Monday, August 31 - Thursday, September 3, 2026 Convective Episodes

[weatherwiz]

The weather pattern across the CONUS the past few months has been dominated by a large ridge of high pressure across the southern Plains with the ridge centered within the New Mexico - Louisiana vicinity. This has resulted in a prolonged period of some extreme heat within this region while also yielding convectively active periods within portions of the Great Plains, upper-Midwest, and Ohio Valley region. Computer forecast models have been consistent in the eastward expansion of this ridge across the deep South with an eastwards shift in the ridge axis farther northeast, potentially into the Mississippi or Tennessee Valley region (this does greatly impact us). The shift in the ridge axis would push the periphery of the jet stream across the northern tier of the Great Lakes region and across New England. 

As we speak, high pressure is building into the region and will dominate through the weekend, however, late Sunday a weak cold front approaches from the north. Computer forecast models then stall the front within the region on Monday and this is where the fun begins. An unseasonably strong northwesterly flow is expected to overspread the region along the periphery of the upper-level ridge early in the week, meanwhile a more westerly surface flow (south of the weak stationary front) will advect warmer and more humid air from the Ohio Valley into the region. Multiple shortwave impulses will traverse the jet, originating from the upper-Midwest/Canada. This will offer the opportunity for multiple thunderstorm clusters to develop across southern Canada and the northern Great Lakes which and traversing the region Monday and again on Tuesday. The biggest key here is where will the instability gradient reside? Historically, this seems to favor New York, Pennsylvania, New Jersey, and perhaps far southwest Connecticut but this is going to be highly dependent on where that stationary front resides and how strong is the push of warmer and more moist low-level air.

The more intriguing day is expected to be on Wednesday. This is when computer forecast model guidance advances a sharper trough across southeast Canada with a cold front moving into the region at the surface with the stationary front perhaps lifting back northeast as a warm front. In addition, there have been some hints at the potential advection of remnant elevated mixed-layer air. In addition, flow aloft, particularly  in the lower levels is expected to increase and should the low-level flow become more southwesterly or southerly, this would result in a greater surge of moisture into the region and potential for moisture pooling. Within the warm sector, 850mb temperatures are forecast to climb to +17C to +20Cwith 850mb dewpoints +15C to +17C. This would yield potential for surface temperatures well into the 80's and surface dewpoints well into the 60's to lower 70's. This combination, potentially under the presence of steep mid-level lapse rates under the presence of an advecting elevated mixed-layer would yield potential for moderate instability (MLCAPE > 2500 J/KG) to develop. 

The combination of a moderate unstable airmass with increasing shear and forcing would net the likelihood for scattered-to-numerous thunderstorms developing during the afternoon on Wednesday; including potential for line-segments and supercells with hazards of damaging wind gusts, large hail, and perhaps even the risk for a few tornadoes if we can get some turning of the low-level flow and enlarged hodographs. At this time, the greatest potential seems to be across Pennsylvania, New York, and northwest New Jersey, however, this is all highly dependent on key surface features but western southern New England would definitely be in play. While the threat for strong-to-severe thunderstorms would gradually wane with the loss of daytime heating, showers and thunderstorms could work their way through the coast Wednesday night. 

Lots of details to iron out over the coming days!

[CT Valley Snowman]

A thread for severe in New England 3-5 days in advance, lol.  What could go wrong?  Seriously though nice write up. Wiz should work for the SPC, move to Norman, OK.  Live the dream in tornado alley.  Hopefully this produces, but I'm keeping expectations in check at this juncture.  We'll see how things set up as we get closer.  

[weatherwiz]

Tuesday shaping up to probably be a tornado outbreak NY/PA and maybe even including SW VT/W MA/W CT so long llvl flow is more southerly. 

[weatherwiz]

Tuesday may end up holding the day with most potential here for western sections. What happens on Tuesday may end up pushing the boundary well southwest on Wednesday and we end up very stable 

[Cyclone-68]

I’d usually decry a jinx thread for a threat this early until I remember my overall odds have been crummy all season anyway. So let’s do it! (CT/NY/PA/NJ) sigh….

[Typhoon Tip]

Wiz' is gonna have a thread some day that's titled "May 1st - October 2nd, convective episodes so plenty I'm totally bunning out"

[dendrite]

Da da da da da
It's the motherfuckin Weather W-I-Z

 

[Damage In Tolland]

Not looking like storms anywhere in New England now 

[Modfan2]

5 minutes ago, Damage In Tolland said:

Not looking like storms anywhere in New England now 

Yup, wagons south. Congrats NJ

[CT Valley Snowman]

I wouldn't completely rule out storms, but probably more elevated if they do occur and obviously the better chances for severe further SW based on current guidance.

[Damage In Tolland]

What a mess 

[Torch Tiger]

Tuesday looked the best a few days ago, now the whole period looks like crap

[weatherwiz]

Morning clouds/rain could certainly a bit of a damper on Tuesday but nonetheless the environment will be supportive so just have to see what kind of recovery can occur. Potential will be NY/PA/western MA/western CT. Unless of course the warm front can sneak a bit farther northeast but the Tuesday AM stuff probably negates that as well. 

[weatherwiz]

Lutchfield/Fairfield County definitely in the game for Tuesday on the 12z NAM. Right along the warm front and instability gradient and also perfectly positioned where shear/instability are maximized. This is going to be a really fun nowcasting situation 

[Cyclone-68]

Jesus….This summer blows like few others 

[Torch Tiger]

once we accepted there would be little rain and no storms, it's not too bad.  Hopefully SW areas get rocked Tuesday

[CoastalWx]

I don’t know, I think Tuesday and then Thursday could produce in some areas. Thursday may be best chance further east? But good trajectory especially on NAM. Good 850 theta e advection in Nam. 

[Damage In Tolland]

12 minutes ago, CoastalWx said:

I don’t know, I think Tuesday and then Thursday could produce in some areas. Thursday may be best chance further east? But good trajectory especially on NAM. Good 850 theta e advection in Nam. 

This is almost exclusively DXR South and west . May even miss CT entirely 

[CoastalWx]

14 minutes ago, Damage In Tolland said:

This is almost exclusively DXR South and west . May even miss CT entirely 

For both? I dont think so.

[Damage In Tolland]

3 minutes ago, CoastalWx said:

For both? I dont think so.

Not boring rains . I mean severe / storm 

[CoastalWx]

50 minutes ago, Damage In Tolland said:

Not boring rains . I mean severe / storm 

I could see pre dawn Thursday for sure having storms, but they’ll be some around Tuesday morning

[Damage In Tolland]

2 minutes ago, CoastalWx said:

I could see pre dawn Thursday for sure having storms, but they’ll be some around Tuesday morning

Won’t be holding breath 

[JACKASS]

1 hour ago, Damage In Tolland said:

Won’t be holding breath 

Please do!

[Damage In Tolland]

No storms unfortunately 

[weatherwiz]

Maybe a delayed but not denied situation with Thursday potentially being the day for some strong-to-severe storms.

But tomorrow is going to be a pure almost nowcast 

[Damage In Tolland]

Boring 

[CoastalWx]

1 hour ago, weatherwiz said:

Maybe a delayed but not denied situation with Thursday potentially being the day for some strong-to-severe storms.

But tomorrow is going to be a pure almost nowcast 

Yeah Thursday beat potential but tomorrow will have some. CT favored.

[weatherwiz]

4 minutes ago, CoastalWx said:

Yeah Thursday beat potential but tomorrow will have some. CT favored.

It's usually difficult for us not to get at least one day in when we have these type of setups. Tomorrow is going to be interesting to see play out, its been a heavy mix on how tomorrow evolves. A good part of CT may end up right along the instability gradient

[weatherwiz]

That is some environment that will be evolving just west of CT tomorrow afternoon and probably into western CT late afternoon/early evening. Guidance isn't showing a ton developing, forcing isn't particularly strong and looking at several soundings, the LFC is quite a bit higher than the LCL. With this said, that promotes an environment for discrete storms and any storms that fire in the afternoon could be particularly nasty. Probably not strong enough llvl shear for a strong tornado but not out of the question should a supercell become mature enough, especially when considering potential for boundary interactions 

[Brian5671]

2 hours ago, weatherwiz said:

It's usually difficult for us not to get at least one day in when we have these type of setups. Tomorrow is going to be interesting to see play out, its been a heavy mix on how tomorrow evolves. A good part of CT may end up right along the instability gradient

Quite the temp gradient b/w NJ and CT upper 80's to 60's eastern half of CT