Newman

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

As I talked about yesterday, the PNA spike will result in downstream troughing across the Eastern US. The Euro and GFS both have some sort of coastal storm (weaker as of now) as a rather strong upper level jet streak will likely introduce cyclogenesis in the right entrance region along the coastline. It's very similar to something you'd see in winter, not as often in July/August as it's tough to get troughing all the way down to the Gulf Coast.

Cooler stretch incoming to start August as a massive PNA spike will subsequently produce lower heights downstream and a NW flow across the NE. Fall is coming and I can't wait!

*I am posting this as advice as we head closer to winter and in general. I posted this all in another board (NYC-centric) and wanted to share here too* This is why using pre-1980 analogs simply do not work anymore in the warmer climate we now have. First of all, you have to take into account most NOAA/NCEP reanalysis data compiles anomalies based off certain climate eras, most notably being 1981-2010. So, here I will show you a very simple graph demonstrating the increase in temperature at the KJFK location since 1950: So, obviously even a 2-3 degree increase will skew anomaly results dramatically. I went through Quasi-Biennial Oscillation data and pulled out all the winter years that featured moderate to significant averaged -QBO values (magnitudes of -10.00 or greater). I sorted them by 1950-1990 and 1991-2020. There were 10 cases I pulled out for the earlier time step and 7 for the more recent one. *Disclaimer* -> I am aware that synoptic and global atmospheric conditions are more than just dependent on the QBO. However, it has been postulated that -QBOs typically feature/favor lower averaged 500hPA heights over the United States and higher averaged 500hPa heights over the higher latitudes. Below you'll see the resultant maps: My first thought when comparing these maps was the obvious smearing of much lower heights all across the board in the 1950-1990 time frame. Why is this? Because of a changing climate. You CAN NOT compare early early years in available data sets to current 1981-2010 climate averages. You will skew everything towards lower heights/colder averages. It's as simple as that. Also, it would be hard to dismiss there are *some* similarities to the two. Noticeably the lower averaged heights in China and Europe. However, it becomes increasingly difficult to distinguish whether or not the placement or trends of higher heights is by chance or reason. In the 1950-1990 map, the usual '-QBOs create higher heights in the high latitudes and colder weather in the mid-latitudes' notion could be supported by the data (however, perhaps caused by the skewing therefore not supporting it). In the 1991-2020 map, it is very hard to pick out any lower heights/colder areas in North America. Regardless of it all, if anything this exercise goes to show that analogs from before 1980 (that might be generous, maybe even 1990) should not be used or compiled into modern era anomaly maps/charts/graphs to avoid unnecessary skewing. I know lots of y'all know this, however if you go around on twitter or other boards and come across this... please ignore whoever posted it.

Beautiful evening for a hike, gonna miss these past two days come next week

The vertically integrated liquid (VIL) on that cell is insane, well off the charts. Gotta be some large hail in that core, plus the velocity signature shows some strong winds

They just upped it to 80!

Montgomery and Bucks storm is warned for 70mph winds and 1.25" hail

Storms completely split me here in Millersville, not a single drop. Heard some thunder though

Excited for this cold front to come through that's in north central PA right now. NW flow and low dew points the next two days. Yes please

Severe watch up

Did you make these graphs yourself? If so, did you use Python, Excel, or something else? Nice work regardless, and interesting to look at

Looks like Low level lapse rates will slowly improve through the day as the residual cloud cover from the east continues to burn off. That's almost a given, the surface heating will almost always bump LLLRs to >7C/km range. MLLRs are forecast by the RAP to improve throughout the day as well, into the evening. In fact, the SCP is expected to increase from the already high value its at right now, likely aided by the increased lapse rates. Same with helicity values.... basically what I'm getting at is things are conducive for tornados later. Whether or not we can get any is of course the big question. With the cold front approaching from the west, only into the Indiana region, I think western areas will see the greatest area/influence of enhanced frontal lifting so hence why much of the CAMs keep convection further to the west. We'll see though, I'll be keeping an eye out. It's been active here in Lanco recently, that's for sure

Bulk shear values are actually pretty impressive compared to previous days across PA. I picked the Harrisburg area as a pinpoint for SPC tornado climatology, the red bars represent current values. I'm not expecting any tors per-say, but low LCLs, high bulk shear, high supercell composite values, high CAPE, high STP values means it's certainly not out of the question. Problem always seems to be mid-level lapse rates around here, they are on the meager side if you're looking for something to nitpick and enjoy severe weather.

It's gotta be like 5 of the last 7 days the Berks/Lehigh Valley have been under a Severe Thunderstorm Watch. Can't remember the last time we've been under such a consecutive streak of possible severe days.

The one warning is for 80mph winds geez

Tornado risk for much of west central PA today

That storm in Bergen/Rockland counties is warned for 2 inch hail

Heading backpacking tomorrow-Sunday. Don't need Elsa to ruin things and rain on me. Keeping things I-95 SE is fine with me.