csnavywx

3 minutes ago, eyewall said:

Yeah we will have to see if that will occur or if it event slips east of NOLA like Katrina did and slams Bay St. Louis.

Stronger earlier plus right of center adjustments are not great. Still have some hope it stays far enough west to spare NOLA. At least in this case there's no trough trying to dig the 'cane out and eroding the ridge as it does so.

5 am advisory now forecasting borderline cat 3 on landfall but notes the following wrt intensity: 

It should be noted that this intensity is lower than that forecast 
by the HMON model, the HCCA corrected consensus model, and the 
Florida State Superensemble. 

MWCR 270900Z 28008KT 250V130 9000 -SHRA BKN014 SCT028 26/25 Q1003
MWCR 270800Z 32008KT 290V350 9999 -SHRA BKN010 26/25 Q1003
MWCR 270700Z 35010KT 330V040 9999 BKN018 26/25 Q1004
MWCR 270600Z 06010KT 9999 FEW016 BKN030 27/24 Q1005
MWCR 270500Z 09017KT 9999 FEW016 BKN030 27/24 Q1007 

Looks like the center is passing north of Grand Cayman. Radar confirms this.

Just now, MUWX said:

Forecasting a major in the initial forecast is unprecedented. This initial advisory is about as aggressive as they ever get. 

Pretty much this. It's already an aggressive forecast. Warranted, mind you, but already explicitly forecasting RI.

Having said that, the LLC got going in a hurry this morning and we're already on the northern side of the guidance envelope (from yesterday's runs), so -- not great news. We'll get Cuba as a speed bump at least, but I'm not sure how much that's really going to help. The "good solution" space is even narrower than yesterday.

Convection now coalescing on the northern end of the wave. Should get a nice convective burst out of that tonight.

13 minutes ago, NavarreDon said:

Not pointing this at anyone directly but, not sure how we can predict landfall from a system without a closed circulation. History tells us that this is a crapshoot at best. Using Grace as an example, before formation models trended from the FL big bend W to the MS/AL border. After formation they trended back E thru AL then into the FL Panhandle. The only thing that’s relatively sure now is a more N formation should equal a more E track & a more S formation should equal a more W track. At this point ,In the USA, people from Brownsville to at least the W FL Panhandle should have a eye raised for 99L.


.

TC formation generally favors the north end of the wave circulation envelope, where the curvature vorticity is naturally maximized. So, the modeling developing there isn't particularly surprising. Also, the synoptic steering features for Grace were more uncertain. Steering here is driven by a very large and displaced subtropical ridge, so there's less uncertainty on that component.

There's just not much "good" solution space. The best case seems to be on the lower-prob south end or a messy/slow initial vortex formation. And as mentioned before, that's not a very long list.

4 minutes ago, Ed, snow and hurricane fan said:

Because a likely major hurricane hits New Orleans in 4 days, or something seems wrong with the modeling.

Thanks.

We don't need a 'cane into NO in this kind of setup and steering flow. Luckily, still a 1-2 days of run-to-run variability left (until it forms), so it likely won't stay there.

Hard pass on that run. Luckily, still 5 days out on an unformed invest.

Just now, nwohweather said:

Yeah we can but all those people locally would lose the work. We’d basically move everything over to Houston and close that down permanently

Lots of spread still -- plenty of time for it to change. Crossing my fingers for ya.

The list of potential negatives for this thing is pretty short. With virtually all lower-res global guidance and ensembles calling this, it's starting to look like one of those events I like to call "synoptically evident".

Gotta hope for some sloppy early-stage development or (destructive) land interaction. I don't think outflow shear in the gulf from an Epac storm alone is going to cut it in this case.

1 minute ago, CoastalWx said:

Yeah moving N or a bit east of N which is expected.

That very well may just be convection wrapping upshear as the shear magnitude lessens (down to ~13 kt on CIMSS, probably sinking <20 in the mid-upper levels).

We're at/near peak shear and Henri seems to be holding up. 27kt analyzed on the 06z GFS and 31kt on CIMSS. It decreases through today and into tomorrow, dropping to or below 20kt by 06z tonight and down to 10-15 by tomorrow evening.

Regardless of track, if this thing does hit NE, it won't be trucking along. The trough is weak and trapped underneath a ridge. It'll be over cold water for a while, which caps LF strength.

As OSU pointed out, this thing is already pretty far east. Much will depend on how Henri gets through the next 24-48hr. Shear peaks in the ~36hr timeframe at around 25kt (from 16 now). That's probably not enough to decouple it completely, but depending on how convective trends end up, we could see some further southwesterly adjustments -- albeit the ensemble spread suggests not as much as we've had over the past day or two.

The airmass getting entrained via shear isn't particularly dry during max shear either, so I'm leaning stronger than I would normally.

They're late to the punch. It's already happened twice in the last couple of weeks. EOSDIS shows that pretty well. And I don't know about the "first time" part. Been some pretty big fire seasons up there the past few years.

24 minutes ago, Typhoon Tip said:

Through both indirect and direct geo-physical various circuitry ...the following article probably is more connected/suitable for this thread. Example, "..Complex interplays between the AMOC and North Atlantic sea-ice cover in conjunction with salinity and circulation changes have been proposed as physical causes underlying the DO cycles..."

https://www.nature.com/articles/s41558-021-01097-4.epdf?sharing_token=qWMQcnRcVRZQmZ_yahYbd9RgN0jAjWel9jnR3ZoTv0ODQw4Na6S4LwvIIwjZ_S3NdBoG6pi8c5NBfIwoUKp1VK_OHHszXMnB3OMoyz8L8emOhG-hoDsJyn1YMubz_IampYbIRg_8P9vjnfIPPzRQwm6m9BfwEGfoLu0JsB4E2trSfyu4r947mOz1oZQlyxQxZLxaMkEINR4Wt7XEIrPrRkahci-lKgCSTZahFzlH7wM%3D&tracking_referrer=www.washingtonpost.com

"...Here, a robust and general early-warning indicator for forthcoming critical transitions is introduced..." c/o above -

I'd also point out that we in the field began involved in conjecture as well as reading formulated papers/science on the subect matter all the way back to the early 1990s.   Really interesting embedded statements, like:

"...Different lines of evidence from palaeoclimate proxy records indicate that Northern Hemisphere temperatures have varied abruptly at millennial time scales during previous glacial episodes, with corresponding changes of the AMOC between its weak and strong modes1,15,16...."

Read through that paper once this morning. Will be combing it a few more times before I make up my mind on it. It obviously needs more confirmation and research, but if Rahmstorf et. al and now Boers are on to something with AMOC stability states, this is extremely bad news. AMOC instability falls into the category of low prob. but very high impact. Whelp, the probability might be higher than we appreciate.

Reminds me of a paper not too long ago, but it was more focused on the sub-polar gyre. Boer's paper is making the case that *most* CMIP models are too stable.

Link to that one: https://www.nature.com/articles/ncomms14375

On 7/20/2021 at 6:46 PM, A-L-E-K said:

Naso keen on our new summer doldrums smoke watching season 

Gonna be a LOT more of that this year and in the future. While the stuff out west is going first, as the Manitoba fires show, those jack pine forests can go up in smoke too.

3 minutes ago, BuffaloWeather said:

https://en.wikipedia.org/wiki/Year_Without_a_Summer

That was mainly via SO2 forcing via the stratosphere.

18 hours ago, donsutherland1 said:

This is another bad break on the climate change front. There had been some hope that cloud changes could somewhat dampen the warming. Research by Jessica Tierney et al., hinted at amplification from the paleoclimate record, but there was no direct evidence. This paper provides that evidence. Its findings underscore the urgency of moving faster rather than more slowly in curbing greenhouse gas emissions.

Yeah, that's almost a complete shutout of ECS <= 2C by their calculations. While the mean looks to be around 3.2, that PDF is .... not great. Anything under 2.5 is pretty unlikely and pretty decent probs of something closer to 4.

From what I'm gathering, that's also just from the observational record. Paleo suggests ECS itself might be variable depending on the state (higher during warmer climates for instance). https://advances.sciencemag.org/content/5/9/eaax1874

Having said all of that -- I'm also wondering if the laser-like focus on ECS is a bit troublesome in itself. It's possible, for instance, that we're focusing a bit too hard on global temps and not enough on downstream effects -- like asymmetric hemispheric response. All evidence points towards the NH losing ice much faster than the SH and indeed paleoclimate tends to suggest that the NH and SH can exist in a "decoupled" state where most of Antarctica can still be relatively cold and glaciated and the NH is essentially much closer to something resembling a greenhouse climate. The GIS will still be around for quite a long time but the amount of resistance it can put up pales in comparison to the combination that the circumpolar current and EAIS can put up. It's worth noting that Antarctica glaciated pretty early on (30-40mya at around 650 ppm I think?). I'm sure the isolating power of the circumpolar current helped, but if folks like Tierney are right, that doesn't have as much of an effect as one might initially think.

1 hour ago, WxUSAF said:

It was pretty evident driving home that the smoke is reducing visibility at ground level as well.

Yep, HRRR has some pretty nasty (4-6SM vis) smoke descending to the surface tomorrow and especially late Wed. I would expect a lot more smoke haze aloft over the next couple of days, but the weak cold advection behind Wednesday's little front will probably help drag more of it to the surface. Not going to be great for folks with respiratory issues.

Can't imagine what later this summer and fall are going to look like with the way it's going out West this year.

16 minutes ago, George BM said:

That 25-27K theta-e difference. Is that between the 1000mb and 500mb level?

I generally use the difference between the mixed boundary layer and a representative sample of the theta-e minimum aloft (generally 700-600mb), though there are a few effective methods to choose from depending on the situation.

Latest skew-T fcst soundings spitting out widespread 45-55kt wind gusts (and theta-e differences between the mid-levels and boundary layer of about 25-27K, which matches) so probably a good call there by the SPC on emphasizing the wind potential. Though I think it'll mostly be outflow dominated by the time it approaches the bay, wouldn't be surprised to see some weak rotation in any discrete activity and a bit better organization in general as the windfield is already backed and dews are higher there. We're at the time of the year where the Bay is very warm (80+F) and tends to help convective activity by pumping dews and providing instability after sunset.

Convective initiation west of IAD and down closer to CHO. The cell west of IAD started putting off quite a few strikes before there was much of a BR signature. Some high grade instability to work with today and a strong sign that today's storms will likely be electrically active.

90/77 here. Absolutely soupy and miserable.