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Wednesday, June 30, 2021 Severe Potential


weatherwiz
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24 minutes ago, Typhoon Tip said:

I wonder what the 12z actual soundings look like.

Regional hi res vis loop sat coverage is impressively barren SE of a baroclinic cloud swipe over far NW/St L Seaway - there's not even early fractal CU there despite 88 to 92 F by 10:30 am.  

DPs may be 2 to 3 off yesterday at this time, but still in the upper 60s, but the LC level should have more fractals. 

also, I wonder if there is CIN/'cap' in in the region.  Noted, 588 dam isohypses still runs roughtly PIT-PWM so, we may need some recession/ .. falls to commence - that could be interesting as a "release" type of initiation.   Pretty cool, you see a CU, go get a soda, and by the time you get back it's a cotton ball with overshooting hot tower expanding -

Great post. I ended up just going down a "Loaded Gun Theory" rabbit hole. 

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image.png.961ce7663fef32a1ccf8ed18df560924.png

  Mesoscale Discussion 1128
   NWS Storm Prediction Center Norman OK
   1004 AM CDT Wed Jun 30 2021

   Areas affected...Portions of far northern PA into much of NY...far
   western MA...VT...NH...and southern/central ME

   Concerning...Severe potential...Severe Thunderstorm Watch likely 

   Valid 301504Z - 301700Z

   Probability of Watch Issuance...80 percent

   SUMMARY...The threat for scattered severe/damaging wind gusts and
   isolated marginally severe hail will increase late this morning into
   the afternoon. One or more Severe Thunderstorm Watches will likely
   be needed.

   DISCUSSION...40-50 kt of mid-level west-southwesterly flow
   associated with an upper trough centered over Ontario/Quebec and the
   Great Lakes will remain over much of the Northeast today. With the
   lack of an appreciable surface front, low-level convergence should
   remain fairly weak across this region. Still, a zone of differential
   heating between morning clouds/precipitation and partly to mostly
   clear conditions to the south, as well as some convergence off of
   Lakes Erie/Ontario, will probably serve as foci for storm
   development. As surface temperatures generally warm into the upper
   80s and low 90s over the next couple of hours, convective
   temperatures will likely be reached as 1000-2000 J/kg of MLCAPE
   develops.

   Around 30-40 kt of effective bulk shear should prove favorable for a
   mix of small clusters/multicells and supercells as storms form and
   then move eastward across NY and New England. Steep low-level lapse
   rates and strengthening flow with height through low/mid levels
   suggest that scattered damaging wind gusts will likely be the main
   severe threat. With some supercell potential given the mostly
   long/straight hodographs expected, isolated marginally severe hail
   may also occur. But, modest mid-level lapse rates will probably
   limit a greater hail threat. Current expectations are for robust
   storm development to occur by 16-17Z (Noon - 1 PM EDT), and multiple
   Severe Thunderstorm Watches will likely be issued to address this
   increasing severe threat.

   ..Gleason/Thompson.. 06/30/2021

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...CAR...GYX...BTV...ALY...BGM...BUF...

   LAT...LON   43007067 42747134 42777303 42237338 42017395 41787480
               42017693 42047831 42387844 42947751 43557587 44047524
               44457389 44817215 45157102 45586995 45626747 45226712
               44776688 44056854 43766954 43457022 43007067
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https://forecast.weather.gov/product.php?site=BTV&issuedby=BTV&product=AFD&format=CI&version=1&glossary=1

NEAR TERM /THROUGH THURSDAY/...
As of 1045 AM EDT Wednesday...Overall forecast for today
remains on track with the potential for strong to severe storms
persisting. Despite SPC pushing the slight and enhanced risk a
little bit northward, looking at current satellite trends still
feel the best potential for severe will be from southern Essex
County NY northeast through VT Washington, Caledonia, and
southern Essex Counties southward, and especially across
Rutland/Windsor Counties where the greatest surface heating and
instability will be found. Current mesoscale analysis shows what
the previous forecaster mentioned in regard to deep layer shear
with the strongest values >40kts at 0-6km north of the surface
boundary draped along and just south of the international
border, and 30-40kts southward. While not lining up as much as
we`d like to see a more widespread convective threat, it still
should be enough to support some organization of cells this
afternoon with the primary threat continuing to be damaging
winds and heavy rainfall.
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Severe Thunderstorm Watch has been issued.

image.png.6d4e7fde614581b36c35b869a26b0070.png

 SEL7

   URGENT - IMMEDIATE BROADCAST REQUESTED
   Severe Thunderstorm Watch Number 327
   NWS Storm Prediction Center Norman OK
   1205 PM EDT Wed Jun 30 2021

   The NWS Storm Prediction Center has issued a

   * Severe Thunderstorm Watch for portions of 
     Southern Maine
     New Hampshire
     Extreme northeastern New York
     Vermont
     Coastal Waters

   * Effective this Wednesday afternoon and evening from 1205 PM
     until 700 PM EDT.

   * Primary threats include...
     Scattered damaging wind gusts to 70 mph likely
     Isolated large hail events to 1 inch in diameter possible

   SUMMARY...Scattered thunderstorm development is expected through the
   afternoon across northern New England, in an environment supporting
   both supercells and clusters/line segments capable of producing
   damaging winds and isolated large hail.

   The severe thunderstorm watch area is approximately along and 60
   statute miles north and south of a line from 50 miles north
   northwest of Glens Falls NY to 40 miles east of Bar Harbor ME. For a
   complete depiction of the watch see the associated watch outline
   update (WOUS64 KWNS WOU7).

   PRECAUTIONARY/PREPAREDNESS ACTIONS...

   REMEMBER...A Severe Thunderstorm Watch means conditions are
   favorable for severe thunderstorms in and close to the watch area.
   Persons in these areas should be on the lookout for threatening
   weather conditions and listen for later statements and possible
   warnings. Severe thunderstorms can and occasionally do produce
   tornadoes.

   &&

   OTHER WATCH INFORMATION...CONTINUE...WW 326...

   AVIATION...A few severe thunderstorms with hail surface and aloft to
   1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few
   cumulonimbi with maximum tops to 500. Mean storm motion vector
   27035.

   ...Thompson
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The best shot probably say south of the CT/MA border is to get a solid line organizing dropping through MA and then interacting with any leftover boundaries from yesterday. The HRRR looks like crap but it's been quite inconsistent and given how it's handling the atmosphere I think we toss the HRRR

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Presently high res sat loop indicates east to ene leaning TCU turrets streeting along an axis west of ALB and the NW region of the Capital District and lower Mohawk Trail...

This region - I suspect - is probably the swap out explosion axis, when the early cells in the broken line that is W-N of that region outflows/ .. and or this lead region uncaps and steals the inflow away and sort of takes over. But the original will still probably aggregate into clusters as they hit the terrain of NW-W VT

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