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Wednesday, May 26, 2021 Convective/Severe Weather Potential


weatherwiz
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A warm front is expected to move west-east across southern New England through the day Tuesday. While isolated showers and thunderstorms are possible along/just behind the warm front, a better chance for thunderstorms exists Wednesday ahead of a pre-frontal trough/low-level wind shift. Combination of temperatures well into the 80's to even lower 90's away from the shoreline and dewpoints into the lower-to-near mid-60's will contribute to a modestly unstable atmosphere with mixed-layer CAPE on order of 1500 J/KG. While not terrible strong, winds aloft are enough to warrant the likelihood for convection to develop and become organized with 35-45 knot mid-level jet. There is a wildcard that could result in a more significant severe weather threat and that is a plume of elevated mixed-layer air. Forecast guidance indicates a piece of EML air may break from the central Plains and move into our region, however, the timing of this feature looks to be Wednesday morning/early afternoon before moving into the Atlantic. This would be timed well before the greatest ingredients arrive. Right now, the greatest chance for scattered-to-numerous thunderstorms looks to be NY/PA/western New England, however, depending on timing this could certainly extend farther east.

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The main forecast concern is the potential for a few strong to 
severe t-storms in the afternoon in the interior. Mid level 
shortwave will be moving across Gt Lakes with a pre-frontal trough 
moving into SNE in the afternoon which will be a focus for 
convection. Decent instability develops in the interior with CAPES 
1000-1500 J/kg and increasing wind field results in deep layer shear 
30-35 kt supporting storm organization and potential severe weather. 
CAMs are showing some broken line segments moving into interior SNE 
during afternoon with damaging wind being the main threat. However, 
forecast soundings also show decent turning in the lowest 3km in the 
CT valley with effective SRH 100-200 m2/s2, aided by backed low 
level flow and there is favorable 0-3km CAPE, so can't rule out an 
isolated tornado with any discrete storms. Will continue to monitor 
with later forecasts.
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5 minutes ago, CoastalWx said:

Meh. Congrats NY and NNE.

There looks to be a window of opportunity from northeast MA into northern CT perhaps for some rapid growing convection late afternoon right along what appears to be a theta-e ridge/higher instability axis. 

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8 minutes ago, wxeyeNH said:

What potential is this to go enhanced or moderate any place in New England?

I don't think we see a moderate risk with this...I don't think the aerial coverage will be great enough and would like to see stronger instability and a bit stronger shear. It is possible to see an area of enhanced added if enough confidences increases in a narrow swath for enhanced wind damage potential. 

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2 minutes ago, wxeyeNH said:

What potential is this to go enhanced or moderate any place in New England?

I don’t think mod is on the table—that’s quite hard to do around here. I wouldn’t be surprised to see a limited enh zone though in upstate NY or NNE on D1 though. It looks like a decent severe setup especially up there. 

Down here in CT I agree with Wiz that there’s a relatively brief window for severe. Would like to see a discrete cell or two to maximize potential.

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39 minutes ago, weatherwiz said:

NAM NEST has a long-tracked superell from E NY to the NH coast

 

:weenie: 

Mm hm... takes an EF4 tornado vortex up the western side of Mt Monadnock, over the bald rocky summit, and right down the other side, too -

...pretty cool, huh -

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15 minutes ago, WxWatcher007 said:

I don’t think mod is on the table—that’s quite hard to do around here. I wouldn’t be surprised to see a limited enh zone though in upstate NY or NNE on D1 though. It looks like a decent severe setup especially up there. 

Down here in CT I agree with Wiz that there’s a relatively brief window for severe. Would like to see a discrete cell or two to maximize potential.

Kind of a good thing in this setup not to be overpowering with lift/forcing. Should help to keep activity more discrete but I'm sure we'll see a cluster or two evolve and that's where any enhanced would be possible.

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Just now, Typhoon Tip said:

Mm hm... takes an EF4 tornado vortex up the western side of Mt Monadnock, over the bald rocky summit, and right down the other side, too -

...pretty cool, huh -

The more I look at this the more I become intrigued across central MA and more specifically around ORH County. Actually a pretty good overlap there of strong llvl CAPE and shear. 

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Kidding... of course -

But the gist of the mid week 'potential' is a specter that's been looming on the charts for a week now actually - I remember commenting on this literally last Wednesday.  It's just interesting that these open wave scenarios seem like they are better performers - so we'll see.

Heh, just think, Wiz'  ... you may actually get a severe event in May like you seem to think you should, IN MAY   lol

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10 minutes ago, Typhoon Tip said:

Kidding... of course -

But the gist of the mid week 'potential' is a specter that's been looming on the charts for a week now actually - I remember commenting on this literally last Wednesday.  It's just interesting that these open wave scenarios seem like they are better performers - so we'll see.

Heh, just think, Wiz'  ... you may actually get a severe event in May like you seem to think you should, IN MAY   lol

The pattern wants to throw EML's at s over the next few weeks but I think the jet structure/placement is killing us. The jet looks to get shot pretty far northward so the EML plumes riding along the southern edge of the jet move into Canada. 

and going back to the May thread...there are also emerging signals for things to turn very warm to hot rather quickly after this miserable weekend. 582dm heights trying to poke into our region second half of next week

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5 hours ago, weatherwiz said:

There looks to be a window of opportunity from northeast MA into northern CT perhaps for some rapid growing convection late afternoon right along what appears to be a theta-e ridge/higher instability axis. 

Some nice Hills with  awest view on  Rt 31 in Charlton near the old Dresser Hill Ice cream stand,  or further south in Dudley Ma overlooking NE CT

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Surprised that @weatherwiz isn't tossing the :weenie: on the afternoon SPC 1730z OTLK

 ...Central and Northern Appalachians...
   An upper-level trough will move eastward across the Great Lakes
   region on Wednesday with west-northwesterly mid-level flow located
   across much of the northeastern U.S. At the surface, a cold front
   will advance southeastward into the lower Great Lakes region during
   the afternoon. A moist airmass will be in place ahead of the front
   with surface dewpoints in the lower to mid 60s F. Although Lake Erie
   and Lake Ontario will keep the airmass stable just downstream of the
   lakes, moderate instability is forecast to develop in much of New
   York and Pennsylvania by midday. Thunderstorms will  develop along
   the western edge of the moderate instability and move eastward into
   central New York and northern Pennsylvania during the afternoon.

   NAM Forecast soundings along this corridor at 21Z/Wednesday show
   moderate deep-layer shear with very steep lapse rates in the
   boundary layer. This will be favorable for damaging wind gusts with
   supercells and organized multicell line segments. Supercells with
   large hail will also be possible, mainly with discrete storms that
   form further east in the stronger instability. A tornado threat may
   also develop during the mid to late afternoon. The greatest
   potential for tornadoes is forecast across eastern New York and in
   western New England, where 850 mb winds are forecast to be stronger
   and 0-3 km storm relative helicities are forecast to be in the 250
   to 350 m2/s2 range during the afternoon.

   ..Broyles.. 05/25/2021

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4 minutes ago, yoda said:

Surprised that @weatherwiz isn't tossing the :weenie: on the afternoon SPC 1730z OTLK

 

 

It is very intriguing. Looks like that alludes to what I mentioned earlier regarding theta-e ridge that becomes established across northeast MA through western/central CT. This is a bit east then what SPC mentions but it's something to watch. 

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