RitualOfTheTrout

Took the trash out and it's pouring plain rain still. No ice on anything, pretty strong breeze so it feels awful.

Yeah, that and typically waves riding up a front tend to slow it down. Wasn't our Christmas Eve storm in 2020 a wave riding up a boundary?

Sorry, had to do it. With our track record with storms this might be my last best chance to use it this winter.

Can't hurt we are getting close to sunset either.

Maybe... or maybe the heat generated from the motors sets us back 6 hours.. Do you really want to take that risk?

Yes to early. It was clear yesterday we weren't dropping below 32 until at least 6pm-9pm. The short term models had a good handle on the front becoming stationary. I just hoped it would make a bit more progress.

They will probably flip before us lol

That's once it goes through, 12 hours to move 50 miles then it will blast 500 miles in 6 hours. Just the bad luck of the draw. lol 18z NAM seems to indicate an even later change over to freezing rain now...

Well so far 3K NAM has nailed the temperature situation showing temperatures in central / eastern Allegheny hovering at 33 degrees for almost 12 hours. I can't believe we couldn't get that eastern ridge to be a little flatter to get this through, then again we probably wouldn't be talking snow, just a severe ice storm. Remains to be seen what the effect will be overnight.

That lines up pretty well with where guidance indicates the front slows / gets hung up. It would make sense that areas just to the west of that line will have freezing rain for most of the day.

Right, some models just show basically (If Surface Temperature is <=32) and precipitation is liquid based on higher levels of the atmosphere being above 32. Then show as ice. It's literally just a total of how much qpf falls as rain while surface is at or below 32. Pivotal does have ice maps that utilize the FRAM method which is much more accurate at depicting actual accretion but they are for pay only. It's not a simple this % will accrete type deal, you need to take into account surface and air temperature, solar radiation, albedo of the object, winds, latent heat release and that effect on already accreted ice, how thick the warm layer is (is the droplet super cooled or above freezing) even the kinetic energy of the droplet when it hits the object. Needless to say it's a lot of complicated interdependent factors lol

Check the soundings on the 12z 3K NAM, I used the actual city as my point of reference and it has surface temperature a 33 degrees from 9am until about 9pm. I'd say let that be your point of reference, if you drop to 32 or colder before that 9pm then maybe we are getting colder faster. Crazy the front is stuck for 12 hours, then once it passes us seems to have no issue blowing off the coast, really a near miss here if it plays out like that. And when I say near miss I mean from a very impactful ice event. I guess we can prove my theory after the fact if counties just to the west of the Allegheny have severe icing but its more or less nuisance especially from the city east.

This part to me is even more fun than the tracking, checking obs / now casting. We don't have a lot of experience with this type of situation so it's going to be really interesting to see if models nailed the front getting hung up, or if they are not able to handle the low level cold air bleeding underneath. Typically on the other side of the apps low level cold is underdone and we still have snow pack in most of the area too. So we have that going for a possible quicker temperature drop. On the other hand, I'm not entirely sure temperatures don't rise a few degrees while we are under the influence of the weak but not completely inconsequential warm nose.

I'm sort of with you on this, there's 9 months of the year for plain rain essentially with some thunderstorms sprinkled in but otherwise not interesting weather. I track to see the extremes and the unusual partially, but totally get that ethical debate that gets brought up like with people rooing for a hurricane landfall.

Yeah I think if 50 percent of the area / population is likely to experience the criteria then it triggers.

Yeah I don't get grouping it altogether when there will be such drastic differences across the warned area. Schools already closed by me for tomorrow but it will likely rain til 10pm. I get that with the ability to just go virtual it makes it easier to just call it now and avoid any surprises and err on the side of safety but seems a bit extreme.

Well look at the graphic, there's literally 50 - 100 miles between starting at 10am and starting at 10pm. So it the discussion was written relative to the NWS office that's probably accurate.

Latest NWS freezing rain start times for anyone else thinking about what to do tomorrow. Looks like what Euro and GFS had. Must not be buying into short term models yet.

Yeah, definitely not a good trend on the short range stuff, 3k nam says front doesn't get to western Westmoreland until like 11pm.

Same, I've got a pretty low bar set mentally given my location. Thinking maybe an inch or 2 some ice and a lot of rain. Those ice maps are way overdone, that's not to say even a glaze of ice is anything to sneeze at and no doubt somewhere to the west probably gets it bad. I was really hoping to get another 50-100 mile push on the boundary and get a sleet bomb, would have been alot more interesting. At least with a low bar it's easy to be pleasantly surprised if it turn out better.

I still think any travel issues around the city wont be to at least 6pm - 7pm. I'm by no means an expert though so do what you gotta do. I'm fortunate enough I'll be able monitor obs tomorrow and if it looks like things might get icy sooner I can head out early. Might just be easier for some to not go in verse to trying and leave early. Friday morning commute should certainly be the main problem time as we should be in the lower 20s by then and precipitation still coming down, of what form who knows lol.

That's my guess, maybe a band 2 -3 counties wide in OH where snow and ice totals due to sleet both fall under criteria for a warning. I agree advisories get extended east to areas that currently have nothing.

Everything I've seen the FRAM method is way more accurate (still not perfect) in forecasting ice accretion so I'm glad you posted a map that's utilizing that. If anyone needs any bed time reading, here is agreat article on the science of freezing rain: https://journals.ametsoc.org/view/journals/wefo/31/4/waf-d-15-0118_1.xml

I hope so... but not because anyone really expects to get 10 clean inches of snow out of this in our local area.. If so I can already hear the crying.

It looks like at least on the GFS between 4pm - 7pm the front will be sliding across Allegheny county, NAM is more like 7pm - 10pm. GFS did tick slightly faster at 12z than 6z but still slower than 00z, we are really talking like 25-50 miles differences here which is probably just run to run noise but if you are on the eastern edge it makes a difference.