MAG5035

Definitely mixed feelings as I’m def excited for the event from a meteorological standpoint but on the other hand not too enthused with the likely major flooding impacts around here (and everywhere else) if we in fact see those 4-7”+ amounts back here in the more mountainous ridge and valley region.

I know earlier Cantore was wondering aloud on his live report earlier if the entire city being out took out some/most of the pumps that’s take care of getting storm water out. It’s been reported that a transmission tower failed taking a line down over the Mississippi. Either way, I’m sure there’s portions of the city that are having problems with flooding just from the excessive rainfall. As bad as things are, the center coming up just west of New Orleans instead of taking a Katrina like track just east should be keeping major surge off of the Ponchartrain levees, which was where a lot of the 2005 failures were (obviously much improved now) Instead, the major surge is on the NW corner of Lake Ponchartrain with the northern and eastern eyewall going up just west of most of the metro area. At this point of the storm, the fetch is southerly or away from the Ponchartrain shoreline in New Orleans.

Here’s the Hr 90 frame, which I chose 1 hr QPF to show roughly where the precip shield still was. And here is the 48 hr QPF total to that point, most of this falls in 24hr back where these extreme totals are in the central counties. That’s definitely the most extreme of the model suite I’ve seen for sure, and I hope it is being a bit too over amped.

I was just looking at the 18z Euro and its QPF output, which wasn’t even done through hr 90. This area back here would be in big trouble if we ended up with something like that, wow. While the Sus Valley had Lee more recently as the last major tropical flooding event, gotta go back to 2004 with the one-two of Frances and Ivan in a one week span back in this part of central PA for historic tropical related flooding. The 7.55” and counting the 18z Euro put out at KAOO would probably amount to something worse than even that if that actually came to fruition.

Ida definitely represents a pretty significant flooding threat for the area, especially for the southern half of PA. Talking big picture of our region as a whole, we’ve been fairly wet as of late.. with the remnants of Fred being the big recent rain event. We’re not saturated, but flash flood and headwater guidance are such that a 3-6”+ type event would likely send tributaries to moderate or major flood categories. For example, here’s today’s headwater guidance in CTP region. So this shows the estimated rainfall to reach each category (minor, moderate, major) at 1hr, 3hr, 6hr, and 12hr timeframes. The Swatara at Harper Tavern for example would need about 5” in 12hrs to reach major flood stage.. definitely doable with the numbers the models are cranking out. Big key as always, track of what will be probably either a depression or remnant low once it gets to us. Track of the low just underneath PA in this setup puts at least some part of our region into where what’s left of the core tracks through, and that’s where the business end of this potential major rainfall and flooding will be at. Given how organized this hurricane was (and still is), it’s likely to maintain a notable core remnant. That is where within the overall event you could see say 2-4”+ in under 6hrs, which would deal major issues on small and some bigger tributaries. As far as the main stem Susquehanna, its going to depend on the location of the swath of excessive rainfall. If it targets southern half of PA like the Euro does, it doesn’t quite get the whole basin and might not deal much more than minor flooding on the lower end of the Susquehanna main stem. If it tracks more like the GFS seems to have today, which catches more of northern PA and all the West Branch and Juniata basins.. response on the main stem would likely be more significant.

Didn’t have too many major issues locally today, despite having some pretty significant rain totals along and east of I-99. Doppler estimates right over my house are in the 1.5” or so range, which seems about right as I had the first band that triggered the early flash flood warning just to my east only briefly. CTP noted in their disco earlier that KAOO saw over 2” in 40 minutes between that 12-1pm hour. Did some driving in the large area of 3-4” (purple and blue) this afternoon as well as in what ended up being the eventual local bullseye of 4-6” in NW Huntingdon County. Surprisingly I didn’t come across any major flooding issues or impassable roads, just a lot of washouts and decent run off. It hasn’t been overly dry around here but it also hasn’t been wet either, thus I think the ground and vegetation was able to mitigate what can be a pretty major flash flood event with precip numbers like that in a 6-12 hr span. Both Frankstown and Little Juniata branches of the main stem Juniata River easily stayed below flood stage despite the gauge stations being right in that 3-4”+ area.

That might have been the one storm with the couplet I made a post about earlier back on Page 176 when it was south of Halifax at the time.

The storm just west of Marysville is showing a half decent couplet. There are several areas in these line segments in the LSV that have these couplets. A lot of times in these tropical system situations the couplets present more as a velocity max rather than really seeing a true couplet (with notable opposing velocity) A quick spin up can’t be ruled out with them but the bigger possibility would be potential severe gusts or at least non severe “tropical storm force” gusts.

I just had one of the bands come through a little bit ago, and it was very intense. That band is now just east of town and it is likely to trigger flash flood warnings (surprised it hasn’t already) as the motion is starting to align with it’s orientation. In other words, basically training south to north over the same general corridor with very slow overall propagation towards the east/northeast. It’s also trying to fill back in here some.

I should be able to make some obs and discussion as this unfolds tonight and tomorrow. Since I literally sat on the edge of the precip with Isaias pretty close to this time last summer, it’s been awhile since I’ve had a decent tropical remnant event come right through here.

It looks like the HRRR smoke product works most of it out later tomorrow with the passage of the shortwave trough... at least at the low levels anyways. After the brief shortwave passage, we continue to be under the general influence of the sprawling 500mb ridge that has been sending it over here. So while it might not be the lower level stuff that is currently causing degraded air quality over a pretty widespread area of the northeastern US, we might continue to see it in the upper levels later this week.

The obligatory “it’s smoky out” pictures. I'm also surprised there isn't an air quality alert in this particular area. It's currently in the "Unhealthy" category with 2.5 PM at 153. Pretty rare for those type of issues around here.

With it looking to dry out some, it appears the big weather/atmospheric story in our area for at least the first part of the week is going to be a significant amount of wildfire smoke overhead. Which by the way, I don't ever recall this happening anywhere close to as often as it has in the past two summers. Full loop HERE There's also loops for near-surface, 1000', and 6000' AGL on the NOAA site, which the HRRR also eventually shows into PA the next couple days at those levels. Kinda surprised CTP disco didn't have any mention about it today.

It almost looks like the circled portion of the line is taking on the signature of an MCV.

Yea everything's good, I'm just a lot busier during the summer months and don't get a chance to post as much as the wintertime. Other than a pretty significant flash flood event in town on the morning of June 10th (3"+ of rain in an hour) we were having a really quiet summer around here severe wise (non-existent) until this past week. Wednesday's severe weather did a lot of tree damage in some parts of town and especially the next valley over. I wonder how @Cashtown_Coopwould feel having to clear 50+ damaged trees off the course 3 days before a golf tourney haha. https://www.altoonamirror.com/news/local-news/2021/07/volunteers-flood-sinking-valley-course/

He'd probably know first hand since it looks like the center of that couplet passed over the part of town where the university is. There's def good low level rotation but velocities aren't super high and the couplet isn't really tight with opposing high velocities. I'd still say there's a good chance of a weaker tornado being spawned in there and definitely some severe winds at the least.

Fresh tornado warning issued for the section of the line over Lock Haven. Pretty decent couplet showing back up. I believe this was the portion that had the pronounced hook/couplet a little while ago. This is pretty close to CCX so the radar's getting a pretty good look at the low levels.

I wasn't sure how well that was gonna work since videos are always hit and miss posting on here if its not a youtube link or something like that. I can see it on my phone and laptop.

I think the line probably makes it but it does seem the real business part of that line is gonna go north. Very pronounced bow on velocity working from just east of State College down to just below Lewistown and that seems to be generally pressing towards Sunbury/Selinsgrove.

Above post is a quick time-lapse of the severe warned storm I just got right after it passed north.

IMG_3583.MOV

I haven't seen a legitimate thunderstorm all year around here until an hour ago. That stuff coming towards State College means business.

Yea I thought that was pretty wild. It makes me wonder what the air quality was like here back in Altoona's Pennsylvania Railroad heyday.

All the local fireworks backyard and otherwise this evening actually made a noticeable impact on the Air Quality monitor here with the combination of Altoona being in a valley and a bit of a temp inversion with some mostly clear skies and cooling tonight, trapping all the smoke and etc and making it pretty hazy here right now. The PM2.5 really shot up after dark. Edit to add a current outside pic (3 sec exposure)

Fun fact about the run of record low maxes in 1972. That actually occurred during Hurricane Agnes as the tropical system was absorbed by an anomalous trough and associated mid-latitude system over PA. That whole mess sat and spun over us for days, leading of course to all the insane rain totals and flooding. With the historic flooding obviously being the most memorable aspect, it's not often mentioned how chilly it actually was during most of that event in central PA.