purduewx80

can see it on this cam at the rockaways (when it zooms out especially....wait for it).

Suspect the enhanced risk for tomorrow (wednesday) will have to be expanded farther north into areas similar to today. Fairly good consensus among the early hi-res guidance for tomorrow afternoon, including the 00z NAMs, HRRR and RPM. A surface low is forecast to track W-to-E across the city (vs WNW-to-ESE today) during the late afternoon. It appears a squall line will eventually form given the strong unidirectional flow, but scattered supercells may precede it and produce a risk for tornadoes just W-SW of the city during the afternoon.

definitely concerned for union/middlesex, NJ and staten island since these will be riding that old boundary. cell mergers about to occur will also ramp up rotation on the southeastern storm.

yeah...surprised it doesn't have a tornado warning like the one behind it. definitely a well-defined low-level circulation. seeing the new cells pop up in the area supports the modeling that has indicated an increase in 850 flow this evening. that should help produce an uptick in the severe threat near and especially just W-SW of the city the next couple hours.

these dudes troll all year long, apparently.

that's the disturbance that will bring another severe weather event to the region tomorrow PM.

agreed. boundary from LI Sound is settling just S/W of Newark now. Severe cells fairly likely even on the cool side of it.

Definitely a large circulation there E/SE of Scranton:

lack of sfc-based instability means the mesocyclones w/ the supercells may spin up tornadoes where there are pockets of higher instability. that's a nasty hail core w/ the primary cell N of AVP. warned for 2" hail now.

Cell in NE PA should have a tornado warning on it. TDS showing up w/ 1-2 velocity scans showing a probable tornado. that cluster should end up riding the differential heating boundary/CAPE gradient/modified warm front SE towards us.

the cells to watch later will be those showers developing near the surface low upstate. those should ride southeast towards the city given the shear and instability gradient in place.

it's smart placement for the time being. plenty of time to expand it should instability build farther N/E during the late afternoon.

there's a thread.

latest RAP sounding for EWR valid at 22Z: it suggests the warm front mixes northwards quickly behind these last few showers/iso storms, which is certainly possible given 925mb flow turning SW'rly momentarily. you can see the warm front mixing northwards quickly on the latest visible loops, but its continued progression will depend on how quickly those cells out in central PA develop the next few hours. any large increase in those may slow the warm front down.

HREF (SPC hi-res ensemble) has a substantial signal for rotating supercells grazing the city late afternoon/early evening. Junky warm advection precip may continue over the city too long into the afternoon to get much sfc-based instability, but most of NJ/PA remains in line to see a severe thunderstorm outbreak later.

Right on top of the radome. Should be able to see it from the NWS office if on the ground (probably taking shelter though).

looks outflow-dominant for now. will probably help keep the warm front from surging through the entire metro.

fingers crossed this thing doesn't take out the KLOT radar. main hail core will pass north but there are some higher reflectivities beginning to show up farther south.

legit threat seeing what's out west and knowing that a lot of folks will be bbq'ing or at the beach today.

Strong heating ahead of the convective remnants in western PA should allow at least scattered thunderstorms to develop into the metro after 4PM. 12Z 3K NAM and RGEM, while not perfect, have the best handle on this activity and bring precip in after ~5PM. Mid- and low-level lapse rates may allow for a few wind gusts 40KT+ (isolated severe) during the late afternoon/early evening. Given the ~westerly flow, it's not unreasonable to expect these to persist into parts of LI as well. Also wondering if JFK sees its first 70F dewpoint of the year. Water temps are probably a bit too cool, but there is already some localized moisture pooling occuring there (66F Td vs 61F at LGA).

getting good pressure falls near and north of the warm front now, which is allowing the bubble high over chicagoland to to weaken and shift northeast over the lake. there is also subsidence behind the earlier convection, which will be replaced w/ lift and fairly widespread convection later in the evening as the LLJ increases. severe weather is possible but i'd think some flash flooding is probably the bigger threat across MO, IA, IL and maybe southern WI overnight.

Totally agree; 12Z 3km NAM may have the best idea, but nothing has really captured the warm sector staying as far S as it is now. That warm front will be hard to budge w/ the new sfc-based severe storms riding it.

New development showing up in PA ahead of the cold front (still N of BUF)....note the ACCAS streaming in just NW of this, which is often a harbinger of convective initiation. WV loops show fairly significant subsidence behind the first round, but it doesn't look to last long. The 18Z 3k NAM is probably a bit hot, but it seems to be picking up on this. I think at least a few severe storms are in store for PA tonight. Can't rule out something isolated making it to the city overnight.

the 00Z OKX sounding came in just shy of that. it looks like the incoming mesoscale convective vortex will use every bit of that to produce a stripe of heavy rain and embedded storms. new cells developing S-SW of the city now.

no shortage of rain the next few days. after this evening's showers, there may be another round in the area late tomorrow morning, followed by weakening convection late tomorrow night. sunday's system has seen numerous pieces of guidance trend towards the more northern system the euro has had for a number of runs now, as the west atlantic ridge continues to flex. there is still considerable spread (as indicated in the gefs guidance below), but a heavy rain event would appear to be a growing possibility sunday morning. the 18z euro pegs widespread 1-2" amounts in a true nor'easter, while the 18z gefs mean is up to 1.17".