Tuesday, August 25, 2020 Severe Potential

[weatherwiz]

There is a bit of uncertainty regarding the overall potential due to the anticipated timing of the strong cold front, however, the potential exists for multiple fast-moving line segments capable of producing damaging winds and perhaps hail (especially with any splitting supercells). A fairly vigorous shortwave trough amplifies as it approaches New England with a plume of steeper lapse rates moving through aloft and a strengthening mid-level jet on order of 50-60 knots. At the surface we'll see temperatures pushing well into the 80's...perhaps near 90 depending on overall timing of the front with dewpoints well into the 60's to near 70. Combination of heat and humidity with steeper lapse rates should yield a moderately unstable atmosphere...BUT this could be limited with a faster fropa. Should timing of the front slow down we could see some pockets of widespread wind damage. Forecast soundings indicate a textbook inverted-V signature indicating increased potential for damaging winds and long/straight hodographs suggest splitting supercells/hail potential 

[kdxken]

Light 'em up!

[Damage In Tolland]

Looks very scattered. Not a big day at all

[CoastalWx]

Timing of fropa seems in question. 

[Torch Tiger]

dry cfp

[weatherwiz]

7 minutes ago, CoastalWx said:

Timing of fropa seems in question. 

Also looks like some sort of pre-frontal trough may come through a little early? Near westerly sfc winds should limit convergence which should limit aerial coverage but I still think we'll see multiple short line segments...whatever develops will have plenty of dynamics to tap into. That's why I think we'll see widespread damage but localized/concentrated 

[weatherwiz]

There is also a quite a bit of dry air in the mid-levels...which will also limit widespread coverage, but increases damaging wind potential with any storms that fire. 

[CoastalWx]

NAM looks better tomorrow. 

[weatherwiz]

3 minutes ago, CoastalWx said:

NAM looks better tomorrow. 

Looks like some pseudo-EML air that might move overhead? I bet we see one or two microbusts with winds 65-75 mph. 

[Cyclone-68]

What’s the limiting factor on tornado potential tomorrow?

[weatherwiz]

Just now, Cyclone-68 said:

What’s the limiting factor on tornado potential tomorrow?

unidirectional flow and subsequent storm mode, inverted-V soundings, high LCL's, southern New England

[Cyclone-68]

2 minutes ago, weatherwiz said:

unidirectional flow and subsequent storm mode, inverted-V soundings, high LCL's, southern New England

I thank you 

[Torch Tiger]

Tricky forecast tomorrow. 

[weatherwiz]

looks like 18z is slowing down a tad more. still have a more W sfc wind though which will limit convergence but boy...what does develop is going to produce some good wind 

[Damage In Tolland]

12 minutes ago, weatherwiz said:

looks like 18z is slowing down a tad more. still have a more W sfc wind though which will limit convergence but boy...what does develop is going to produce some good wind 

Better chance Fri or Sat. Sell much tomorrow 

[Henry's Weather]

Why do west winds limit storm convergance?

 

[Damage In Tolland]

1 minute ago, Henry's Weather said:

Why do west winds limit storm convergance?

 

Downsloping/ drying 

[weatherwiz]

Just now, Henry's Weather said:

Why do west winds limit storm convergance?

 

I should actually clarify...west winds alone doesn't mean less convergence...it's more of the winds with respect to the front. Typically with cold FROPAS they do so in a more northwest to southeast fashion...so if you have like S, SW, SE winds...they're going into the front ...air is converging which means upward motion. If sfc winds are more W its kind more parallel to the front so there isn't much convergence. At least that's how I've always understood it 

[weatherwiz]

5 minutes ago, Damage In Tolland said:

Better chance Fri or Sat. Sell much tomorrow 

good news is we have the chances! 

[ma blizzard]

43 minutes ago, weatherwiz said:

I should actually clarify...west winds alone doesn't mean less convergence...it's more of the winds with respect to the front. Typically with cold FROPAS they do so in a more northwest to southeast fashion...so if you have like S, SW, SE winds...they're going into the front ...air is converging which means upward motion. If sfc winds are more W its kind more parallel to the front so there isn't much convergence. At least that's how I've always understood it 

this is important to call out .. a good number of our high end severe weather events have W / NW flow aloft 

[Henry's Weather]

16 minutes ago, ma blizzard said:

this is important to call out .. a good number of our high end severe weather events have W / NW flow aloft 

Such as?

[weatherwiz]

50 minutes ago, ma blizzard said:

this is important to call out .. a good number of our high end severe weather events have W / NW flow aloft 

yeah some of our biggest events come from;

1) NW flot aloft (mid-levels)...which also tend to match well with EML advection but not all NW flow events are associated with EML's

2) EML's 

3) cold pools aloft 

but our severe wx events can be maximized with the combo of a NW flow/EML 

[PowderBeard]

1 hour ago, weatherwiz said:

I should actually clarify...west winds alone doesn't mean less convergence...it's more of the winds with respect to the front. Typically with cold FROPAS they do so in a more northwest to southeast fashion...so if you have like S, SW, SE winds...they're going into the front ...air is converging which means upward motion. If sfc winds are more W its kind more parallel to the front so there isn't much convergence. At least that's how I've always understood it 

Tip had a great post a while back on storms dying east of the river with S winds I believe.

[weatherwiz]

Just now, PowderBeard said:

Tip had a great post a while back on storms dying east of the river with S winds I believe.

Depending on the season south winds can be a killer b/c of marine taint but IMO I think this is more of a factor during the spring through late June. Once the waters warm I don't think it becomes as big of a factor. I've always wanted to do research on this but my thinking is that storms just tend to out run the better dynamics/upper-level support. The better dynamics/upper-level support seem to be up around the NYS/Canadian border or traverse NNE...so taking into account the curvature of the Earth, when storms just get past a certain point they just lose that assistance and fizzle...partly too b/c our instability here tends to be on the weaker side and predominately sfc parcel driven (days where we may have 2500 SBCAPE but barely 750 MLCAPE). the good SBCAPE helps get things to develop but for them to really mature the updrafts need additional assistance (good MLCAPE, dynamics, upper-level support)...and with that lacking convection struggle to get very deep.

[Damage In Tolland]

South winds do not matter once into Augdewst. SST are so warm they help severe . That’s only when water temps are cool 

[Damage In Tolland]

 

[Baroclinic Zone]

36 minutes ago, PowderBeard said:

Tip had a great post a while back on storms dying east of the river with S winds I believe.

Southerly winds over Narragansett Bay kills storms here.  We do better on N and W winds for storms.

[Damage In Tolland]

2 minutes ago, Baroclinic Zone said:

Southerly winds over Narragansett Bay kills storms here.  We do better on N and W winds for storms.

In Aug they help storms tremendously 

[Baroclinic Zone]

8 minutes ago, Damage In Tolland said:

In Aug they help storms tremendously 

These last 2 days beg to differ.  2 severe days where storms fell about mere miles away from here.

[Damage In Tolland]

Just now, Baroclinic Zone said:

These last 2 days beg to differ.  2 severe days where storms fell about mere miles away from here.

South winds didn’t have jackmeoffer to do with storms last couple days other than perhaps a Seabreeze interaction