear this will be dominated by the southern stream wave--and the only way this things tracks up the Apps or nearly straight N in this configuration is that it A) Digs deep near the GOM or into the GOM, B)Does not directly phase with the northern stream in any way as it ejects NE.

First, the GOM is needed for sufficient warming of the low levels for height field amplification to occur. What folks here want is a big rainstorm for the EC. Why? A mass amount of GOM moist air is going to be needed to advect N in the warm sector to amplify the height field aloft and develop a large upstream ridge. Only way this scenario happens is a nearly complete cutoff solution. The CMC now is close to that with a very strong southern S/W pivoting near the base of the trough. Second--if this trough "phases" too early with the northern stream--height field amplification will not penetrate inland into the CONUS far enough W to take the trough up the Apps or nearly due N and the storm will be shunted well E. The 12Z CMC is close but has too much northern stream interaction.

Compare these notes to the best runs such as the 0Z ECMWF and the 0Z CMC.

If this unphased/cutoff scenario went all the way, wouldn't there be a risk of a cold air problem on the northwest side? Maybe less likely at this time of year.

[snowstormcanuck]

Phasing is not the key here--it is height field amplification. It is pretty clear this will be dominated by the southern stream wave--and the only way this things tracks up the Apps or nearly straight N in this configuration is that it A) Digs deep near the GOM or into the GOM, B)Does not directly phase with the northern stream in any way as it ejects NE.

First, the GOM is needed for sufficient warming of the low levels for height field amplification to occur. What folks here want is a big rainstorm for the EC. Why? A mass amount of GOM moist air is going to be needed to advect N in the warm sector to amplify the height field aloft and develop a large upstream ridge. Only way this scenario happens is a nearly complete cutoff solution. The CMC now is close to that with a very strong southern S/W pivoting near the base of the trough. Second--if this trough "phases" too early with the northern stream--height field amplification will not penetrate inland into the CONUS far enough W to take the trough up the Apps or nearly due N and the storm will be shunted well E. The 12Z CMC is close but has too much northern stream interaction.

Compare these notes to the best runs such as the 0Z ECMWF and the 0Z CMC.

I would have thought an earlier phase would be conducive for a further west track. Having trouble wrapping my head around he bolded part. lol, I know you may be busy, but maybe a graphic demonstration?

[jcwxguy]

pretty big differences from 12znam to 18z for nebraska through hr 42

and hr 48 . Definatly a shift west on the qpf.

(bigger area of dark blue is the 12z)

[pondo1000]

Do you have a link to DT's article?

http://www.wxrisk.com/

[baroclinic_instability]

Baro, why's that? (bold red)

I just used the CMC only as an exhibit--in no way do I suggest either will pan out--but the 0Z and 12Z solutions work great for this example.

12Z first. Note the ridge axis and the trough axis I placed in the height field. Also note how the stretching def zone is shunted E in this scenario (look at the resulting qpf). This is a phased scenario.

Compare to yesterday at 0Z with no phase. Note the huge ridge that develops ((built via warm air addvection and height field amplification). Also note the stretching deformation zone is NOT shunted so far eastward and is allowed to develop a comma head.

[snowstormcanuck]

http://www.wxrisk.com/

lol, I didn't realize he still updated that site. Last time I checked his discussions were 3 weeks old.

[snowstormcanuck]

I just used the CMC only as an exhibit--in no way do I suggest either will pan out--but the 0Z and 12Z solutions work great for this example.

12Z first. Note the ridge axis and the trough axis I placed in the height field. Also note how the stretching def zone is shunted E in this scenario (look at the resulting qpf). This is a phased scenario.

Compare to yesterday at 0Z with no phase. Note the huge ridge that develops ((built via warm air addvection and height field amplification). Also note the stretching deformation zone is NOT shunted so far eastward and is allowed to develop a comma head.

Very interesting. I guess I got into the habit of assuming more phased = west, less phased = east without understanding that each particular situation has its own nuances. Would you say as a general rule phasing tends to lead to more amplified storms that tend to be dragged further N&W?

[Stevo6899]

"Compare to yesterday at 0Z with no phase. Note the huge ridge that develops ((built via warm air addvection and height field amplification). Also note the stretching deformation zone is NOT shunted so far eastward and is allowed to develop a comma head."

So yesterdays models had the northern wave held back in the plains and not phased, which allowed this storm to be more negative tilted and head further west. Weird because I always thought we needed a phase with the lagging system to pull the southern low west. Instead you are saying the phasing northern low would push this storm further east. The xmas storm was phased and it didnt push it east off the coast. Or maybe it did?

[baroclinic_instability]

Expanding on this. It can be shown through the dynamical equations that low level warm, moist advection will alter the height field aloft. Ridges don't build themselves magically. We need a long, drawn out and persistent fetch of GOM air--and since the GOM is so dry and depleted early on with both the front passing through now and the incoming wave over the next 24-36 hrs--it needs to moisten. An early phase takes this storm up the coast and there is no amplification. GFS doesn't phase--but notice how fast it is--and as a result--how dry it is early on.

Moisture aids in rapid height field amplification since low level latent heat release in the warm air advection regime enhances the development of the upper level ridge EVEN more--so that GOM moisture is key. Without it--this thing tracks along the coast and is generally weak and doesn't bomb out.

[baroclinic_instability]

Very interesting. I guess I got into the habit of assuming more phased = west, less phased = east without understanding that each particular situation has its own nuances. Would you say as a general rule phasing tends to lead to more amplified storms that tend to be dragged further N&W?

"Compare to yesterday at 0Z with no phase. Note the huge ridge that develops ((built via warm air addvection and height field amplification). Also note the stretching deformation zone is NOT shunted so far eastward and is allowed to develop a comma head."

So yesterdays models had the northern wave held back in the plains and not phased, which allowed this storm to be more negative tilted and head further west. Weird because I always thought we needed a phase with the lagging system to pull the southern low west. Instead you are saying the phasing northern low would push this storm further east. The xmas storm was phased and it didnt push it east off the coast. Or maybe it did?

Typically phases are good--but under this height field configuration--and becase the GOM is so dry (read above comment)--a phase will result in too fast of a solution. A phase is not necessarily good here. Stevo--this can't be compared to the Christmas bomb in any way both because of the configuration and the setup for that storm--not to mention that was over the Gulf Stream.

[Harry]

I just used the CMC only as an exhibit--in no way do I suggest either will pan out--but the 0Z and 12Z solutions work great for this example.

12Z first. Note the ridge axis and the trough axis I placed in the height field. Also note how the stretching def zone is shunted E in this scenario (look at the resulting qpf). This is a phased scenario.

Compare to yesterday at 0Z with no phase. Note the huge ridge that develops ((built via warm air addvection and height field amplification). Also note the stretching deformation zone is NOT shunted so far eastward and is allowed to develop a comma head.

And the reason why that is is because of HOW LATE the phase happens. The northern energy arrives to late/too far north/weak. However if that ( northern energy ) is able to dig/slow down some then boom guess what happens? yes we have bomb further west and probably west of the apps too. NOT saying that happens ( even though the seasonal trends with the northern stream say it is more possible ) but it is on the table. GFS has the northern stuff to make it happen but ala is missing the southern energy to go boom.

remember i said IF. Not arguing that will happen. Just pointing out why it *could* happen.

BTW. A number of the euro ensembles are further west vs 00z run. Even a few now that end up near lake Huron where as 00z run had none west of apps.

[baroclinic_instability]

Here is front number 1 pushing through the GOM. Dewpoints tank into the 30's and 40's--and we have another system pushing through the plains now that will only reinforce that. It will take a long time for moderation and moistening of the low level air mass to take place. Slow is good here so the GOM can re-moisten--hence why a phase is not necessarily good. 12Z GFS is so dry for a reason--just ejects NE too early.

http://www.hpc.ncep.noaa.gov/sfc/lrgnamsfcwbg.gif

[buckeye]

18z nam at 66 says beau

[baroclinic_instability]

And the reason why that is is because of HOW LATE the phase happens. The northern energy arrives to late/too far north/weak. However if that ( northern energy ) is able to dig/slow down some then boom guess what happens? yes we have bomb further west and probably west of the apps too. NOT saying that happens ( even though the seasonal trends with the northern stream say it is more possible ) but it is on the table. GFS has the northern stuff to make it happen but ala is missing the southern energy to go boom.

remember i said IF. Not arguing that will happen. Just pointing out why it *could* happen.

BTW. A number of the euro ensembles are further west vs 00z run. Even a few now that end up near lake Huron where as 00z run had none west of apps.

I don't discount anything here now since the wave pattern is a big mess with waves and troughs all over the place. I have yet to see anything that has a early phase that tracks this up the apps--so for now I can only make comparisons based off what most guidance suggests the height field will look like. I will say with the GOM so stinking dry--that phase will have to be perfectly timed so both the southern wave can cutoff and allow for a long drawn out GOM fetch to develop--but also so the northern stream does not hamper the height field amplification. The CMC would look much better today (12Z) if it phased with the southern stream wave ahead of the northern stream. In reality it really wouldn't be a phase at all--but instead the northern stream would act as a kicker low. We will have to see--not saying it isn't viable--but a phase right now doesn't look terribly favorable. 12Z CMC is close--but in some ways we are all overanalyzing the individual runs too much since this will all change by 0Z.

[buckeye]

And the reason why that is is because of HOW LATE the phase happens. The northern energy arrives to late/too far north/weak. However if that ( northern energy ) is able to dig/slow down some then boom guess what happens? yes we have bomb further west and probably west of the apps too. NOT saying that happens ( even though the seasonal trends with the northern stream say it is more possible ) but it is on the table. GFS has the northern stuff to make it happen but ala is missing the southern energy to go boom.

remember i said IF. Not arguing that will happen. Just pointing out why it *could* happen.

BTW. A number of the euro ensembles are further west vs 00z run. Even a few now that end up near lake Huron where as 00z run had none west of apps.

cool ....well not the lake huron part

[buckeye]

sounds conflicting.....last line

[Harry]

I don't discount anything here now since the wave pattern is a big mess with waves and troughs all over the place. I have yet to see anything that has a early phase that tracks this up the apps--so for now I can only make comparisons based off what most guidance suggests the height field will look like. I will say with the GOM so stinking dry--that phase will have to be perfectly timed so both the southern wave can cutoff and allow for a long drawn out GOM fetch to develop--but also so the northern stream does not hamper the height field amplification. The CMC would look much better today (12Z) if it phased with the southern stream wave ahead of the northern stream. In reality it really wouldn't be a phase at all--but instead the northern stream would act as a kicker low. We will have to see--not saying it isn't viable--but a phase right now doesn't look terribly favorable. 12Z CMC is close--but in some ways we are all overanalyzing the individual runs too much since this will all change by 0Z.

Thanks. I agree as well with the over-analyzing but not much else to do. Also a good inflow from the GOM would be good. I should probably go peak at a few of our past systems that did phase and had a similar set up. Maybe the answer is there.

[dilly84]

sounds conflicting.....last line

Good or bad? Typically a low around WV would be good, but with this winter who knows.

[buckeye]

Good or bad? Typically a low around WV would be good, but with this winter who knows.

he seems to describe several western solutions and then at the end says overall the ensembles are east of the op??? Also the part where he says some are as far east as sw VA, (im thinking he might have meant west).

[buckeye]

Baro,

looks like the gulf is open for business on the 18z nam at least