Feb 6-7 storm?

[cyclone77]

Snowing much better now with this 15+ DBZ band.  Flakes are still small, but not pixies anymore.  We'd been under 6-12 DBZ returns the entire time up until recently.

[Radtechwxman]

50 minutes ago, Chicago Storm said:

It’s wasn’t really supposed to be snowing down that way yet. The atmosphere is no drier south than it is north... Give it time.


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It surprisingly saturated pretty quick. Flake size not great but coming down at a decent clip. A heavier band to my nw is trying to sink se very slowly. Hoping for 1-2in at this point but maybe can luck out with 2-3in if I get into some banding. 

[hawkeye_wx]

I have received only 0.7" of snow this afternoon.  I expected a bit better, but the ratio is lousy.  The 0.7" of snow melted down to 0.07" liquid, so a 10:1 ratio.

[Radtechwxman]

1 minute ago, hawkeye_wx said:

I have received only 0.7" of snow this afternoon.  I expected a bit better, but the ratio is lousy.  The 0.7" of snow melted down to 0.07" liquid, so a 10:1 ratio.

Crazy. Just goes to show you even with very cold temps, crappy ratios are possible if your best omega doesn't line up well with DGZ. 

[WeatherMonger]

Flurries just started here, wish it were a bigger event

[Hoosier]

When I was looking at forecast soundings over the past couple days, there was a decent amount of omega in the dgz, but there was a decent amount above it as well.  I'm sure the better banding has higher ratios but unfortunately it's not that surprising to see reports of struggling ratios.  I also wonder if the dgz has been able to saturate all the way because the NAM at least was suggesting a potential problem.

[janetjanet998]

2-3 inches down in that band over Knox into Marshall county

per LSR

[WeatherMonger]

Lightly traveled streets amd sidewalks with a coating, doesn't contrasts with the grass enough to see it on yards. Stesdy light snow currently

[ChiTownSnow]

https://m.facebook.com/TomSkilling/posts/pcb.276963730455244/?photo_id=276957383789212&mds=%2Fphotos%2Fviewer%2F%3Fphotoset_token%3Dpcb.276963730455244%26photo%3D276957383789212%26profileid%3D30407707%26source%3D48%26refid%3D52%26_ft_%3Dmf_story_key.276963730455244%3Atop_level_post_id.276963730455244%3Atl_objid.276963730455244%3Acontent_owner_id_new.100044248578383%3Athrowback_story_fbid.276963730455244%3Apage_id.100044248578383%3Aphoto_attachments_list.[276957383789212%2C276957433789207]%3Aphoto_id.276957383789212%3Astory_location.4%3Astory_attachment_style.album%3Atds_flgs.3%3Aott.AX9yeGoFpl9dSrTu%3Athid.100044248578383%26__tn__%3DEH-R%26cached_data%3Dfalse%26ftid%3D&mdp=1&mdf=1

Good write up/chart regarding ratios and snowflake growth by skilling

[mimillman]

Pretty outside. Heavy coating down and SN

[Baum]

^ per euro i've got 22.5" more to go through the next 10 days. Pumped.

[purduewx80]

31 minutes ago, ChiTownSnow said:

Good write up/chart regarding ratios and snowflake growth by skilling

Unfortunately, as today is proving, it's far more complicated than that. 

Take DSM for example. Assuming the snowfall and QPE numbers are right, they recorded 1" of snow on 0.10" of liquid between 6AM and noon. That's a 10:1 ratio. Their surface temperature was 6-7F, which according to Skilling's chart, would end up producing snow of 4". 

It has more to do with the vertical velocities in the cloud layer than just about anything else. Those 20-40:1 ratios would only occur where the best lift coincided with a saturated cloud layer with a temperature from ~-10 to -20C (the middle of that range is best).  

There are many other variables that affect snow:liquid ratios that involve cloud microphysics, chemistry, physics and so on. It's a difficult thing to model perfectly, and we probably have a ways to go before your typical model websites are able to accurately portray what's going on.

Ricky covered this at the top of the page, so re-read his message to see a little bit of why today didn't work out for everyone.

[Baum]

wow. Purdue just pinned some donkey ears on skillet head. Social media can be brutal.

[purduewx80]

Just now, Baum said:

wow. Purdue just pinned some donkey ears on skillet head. Social media can be brutal.

I have a huge amount of respect for someone like him who has to dumb this down for the average TV viewer. There isn't always an easy way to communicate science, unfortunately.

[Chicago Storm]

Looks like the best forcing ended up just south of where guidance had placed it, and in a wider corridor as well... Between I-80 and I-72.


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[Chicago WX]

Coming down really nicely right now. Flake size is good, not great,..but good. Shame it can't do this all night...

[cyclone77]

Winding down here, with 0.8" as the total.  LSR seems pretty low, as the snow is very sugary as Josh would say.  Kind of a disappointment, but still a nice little refresher and always nice to see it snow during the daytime.  

[janetjanet998]

interesting pencil thin line of higher returns from Gary IND back SW to PIA

 

[Baum]

Alek hype storm fail. First chink in the armor. And he's MIA.

[WeatherMonger]

Probably right at an inch, maybe a hair over. Considering how things panned out elsewhere I'll take it. It will at least look as cold as it feels when looking out the windows. might be able to make it to 1.5" be tough though.

[Jackstraw]

Well these reports aren't encouraging.  Thought we might squeeze out a couple around here.  Have to reduce the 10 day clown maps by 2 inches now 

[Dalfy]

Downtown STL is around .6ish I think. Not too much but made for a nice walk. 

[vortex]

Guesstimate  about 1.5” or so here.  

[WeatherMonger]

Official tally goes down as .9" on .06" QPF for a 15:1 ratio. Think I have a tad more than that IMBY but unless it's a sharp cut off usually go with the airport recording as only a few miles away.

 

 

 

[Jackstraw]

Had about 30 min of fat flakes and vis down to a 1/4 mile, at least thats how I measure vis to my neighbor thats a half mile away.  I couldnt see his street light for about 20 min thats usually a 1/4 mile vis.  Swept a half inch off the deck.  Fat flakes were 3/4 by themselves lol.  I'll call it a disappointing half when the offices were forecasting 1-3.  Temps rose from 11 to 16, but finally now falling towards the forecast 0 low.  We shall see

[purduewx80]

O’Hare came in w a 10:1 ratio too (0.7” on 0.07” liquid). 
 

The observer near Midway had 0.8” on 0.05” liquid (16:1). 

[RCNYILWX]

Revisiting this, some of the early HRRR/RAP runs and to a bit lesser extent the NAMs and HRWs clearly were far too aggressive. Had thought 2-4" was attainable across a good chunk of the CWA in expectation that the ratios could perform even outside banding. This was before it started to become more clear that this would be one of those fairly common setups where only in the banding would ratios perform to their capability and the CAMs were overdoing QPF.

 

It appears that the CAMs were reacting to mesoscale banding and distributing this QPF over much too widespread an area and were in general too wet. These are tough forecasts because the globals don't necessarily do as good a job picking up on the f-gen banding, while the CAMs do but might be too aggressive in doing so. Plus the ratio question really takes being precise in ascertaining where banding will set up to forecast the localized 15-20:1 ratios while the rest of the area comes in close to 10:1.

 

 

 

 

 

 

[purduewx80]

36 minutes ago, RCNYILWX said:

Revisiting this, some of the early HRRR/RAP runs and to a bit lesser extent the NAMs and HRWs clearly were far too aggressive. Had thought 2-4" was attainable across a good chunk of the CWA in expectation that the ratios could perform even outside banding. This was before it started to become more clear that this would be one of those fairly common setups where only in the banding would ratios perform to their capability and the CAMs were overdoing QPF.

It appears that the CAMs were reacting to mesoscale banding and distributing this QPF over much too widespread an area and were in general too wet. These are tough forecasts because the globals don't necessarily do as good a job picking up on the f-gen banding, while the CAMs do but might be too aggressive in doing so. Plus the ratio question really takes a being precise in ascertaining where banding will set up to forecast the localized 15-20:1 ratios while the rest of the area comes in close to 10:1.

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A deep-dive into the system’s innards on AWIPS and BUFKIT was revealing yesterday. They all did a nice job showing the best crosshairs signal (lift + DGZ) where the relatively heavier snow occurred, despite QPF placement being incorrect. Shame the forcing was so high up when the super deep DGZ was based at the surface. Good reminder that model QPF and weenie snow maps have a long way to go.

NE did see some stellar ratios out of this at least. Omaha saw 31:1 ratios and Lincoln had 36:1. 

[Chicago WX]

1.8" total here. Got lucky, relatively speaking, with some nice bands and flake size. 

[Radtechwxman]

Got like 1.5-2in here. Definitely think the ratios weren't as good here. Snow was like pixie dust a while. Once we got into a good band towards the last few hours of snow, flake size improved but was a little too late.