Snowstorms

January 17-18 Winter Storm

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Seems pretty bullish on evap cooling to maintain snow longer in N IL, but yeah, that looks a little precarious.  
Recall that's essentially what the non NAM guidance was showing for Feb 12, 2019 ice event.

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4 minutes ago, RCNYILWX said:

Recall that's essentially what the non NAM guidance was showing for Feb 12, 2019 ice event.

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I actually didn't remember.  Thanks for the reminder.  

In regards to your previous post about faster than modeled surface warming with ESE/SE flow, I'd almost count on it as it sure seems like models are too slow to warm temps in these situations when there's any type of southerly component to the flow.  But if the warming aloft also happens quicker, then it could sort of cancel out and still result in a decent period of icing.

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Good to see the Euro come in colder aloft. It looks like the 500 mb wave is less amped than the previous run and eventually the surface low comes out farther south. It's a solid antecedent air mass with the cold dry high pressure influence slower to depart and 850 mb level starts out quite dry and doesn't moisten as much as 12z run.

But still odd to see the 850 mb level staying that cold due to evaporative cooling alone with straight southerly flow of 30-40 + kt. The southerly flow aloft is weaker than the 12z run, but still plenty for strong isentropic lift.

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6z GFS improved again and is quite snowy here. Helps having a 1040+ sfc high bleeding into the area 12-15 hours before snow would begin. Thing to also watch is fast moving wave that moves through the Great Lakes on Wednesday as that’ll help to keep heights lower across the area before ridging eventually takes over. The GFS has slowly been trending south with that feature the last several runs. 

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44 minutes ago, cyclone77 said:

Yep, this is gonna be a good one.  So nice to see a spread the wealth type system again on the models.  Liking the probs for a sig event for the DVN/LOT cwas.  

I’m still not ready to be an optimist 

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might as well ride the seasonal trends (cringe) and go with a weak/progressive wave at this point

euro in the dog house until it gets something right again

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some of our best snows have come as front end thumps to slop....however...they almost always occur when deep cold has been in place for awhile.   This would be an unusual set up for a good front end frozen thump.   We are essentially at or above normal temps for a few days and then a weak front backs in and drops us to near normal or slighty below right before the waa precip comes in.   Seems to me the cold air is going to lose out much quicker than what the models are implying.    We would need a wholesale change in the track of the low for me to get excited about this one.  

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10 hours ago, RCNYILWX said:

Looks like a decent icing setup for a time because of the position of the high pressure off to the east and warm front stays south. Your east southeast wind trajectories are pulling from lower dew point air off to the east which would help with evaporative/wet bulb cooling. I do wonder if with that exact setup shown on GFS the surface warming would occur quicker once wind goes more southeast due to lack of any snow cover over the region.

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Yea it's an odd setup with regards to surface flow. Seems like models are trending more towards a WAA snow event and less icing now. Euro/gfs in decent agreement which is surprising this far out

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12z GFS is a bit colder initially, but still ends up far enough north to bring light rain to my area.  The 12z Canadian is like the 00z Euro, keeping my area in snow throughout.

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Having trouble with making a gif on TT but anyway, here is a visual representation of the evap cooling.  The band of colder 850 mb temps extending nw-se is near the leading edge of the precip.  There will be evap cooling initially of course as the airmass saturates, so the question is how long it can fight off increasing waa.

gfs_T850_ncus_17.thumb.png.ba122bfd332d566964a447b0e3d6d3e4.png

gfs_T850_ncus_18.thumb.png.181384fe0a3ecb380a48fcc8b93252fb.png

gfs_T850_ncus_19.thumb.png.c7153cd8be5f412c4222c8e06126e3bd.png

gfs_T850_ncus_20.thumb.png.f3934fa11b27d7eddcd0dfb1c7ff5bcb.png

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Hmm looks much better. Anything to give me a reason for working from home for a few days I'm here for. Classic 6-10" heavy snow event for this area at this point

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Kind of wild to see the ridging that enforces the cold air ahead of this thing, should lead to quite a bit of CAD east of the Appalachians. Worries me quite a bit with moisture content, I know it has a solid flow out of the gulf but sucking cold dry air in from the Cold Conveyor Belt has me nervous, that moist air is key to heavy snow totals

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2 minutes ago, hawkeye_wx said:

Euro coming in with a stronger low and a bit less cold again, although still cold enough to give my area a nice thump.

Definitely warmer than 0z run. But like you said still a nice swath of snow and looked like more ice. Wish I could see ice totals on pivotal 

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4 minutes ago, Malacka11 said:

Yet again it appears that some sort of cutoff will evolve right over N. IL. I fear this will be another nail biter

Almost 10 years into this hobby and I am immune from all pain after getting burned time and time again.

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6 minutes ago, ChiTownStorm11 said:

Almost 10 years into this hobby and I am immune from all pain after getting burned time and time again.

I'm getting there, albeit slowly.

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More or less honing in on a general solution it seems.  Thump snow chances best near/north of I-80, fairly wide area gets some ice due to northward progression of waa.

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