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Dr. Dews

June 29-30 2019 Thunderstorms

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NAM's 12z particulars gum up the works... 

It brings some sort of convectively induced/MCS low through central NE Saturday afternoon and evening... that it initializes ..actually now-ish north of Iowa.  

The questions are whether A ... that feature actually exists;  if so, to what mechanical presence - and by this latter facet we mean, does it really baroclinically operate.  It appears to evolve warm and cool frontal tapestry as it's passing through the area... enough so to insert stability into SNE by Saturday evening.  Around 18z that day ...regional LIs bottom out around -5 ( which is a bit of a low anomaly ) ..then by 00z and 06z in the night that particular metric bounces all the way back to +1 ... with winds slipping from SW to NW... transitioning with 0 QPF modeled S of CON NH..  all this does is effectively evacuation unstable parameters out.

That could evacuate the good seaward...such that when the deep layer instability arrives Sunday morning  ... the attack on convection enthusiasts is complete in that nothing happens anywhere because this odd interference journey.   

Kidding there but .. wouldn't shock me if that NAM is over doing that MCS attributed wave and thus that changes the landscape over the weekend. 

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5 hours ago, Chrisrotary12 said:

Day 3 Marginal Risk - get in your basements.

We know how that goes. Hope they remain with the marginal outlook...

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I am just not overly impressed with this...although granted it is our "best potential" of the season so far. I'm not even sure we see widespread or even scattered convection...perhaps more isolated. 

As stated in the other thread, there are concerns over timing. Even on the slower GFS there are still concerns and those concerns due with the potential for a more westerly component to the llvl and sfc flow...this (along with strong mixing) would not only promote drier air mixing down, but limit convergence. Maybe eastern MA has a better shot...and for more in the way of scattered convection as there may be some stronger moisture convergence. 

Another issue is that potential MCS moving through NNE overnight...suppose that verifies...we could see some mean subsidence on the backside of that and this could also result in a more W component. 

We'll see what happens but right now not excited...am only interested b/c we've had nothing else 

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I think this looks pretty good, at least at this point in time. Could be mucked up by CIN? Debris?Timing?  Sure..

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14 minutes ago, weatherwiz said:

I am just not overly impressed with this...although granted it is our "best potential" of the season so far. I'm not even sure we see widespread or even scattered convection...perhaps more isolated. 

As stated in the other thread, there are concerns over timing. Even on the slower GFS there are still concerns and those concerns due with the potential for a more westerly component to the llvl and sfc flow...this (along with strong mixing) would not only promote drier air mixing down, but limit convergence. Maybe eastern MA has a better shot...and for more in the way of scattered convection as there may be some stronger moisture convergence. 

Another issue is that potential MCS moving through NNE overnight...suppose that verifies...we could see some mean subsidence on the backside of that and this could also result in a more W component. 

We'll see what happens but right now not excited...am only interested b/c we've had nothing else 

One thing to be aware of with veered surface flow is to check the flow aloft. Because if the flow is more strongly NW aloft, you still get a nice change in direction from surface to 500 mb.

Normally we think in terms of south surface, west aloft. But SW surface, NW aloft is still 90 degrees. 

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17 minutes ago, OceanStWx said:

One thing to be aware of with veered surface flow is to check the flow aloft. Because if the flow is more strongly NW aloft, you still get a nice change in direction from surface to 500 mb.

Normally we think in terms of south surface, west aloft. But SW surface, NW aloft is still 90 degrees. 

May be even better turning with a little more ageostrophic SSW/S in the river valleys with the NW upper level flow.

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Just now, dendrite said:

May be even better turning with a little more ageostrophic SSW/S in the river valleys with the NW upper level flow.

I've always been a fan of NW flow events.

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1 minute ago, OceanStWx said:

I've always been a fan of NW flow events.

Me too. Seems like we do our best severe here when cells are ripping my way from Gene’s house.

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Saturday looks like we see a broken line with maybe a couple sups. I so/scattered. If the faster solutions are more correct this may be nothing for a majority.(nothing meaning higher-end regionally or otw).but regardless I would still say there is potential in SNE

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5 hours ago, OceanStWx said:

One thing to be aware of with veered surface flow is to check the flow aloft. Because if the flow is more strongly NW aloft, you still get a nice change in direction from surface to 500 mb.

Normally we think in terms of south surface, west aloft. But SW surface, NW aloft is still 90 degrees. 

I like the W/NW flow aloft...for the obvious reasons but I didn’t really like seeing the sfc flow be more W. 

Seems like the 18z NAM not only slowed down things a bit but now have more of a SW flow at the sfc. 

With these steep lapse rates continuing to be shown and the NW flow aloft hopefully everything else can come together 

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11 minutes ago, weatherwiz said:

I like the W/NW flow aloft...for the obvious reasons but I didn’t really like seeing the sfc flow be more W. 

Seems like the 18z NAM not only slowed down things a bit but now have more of a SW flow at the sfc. 

With these steep lapse rates continuing to be shown and the NW flow aloft hopefully everything else can come together 

AMOUTET

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47 minutes ago, weatherwiz said:

I like the W/NW flow aloft...for the obvious reasons but I didn’t really like seeing the sfc flow be more W. 

Seems like the 18z NAM not only slowed down things a bit but now have more of a SW flow at the sfc. 

With these steep lapse rates continuing to be shown and the NW flow aloft hopefully everything else can come together 

New England just needs that W component to save the marine influence (unless you have dews like Kevin's mulch bed advecting off the Atlantic).

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Northeast...
   An upper-level trough will dig southeastward across Ontario on
   Saturday as a cold front advances southeastward across the
   northeastern U.S. A moist airmass is forecast ahead of the front
   with surface dewpoints across southeast New York and southern New
   England in the mid to upper 60s F. In response, a pocket of moderate
   instability is forecast to develop by Saturday afternoon.
   Thunderstorms should develop along the front and move
   east-southeastward across the region during the early to mid
   afternoon. Moderate deep-layer shear, veered low-level flow and
   steep low-level lapse rates will be favorable for damaging wind
   gusts with the stronger storms. The severe threat should move toward
   the New England coastal areas by late afternoon.

 

Merp

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8 hours ago, OceanStWx said:

New England just needs that W component to save the marine influence (unless you have dews like Kevin's mulch bed advecting off the Atlantic).

:lol: 

I guess it's nice to at least have something to track. Thought I can't believe 1953 was being thrown around 

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Sunday actually looks a bit more impressive now. Some pretty beefy CAPE values showing up and with that cold pool that could be pretty fun 

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18 hours ago, OceanStWx said:

One thing to be aware of with veered surface flow is to check the flow aloft. Because if the flow is more strongly NW aloft, you still get a nice change in direction from surface to 500 mb.

Normally we think in terms of south surface, west aloft. But SW surface, NW aloft is still 90 degrees. 

I've been trying to explain this folks all week :unsure:

As others have likely noted by now, SPC's hand is forced and they've had to pull the trigger on at least Slight risk for tomorrow ...

I personally think they do that grudgingly due to our separate little climate criteria of failure and always seeming to find the least plausible verification relative to input values ...  

Anyway, as you are now also elucidating,  take the standard vector directions at all sigmas ...and rotate the total columns some 30 to 45 degrees; you'll end up with the same bulk shear - folks need to remember... the numerology doesn't care what direction, just that it hits the numerical correlations.  I mean this is all predicated on the assumption that shear is an important metric in this particular evolution, which I think it is ... 

Without studying 10 soundings ( modeled input ), just the synopsis looks like a right exit jet acceleration occurs at mid / somewhat upper air late in the day, which means velocity/difluence increases rather abruptly toward late afternoon.  Erstwhile, the day appears now ...given to model RH at ceiling heights, ...to be sufficiently open to allow enough insolation for significant heating.  Theta-e .. check. DP appears to pool SE of ALB-RUT-CON with mid 60s... I'd actually be tempted to add a tick or two there, but the surface wind being more west-southwest may katabatically offset.... But that's minor.  But again...I didn't focus on particular sounding details ...this is just using the synoptic inference/tech

Anyway, I wouldn't surprised if we get Watched ..with even a category risk up tick from that.  This has been flagged for a week's worth of modeling output... Remarkably stable in both time and space in the majority of guidance'  

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Just now, STILL N OF PIKE said:

JB is the hype master. 

Pimps whatever sells. Don’t have an issue w him. It’s the world we live in

It's futile aversion ... I know ... but I take issue with both. 

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11 minutes ago, Typhoon Tip said:

I've been trying to explain this folks all week :unsure:

As others have likely noted by now, SPC's hand is forced and they've had to pull the trigger on at least Slight risk for tomorrow ...

I personally think they do that grudgingly due to our separate little climate criteria of failure and always seeming to find the least plausible verification relative to input values ...  

Anyway, as you are now also elucidating,  take the standard vector directions at all sigmas ...and rotate the total columns some 30 to 45 degrees; you'll end up with the same bulk shear - folks need to remember... the numerology doesn't care what direction, just that it hits the numerical correlations.  I mean this is all predicated on the assumption that shear is an important metric in this particular evolution, which I think it is ... 

Without studying 10 soundings ( modeled input ), just the synopsis looks like a right exit jet acceleration occurs at mid / somewhat upper air late in the day, which means velocity/difluence increases rather abruptly toward late afternoon.  Erstwhile, the day appears now ...given to model RH at ceiling heights, ...to be sufficiently open to allow enough insolation for significant heating.  Theta-e .. check. DP appears to pool SE of ALB-RUT-CON with mid 60s... I'd actually be tempted to add a tick or two there, but the surface wind being more west-southwest may katabatically offset.... But that's minor.  But again...I didn't focus on particular sounding details ...this is just using the synoptic inference/tech

Anyway, I wouldn't surprised if we get Watched ..with even a category risk up tick from that.  This has been flagged for a week's worth of modeling output... Remarkably stable in both time and space in the majority of guidance'  

In my posts where I've talked about the veered wind shear...I was not referencing that in terms of bulk shear.

 

My point when mentioning the W sfc winds and W llvl winds solely had to do with how they can impact moisture and convergence. My worry was a more W flow in these levels would promote a drying and limiting convergence. If we were to talk shear then of course you're now limited with directional component...especially if the mlvl flow is also more W...now of course...if you have a W flow at the sfc and a NW or NNW flow aloft you're still generating bulk shear/directional shear.

I was only referencing moisture/convergence impacts. 

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5 hours ago, weatherwiz said:

:lol: 

I guess it's nice to at least have something to track. Thought I can't believe 1953 was being thrown around 

JB still appears to be onboard. 

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