jwilson

Voice of my childhood there. Enjoy retirement! He's probably half the reason I got into weather as a kid.

Hope you fine Philly folks get nailed on this one, especially given this slummy winter. I'll be watching from the bushes.

Pittsburgh NWS twitter explains their reasoning behind the warning: (https://twitter.com/NWSPittsburgh/status/1101932802080157696)

Yeah, I get why they were complaining (I think they were at historic levels of futility for snow), but everyone knew they'd play catch-up before long. Some people just need perspective, really. There's quite a few in the MA forum especially that would go insane living here. I can't imagine some of those guys making it 10 years without a double-digit event.

I've seen this on the coast and they tend to be modeled somewhat by the meso models. I don't see a single model (mesos included) getting anywhere near 6" for Pittsburgh metro unless I'm missing something. The closest is the Euro with 4" (and it maybe paints a small strip of 6" in eastern Washington county). Warning (in this case) means 6" in 12 hours is imminent. I don't know that that's the wording I would use.

That warning is bizarre given it requires 6" in 12 hours or 8" in 24 hours. I don't expect to hit either of those marks. A watch might have made sense, then downgraded to WWA when it became clear we weren't hitting warning criteria.

This has been one of the worst winters for modeling, I believe, at least in the long-term. It probably isn't as bad as I think, but I would like to see verification scores relative to other years. Constant short-term adjustments, disagreements, etc. I do agree the Euro has not been strong in a year when verification scores say the GFS has been abysmal. Twice now it has caved to the GFS, though. Seems the models couldn't handle the pattern overall of this winter. I'm sure this will make for an interesting case study for those in the field. It was so bad the FV3 has been put back to sleep. The Sunday storm is losing much of its impact over the entire northeast. Given how the January system went, it wouldn't surprise me if the Sunday storm went even further southeast or drier than is being modeled. Well, I guess we learn to not get suckered in when there are all these little balls of energy trying to vie for the limited amount in the atmosphere. The paradigm of "choosing the model that looks worse for us" certainly hasn't been shifted by this season.

Yeah I think you're right. Mistake on my part, thinking those maps only showed a single event synopsis. Storm is definitely less amped, though. Truthfully, this was never going to be a "big one" because of the progressive flow. If there weren't so many waves scrambling close together, I do think this weekend could have been a major event (maybe not for us - depends on other factors - but for someone). I do agree, beggars can't be choosers and all, but we've still managed a fair amount of snow this year. For me, the little to modest events have simply lost their appeal. Is 2010 still the last double-digit snowfall for Pittsburgh metro?

Euro still considerably less impressive than it was (cutting totals in half or more). Honestly, at this time I'm over the nuisance snows. I'm big game hunting. If we can't get a big one, then I don't really care if the GFS verifies and we get flurries.

As predicted, the GFS has gone in a poor direction based on its own interpretations. We still have the Euro on our side, but right now it is alone in terms of a stronger and further NW solution, by far. The NAM is halfway in-between the two and considerably faster than the GFS. I tend to side with the NAM here, for now. It's a split and it nailed the far faster movement with the shortwave we had this morning. Obviously, lots of ways this can still swing. Range of possibilities from 1" to 12" .. how's that for a forecast?

We got NAM'd with the 18Z suite for tonight. Started showing 6" lollipops in Washington and Southern Allegheny county, including the high-res (it is closer to 4" with Ferrier corrections). The half-foot is probably too wet, but there might be a couple places that snag 4" or just over. Some of the soundings are showing really strong Omega in the DGZ and that's how it can happen. As for the weekend, the NAM is not impressive. Much less organized than other models. The other change at 18Z I noticed was the GFS wanting to crank that first low once it gets in the Atlantic on Saturday. That could rob some energy from the Sunday system and/or push it south. Not a favorable change, in my estimations. 0Z runs tonight will be telling.

Funnily enough, all the overnight models pretty much caved to it. NAM leading the way. Looks like a fair 1-3" event overnight. Could make tomorrow morning's commute a mess. Still not in comfortable range for Sunday. The NAM at distance - so take it with a grain of salt, of course - looks a good bit different than the others (GFS bounced a bit south from 0Z at 6Z).

The NAM gives us a little powder bomb early morning Friday (2-3"). No other models are on board, though. FV3 is nothing. GFS and ICON are a dusting. CMC tries to get southern Allegheny an inch. High-res NAM is drier (looks like a ridge special). Appears it will depend how moisture deprived the system is with a high sitting nearby. At least we have some wiggle room for the Sunday storm to come north (unless you're the Euro, of course). Better that than it being a cutter, but of course given the preceding low, we could easily miss the sweet spot thanks to suppression.

NAVGEM looks like the Euro, which IMO is a bad sign. It has a progressive bias, so it is unusual to see an amped signal there. Normally I wouldn't care, and back in January the Euro lost to the GFS, but I'm hesitant to bet against it twice. It largely depends on how amped the Friday storm gets north of us. My non-scientific analysis: pick whichever result looks worse for us and bet on that one.

There hasn't been a coastal all year. I believe any threat of a Miller A in this pattern is quite DOA. Flow is flat at best, there are too many little waves taking energy from each other. I'm ready for next year, honestly. Maybe we can finally escape this pacific flow (and lose the moisture train in the process). Unless we get a '93 repeat, but chances of that are about one in a million. JINX

The FV3 has given us about 10 feet of snow over the course of this winter. It owes us big time. Add in this beast and it means the FV3 will be paying on the principal until it dies. (Sort of like me and my student loans)

Sadly, yes. This was the biggest snow we've had all winter and it came and went in about four hours. Precip ending much sooner than expected, honestly. At least it appears we won't get much plain rain to wash things away.

All sleet now in Bethel Park/Mt. Lebanon. I was out for about an hour or so and couldn't even keep my car clean, so I gave up. Even an hour ago with some intense rates, it was not a pure snow. Lots of ice pellets/graupel mixing in. I have some pictures I'll post later. We're approaching 4" but I think accumulation is over in terms of snow.

I think a lot of the clown maps are deceiving due to their failure to differentiate snow and sleet. Heavy wet snow would probably fall as a 7:1 to 12:1 ratio, while sleet is in the 2:1 or 3:1 range. As an example, averaging out 10:1 snow ratio and 2:1 sleet ratio, the NAM gives Allegheny county between 1 and 1.25 inches of total precip. Ferrier correction calls for 2.5" of snow, or so, which would be about 25% of the total precip. Under that calculation, I'd estimate there's about an inch of just sleet, then some plain rain plus ZR towards the end. That half inch of precip that falls as sleet shows up as another ~3-6" of snow on some models. Looks like the 850s warm somewhere between three and six hours after onsent of precip. Given our history and the way things have gone this winter, I'm inclined to sway towards a conservative snowfall estimate and thus a warmer overall solution. The high being off to the East instead of our North gives me even more pause. Using another example: the HRRR simulated radar still shows snow at 15Z, but the surface temps have already warmed above freezing. That's four or five hours of snow, maybe even less. This system could manage heavy rates (say >1" per hour), for sure, but I believe a system with that sort of convection is also more likely to flood in warm air at a quicker rate (someone correct me if I'm wrong on the science). This is a long-winded way of me saying I'm still not buying into a significant snowfall along the warm "plain." Places in the mountains and further north will probably see upwards of 10"; a shame we can't get in on that game. It will be interesting, though, seeing how this storm verifies relative to the GFS vs. the Euro.

I'm not finding much reason to be impressed. Given history, I'm sure 1-3" is a safe bet. The 850s are screaming from the south, so the flip is always imminent with the position of the retreating high. We aren't in a strong CAD location. Might it be our last snow until March?

Agreed with you and then Mike (about the screaming southern jet). I don't really trust the guidance beyond Day 4 this year, so I guess it would be unfair of me to say with certainty what will happen. All we have is how the preceding days of winter have gone. The tropical forcing might be changing a tad, though we're still dealing with Phase 7 MJO effects, so that's where the hesitance comes in. If we can get the MJO to actually move towards Phase 1 at a decent amplitude and stop meandering, there's our chance. The western trough will hurt us in the meantime. Hopefully, as you've shown, it does flatten and limit that SE ridge influence in the coming days. I don't know enough to say which is cause vs. effect, as we've also been dealing with a pretty strong high over the Azores most of the winter. Maybe we luck into something eventually.

The only thing that might save this storm is the timing of it with a transient -NAO. If we can close a block in at the right time, we may be able to keep the confluence locked in rather than escaping and the low tracks underneath us. Right now, though, I agree that this storm is heavily favored to cut like the rest of them. The Euro keeps the low in Tennessee, which is about as far north as we can let it go. There is another wave behind it (Friday/Saturday) which could be a better shot, or perhaps more likely suppressed. I give us about a 2% chance to get the timing right.

Thank you! I thought that storm back in November was our biggest of the season, but I guess it wasn't as big as I thought (most area measurements for it I see are <2").

We technically had an advisory for the storm that missed to the north back in January. Of course the advisory was cancelled, so you probably can't count that because it didn't verify. Officially, I'm finding the biggest snowfall at the NWS location is 3.4" on January 20th. Locally, we've had a number of 2" storms this year, but 3" is probably the absolute max. Annoying I can't measure at my place so I don't have specifics.

We just had the wettest year on record and we're already starting out this year wetter than last. Despite that, we're below normal on snowfall. I guess the question becomes whether the pattern changes before next winter, and if it does, do we end up in a dry pattern. Seems like a waste of all this moisture to not get a decent snowfall out of it.