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Wednesday, April 22nd, 2015 strong t'storm potential


weatherwiz

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A very potent s/w will be moving through during the afternoon hours accompanied by very cold mid-level temperatures and also a pretty favorable wind field aloft.  While surface temperatures may not get out of the 60's and dewpoints will be on the lower side, there will be instability present in the mid-levels thanks to the steep lapse rates (>6.5-7 C/KM) that will be present due to the cold pool.  It won't take much surface heating to yield some minor instability towards the surface either.  

 

With the s/w moving through during the day timing will be favorable for the development of showers and even thunderstorms.  Given a strong wind profile aloft, and very cold mid-level temperatures, a few of these storms could contain hail and strong gusty winds.  There is even the possibility of a storm or two producing severe hail (>1") or a damaging wind gust.  

 

Forecast soundings yield an inverted-v  signature which will 1) work to draw down direr air aloft, mixing out the dews and 2) draw down some of these stronger winds aloft.  Soundings also show a degree of turning between the lower and mid levels of the atmosphere making for some elevated helicity values.  This will further aid in any hail potential.  With lack of stronger instability this will probably mitigate the potential for a very brief tornado, however, a storm could really take off and take on supercell characteristics and it would be this case which would yield best chance for severe hail.  

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Nice disco Wizard. We've been all over this threat for days. Prob see mostly pea to marble with scattered nickels. Gfs shows potential for some 50 knotters

 

Thanks!

 

I wouldn't have known if I didn't see your posts lol.  Also good call on the storms last night...had no clue either until I saw your post about the potential.

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nice write-up wiz! any concern if the upper lvl forcing holds off til later in the afternoon / evening after peak insolation? also strong southerly low lvl winds might not be the best look with LI sound around 40 degrees.

 

Cold pool setups seem to rely more on instability generated in the middle levels as opposed as towards the surface so I don't think loss of daytime heating would really mitigate this much...maybe just pretty much make the percentage of a large hail report even lower.  I also don't think the southerly llvl winds would be a big factor here either...pretty much for the same reason described in the first sentence.  This is how even the south coast can get big time storms during cold pool setups...sea-breeze doesn't seem to impact this type of convection much b/c the instability is more aloft (above the BL).   

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nice write-up wiz! any concern if the upper lvl forcing holds off til later in the afternoon / evening after peak insolation? also strong southerly low lvl winds might not be the best look with LI sound around 40 degrees.

That would def be a concern if we didn't have steep lapse rates and cold air aloft. But this threat is more about dew depressions and cold core so won't matter
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oh the wind is gonna crank big time and cold squalls will hit, big TTs windexy for you

Honestly haven't looked at much but looping a few NCEP maps on the phone. Driving back to VT around midday....would be nice to see something exciting haha. Last nights storms were rocking pretty good.

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Starting at 34 degrees here. Satelitte imagery indicates Sun mixed with some clouds through early PM. A line of low topped convection will be approaching by mid to late afternoon.Surface based cape really only gets to 150-200 j/kg and some of the modeling completely weakens the Cape east of the CT river valley. Like others have alluded to, the depth of the cold pool aloft and wind fields are impressive enough to warrent the potential for some scattered hail cores and brief gusty winds in some of the strongest updrafts . I'm thinking pea sized and about 45mph is about the limit to what most could see. I'm not really keen on eastern areas with a later arrival time and possibly more convective inhibition . We'll see how it plays out.

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