January 12-14, 2019 Storm Threat

[anotherman]

3 minutes ago, mappy said:

Yes. ~2"

Nice, thanks.  Just happy to get some snow to cover and ground and make it feel like winter before the main event(s) get here (hopefully).

[winterymix]

9 minutes ago, showmethesnow said:

But the weaker and progressive flow is in response to the NS. Weaker because the NS is not giving the storm room to amplify and more progressive because we see very little height rises in front of it to slow the flow.

agree...happy we have a snow event, trying to avoid wish casting.

[MillvilleWx]

Models are beginning to hone in on the median ground for the setup. The trimming on the northern side is occurring because of the confluence and dry mid-level northwesterly flow north of our area. It’ll probably be a sharp gradient of nothing to accumulating snow across PA. I still see our northern reaches getting in on the action and secondary band like structure right on the edge of the confluent zone where mid and low level convergence sets up. Pinning that will be something that gets settled closer to game time.

As for rest of forum, increasing likelihood of Advisory level snows with 1-3/2-4 inches from I-70 corridor to NoVa and 3-6” within the area that’s gets a cross of the best WAA snows and the redeveloping coastal. That part still has yet to be solved, so those numbers could bump if we get a trend towards a better NW expansion of precip field when the secondary takes shape. The max snowfall I could see from this is 6-8” with the Central Shenandoah the prime spot due to better position within the left exit region of the southern jet streak and aided orographic enhancement, maxing out on lift within the DGZ.

So far, what I mentioned yesterday and what LWX has in their discussion lineup, so I don’t feel the need to change my forecast right now. I still wouldn’t rule out a dual “max” and someone along Parr’s Ridge getting 3-5” of cold smoke due to that convergence zone along the confluent setup to the north along with aided orographic enhancement. Ratios from storm will range from 8:1 within very light snowfall where needle type crystal structures the common snowfall type to 15-20:1 where best lift/omega resides within the DGZ on both the jet streak and orographic enhancement, as well as the deformation axis on the northwest flank of the secondary. That latter part will probably take another day or two to be solved.


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[osfan24]

Ouch, 6z Euro was a big step back overall, especially in VA. GEFS has been so consistent but I still wonder if it's being skewed by big hits.

[PivotPoint]

54 minutes ago, MillvilleWx said:

Models are beginning to hone in on the median ground for the setup. The trimming on the northern side is occurring because of the confluence and dry mid-level northwesterly flow north of our area. It’ll probably be a sharp gradient of nothing to accumulating snow across PA. I still see our northern reaches getting in on the action and secondary band like structure right on the edge of the confluent zone where mid and low level convergence sets up. Pinning that will be something that gets settled closer to game time.

As for rest of forum, increasing likelihood of Advisory level snows with 1-3/2-4 inches from I-70 corridor to NoVa and 3-6” within the area that’s gets a cross of the best WAA snows and the redeveloping coastal. That part still has yet to be solved, so those numbers could bump if we get a trend towards a better NW expansion of precip field when the secondary takes shape. The max snowfall I could see from this is 6-8” with the Central Shenandoah the prime spot due to better position within the left exit region of the southern jet streak and aided orographic enhancement, maxing out on lift within the DGZ.

So far, what I mentioned yesterday and what LWX has in their discussion lineup, so I don’t feel the need to change my forecast right now. I still wouldn’t rule out a dual “max” and someone along Parr’s Ridge getting 3-5” of cold smoke due to that convergence zone along the confluent setup to the north along with aided orographic enhancement. Ratios from storm will range from 8:1 within very light snowfall where needle type crystal structures the common snowfall type to 15-20:1 where best lift/omega resides within the DGZ on both the jet streak and orographic enhancement, as well as the deformation axis on the northwest flank of the secondary. That latter part will probably take another day or two to be solved.


.

This is called expert analysis and we are lucky to have them. Good write up and well explained 

[MD Snow]

10 minutes ago, osfan24 said:

Ouch, 6z Euro was a big step back overall, especially in VA. GEFS has been so consistent but I still wonder if it's being skewed by big hits.

If that’s the case we should know soon imo. If the big ticket item is off the table, expect the gefs to start dropping those ensembles members at 12z today. The big thing I’m looking for today is whether the models go for a strung out blob of SLP that just slides off the coast (EURO and ICON). This would result in a low end advisory for areas north and east of DC. Or if we can get a more consolidated SLP that can dig a bit (gfs twins and ggem). This would result in a higher end advisory or even warning level event for areas north and east of dc. I don’t trust the NAM outside of 48hrs so I wouldn’t put much weight on its handling of the coastal towards the end of its run until tomorrow’s 12z runs. 

[Beachin]

Gefs 6z

[osfan24]

NAM is a big whiff.

[North Balti Zen]

3 minutes ago, osfan24 said:

NAM is a big whiff.

See the storm mode thread, osf.

[BristowWx]

EDIT: From my earlier post until now, I am much less excited after seeing the trends at h5 at 12z.  if it gets any worse or dampens much more this is a non event.  Mood flakes for a period of time that accumulate because its cold enough. Fine if we could lock that in but lots of model time to go.  Big meh so far today