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Tuesday, July 12, 2022 Stupid Severe Potential


weatherwiz
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Not even sure why I'm making this thread because it really is stupid and this summer sucks. First off, this isn't going to be a widespread severe weather threat and event, ok. I mean those don't happen around here very often. So when one gets excited for severe potential you're doing so with the understanding that you're really just hoping to see a thunderstorm and anything else is a bonus. But anyways, this sucks, this summer sucks, but on Tuesday...yeah there is the chance for thunderstorms and the best potential will probably be western Massachusetts and western Connecticut because the stupid timing looks too freaking slow...as always. 

Anyways on Tuesday shortwave energy rounding the base of a longwave trough will move across southeastern Canada and northern New England with a cold front at the surface. Ahead of the cold front it will actually be quite warm and humid with temperatures climbing well into the 80's (cooler for you mountainous folk and for those who live under a forest). Dewpoints will continue to climb through the day into the evening so highest dewpoints will likely be towards evening. While crappy mid-level lapse rates (b/c that's all we freaking get is stupid, garbage mid-level lapse rates) will hold back how unstable we can become, combination of temperatures into the 80's and dewpoints pushing through the 60's should contribute to 1000-1500 J/KG. Note: Despite the loss of surface heating moving into the evening the increasing dewpoints will offset this to keep the CAPE in place. 

Shear...shear is actually pretty strong with as much as 40-50 knots of bulk shear modeled. This is unseasonably strong and would help with thunderstorm organization. There may even be enough low-level shear present to warrant the potential for a tornado, especially in any discrete storm. but let's remember THE GREATEST POTENTIAL IS WEST B/C EVERYTHING SUCKS. 

We should see one or multiple lines of convection develop and push towards southern New England during the evening. We will see this weaken and given the stupid weak lapse rates and modest deep CAPE lightning probably won't be much. 

Stupid but we'll see. Let's just get this over with. 

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Actually you know what...is there really a true warm front which lifts north? I can't find anything really supporting a warm front. I guess the advection of the higher theta-e airmass is just due to the developing southwesterly flow ahead of the approaching trough? 

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9 minutes ago, Torch Tiger said:

HRRR looks decent

It's a bit faster with the timing but this may be due to the fact that convection forms ahead of the pre-frontal trough as opposed to the cold front which is typically the case anyways. We actually have a quite a bit going for us, but because the mid-level lapse rates are so weak and mid-levels relatively warm this really cuts back on the overall potential. While widespread severe is certainly not happening there may be some localized intense storms. Wind shear is very strong aloft with some indications of winds backing a bit in the llvls. Storm mode will be predominately linear but an embedded supercell would be possible. 

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6 minutes ago, weatherwiz said:

It's a bit faster with the timing but this may be due to the fact that convection forms ahead of the pre-frontal trough as opposed to the cold front which is typically the case anyways. We actually have a quite a bit going for us, but because the mid-level lapse rates are so weak and mid-levels relatively warm this really cuts back on the overall potential. While widespread severe is certainly not happening there may be some localized intense storms. Wind shear is very strong aloft with some indications of winds backing a bit in the llvls. Storm mode will be predominately linear but an embedded supercell would be possible. 

with the relatively fast low and mid-level jet, I'd probably argue for slightly faster timing, or at least watch for it. If there's a squall line coming out of NYS or VT it'll be moving along pretty good

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9 minutes ago, Torch Tiger said:

with the relatively fast low and mid-level jet, I'd probably argue for slightly faster timing, or at least watch for it. If there's a squall line coming out of NYS or VT it'll be moving along pretty good

That is certainly true but with that you run the risk of the thunderstorms outracing the better shortwave forcing. But looks like we'll see another two line scenario with one line impacting PA/NJ/NYC and the second line NYS through southern VT, NH, and parts of MA. 

If we had steeper mid-level lapse rates (even ~6.5 C/KM) and mid-level temps weren't as warm I think we would be dealing with a much higher potential. 

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3 minutes ago, Cyclone-68 said:

Not a pro obviously but it’s difficult to imagine any “exciting” severe chances in our current weather pattern?

ehhh it's a bit more complex than that. There are aspects to this pattern which actually would favor some more exciting severe chances but there's persistent features which are mitigating that potential. For example, tomorrow. That's an unseasonably strong mid-level wind field overspreading the region with the flow WSW. While the cold front is not terribly strong shortwave forcing actually is pretty solid along with height falls.

But because mid-level lapse rates and mid-level temperatures are so warm this will significantly reduce upward parcel acceleration which will ultimately result in weaker updrafts. Surface CAPE will be high which will assist in convection rapidly forming once the ConvT is reached but once parcels rise above a certain level the acceleration upwards will be slowed significantly which will hinder deep convection from being established. This will be shown very well with the degree of lightning density tomorrow. 

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3 minutes ago, weatherwiz said:

ehhh it's a bit more complex than that. There are aspects to this pattern which actually would favor some more exciting severe chances but there's persistent features which are mitigating that potential. For example, tomorrow. That's an unseasonably strong mid-level wind field overspreading the region with the flow WSW. While the cold front is not terribly strong shortwave forcing actually is pretty solid along with height falls.

But because mid-level lapse rates and mid-level temperatures are so warm this will significantly reduce upward parcel acceleration which will ultimately result in weaker updrafts. Surface CAPE will be high which will assist in convection rapidly forming once the ConvT is reached but once parcels rise above a certain level the acceleration upwards will be slowed significantly which will hinder deep convection from being established. This will be shown very well with the degree of lightning density tomorrow. 

Thanks for the explanation and I’d be delighted to be wrong lol 

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2 minutes ago, Cyclone-68 said:

Thanks for the explanation and I’d be delighted to be wrong lol 

It's the primary reason we don't do severe well here. Folks blame alot on the marine influence but IMO that is not the biggest reason. It certainly doesn't help, but when you have the proper ingredients/setup the marine influence is nada. Obviously early in the season it's going to be a big factor. IMO, these are the top reasons why we don't do well with severe here:

1) Poor mid-level lapse rates: There is a difference between low-level or surfaced-based CAPE and mid-level or mixed-layer CAPE. You can have robust surface CAPE but weak mixed-layer CAPE. What happens here is the strong surfaced-based CAPE will accelerate your parcels to the LCL and LFC and boom that's when you see rapid storm development...but at a certain point in the storm development the strengthening stops. With weak mid-level lapse rates the temperature difference between the parcels and environment lessens which results in less buoyancy and slower acceleration. When you have steep mid-level lapse rates (driven by EML or cold mid-level temperatures) the temperature difference remains great and parcels can continue to accelerate rapidly. 

2) Weaker forcing: It is possible the curvature of the Earth plays a role in this, but often times as shortwave troughs advance into southeastern Canada we'll see the strongest shortwave forcing remain north of the International border and subsequently the stronger dynamics will also remain north. In these scenarios as the cold front drives east along with the thunderstorms, the thunderstorms become removed and displaced from this stronger forcing/dynamics. This becomes critical because this stronger forcing can aid significantly in the acceleration of parcels through the troposphere so convection can remain deep. 

We've seen setups before with severe occurring down to the coast and even some significant severe. If the marine influence was as strong as some say, we probably wouldn't see that happen. Don't get me wrong, marine air does play an influence but it holds much weight than what some think. The biggest reasons why severe chances weaken as you move south and east are really more tied into my #2 above. The situations where we do have favorable ingredients and the stronger forcing is south of the border...we see severe persist closer to the coast. 

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This really isn't going to be anything to write home about but hopefully some thunder/lightning. Best part of this setup really is the very strong bulk shear. But the awful lapse rates and warm mid-levels really put a dent on potential. THIS WILL NOT BE WIDESPREAD

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This looks to me like it has a sneaky chance at 0-3km direction helicity being more positive than the "unidirectional" bulk shear contribution/focus noted by SPC.

It's just awareness of local climatology when you have a pre-frontal trough tending to form ahead of the main cfront, and then along and ahead of that feature, the lower level gradient not being too strong to overwhelm, the wind actually veers more S in the Hudson and CT R Valley and also somewhat so east of ORH hills - should anything survive into that area.  

The other aspect is that with DP coming in overnight/predawn  ( diffused warm front associated with hygroscopic advection) and that fits climo for things to cut loose later those afternoons.  

I also suspect we may do better with morning heating.  One, sw flows tend to be too pessimistic with ceilings in the models.  Two, aridity in the area is likely to gobble up some wet bulb and dry the column as the theta is advecting in.   You win for more sun, and getting CAPE back with the T

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ALB FOUS grid exemplifes ^

24007695916 -1694 031913 73261911    ... up to 26 C in the T1 WITH RH in the ceiling levels < 60% ... also note the wind is popped around to 190 deg

in mid boundary layer.  Hydrostatic  hgts to 573 dm also suggests the theta-e is stacked some in the sounding so this looks like CAPEy 18z NAM run. 

NAM,... abut the only thing good about that models is 30 hr lead convective signaling... At least that was the case back when it was the ETA lol

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This really isn't going to be anything to write home about but hopefully some thunder/lightning. Best part of this setup really is the very strong bulk shear. But the awful lapse rates and warm mid-levels really put a dent on potential. THIS WILL NOT BE WIDESPREAD
Looking forward to the swing and miss.

Sent from my SM-G981U1 using Tapatalk

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