Newman

* Tornado Warning for... Southwestern Somerset County in south central Pennsylvania... * Until 245 PM EDT. * At 212 PM EDT, a severe thunderstorm capable of producing a tornado was located near Seven Springs, moving southeast at 25 mph. HAZARD...Tornado. SOURCE...Weather spotters reported funnel cloud. IMPACT...Flying debris will be dangerous to those caught without shelter. Mobile homes will be damaged or destroyed. Damage to roofs, windows, and vehicles will occur. Tree damage is likely.

The latest 1800z Mesoanalysis basically shows almost any CIN eroded. SBCAPE up to 2000 J/kg for much of Lancaster/York/Adams and MLCAPE up to 1000 approaching ~1500 J/kg. Bulk shear has very nicely increased as expected. Low level lapse rates have been increasing as well, LCLs are low (support tornadoes). So while CAPE is certainly not incredible by any means, it should get the job down with the ample shear. Damaging winds will be the primary threat, maybe an iso tornado later

There's a tornado warning out in far western PA for a lone supercell *Reported funnel cloud with it too

Another tornado warning out in western PA for Westmoreland and Fayette counties

I don't expect the tornado threat to end up materializing, but I could definitely see a bow echo roll through the Philly area similar to last May's event, maybe not to the extreme that was. But even with all of us socked in clouds, the CAPE values should be sufficient enough to support some severe storms and the deep layer shear will help to maintain any line segments. We shall see, I think the NWS and SPC did a great job with this expressing the possible dangers of the event, while also recognizing the chance of failure as well. We might be leaning more so towards "failure" here, but that's what comes with living in this part of the country.

Latest 1630z outlook still has the enhanced risk, shifted the tornado threat furthest east to the coast.

Tornado warning for far NW PA in Erie and Crawford counties

I can't pull up any current skew-t data (which sucks, MDT should send up a weather balloon lol). But the latest 12z 3k NAM has plenty of deep layer shear and a TOR sounding for the MDT region. In layman's terms... atmosphere go spinny, just need some sun...

Latest 1500z update has MLCAPE continuing to grow. Up to 1000 J/kg across Lancaster and a pocket of 1500 J/kg across the Chesapeake Bay. Those values will continue to spread north as the low-level clouds wear thin and the warm front lifts north (hopefully).

SBCAPE and MLCAPE continue to increase in coverage and intensity across the area, favoring eastern areas as of now

Latest 3k NAM (which is among all the CAMs that have been struggling with this event) has some gnarly storms later for the area. Even a PDS TOR sounding for @CoolHandMike

SPC meso site showing pocket of MLCAPE ~ 1000 J/kg around the Chesapeake Bay area and SBCAPE between 1500-2000 J/kg for much of MD

https://weather.cod.edu/forecast/ You can choose which model to look at, then click on the map itself once selected all the parameters to create a sounding

1300z Outlook

Here is a sounding for Berks later on. Notice there is AMPLE deep layer shear and a huge amount of veering in the lower levels. 61 knots of EFF Shear is insane around here! Plenty of SRH too. The problem is the amount of SBCAPE for the storms to tap into. Lots of low level cloudiness this morning. It's still very early though, so if we're still socked in clouds by 11-12, then I'd say the storm chances dramatically diminish. However, Mount Holly mentions that even if we don't completely clear out, there will still be enough MLCAPE to tap into As described above, the forecast is for the morning showers and isolated thunderstorms to slowly translate east. As this occurs a fractured stratus deck will start to lift. The stalled front currently near the fall line will also lift north as a warm front with rich theta-e air surging northwards. This recycled moisture regime will help to destabilize the region even if the stratus doesn`t ever completely clear. Both the GFS and NAM are indicating MLCAPE values of around 1000/1500 J/kg. Still though, the amount of available instability is one of the potential failure modes today (esp. if morning showers prove to be more robust than initially forecast). Generally though, during late July it doesn`t take much to destabilize the region. Early this afternoon the MCV will be approaching from the west with showers and thunderstorms across central PA. Ascent will increase across the region as the MCV approaches. Across the warm sector, effective bulk shear values of ~45 kts will be more than sufficient to support rotating updrafts. Some upscale growth is forecast as multiple cold pools start to be deposited and merge. The primary threats with these storms will be damaging winds, large hail, and an isolated tornado (thanks to slightly back southeast flow and impressive directional shear).

All depends on what happens tonight and tomorrow morning. The DCA AFD explains it best. Short answer is yes I do think a tornado watch is likely tomorrow afternoon and evening. The environment in the wake of the leftover convective debris as the convectively enhanced speed max moves overhead is concerning. Models such as the NAM and Euro spread a belt of 40-50 knot flow in the 700-500 hPa layer over the northern half of our CWA by around peak heating. If we were to destabilize and storms were to form in that type of environment, the potential is there for a significant severe weather event, with very high winds, large hail, and tornadoes all possible. However, there`s considerable disagreement amongst the various models as to if and where storms will form in the wake of what`s left of today`s Upper Midwest system. Strong MCSs are often not handled well by both the CAMs and global guidance, and any system that forms today will have a strong influence on our weather for tomorrow. As a result, confidence in the evolution of storms tomorrow remains low. Confidence should gradually increase over time as today`s system gets going and becomes better handled by model guidance. We`ll continue to refine our forecast for what is a low confidence, but also potentially high impact severe weather event tomorrow.

Some showers/storms popping up across the area

Overall tornado threat for tomorrow shifted south on the latest Day 2 outlook

Tornado threat increased for everyone in the latest day 2 outlook

This is from Mount Holly AFD, they mention that morning convection or cloud debris could make tomorrow a non-event (especially for eastern areas). So, that'll be the wild card as is typically the case in high-end severe events around here. If we can have the MCS/derecho forming in the upper midwest tonight clear out of the region early AND we can limit any morning convection associated... tomorrow will be the best day yet this year in terms of severe storm chances. I'm already thinking about chasing out in Adams/York/Cumberland/Perry counties tomorrow With those caveats mentioned, the dynamics on Thursday are no doubt impressive, unlike any we`ve seen this year in terms of the potential overlap of instability, shear, and forcing if everything comes together right. 28.0z CAM guidance largely clobbers the region with severe convection Thursday afternoon and evening, but run-to- run consistency has been poor. Should several of those 0z CAM solutions (i.e. 3km NAM, ARW) and their associated forecast soundings come to pass, then a significant severe weather event with all severe hazards would be likely. The Storm Prediction Center has added a Slight Risk of severe weather over much of the region. Feel that is very reasonable at this stage, and highly recommend referencing the SWODY2 discussion for additional information. We should stress again that confidence in the details of the Thursday forecast is low, but encourage all users to monitor the forecast due to both the uncertainty and the higher than normal potential threat level if all factors were to come together

3k NAM sounding for Adams county tomorrow. Curvy hodograph, lots of deep layer shear!

Massive PNA spike coming up will introduce downstream troughing across much of the NE US. Cooler weather and lower dew points to end July/start August with a NW flow. Some rain chances will keep temps down too.

Severe storms tomorrow, tornado threat too