Newman

LOL this might be a bit too much, taken from Mid-Atlantic forum

Latest 11am NHC cone continues to nudge further west

The sun continues to peak in and out here. CAPE on the increase

Latest 12z Hurricane tracks

Yeah for Central PA, it would take a miracle and a half to get any impacts (other than maybe some breezy conditions?) from Henri. But very fun to watch evolve regardless, SNE and perhaps even as far west as NYC are still very much in play as of now. More hurricane spaghetti models continue to show that capture and tug back west. GFS and UKMET are on board.

Posting this not because I believe it, but because it's funny and deep down we're all weenies... HMON captures future Hurricane Henri into the coast. The GFS is similar, only it captures it into SNE. Same with the UKMET. Whether or not the Philly region gets any impact is up in the air (leaning hard no as of now), but fun to watch it evolve

I think much of South Central PA has a chance at something significant later today, but Harrisburg is probably the bullseye spot to be.

Where the most shear and CAPE overlap... Leads to parameters like this: And ultimately the chance for something like this: I would never call for tornados, that's something you simply can't do. Look at that severe event a few weeks ago that looked great for tornados: it ended up missing our area but smacked the Jersey and Philly area. Simply put, every CAM is pointing towards lots of shear and helicity with the remnants of Fred tomorrow. In the warm sector, discrete rotating cells are a real possibility. There were 13 tornado reports out of the SE today -> That's heading this way tomorrow (does it remain as potent or weaken?). Each NAM and HRRR run today kept to the idea of potential tornados tomorrow, the scariest part being the timing leaning towards dusk and overnight. In 24 hours we'll see if they had the right idea or not.

Mount Holly on tomorrow: With impressive curved hodographs and low-level helicity values from 200 to 300 m2/s2, there easily could be a quick spin up tornado or two. Again, this depends on the exact track of the low and how much surface heating we can realize tomorrow. Shear and helicity may be enough to overcome the low CAPE values generally less than 2000 J/kg across the region.

For you New England tropical chasers, a great trend on this GFS run. Stronger ridge sprawling further east and that weak trough on the EC trying to pull it back to the coast is similar to what Yakkov said in his tweet regarding the 1938 Great New England Hurricane. Slowly stepping towards putting an even bigger eye on Henri...

The 18z GFS is trying to have that weak trough/Upper low on the East Coast pull Henri back in like the ICON did, not quite as successful but 100% trended that way. Stronger ridge over the top and everything. This run might possibly be a hit.

18z 3k NAM not backing down, in fact it increased the already impressive bulk shear values and storm relative helicity values from it's previous run. And my God, SCP of 20.2 and STP of 6.2. I know the NAM is notorious for overhyping these types of things, but look no further than what we're seeing in the SE today for what could be instore for us tomorrow

If these CAMs come to fruition for tomorrow, there's a legit tornado threat for much of the Lehigh Valley towards the evening. Sounding below is for Berks county, there's some PDS TOR soundings coming out of Harrisburg on the 3k NAM. With ample daytime heating, along with a remnant tropical system moving to our west putting us in the warm sector with increased Storm Relative Helicity and Effective Shear... yeah it could mean lots of rotating cells like what we're seeing in Georgia and South Carolina today

Latest 12z EPS spaghetti plots for Henri, continues to trend a bit further west. Some members are even trying to hook back west. At the minimum, lots of rough surf along the Mid-Atlantic and New England coasts. The Euro camp seems to be on the weaker side of most guidance as of now, compared to the other global models and the hurricane models.

All depends on this large cyclonic flow and deep trough in the North Atlantic which is ultimately creating the weakness for it to escape. You would need it to not only be weaker for an even more conducive environment, but also move east. That would allow for the ridge to build over the top and to the east, possibly blocking it from moving out east. This past 12z run was not as favorable if you want a hit, with a deeper and stronger Upper low feature and a weaker eastern Canada ridge. Not to mention that low barely moves and sits/spins in place.

Thank you all! As a met student, I try my best to learn on my own and equally try to convey the information to the public in a detailed and scientific, yet clear and understanding way. I'm just here to help everyone stay informed, plus I love sharing info as well. Just as another note, there have been some tornado warnings down in the south this morning with "radar confirmed" tornado messages. Plus some confirmed tornados and damage across Georgia yesterday with Fred. We'll see if that all can or will make it's way up here tomorrow. Now to play devils advocate, its also very possible the primary low tracks too far east and many end up with 1. Just some moderate rains or 2. A brief period of rain and nothing after. In a time of the year when the weather seems to slow down and eyes turn towards the tropics, it's nice having something to watch.

As of now, just a slight conditional 2% risk from the SPC, which I would agree with. It won't be a widespread event and is highly dependent on track among other factors too. But absolutely worth keeping an eye on, any time you have a tropical system (even a remnant one) track to your west, you have a shot of tornados.

As I said above, the HRRR is not too dissimilar from the NAM. The difference is timing, where the HRRR brings storms in around ~5pm compared to ~10pm on the NAM. Still very curvy hodographs with lots and lots of veering up the column in the low levels, plenty of effective bulk shear (over 50kts!). LCLs are low, which help to favor tornado formation as well, and MLCAPE is solidly in the 1000 J/kg to 1500 J/kg range (although it wouldn't hurt if it was a bit higher).

Lets not sleep on tomorrow (literally). With the remnants of Fred moving in, lots of shear will be in place. And unfortunately, in the evening and towards the overnight hours when some might be sleeping. The 3k NAM has some impressive hodographs showing up in the area, the one below for Harrisburg with a PDS TOR sounding. The HRRR is in the same boat as well with discrete cells ahead of the primary low pressure system. Surface warming during the daytime may allow for sufficient CAPE for a sneaky tornado or two, although it'll ultimately depend on the hourly track of Fred and where it decides to go. Not often, if ever, you see a nocturnal tornado threat in this part of the country. We shall see...