January 6-7 Storm Discussion: we’re due?

[ers-wxman1]

The warmer, less amplified solutions are likely trending toward the proper setup for this pattern. Not to say the area won’t see a slug of moisture, likely will, but BL won’t be supportive even in the immediate suburbs. 

[clskinsfan]

CMC jumps to the mouth of the Bay. Which is what the GFS was doing yesterday. 

[Terpeast]

How the models shifted on H5

GFS:

 

GEM:

 

The Euro had an opposite shift from yesterday's 12z to today's 0z. 

I'll let you guys make your own interpretations.

[Eskimo Joe]

1 minute ago, aldie 22 said:

That's one sharp gradient...you could almost walk from 10" to nothing...like a lake effect event

CMC with old Pittsburgh - DC rule. If one location is getting 6"+ of snow, the other likely isn't.

[Buddy1987]

Do the pros in here think that primary will end up driving that far north into the OH Valley or is the GFS bias playing into this some in your opinion? 

[psuhoffman]

8 minutes ago, Heisy said:

OV primary stronger on GFS, sigh


.

No it's actually weaker...the problem is the coastal is WAY weaker...so it doesn't develop as much northerly flow to the NW of the low to resist the WAA ahead of the trough axis.  A weaker wave doesn't work here, regardless of the track it will end up warmer it seems.  

I can see how some think the primary is stronger, it looks that way because its in relation to the coastal which is a LOT weaker.  That is the real difference.  The primary is weaker also but because the whole wave is weaker it doesn't develop the closed circulation needed to cut off the WAA.  We need a wound up system to offset the marginal thermals.  

[SnowDreamer]

2 minutes ago, aldie 22 said:

That's one sharp gradient...you could almost walk from 10" to nothing...like a lake effect event

Brutal. DCA gets a dusting and Leesburg gets a foot. 

[mappy]

1 minute ago, SnowDreamer said:

Brutal. DCA gets a dusting and Leesburg gets a foot. 

the line is going to waffle back and forth as we get closer. everyone should know their climo in these situations and go from there. 

[psuhoffman]

12 minutes ago, clskinsfan said:

Ohio vort no good. 

The system is weaker so its not being pulled in and phasing with the coastal.  It's the same vort that was always there its just not as amplified 

[ers-wxman1]

2 minutes ago, SnowDreamer said:

Brutal. DCA gets a dusting and Leesburg gets a foot. 

12” totals will be over the higher terrain for this event. CMC likely overdone, even into the far NW suburbs. Model doesn’t account for temps effectively. It could be 36F and snow with no accumulation efficiency, but the model still adds up the total snow in general ratio. Essential to analyze the pattern unfolding and projected vs the dump of snow in the more amplified solutions. What in this pattern would actually drive double digit accumulations? You’ll be hard pressed to find the features. 

[baltosquid]

I95 seems no longer IN the goalposts but rather is itself one of the posts… needle thin path to a mostly snow event may remain in the realm of reason. But if the incoming euro is bad and the runs through 00z don’t start a trend back to the good, might be exiting that realm of reason. Might be taking down the tree after all…

[WinterWxLuvr]

If you loop the last few runs of the gfs on the Atlantic side there isn’t much change. But now there’s a big chunk of energy that has all of a sudden showed up in the sw. Looks to me like that acts like a seesaw and kicks our sw north. That piece is currently over the North Pacific. Not drawing conclusions, just how it looks on the gfs.

[wtkidz]

3 minutes ago, baltosquid said:

I95 seems no longer IN the goalposts but rather is itself one of the posts… needle thin path to a mostly snow event may remain in the realm of reason. But if the incoming euro is bad and the runs through 00z don’t start a trend back to the good, might be exiting that realm of reason. Might be taking down the tree after all…

This is normal.  We have to thread the needle on miller B type systems.  

[umdterps29]

4 minutes ago, ers-wxman1 said:

12” totals will be over the higher terrain for this event. CMC likely overdone, even into the far NW suburbs. Model doesn’t account for temps effectively. It could be 36F and snow with no accumulation efficiency, but the model still adds up the total snow in general ratio. Essential to analyze the pattern unfolding and projected vs the dump of snow in the more amplified solutions. What in this pattern would actually drive double digit accumulations? You’ll be hard pressed to find the features. 

I'm thinking that if the CMC run were to come to fruition, Deep Creek or somewhere else out that direction is the real place to be since temps shouldn't be an issue and perhaps what is showing on the snow map is more realistic to occur than in locations closer to the cities where temps are borderline. Might miss out on some of the dynamic action that happens closer to the R/S line, but it would be more of a sure thing.

[jayyy]

95 is not out of the game yet. Better to be in Carroll county than Baltimore or DC for this one though it seems (hello, climo) Need the coastal low to develop and deepen quicker to flip wind direction and mitigate onshore flow for the 95 corridor / metros to be able to maximize. Going to be a close call for those areas for sure.

[Chris78]

4 minutes ago, WinterWxLuvr said:

If you loop the last few runs of the gfs on the Atlantic side there isn’t much change. But now there’s a big chunk of energy that has all of a sudden showed up in the sw. Looks to me like that acts like a seesaw and kicks our sw north. That piece is currently over the North Pacific. Not drawing conclusions, just how it looks on the gfs.

Also the high dropping out of Canada doesn't have as strong as south push over the last 4 runs.

[clskinsfan]

1 minute ago, umdterps29 said:

I'm thinking that if the CMC run were to come to fruition, Deep Creek or somewhere else out that direction is the real place to be since temps shouldn't be an issue and perhaps what is showing on the snow map is more realistic to occur than in locations closer to the cities where temps are borderline. Might miss out on some of the dynamic action that happens closer to the R/S line, but it would be more of a sure thing.

Anywhere west of the Blue Ridge would still be in the game. But IF the GFS is correct even the 81 corridor would not be all snow with that depiction. I have seen it numerous times in the past. 

[Terpeast]

I-95 west is not out of the game yet. Maybe we won't get an all-snow event, but we'll see how the mesos handle the thermals going in. A lot of the time, they bleed colder than the globals the closer the event gets. 

[Chris78]

1 minute ago, jayyy said:

95 is not out of the game yet. Better to be in Carroll county than Baltimore or DC for this one though it seems (hello, climo) Need the coastal low to develop and deepen quicker to flip wind direction and mitigate onshore flow for the 95 corridor / metros to be able to maximize. Going to be a close call for those areas for sure.

It's going to be a close call for northern areas. 6z Euro control and 12z Gfs  runs the rain/ snow line pretty darn close to the M/D line.

Doesn't mean it's correct but with the latest trends you may need to be in central PA to feel secure with this set up.

[Alfoman]

4 minutes ago, Chris78 said:

Also the high dropping out of Canada doesn't have as strong as south push over the last 4 runs.

Looks like that shortwave up in Canada also translating down towards the surface and not allowing the High to flex a little further south - interesting detail in the northern stream evolution. 

[MDScienceTeacher]

2 minutes ago, Chris78 said:

It's going to be a close call for northern areas. 6z Euro control and 12z Gfs  runs the rain/ snow line pretty darn close to the M/D line.

Doesn't mean it's correct but with the latest trends you may need to be in central PA to feel secure with this set up.

Yeah.. we will have to wait and see what happens tonight before we know for sure.  One thing I dont buy is a weak/ moisture starved system.  We have been in a pattern here over the last couple of months of vigorous subtropical jet energy resulting in higher end QPF totals and overall stronger/ more dynamic storms.  

Temperatures are a valid concern, however I really think that what we get QPF wise will be greater than what was shown in the 12 GFS.

[psuhoffman]

unfortunately the GEFS followed the op.  The track is fine, but the see saw went towards a stronger SW in the southwest and a weaker one associated with our system.  The SLP track is identical to previous runs, but its weaker,  less moisture, and warmer.  

[Chris78]

1 minute ago, psuhoffman said:

unfortunately the GEFS followed the op.  The track is fine, but the see saw went towards a stronger SW in the southwest and a weaker one associated with our system.  The SLP track is identical to previous runs, but its weaker,  less moisture, and warmer.  

Not surprising being 4 days out now. Ensembles going to do alot of following from here on in.

[CAPE]

 

 

15 minutes ago, Chris78 said:

Also the high dropping out of Canada doesn't have as strong as south push over the last 4 runs.

I mentioned this in the other thread this morning, and to me its a big problem on the GFS- the timing/depth of the vorticity over eastern Canada phasing into the 50-50 vortex has changed over the last few runs. The confluence it created was key to the strength and position of surface HP over SE Canada as the storm approaches, facilitating weakening the OV low sooner, and allowing the coastal low to strengthen more south of our latitude. 

[Terpeast]

3 minutes ago, CAPE said:

 

 

I mentioned this in the other thread this morning, and to me its a big problem on the GFS- the timing/depth of the vorticity over eastern Canada phasing into the 50-50 vortex has changed over the last few runs. The confluence it created was key to the strength and position of surface HP over SE Canada as the storm approaches, facilitating weakening the OV low sooner, and allowing the coastal low to strengthen more south of our latitude. 

Great analysis, and that's what changed in the last couple of cycles.

[RockabilyJunior]

There is still plenty of time for things to change, but about 12-24 hours before a snowfall, if I see snow maps like the ones posted above, this is what they actually mean ....

We need a nice 50-100 mile shift for this to be of real interest, and there is still plenty of time for that. 

[CAPE]

1 minute ago, Terpeast said:

Great analysis, and that's what changed in the last couple of cycles.

Wave timing was always going to be especially critical in this setup, given we don't really have a block in place yet, and the antecedent air mass is only marginally cold. Several of us said it, I think you were one- the 50-50 needs to be a beast, but it also needs to be in a good spot to have the HP strong enough and not retreat too quickly.

[Terpeast]

1 minute ago, RockabilyJunior said:

There is still plenty of time for things to change, but about 12-24 hours before a snowfall, if I see snow maps like the ones posted above, this is what they actually mean ....

We need a nice 50-100 mile shift for this to be of real interest, and there is still plenty of time for that. 

Even a 20 mile shift in the right direction would change everything, and we won't see it until close to game time. That's if the r/s line stays where it is and doesn't continue trending north. 

[Chris78]

Ukie did improve.

Still not great but does get some snow into Central MD.

Last nights run was confined to the mountains.

[WxUSAF]

2 minutes ago, CAPE said:

Wave timing was always going to be especially critical in this setup, given we don't really have a block in place yet, and the antecedent air mass is only marginally cold. Several of us said it, I think you were one- the 50-50 needs to be a beast, but it also needs to be in a good spot to have the HP strong enough and not retreat too quickly.

Good news is that this could easily bounce back the other way. If you look at H5, the northern stream has been shifting quite a bit. This isn’t the final solution.  But it highlights the sensitivities.