MAG5035

I was looking back at the SPC mesoanalysis from yesterday and parameters were really not all that impressive outside of the shear and low level winds. I just don’t think we had sufficient enough mixing out of the boundary layer or daytime heating (lots of cloud cover) to really tap into much potential. DCAPE’s were only on the order of a few hundred j/kg. Standard CAPE’s were only about 500 or so at best down south where there were still a decent amount of severe wind reports. But I noticed from the SPC map ITT shared up above that they were all of the standard severe wind variety, with 0 tornado or 75mph or greater reports. Short range meso models were hinting at these limitations some which was why I was reserved on the severe potential a bit. I was still concerned some, I was figuring on a couple spin ups so I’m surprised there weren’t any reports at all. But would I have claimed essentially the weather rapture if I had 243k followers? Probably not haha. If we would have had the air mass we had last week when we were basking in the upper 70s- upper 80s in the Mid-Atlantic this absolutely would have been a much more significant event. At any rate, more locally mesoanalysis had a persistent area of CIN in the Lower Sus Valley. Low level stability is going to cap transferring the really high winds to the surface. The radars not very detailed on these maps but that was the cluster that popped a couple tornado warnings in MD before it moved into southern PA. This map is showing mixed layer CAPE (red), CIN (blue dashed), and effective bulk shear (wind barb).

The snow squalls are feisty today. Just had a nice one go through and put down a fresh half inch and take the temp all the way from 29ºF to 22ºF. The cloud wall in the background is the exiting squall

Synoptic stuff is done here. Most things blacktop stayed wet for the most part, but about 2.5” on pretty much everything else. Add some thunder snow and some gusty winds to that and guess I can’t complain about an event like that.

Yup, I’m out and about and I saw a lightning strike in Bellwood about 20 minutes ago. I-99 is a pretty rough drive right now visibility wise and the road isn’t even snow covered yet. Very windy with the heavy snow

Nah, starting to get a bit breezy now behind the front. Everything’s been under 30mph so far today.

FROPA occurred here around 330pm, temps back to 48ºF. There’s been some regeneration of the line associated with the front itself, in the form of some heavier downpours here. Pressure’s been bottomed out around 992mb for awhile as this is a pretty deep storm system. Now to try to reel in just the 2nd measurable snowfall in the last like 50 days. Upstream radars at PBZ and RLX (Charleston) look pretty solid. This is probably going to catch some folks off guard tonight.

HRRR and NBM snow totals this evening.

I think the bulk of the overall severe threat is happening right now with that line coming into the Sus Valley from MD and also the other part of the line further up northeast of State College. This was the time of the day the high res models have been surging the CAPE up and matching with the shear. The line with the frontal passage (now east of Pittsburgh) might not have much CAPE to work with.

Back this way, I think if the weather rapture were to claim me today it’s going to by the snow and wind that is looking more and more likely this evening behind the front.

Pretty solid couplet in the newer tornado warning to the northeast of Frederick. The business end of this line with imbedded QLCS looks to be headed for York/Lancaster.

Still trying to gauge the degree of which the severe potential gets realized tomorrow. High res guidance seems to be tightening the window when the best shear coincides with the surge of some modest CAPE into the Sus Valley, more in the late morning/early afternoon. HRRR looked like it was toying around with some discrete and/or quasi linear convection during that timeframe, while the 3k NAM doesn’t have much at all until the frontal passage. FROPA looked slated for roughly the 4-8pm timeframe west to east in C-PA. Discrete development out ahead depends on if there’s any kind of ample daytime heating via some breaks in the clouds, something I’m not quite sure happens in earnest in PA. Line with the FROPA will be more purely dynamics driven, but we’ll have to see how well it gets organized Also lost in all the attention to the severe is energy rounding the base of the trough during tomorrow generating a secondary wave of heavier precip riding up behind the front. So suddenly it looks quite snowy in at least the western half of PA early to mid Mon evening. This could drive a changeover to a period of snow all the way into the Sus Valley. Given the broad model support I’d be surprised if CTP didn’t at least headline the Laurels and north central Alleghenies for advisories. There’s support for the I-99 corridor as well. That will also be interesting to watch evolve tomorrow in addition to the severe threat. GFS vs Euro 3k NAM vs RGEM

The May 31st, 1985 tornado outbreak was more severe and remarkable than 1998 or any other more recent PA involved outbreak by a pretty sizeable margin. That outbreak spun up 43 tornadoes and killed 89 people (1000 injured) in PA, NY, OH and Ontario (65 alone in PA), produced PA’s only ever EF5 tornado (Wheatland), and also produced what I’m pretty sure was one of the widest tornadoes ever recorded in the US at the time (Moshannon State Forest). Couple screen grabs below but there’s some really informative links about this outbreak CTP’s 35th anniversary link- https://www.weather.gov/ctp/TornadoOutbreak_may311985 New interactive link they made for the 40th anniversary last year collaborated with NWS Pittsburgh, State College, Buffalo, and Cleveland https://storymaps.arcgis.com/stories/e8c12f670d5648a9b64877f42660eeeb

Count me in on this thinking as well, in PA at least. Certainly dynamics look very favorable in terms of shear/helicity, along with very high low level winds to tap down. Whether or not south-central/Sus Valley cracks all the way into the warm sector ahead of the front to take fuller advantage of those dynamics seems to be a main potential limiting factor. 18z 3k NAM never really builds much CAPE in the Sus Valley (cloud cover), having a narrow corridor of modest CAPE further west in the south-central counties. Newest high res model runs doesn’t look particularly organized with any kind of solid QLCS line, which would be the primary threat here over discrete cells… though I wouldn’t rule those out completely, esp with any breaks to help with daytime heating. As a side note the 18z 3k NAM was a prolific snow maker behind the front in western/central PA and other high res like the HRRR has at least a couple inches mainly in the Laurels/north-central. As another side note, this is occurring tomorrow literally one year to the date last year that we had a QLCS type line come through mainly the western and central part of the state with many tornado warnings and an 89mph wind gust at Latrobe.

I was just playing around with the archived radar data that’s on RadarScope Pro the other day. Here’s that tornado, that’s a pretty pronounced velocity couplet for 1998 NEXRAD data. It was roughly reading 110-115mph gate to gate on the data.

Yea sorry about that haha, I was exploring how far back the archived radar data went, that’s from 3/13/93. .