Northern Ohio Obs/Discussion Part 2

[LakeEffectOH]

1 minute ago, NEOH said:

Seems like the 12z models shifted south a bit... or maybe a quicker transfer to the EC. Still like where we sit at this point if the energy can hang back longer. 

Thinking the biggest risk is the transfer of energy to the coastal low.

[dta1984]

3 minutes ago, LakeEffectOH said:

Thinking the biggest risk is the transfer of energy to the coastal low.

Ya it seems we have had this situation in the past, it's helped us a few times by hanging on longer and also gone the opposite way.  Let's hope it hangs on longer before transferring!

[LakeEffectOH]

3 minutes ago, dta1984 said:

Ya it seems we have had this situation in the past, it's helped us a few times by hanging on longer and also gone the opposite way.  Let's hope it hangs on longer before transferring!

It looks like most models are showing us keeping a deformation zone of light snow into Monday morning, so that's good.  It's the transfer that's always so unpredictable. 

[NEOH]

Here's a recap of total precip from the 12z runs... fairly uniform and with ratio's around 15:1 that's a good storm. 

GFS AI - .79

GFS - .71

CMC - .75

 

 

[LakeEffectOH]

47 minutes ago, NEOH said:

Here's a recap of total precip from the 12z runs... fairly uniform and with ratio's around 15:1 that's a good storm. 

GFS AI - .79

GFS - .71

CMC - .75

 

 

Those numbers make sense.

Snow equivalent:

GFS AI - .79/~12"

GFS - .71/~10.5"

CMC - .75/~11"

  

[dta1984]

7 minutes ago, LakeEffectOH said:

Those numbers make sense.

Snow equivalent:

GFS AI - .79/~12"

GFS - .71/~10.5"

CMC - .75/~11"

  

Seems like consistency for a 10-12" range.  Maybe more if the coastal transfer is delayed.  Just hoping we don't waste too much qpf overcoming the dry air that's in place.  

[NEOH]

10 minutes ago, LakeEffectOH said:

Those numbers make sense.

Snow equivalent:

GFS AI - .79/~12"

GFS - .71/~10.5"

CMC - .75/~11"

  

12z euro is .77". Tight cut off to the NW. Hopefully we can avoid any further shifts. Seems like the primary low always winds up a little more NW than forecast so hopefully that holds true. 

[dta1984]

3 minutes ago, NEOH said:

12z euro is .77". Tight cut off to the NW. Hopefully we can avoid any further shifts. Seems like the primary low always winds up a little more NW than forecast so hopefully that holds true. 

I caught a reference to this in the cle discussion 

The past several model cycles have seen a NW shift in the track of the surface low and resultant axis of heaviest snowfall, and there is still time for further refinements to the track as model guidance resolves the aforementioned phasing. Northern and southern stream jet phasing is known to pull systems farther NW than models initially indicate, so this NW trend has not been surprising

[LakeEffectOH]

23 minutes ago, NEOH said:

12z euro is .77". Tight cut off to the NW. Hopefully we can avoid any further shifts. Seems like the primary low always winds up a little more NW than forecast so hopefully that holds true. 

Updated list:

Snow equivalent:

GFS AI - .79/~12"

GFS - .71/~10.5"

CMC - .75/~11"

ECMWF - .77/~11.5"

Average snow accumulation per 12z models: ~11"

[OHweather]

I think NE OH is in a good spot for this one...the heaviest QPF axis will remain a bit to our south, but soundings suggest ratios should be around 15:1 for most of the day Sunday (and likely climbing higher in any lingering lake enhanced snow by early Monday). There have been slight bumps SE in my eyes in both the 0z and 12z runs today, but we're still solidly inside the swath of heavier snow. 

Overall, I don't expect much more than small fluctuations/trends from here on in with this storm but I'll try to look at what could change. There are some sensitivities to both how well the storm phases to our southwest and how much the PV over the Upper Midwest/Great Lakes is trying to press in. A better phase would argue for a further northwest track, but northwest trends have been stunted for the last several runs now due to the PV to the north not lifting out much as the storm deepens and tracks NE Saturday night into Sunday. 

This is the European ensemble mean 500mb heights for the last several runs valid at 12z Sunday. There still are subtle run-to-run adjustments both with the exact placement of the PV and with how well-phased the trough ejecting into the Plains is...to me, the there haven't been substantial trends either way with the PV while the trough has trended perhaps a bit less phased overall. That has resulted in what I think has been a small SE bump in these recent runs. Heights are still rising plenty ahead of the storm and there may be room for a subtle trend back northwest if we see a better phase, but unless we see trends towards the PV lifting out quicker I don't think it makes a huge difference. 

This is just the 500mb height and vorticity trends from the operational Euro...there are not clear trends towards a more or less phased solution overall, though there may be a slight trend for the trough to eject into the Plains slower, which in theory could give the PV a little more of a chance to press in ahead of it. 

The red circles are the main pieces of energy phasing together with this storm...the Baja low and shortwave diving into Canada have not been fully sampled yet, but will becoming increasingly sampled in the next sets of 0z/12z runs. There may be some opportunity for trends regarding how well the storm phases over those next cycles, though my guess is there won't be a significant trend either way. The shortwave circled in blue isn't really phasing into this, but will help dictate how much the PV presses into the upper Midwest/Great Lakes north of the storm. My guess is we won't see a notable trend with the PV from here on out, though I've been surprised before. 

Overall, guidance has bumped SE a bit in recent runs but the overall change hasn't been much for NE OH, as we are pretty solidly inside the swath of heavier snow. There will be some snow from late Saturday night through Monday morning in NE OH, a long duration, with the heaviest occurring late Sunday morning through early Sunday evening as it looks now. Despite the icy lake, there will probably be some form of enhancement amid lingering light synoptic snow through at least Monday morning as the storm pulls away. My guess is rates will generally be modest, but a few hours of rates pushing an inch per hour on Sunday seem feasible. My guess on snow for most of NE OH would be in the 7-13" range...only sticking 7" in there in case the PV presses in a bit more and we see another small bump or two SE, though if you take guidance as it is now we'll pretty solid for like 9-12". It does get iffier for Toledo, they currently look solid for something like 5-8" but are a bump SE away from seeing that decrease some more. 

[OHweather]

6 hours ago, dta1984 said:

That could be.   I'm guessing the totals will creep up as we get closer to the storm. 

Curious to get @OHweather thoughts on the storm.   I'm also wondering if model qpf output takes into account the dry air in place and qpf that will be wasted due to saturation?

A model's QPF does in theory take into account things like low-level RH and if precip will make it to the ground, but some models struggle more with it than others. 

We don't assume a static snow ratio...the NWS snow forecast largely comes from taking QPF (which is usually a blend of many models and ensemble members...outside of lake effect situations) and snow ratios (which do adjust based on the modeled temperature/moisture/lift profile, but certainly can be wrong at times) and multiplying them (more complicated calculations come into play with mixed precip or temps above freezing, which isn't the case here). I would say the CLE snow forecast has been a bit more conservative compared to some model output, but there are enough ensemble members that don't have as much QPF up here that that's likely why the forecast hasn't been as aggressive as say the last several Euro runs.