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Ginx snewx

Mid October 2019 Bombogensis Coastal

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28 minutes ago, weatherwiz said:

I thought the post you made last night was a pretty solid layout for what to expect. 

Just a guess right now. But as always coasts are ripe for the biggest gusts 

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5 minutes ago, Ginx snewx said:

Couple of caveats to wind. Gravity waves and monsoon rains can tap and wash out inversions to the point damaging winds can occur.  Trees are leaved and many are dead, lowering wind speed potential for damage.  Still early on the wind dept. Sucks BOX radar decided to go off line, yes decided. OKX velocity is bent right at my location.  I used BOX during high wind events and it works great here. We wait

I'm always highly intrigued by your gravity waves posts. Eventually I'll get around to studying them more but most of what I know about them is from you. Those are something that is certainly in the back of my mind with this event. 

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1 minute ago, weatherwiz said:

I'm always highly intrigued by your gravity waves posts. Eventually I'll get around to studying them more but most of what I know about them is from you. Those are something that is certainly in the back of my mind with this event. 

Interesting stuff, in Oct 17 right at the dry slot literally minutes before the winds died a sudden burst of very high winds took down dozens of trees in my hood. Up until that time I had power.  Was pretty cool to watch it happen on radar, satellite and in person. The roar was impressive 

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10 minutes ago, Ginx snewx said:

Interesting stuff, in Oct 17 right at the dry slot literally minutes before the winds died a sudden burst of very high winds took down dozens of trees in my hood. Up until that time I had power.  Was pretty cool to watch it happen on radar, satellite and in person. The roar was impressive 

I was at school for that...I remember it being a much more potent event then originally thought. I don't totally remember the set-up for that though...are there any similarities to this setup? (I'm not sure if NARR goes to 2017 yet). That event too also had bombogenesis occur right? Was there energy already in place during that phasing? Or was generated in a way like what is modeled to for today? 

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1 hour ago, Ginx snewx said:

Just because many don't have access . Mslp. No conjecture about wind. Just showing model timing and track. 

download (31).png

download (32).png

download (33).png

download (34).png

Track that a bit further West so we can bring down the pin barrens of plymouth

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1 hour ago, dendrite said:

E MA/E NH/ME would be fairly windy on the 6z NAM as it pulls a blizzard loop and the LLJ gets pulled a bit westward as it swings northward. But yeah.......NAM. 

Yep, you want to be just east of the low track in this setup to get anything decent...and assuming it is a rapdily deepening 970s system...if this stays kind of meh on intensification then I don't expect that much anywhere.

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Yeah the S and SE side of the low as it passes north may have another burst of strong SW winds as CAA starts. Some guidance has a very narrow, but pronounced burst of these winds. Euro and GFS seem to show this. I'd be curious to know what 925 looked like on the euro.

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43 minutes ago, Ginx snewx said:

Just a guess right now. But as always coasts are ripe for the biggest gusts 

Yea I can see it in the warm sector where its collocated with deep convection and then post occlusion in the south eastern quadrant, assuming it tracks near/over ORH as the ageostrphic flow at the surface remains off the 55-65F ocean while the mid/low level circulation begins wrapping in a continental polar airmass. The more maritime tropical air this can flood into the region the more substantial and prolonged the “part II” of the winds will be...RI and south shore MA look like the best places to be....

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1 hour ago, Ginx snewx said:

Interesting stuff, in Oct 17 right at the dry slot literally minutes before the winds died a sudden burst of very high winds took down dozens of trees in my hood. Up until that time I had power.  Was pretty cool to watch it happen on radar, satellite and in person. The roar was impressive 

Same experience here. Heavy rain and just as the dry slot approached the wind went nuts and took off the top of a tree in my yard and blew out a transformer. 

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9 minutes ago, Dr. Dews said:

Still want this to wrap up sooner and west, for a regional wind threat.

Yeah Oct '17 went up the HV in the 960s and had a little embedded meso low that ripped up over the Cape and brought the 90-100 mph gusts. That was the ideal setup as far as wind events go. This looks solid for the immediate coast, as usual, but I'm more interested in the rain aspect than the wind IMBY. 

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11 minutes ago, Dr. Dews said:

Still want this to wrap up sooner and west, for a regional wind threat.

Cant figure you out?  You poo-poo everything, and say you don’t want heavy rains and wind, and now you’re saying you want a wind threat?

 

Which is it?  Why all the silly posts...just be honest and say what you hope happens??  

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3 minutes ago, Hoth said:

Yeah Oct '17 went up the HV in the 960s and had a little embedded meso low that ripped up over the Cape and brought the 90-100 mph gusts. That was the ideal setup as far as wind events go. This looks solid for the immediate coast, as usual, but I'm more interested in the rain aspect than the wind IMBY. 

I thought this one was setting records for Oct. mslp?

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While there may be small meso lows, the NAM and it's offspring 3K just look overdone. Haven't seen much about rain, but along and west of the track has tremendous low level convergence. That's the setup to get 3-5" in like 2hrs. 

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20 minutes ago, Dr. Dews said:

I thought this one was setting records for Oct. mslp?

Maybe for the specific date? Dunno, would have to think Sandy will hold that record indefinitely.

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1 minute ago, CoastalWx said:

While there may be small meso lows, the NAM and it's offspring 3K just look overdone. Haven't seen much about rain, but along and west of the track has tremendous low level convergence. That's the setup to get 3-5" in like 2hrs. 

This is 6-HR accumulations (6z-12z). BS flags all over the place. Also fronto map (9z).

image.png.942cd2490126ca5c66960cacf67c4507.png

 

image.png.6386332e1aab86783a4caca921ce20c3.png

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I think the Euro has the right idea for this one, A slp more consolidated in the high 970's seems more likely then some of these more convective looks that the Nam keeps showing with multiple spokes of vorticity.

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10 hours ago, OceanStWx said:

I'm working on some VERY preliminary research up here on stable/neutral wind events and unsurprisingly the best correlation is 925 mb wind speed followed by 925 mb to surface lapse rates. 

I'm still working out the regression equation but it's roughly 50% of the 925 mb and 80% of the lapse rates (positive is more unstable). But since lapse rates rarely are in excess of 10 C/km, that only "adds" at most 10 knots to the forecast gusts. So 925 wind speed does a lot of the work in my regression. Would suggest 30-35 knots is a fine place to start.

That's using the GYX sounding and PWM gust (we don't track gusts here on the hourly).  Overall I think my first pass is failing to capture the higher end events.  So now I'm working on using the GYX upper air and PWM T/gust to see if that significantly changes things (lapse rates are often more unstable at PWM). 

 

Good! 

Wind prognostics seems to be an area that is sorely needing some polish ..

pressure tendency exceeding the Coriolis/time dependence for 'bending' mass around curvature and all that ( allobarics) ..blah blah... is where/what I'm actually more intrigued about this system for - which may or may not be covered in your evolving efforts?  I'm not sure it does, as your description appears focused in lapse rates - where as allobarics deals with restoration of mass in scenarios where pressure tendencies exceed the Coriolis term ( f^2) .. I mean obviously you know this, I'm just prefacing for blw.

Based upon personal anecdotal experience ... it doesn't seem wind acceleration is as noted when there is deepening low pressure approaching; it is when it then pulls away that you hear white noise over the horizon in some extreme cases of "isollaric wind acceleration"  - and I have noticed that this particular phenomenon has almost nill lead predictive skill.  I've seen charts 'look' like an event could unfold... but they seldom do. Then, I'll be sitting there and the power will blink and it draws my attention to the sounds of turbine whirs over the house and I'm wondering if there was a wind headline out of nowhere.   We never seem to verify the front-side winds as others have noted, the WAA terms ...yeah, that's probably related.  I suspect that backsides have some magic ratio of lapse rate destablization and surface mass restoration, as two separate but comparable metrics.  If they "intersect" ( so to speak ) that region has a shot at bending the forest tree lines seemingly out of no where when the col of the low pressure center moves off that region.  

But that's speculation.   

This system does begin to look like a chance of iso. wind pulse to me though... As the close approach under a warm advection layer does seem to more abruptly require mass restoration .. and has a shot at abrupt cooling in the 0 to 5 km level when that happens.  From a starting point of 970's to 980s mb pressure depths - even in the Euro's shallower depths, I think that's doable - there's a combination of signals super-imposing there.   

Then we need to ask how much?  I mean ... going from light and variable near a low's center to even a mere 30 knots abruptly still qualifies as an iso. wind phenomenon - these speculative prose' do not automatically connote death and destruction, either - ha!

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24 minutes ago, dryslot said:

I think the Euro has the right idea for this one, A slp more consolidated in the high 970's seems more likely then some of these more convective looks that the Nam keeps showing with multiple spokes of vorticity.

Agreed!

We've beaten the convective feed-back expectation .. but there's always late comers to the conversation and/or those that .. .have difficulty with this stuff.   

I'll only reiterate what I was discussing/others noted over the last couple of days, that all models agree that the thicknesses at low levels do not reflect a very rich baroclinic region of lower troposphere where the models are attempting to deepen a surface reflection. 

I suspect this is causing models with sensitive convective sequencing to go nuts... The best Q-G forcing/DPVA is actually taking place south of the best warm frontal slope, which is interesting. But, that pinches off the warm sector aloft - I suspect - and than you are left with a low that has warm air rampart, so the models "mistake" that as warm core - models like the NAM. 

But the Euro most undoubtedly has sophistication in its physical make-up *(i.e., superior convective sequencing/integration therein), it's probably got things about it open to critique but... heh, these NAM notions of hyper meso lows rattling around inside a circumvallate are a smoking gun for a surface front starved environment in a model that is defaulting to the next available mechanical processes for focusing a low.  

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Looking closer at this NAM ... it's certainly eye-candy whether it verifies or not.. .

But, more practically ..there is an emergent property about the NAM's solution - it's [ enter euphemism here ] depth, and integration with the mid level cyclonic featuring, I suspect can account for why it is slowing the low down and evolving it into a full on capture/stall scenario. It even Fuji Wara's the surface low while it is trying to fill... 

I don't believe yet the NAM's total evolution is going to transpire.  Something more like the Euro most likely ...with perhaps some caveats and distractions within the frame-work of expected/acceptable error.  Having said that... you know, the wind in the NAM may end up being blase anyway?  If the front side is sort of "protected" by inversion, then...the low stalls over Worcester for 12 hours like that, the wind in the central region of that vortex is actually going to drop to variable and light for a time... So that's two thirds of the event with wind shirking the barographic layout - that'd get the locals pissed!  

 

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I dunno, maybe I’m oversimplifying this, but to me the whole problem gets reduced to this: either we see nascent signs of a tropical disturbance develop off the SE coast today, or we don’t. If it’s the latter, the less amped 0z/6z euro-esque solution is the most likely outcome.

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The RGEM makes sense to me. You do not have those mini lows on roids, but those small ones that could enhance winds as they pinwheel up. I think that looks logical.

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