jwilson

Sounds like we're going to need another hurricane to break the pattern again.

I think we've gotten used to September warming, at this point. It is rarely a "fall" month anymore. We can even stretch the 80s (and more rarely 90s) into October. Heck, even last November was warm in the beginning. Of course, two years ago November was the coldest month of the winter (I think), so it's hardly definitive beyond a warmer September. I like fall, though, and it's unfortunate we see less of it. My own theory is we're eventually going to have two primary seasons: winter and summer, not much lengthy in-between.

Guess I spoke too soon. Looks like we've started the eastward jog, and it has kept pouring through this so the metro area might verify those high-end totals of 4-6".

We've had a hard rain, as well, for a while but about to dry slot which should save us from a worse fate. We also lost power briefly, clearly a flow problem, but it seems they upped the auxiliary because we're okay for now. Although I did see some power flashes behind us. Everything is soaked at this point. Not a terrible surprise the rain has gone further north than expected.

Not much consensus from the models. A pre-winter delight in storm tracking with Allegheny once again the battleground.

I wondered if the right-turn that Ida took early would result in a more southern solution eventually. Maybe there's no correlation, but for now it looks like that's the case. Although this looks like a winter storm scenario with a northern-stream vort pressing down and a tight precip gradient. I'm with Ritual, on this one. Too many bad memories. While probably nothing, I hope getting "missed" by two tropical systems doesn't portend something for the winter season. If we get missed, that is.

I have friends down in BR riding out this event (one couldn't leave because of his job). I'm hoping they'll stay on the north/east side of the eye to spare them the worst of it, but it looks like it will get close. Regardless, the flooding is going to be quite bad, to put it mildly. As for us, the track is still uncertain. We saw a northward shift with Fred which isn't unusual for us. Maybe something similar happens again (not that a northward shift in this case would really help too much, absent something extraordinary).

Thursday was a nasty one for us. We basically had a three-hour thunderstorm that had varying intensities of precipitation. A lot of close lightning strikes. Makes me wish I had a camera setup on a tripod to record the whole thing. Fortunately we got a break last night, as the worst of the storms skipped us over (perhaps because we used up all the energy the night before). We've more than made up for the dull spring. Now I'm kind of looking forward to cool fall weather, if such a thing will happen this year.

There's this from NWS Pittsburgh showing all the lightning:

Looks like this one weakened below severe levels right before it hit us. The wind wasn't even that bad locally. Hopefully no tornado up north. I had a good view of the line from the southeast and there might have been remnants of a wall cloud, but it became clearly disorganized before moving in. Also didn't visibly see any real rotation.

Sorry, I meant not bad locally. I didn't mean that as a universal attribute.

We've been pretty lucky (or unlucky depending on your POV) here locally. Yesterday was the first storm that actually hit us and it wasn't all that bad. Most of them have been missing just to the west or east. Sorry for those of you dealing with problems. I've seen lots of down trees and flooding elsewhere, including my own old 'hood in Morgantown. Actually, I've always been curious about this microclimate split we seem to have between north of the city and south. For whatever reason, it seems south of the city gets much less incidence of true severe. Does anyone happen to know why? Is it simple terrain/geography?

I was outside prior to the line rolling in, and you could feel the change before the rain ever hit. It went from a warm wind and humid day to almost instantly cooler with a cold breeze. We seem to do outflow-dominant well around these parts.

NWS mentioned yesterday that they've only issued 2 severe warnings so far in 2021, while last year we had 52 to this point. Seems like a country-wide effect, though. All measures of severe weather are way down from the averages, including >200 fewer tornadoes than usual. June and July are typically our biggest months so we'll see if anything changes over the summer.

Looking forward to interesting weather, though I would prefer some thunderstorms to track. Pretty dull spring so far in that regard. I remember last April we had tornado warnings overnight. Two confirmed tornadoes (EF1 and EF0). Intense.

Current model snowfall amounts across Allegheny county with lower totals northwest, higher southeast: SREF Plumes: Mean - 5" (ranging from ~3" to a little over 8") UKMET: 4" to 5.5" NAM: 2" to 4.5" GFS: 2" to 4" Para-GFS: 1.5" to 3" RGEM: 1.5" to 2" CMC: 1" to 2" Euro: 1" to 1.5" Mesoscale Suite - HRW WRF-NSSL: 2.5" to 4.5" WRF-ARW2: 3" to 4" WRF-ARW: 2.5" to 4" HRW-NMMB: 2" to 4" HRRR: 2.5" to 3" HREF Mean: 2.5" HRDRPS: 0.5" to 1.5" Given the spread of 0.5" to 5" or so, landing right in the middle at 2.5" to 3" seems like a fair measure. That's where the majority of the models land. UKMET and SREFs are the high-end outliers, with the latter typically overdone anyway. Also, important to keep in mind on a number of these, the higher end totals only register in the extreme southeastern area of Allegheny. Tomorrow morning looks like the best chance for heavier rates, and it is when we could pick up 50% or more of our end total in just a couple hours. Add on hours of "mood flakes" afterward. We have a northern stream kicker and dry air intrusion to contend with, plus the best forcing remains well south and east of our area.

If you're rooting for snow, time to hope the south trend stops immediately. The Euro is probably the southernmost model right now - at least in terms of shearing off the northwest quadrant of the precip shield - but it isn't pretty. The seasonal trend had been to deamplify systems and kick them south, prevent phasing, etc. It is possible we're headed back to that norm with the Thursday event. The NAM has been dropping this system south for four straight runs now. The GFS jumped from Athens, OH to Athens, GA in a 24-hour period. Like the last storm there are warning signs, including some of the misplaced upper level features, but we won't really know until we know.

Initial reaction to that 6-8" call is it's too high given the precip maximum on most models for this area hovers around .5" total. We'd have to average better than 10:1 ratios for the duration to hit 6" of snow. Under a couple decent bands that can inflate rates and maximize snow growth, that's possible, but I don't see support for it in the models right now. If you go into the detailed view, anyway, the local forecasts call for a "wintry mix." We're close on the NAM to that and maintain southerly winds for the duration, but we do stay below freezing at 850. This isn't the same low pass as yesterday - even if the initial trough position is similar.

This varies per region, but in Pittsburgh the watch is 50% confidence minimum in 6" over 12 hours or 8" over 24 hours (or 1/4" of ice). You're quite close! An advisory event is 3" over 12 hours, any freezing rain, or a "high impact" event. I'm personally relieved and need a break. I don't mind having stuff to track, but having them stack on top of each other only a couple days apart makes it a headache. It is quite difficult to resolve anything. Plus we're coming out of this with nothing significant, so that makes the time sink even more frustrating, at least for us "big game" hunters.

I can't figure out the NAM. The sounding profile says sleet, but the surface reflection shows plain rain. Possible it doesn't matter if it's overamped - although the only meso I can see with an all snow event is the WRF-NMM.

Yep. A more wrapped-up Tuesday storm, traversing into the 50/50 region, could lower heights in the east and thus provide a more optimal path for the system that follows. You can see in the mid-range GFS how the flow gets flattened by the early week events under blocking.

I'm noticing a lot of the short-term models are keeping the initial thump on Monday relatively dry. As that looks like the colder of the two "events," that could diminish the overall snowfall totals. Some models aren't showing a distinct break between the two, but I think a dry slot or period is fairly likely at this point.

Latest SREF plumes are only at 4.5 mean over the period. Not a great sign, either.

I said it in my last post, but the GFS has been trending this way for days. The increased probability of ice is only a continuation of that trend. Decreasing the confluence and influence of the arctic jet up north, while continuing to raise heights in the east with a larger southeast ridge. Here's the look from 0Z GFS back on Thursday: We had a fairly decent lobe pressing down and squashing the flow from the south, almost creating a due west-to-east wavelength. It also compacted the isobars much more concretely and you can see the distance between the lower and upper thresholds is much tighter. The other variable was the shortwave and in this case, it wasn't as deep. Then here's 12Z on Friday: We still have that lobe to the north and it is rather large, but now it is less compressed and has shifted to the west considerably, making it more susceptible to a southerly flow. We also have a much greater influence from the Bermuda high down in the southeast. The isobars are still compact, to an extent, so there was hope, but the overall trend was concerning. Now we come to 0Z today: The lobe to the north has not only elongated, but also reduced its suppressive force and opened up the flow from the south (SW to NE versus flat W-E). Part of that is deepening the energy in the central U.S. However, the westerly trend has continued slightly and the isobars have "opened up" to an extent, allowing for a fast flow of warm air from the gulf and points south. This is why the 850s will be corroded and potentially even the surface (as shown on the NAM). The 06Z NAM now gives us mostly rain with the Tuesday moisture. Caution there as the NAM may be playing its classic overamped card, but it remains a possibility and we'll have to monitor the HREF suite to see if that's worth a further look. If I had a choice between ice and rain, though, I'd almost certainly take plain rain every time. In the short-term vacuum, this is much harder to see. It helps a lot to look at the overall movement from days combined and get a sense of which way this is going. I was hoping the trend would've stopped last night but unfortunately it didn't, in fact continuing. Now we're rooting for a much less deepened and centralized system and something more akin to weak waves passing along the cold front to keep us all snow. That also means less snow, overall.

Agree with others I'd like to see that boundary a little further southeast. This isn't the typical "warm tongue" progression, but we have a screaming flow out of the south and the gulf as evidenced on the 500H patterns. There's also the issue of the atlantic ridging, perhaps enhanced by the typical "Nina" response to develop a southeast ridge. That ridge can be useful for us in Pittsburgh because it can shove the boundary further inland while warming the coastal plain, but there's also too much of a good thing. None of the models have been great with thermal gradients this winter, and this particular pattern is even more delicate. I wouldn't be confident in anything. We'll probably have to wait and see where the boundary sets up on Monday to really get a sense of how this goes. The GFS trends in the east have been to raise the heights along the ridge and decrease confluence or suppressive cold. That trend needs to go back the other way a little.