Mid October 2019 Bombogensis Coastal

[Ginx snewx]

36 minutes ago, OceanStWx said:

Your window is like 10 pm to 4 am or so I think.

HREF is painting quite a bullish picture for QPF for the upslope in NH and VT. Even taking 60-80% of QPF is like 3-4". 

Tried sending you a pm but it says you can't receive messages 

[weatherwiz]

Next few to several hours will be quite telling as we watch off the coast of VA/NC. 

Anyways for being so close this is extremely impressive. I think I saw a max of like 195 -ubs^-1 lmao

[OceanStWx]

1 minute ago, Ginx snewx said:

Tried sending you a pm but it says you can't receive messages 

I'll have to check it out later. I'm crashing after mids. 

Pants off, dance off at work tonight. 

[weatherwiz]

4 minutes ago, Ginx snewx said:

Switch lol only 10 month and a helluva lot more data. Also he gives you a test site lab.weathermodels.com

idk...I think Weatherbell is better really and has more data. 

[CoastalWx]

6z euro crishes Cape Cod. Might even clip S shore and Cape Anne with that. 

[purduewx80]

1 hour ago, jbenedet said:

It seems that this shouldn’t remain a mystery for long. The mesolow—if it develops—is currently developing off the Carolina coast. That much is consistent across the guidance which has it. We watch.

There's definitely a surface reflection near CHS as of 12Z, but convection is displaced off to its SE. Broad pressure falls across the Carolinas and southern VA. 

[Typhoon Tip]

As was advertised, discussed at length ...all week, limited surface to 800 mb thickness gradients ( laterally ) through New England and nearby coastal waters ( i.e., weak surface frontal structures ) means any surface low will quickly move toward a collocation with the better Q-G forcing at mid levels. There's a lack of antecedent cold air in place.

That's why we are seeing these more recent models runs hint more toward gobbling up the secondary low they ( particularly the Euro) develop between PHL and NYC, and then more cohesively focusing a track through CT. This then goes on to a nadir somewhere between there and coastal Maine or thereabouts, end 24 hours, at which point this is already filling... There may be smaller gyres extending SE of that overall structural migration, and I feel reasonably confident that some of these guidance types have been hyper focused on those satellite features - probably based in no small part on the foresaid homogenized lower thickness layout out.. The next physics in the basket defaults to convection based upon those model's specific "Klein and Frisk" sequencing or whatever in the hell it's called that makes them bad for extratropical management...  

Anyway, this synoptic evolution is not without impacts. The extent is up for grabs. There's a lot of mid level dynamics with this thing as we're all aware...and when we start fiddling with those scenarios ... strange things happen sometimes. I could see a couple of bands of thunderstorms east of the low, arcing up from eastern CT/across much of Mass with an ESE wind underneath and someone over SE Mass getting an EOF spinner out of this... It's not likely, no..but there are possibilities in the fray of this thing that are > than we may think.  Also, if a LLJ/inflow core gets into the 925 mb level, neutral buoyancy or even somewhat unstable SST to air along the shore might transfer some of that down - but that's less having to do with surface pg..

For me in particular, I still suggest that the strongest wind impact may be felt in the back side across much of the region. I don't believe based on recent Euro trends ( a very dependable guidance source inside of 3 day leads ) that a stinger is likely to occur, but.. in the spirit of fairness, the low appears to go through some particular mid level VV saturation somewhere between HFD to PWM; folding could be problem S of the Pike for time... But, without that .. this event's back side has very good momentum transfer in CAA kinematics.

The other thing about this that isn't necessarily very easy to see, is that model consensus overall has pressure falling "AS" the low moves in.   It seems the d(pressure) is taking place at a similar rapidity to the motion of the storm itself. That's an offset where storms motion compensating the restoring forcing, so the wind response may end up less on the front side than the individual pressure contoured charts would readily suggest. This may be less so on the coast, and more pronounced inland. I've seen this hundreds of times.  Squeezed contours with fast cloud motion and trees are barely moving insland, while there's power outages in Plymouth. But, ...then the low moves past, and all the deep pressure tries to fill from two overlapping sources:  Low moving away = delta(pressure rise) and the isollabric vector looks impressive in this to me; cold mid levels coming into the underbelly of this with temps in the 40s and 50s is an unstably lapse rate scenario.  For all this, I would not be surprised if the strongest winds are not on the front side.

Creek flooder too -

[moneypitmike]

1 hour ago, Baroclinic Zone said:

James gonna be blown to PTown

 

That map goes from "wow" to "meh" in just a few miles.

[jbenedet]

Wrt last night’s 0z runs, hedge bets in favor of a correction slightly west as guidance tends to underestimate downstream UL ridge amplification due to LHR. The deep tropical nature of this system means the correction inside 12-24 hr could be larger than usual...

[weatherwiz]

5 minutes ago, Typhoon Tip said:

As was advertised, discussed at length ...all week, limited surface to 800 mb thickness gradients ( laterally ) through New England and nearby coastal waters ( i.e., weak surface frontal structures ) means any surface low will quickly move toward a collocation with the better Q-G forcing at mid levels. There's a lack of antecedent cold air in place.

That's why we are seeing these more recent models runs hint more toward gobbling up the secondary low they ( particularly the Euro) develop between PHL and NYC, and then more cohesively focusing a track through CT. This then goes on to a nadir somewhere between there and coastal Maine or thereabouts, end 24 hours, at which point this is already filling... There may be smaller gyres extending SE of that overall structural migration, and I feel reasonably confident that some of these guidance types have been hyper focused on those satellite features - probably based in no small part on the foresaid homogenized lower thickness layout out.. The next physics in the basket defaults to convection based upon those model's specific "Klein and Frisk" sequencing or whatever in the hell it's called that makes them bad for extratropical management...  

Anyway, this synoptic evolution is not without impacts. The extent is up for grabs. There's a lot of mid level dynamics with this thing as we're all aware...and when we start fiddling with those scenarios ... strange things happen sometimes. I could see a couple of bands of thunderstorms east of the low, arcing up from eastern CT/across much of Mass with an ESE wind underneath and someone over SE Mass getting an EOF spinner out of this... It's not likely, no..but there are possibilities in the fray of this thing that are > than we may think.  Also, if a LLJ/inflow core gets into the 925 mb level, neutral buoyancy or even somewhat unstable SST to air along the shore might transfer some of that down - but that's less having to do with surface pg..

For me in particular, I still suggest that the strongest wind impact may be felt in the back side across much of the region. I don't believe based on recent Euro trends ( a very dependable guidance source inside of 3 day leads ) that a stinger is likely to occur, but.. in the spirit of fairness, the low appears to go through some particular mid level VV saturation somewhere between HFD to PWM; folding could be problem S of the Pike for time... But, without that .. this event's back side has very good momentum transfer in CAA kinematics.

The other thing about this that isn't necessarily very easy to see, is that model consensus overall has pressure falling "AS" the low moves in.   It seems the d(pressure) is taking place at a similar rapidity to the motion of the storm itself. That's an offset where storms motion compensating the restoring forcing, so the wind response may end up less on the front side than the individual pressure contoured charts would readily suggest. This may be less so on the coast, and more pronounced inland. I've seen this hundreds of times.  Squeezed contours with fast cloud motion and trees are barely moving insland, while there's power outages in Plymouth. But, ...then the low moves past, and all the deep pressure tries to fill from two overlapping sources:  Low moving away = delta(pressure rise) and the isollabric vector looks impressive in this to me; cold mid levels coming into the underbelly of this with temps in the 40s and 50s is an unstably lapse rate scenario.  For all this, I would not be surprised if the strongest winds are not on the front side.

Creek flooder too -

I continue to agree with this. That has been my thinking as well. 

The potential is certainly there for some pretty impressive wind gusts tonight, however, I don't think it will be very widespread and we're really relaying on exceptionally difficult-to-pin-down details (mesolows, gravity waves, etc.) to generate wind gusts of those magnitudes. 

You're last paragraph explains it very well too...with how it's deepening and where the deepening is occurring it's just not good for region wide winds on the front side...moreso the backside. 

[weatherwiz]

This is right around the time when the GFS has the most intense precip/wind moving through the Cape along with core of LLJ FWIW, also has the sfc at 975mb lol...so you only have to ascend 400-500' to tap into the base of the LLJ lol

[jbenedet]

27 minutes ago, purduewx80 said:

There's definitely a surface reflection near CHS as of 12Z, but convection is displaced off to its SE. Broad pressure falls across the Carolinas and southern VA. 

Think the specific area to watch is the blob of convection south of Wilmington NC. Difficult to tell by radar but appears there may already be a very weak LLC embedded within that.

 

[weatherwiz]

2 minutes ago, jbenedet said:

Think the specific area to watch is the blob of convection south of Wilmington NC. Difficult to tell by radar but appears there may already be a very weak LLC embedded within that.

 

sfc obs seem to indicate this may be 

[Baroclinic Zone]

I would agree that the majority of the region sees it's strongest winds on the backside.  South and east facing coasts and those on the east side of the track will see strongest on initial southerly/ south easterly winds.

[Cyclone-68]

Is this setup what old timers used to call a screaming sou’easter?

[HIPPYVALLEY]

7 minutes ago, Cyclone-68 said:

Is this setup what old timers used to call a screaming sou’easter?

I think Sou’easter comes in W of us?  

[dryslot]

Its usually based on an inland runner, This is a unique system (hybrid) where you have really nothing to go back into an analog to get some type of help determining what may happen with this.

[HIPPYVALLEY]

Just now, dryslot said:

Its usually based on an inland runner, 

Like the storms we generally get Xmas week. 

[dryslot]

Just now, HIPPYVALLEY said:

Like the storms we generally get Xmas week. 

Your a mean one, Mr..........

[weatherwiz]

What might be really cool is it could go from raining buckets to absolutely nothing within minutes...looks like a crazy shark cutoff between precip and dry slot. WV is going to be fun to watch as this evolves. 

[Cyclone-68]

1 minute ago, weatherwiz said:

What might be really cool is it could go from raining buckets to absolutely nothing within minutes...looks like a crazy shark cutoff between precip and dry slot. WV is going to be fun to watch as this evolves. 

Could we be looking at some thunder from this Wiz?

[purduewx80]

33 minutes ago, jbenedet said:

Think the specific area to watch is the blob of convection south of Wilmington NC. Difficult to tell by radar but appears there may already be a very weak LLC embedded within that.

meh, there's a good 850 jet focus there and an MCV over GA supporting it, but it's pretty clear the sfc low will develop much farther north

[dendrite]

3 minutes ago, weatherwiz said:

looks like a crazy shark

[weatherwiz]

Just now, Cyclone-68 said:

Could we be looking at some thunder from this Wiz?

I know Tip explained some thoughts on this...I think he was more curious/impressed with the potential than I was. 

If it happens I think it would be extreme southeastern areas. The 12z HRRR is rolling in now and I've been kinda watching sfc theta-e advection and the higher values look to scrape the Cape so I think that's what you want to watch for. Obviously, if there is any convection potential increases significantly for 60-70 mph gusts. 

[weatherwiz]

4 minutes ago, dendrite said:

I'm dying right now  

At first I was confused by this but then I read my OP

[LSC97wxnut]

6 minutes ago, dendrite said:

Thank you for the ear-worm...

[jbenedet]

7 minutes ago, purduewx80 said:

meh, there's a good 850 jet focus there and an MCV over GA supporting it, but it's pretty clear the sfc low will develop much farther north

Which surface low? Heh.

The synoptically driven one that develops near the Delaware bay? Sure.

But even the 6z GFS is developing a meso low/weak TC that traverses the Carolina coast. Maybe it doesn’t happen, but that’s the other area to watch for surface pressure falls, especially judging by the convection collocated there right now.

[dendrite]

HRRR tells me to close the coop windows tonight.

[weatherwiz]

1 minute ago, dendrite said:

HRRR tells me to close the coop windows tonight.

Coastal ME gets completely hammered. Has like 70 knots gusts pound into the coast. 

[CoastalWx]

HRRR shows the meso low/gravity couplets. Look at the side by side comparison of 12z HRRR wind gust and reflectivity. Very cool.