Newman

Tornado warnings popping off in NE PA. Supercell trying to develop in Berks right now

"The leading edge of a 50 knot mid-level jet (centered around 5-6km) has been sampled by the CCX VWP within the last half an hour. As this overspreads the warm sector, shear will be in place for storm organization, including supercells. Damaging winds will be the primary threat, but some large hail and a few tornadoes will also be possible. The greatest threat will be across southeast Pennsylvania and New Jersey, where the greater instability is in place. However, as the warm front lifts northeastward, the threat could extend into southeast New York and Connecticut this afternoon."

All of the parameters are solid across eastern PA right now and will probably keep improving through the afternoon. But, just like Saturday, there just seems to be too much going on. Will see if that activity in western PA is able to tap into the favorable environment in eastern PA or not, the cloud coverage is really suppressing low level lapse rates rn. Which is ironic because mid level lapse rates, which are usually paltry, are great.

Once again we failed because 1. Early morning WAA crapvection and 2. Too much forcing for ascent driven by a strong synoptic system, which ultimately leads to clusters of storms every which way simply occupying the same spaces. It's the same problem we had with the Moderate Risk bust a few months ago. Too much convection.

That activity will more likely than not become outflow dominant by the time it reaches the Lehigh Valley. Maybe some embedded spinners, but more likely a damaging straight line wind threat

3000 MLCAPE/5000 SBCAPE creeping into Philly now. Low level lapse rates also finally looking somewhat decent too.

You can find the warm front pretty clearly on the latest 18z SBCAPE mesoanalysis. Surface obs are also evident... middle 80s in York, southern Lanco, Philly right now, but low to middle 70s still across the rest of SE PA. I do think this warm front will continue to lift northward but I don't have much confidence in how much in the next 3-4 hours. Some of that messy cloud debris near Harrisburg appears to be thinning out as it slides eastward, and we're getting more sunshine across the Lehigh Valley... All of that to say I think the Trenton/KOP/Philly area will maximize instability and low-level shear just south of the warm front. We shall see...

Satellite and radar imagery definitely getting that "look" west of Florida with the MCV that is moving offshore. Mid-level rotation quite evident. NHC bumped odds up to 10/30 at 2PM. 12z Euro, GFS, Euro-AI all pinwheel this area of vorticity northward tomorrow up the West Coast of Florida

The trough in the east should quickly pull whatever develops down here northward. Maybe 1-1.5 days over water in the northeastern Gulf

Northeastern Gulf of America: An area of low pressure is expected to form during the weekend over the northeastern Gulf of America. Subsequent slow development of this system is possible while it moves slowly northeastward over the northeastern Gulf and or near the southeastern coast of the United States by early next week. * Formation chance through 48 hours...low...near 0 percent. * Formation chance through 7 days...low...20 percent.

..Mid-Atlantic... Farther downstream, scattered to widespread heavy rainfall will be focusing along the wavy, east-west orientated frontal boundary draped over the northern Mid-Atlantic states and offshore south of Long Island. Back building/training of slow moving storms capable of hourly rates rates greater than 2 inches/hour will track across eastern Pennsylvania and New Jersey this evening. Guidance is signaling areal averages of 3 to 6 inches with local maximums of 8+ possible along this corridor. The latest guidance maintains focus of the highest probabilities for the intense rain rates and higher QPF over central to eastern PA, portions of central to northern NJ, and far northern Maryland. The combination of some terrain areas and the highly urbanized corridor makes this area much more vulnerable to flash flooding. While there remains some spatial uncertainty to exactly where the greatest rainfall will occur, the setup favors locally significant flash flooding with the Moderate Risk over eastern Pennsylvania and north/central New Jersey embedded in the Slight Risk that now spans from northeast Indiana and southeast Michigan (including Detroit) through the Mid- Atlantic Coast from NYC to central Virginia.

Allentown gusted to 50 mph with this line moving through, Mount Pocono 54 mph, Lancaster 47 mph, Reading 47 mph

Well the NWS has implemented new policy/guidance that has completely stripped the human input in forecasting for days 4-7. And even days 1-3 are heavily produced based on the NBM. Take a look at the NWS Billings AFD from 3 days ago and the note at the bottom: https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=AFDBYZ&e=202604081847 So certainly the SOPs for forecasting in the NWS have completely changed. Now we're basically hitting the "send" button on whatever the NBM comes up with. And I can't emphasize enough how BAD the NBM was this past winter in many of our snowstorms. It is inherently a poor model to forecast with when you have short term model disagreement OR when you are dealing with a 90th percentile or 10th percentile type storm. The NWS Mount Holly office was still forecasting 18-24 inches of snow the starting day of the late February snowstorm out in its western CWA. And sure enough nobody saw more than 4-5" of snow. Why did this happen? Because they relied on the NBM which lags in data and model cycles AND weights certain models. Forecasting accuracy will plummet in the NWS until they figure out how to better implement the NBM and/or develop it.

The wind right behind the low-topped line is gonna roar for some. KLNS is up to 45 mph sustained and gusting to 60 mph. Brother in Lancaster just lost power

Latest Day 2 from the SPC. 45-60% hatched wind for most, greatest tornado risk is just to the west across south-central PA where a 10-15% hatched risk is outlooked. Given the extremely high shear but low cape environment, damaging QLCS winds will be favored but there will be line mergers and perhaps a few lone cells capable of a stronger tornado. The failure modes I'm seeing are 1. Given the potency of the upper-level trough, there may be "too many" showers and storms developing and competing with each other pre-frontal 2. Early day clouds and showers will limit destabilization 3. Strong southerly winds may or may not create a localized "minimum" in severe weather across SE PA where a narrow marine layer could advect off the Chesapeake Bay Regardless, we haven't seen a severe weather event of this caliber in at least a few years. It will get very cold again behind the front, so make sure if you lose power you have a plan