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General Severe Weather Discussion 2018


weatherwiz

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Wiz, we have a slightly unstable airmass over the southern New England region right now this morning.  The CHH sounding suggests unstable, with a strong convective cap present at 6.9, we have intense turning throughout the middle of the atmosphere, we have NE winds at 800-600mb and southerly winds at 950-surface.

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24 minutes ago, Cyclone-68 said:

Wiz what are your thoughts about Friday?

Last weekend it looked like there was a shot to get some stepper lapse rates to work in around the timing of the FROPA but that idea doesn't look as good anymore. I think central/northern New England will be closer to the better jet dynamics and stronger height falls. If we can develop enough instability I could see one or multiple lines of thunderstorms develop but right now I don't think it will be a crazy type of severe event. With enough heating and steep enough low-level lapse rates I'm sure we can muster up a decent amount of wind damage reports. Timing is still tough to gauge and I'm sure we'll have convective cloud debris to contend with. 

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20 hours ago, weatherwiz said:

Just noticed something...on the bottom left of the hodo there is something that says critical angle. What does that refer too? 

The critical angle is the angle between the surface storm relative inflow and the 0-500 m shear vector. You could view the right mover storm motion as a proxy for the surface SR inflow direction.

Values near 90 are ideal, but serviceable 45 degrees either side of that.

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36 minutes ago, OceanStWx said:

The critical angle is the angle between the surface storm relative inflow and the 0-500 m shear vector. You could view the right mover storm motion as a proxy for the surface SR inflow direction.

Values near 90 are ideal, but serviceable 45 degrees either side of that.

Thanks!

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Well I just had a pretty close lightning strike here a few hours ago that hit the utility pole right across the street which connects to the house.  I actually saw it hit so that was pretty neat!  There was a small bit of fire just after it hit but it quickly went out along with all the power down the street.  However, it seems some of it went through the cable line into the house and fried the phone modem and a wireless router, so that was not so good.

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On 7/3/2018 at 11:15 PM, eire015 said:

Well I just had a pretty close lightning strike here a few hours ago that hit the utility pole right across the street which connects to the house.  I actually saw it hit so that was pretty neat!  There was a small bit of fire just after it hit but it quickly went out along with all the power down the street.  However, it seems some of it went through the cable line into the house and fried the phone modem and a wireless router, so that was not so good.

Not sure to whom I am speaking ( in terms of ages/culture...) but, up through the 1990s ... prior to the transformation of society into one sutured together with wireless technology ... one of the age old NWS caution statements about thunderstorms was to stay off the telephones ;)   ... Just for the very same reason you describe above..  Moreover, said phone system of old didn't have BUS' for charge protection and so forth...  You could literally be talking on the phone, lightning could hit the pole down the street and they find you on the floor with one side of your head cooked ... perhaps days later when the neighbors start phonin' in the dreaded calls to 911 no operator wants to field ...  (phew) ...

Kidding a little there, but, .. that warning message and the era of wireless lessens the urgency/necessity of the former...  People still take showers during thunderstorms though, which is interesting.. - that can be risky too. 

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Heat waves often don't end with a bang ... 

The reason for that, the synoptic circumstances that took shape and governed the phenomenon are intrinsically a limitation on vertical motion ... obviously, to which convection requires that. The middle troposphere ends up in a positive static stability type of sounding ... or in other words, the lapse rates approaches or becomes less than ...  I think it's 7C per vertical KM as a minimum change with height?   I'm sure anyone that doesn't know that, including myself...can go look that up with relative ease. 

As a side... It's peculiar to me (a little) that we witnessed so much convection associated with that frontalysis axis, while it migrated straight under this 594 DAM heights. The resulting convection that continued through yesterday and ruined 4th of July festivities over eastern PA seems like it should not have happened, just on the surface, interestingly.  I think it was the ruining of the PA festivities that was really the goal there... but, that's just me...  Truth be told, the "front" part of said axis was probably more vanquished, but ... the theta-e gradient was sharp and left .. like an echo of where the front formally was.. And, usually along those sort of interfaces (wet abutting dry DPs at depth in the atmosphere) ...mixing destablizes and that erodes the CIN associated with the ridge...etc... towers and boomers.

Anyway, excluding that, which was probably the only way it could have rained during this Venusian furnace blast ... the heights tend to erode more gradually at synoptic scales, when these positive anomaly events end. The more like, go away more so than they are usurped ... There is less "jolting" or sudden height falls ...like you witness with trough approaching.  The large scale flow the constructed the ridge, tends to decay and displace the ridge circumstantially ... so you don't get that mid-synoptic -scaled correction schemes that are associated/needed for the Wizard of Oz...

Friday is ... sort of trying to buck that a-priori type of heat breakdown.  It's trying to end this with a sudden trough bullying through - at least central and NNE as others have noted.  ....  The models might be too emphatic and fast with the ridge decay at the eastern end of this thing/ridge .. it's complicated, but, the pattern tendency through as we end this week is to reposition the positive anomalies west toward the Front Range of the Rockies... I'm sort of suspecting that the models are both rushing that, and, over emphasizing the counter mass-field height falls in the East.  It's like they sniff the base-line opportunity for neutral PNAP (Perennial North American Pattern, which is different than the PNA mind you...) and rush the pattern back to that state. 

The long of the short there is ... there may not be "as" many mechanics for promoting convection as the models presently are indicating come Friday afternoon... Though, there will be some... And, it is important to note that when you are displacing an air mass featuring a thick slab of high hot DP numbers... you can also over produce relative to the synoptic appeal that is verifying at that time.  Devil's in the details...  Just look at the 4th of July over eastern PA!  Although that was about heavy rain... I almost wonder if Friday doesn't hybrid between derecho and frontal forcing in a sense... hm

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2 minutes ago, ct_yankee said:

Your right, that hodo is actually not all that bad for NE. Where is this sounding for?

 

1 minute ago, weatherwiz said:

What station is that? That's actually not bad CAPE values given the shear. 

For BDL. 

Looks similar to the July 2013 events. 

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Couldn't get the timing better situated ... otherwise, wow - this probably would have been a nasty event.. 

There is a narrow gap opening up between the back cloud field and the actual front ... 50 or so miles wide.  There are some TCU visible NW as the sun is coming out here along Rt 2...  Other than a pop storm on the front, oh what might have been -

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