Septorcher 2026 Discussion - Endless Summer

[WinterWolf]

4 minutes ago, Damage In Tolland said:

It’s the strong HP to the north . Pressure gradient winds. Bigtime 

Yes, but Winds will most likely disappoint inland as usual…except of course along the immediate coast.  
 

But At least we have something to track. 

[vortex95]

4 hours ago, CoastalWx said:

I don’t think that strong. 925 would need to be 80-90kts and I don’t see that. Mixing barely to 925 as well. Unless this deepens  more.

You forget how we are at peak SSTs for the season, and they are running 2-4 C above avg not that far S of the region, so better mixing down of 925 winds likely.

[WinterWolf]

1 minute ago, vortex95 said:

The most epic of epic of all Sep nor'easters!  Weenies rejoice!
 

But that’s a pretty low bar…no?  

[Damage In Tolland]

3 minutes ago, vortex95 said:

The most epic of epic of all Sep nor'easters!  Weenies rejoice!
 

Seems like 45-60 mph gusts inland and 50-70 mph coasts right ? 

[LSC97wxnut]

6 minutes ago, kdxken said:

Let's do this. 

 

Can I selfishly root for this even though I'd usually love to see the Euro and AI's win?  Daughter has her first out of state softball tournament in Connecticut this weekend.

[vortex95]

I posted this one another forum.  @CoastalWx in awe of the meteorological and social science analyses?  

 

----------

For several days now, the global models have been indicating an atypically strong

non-tropical low for September developing off the U.S. Mid-Atlantic/New England

coasts by this weekend.  High winds, coastal flooding, and excessive rains are 

becoming more likely, especially in southern New England.

 

Some models, such as the ECMWF and UKMET, are showing a strong warm seclusion

evolving when the low slows down and stalls for a time not far S of New England.  I 

attached the 850, 700, and 500 heights/temp valid 09z September 27 from the 22/00z 
ECMWF that clearly shows the warm seclusion.

 

SSTs S of New England are running anywhere between 2-4 C above average and are

22-25 C in the region where the low is forecast to slow/stall, more than enough for

subtropical development, and with such SSTs we have seen full tropical transition 

before.

 

Now I know this sounds like I am getting ahead of myself here, but one has to 

proactively think in the abstract and outside the box here, especially 
when it comes to atypical/outlier events forecast and their impacts.
 

I know of no case where a strong non-tropical low transitioned to subtropical or 

tropical in this area of the Atlantic so close to the Mid-Atlantic or New England 

coasts.  There was an intense non-tropical low that impacted this region in October

2021 that eventually became TS Wanda, but not until far out of sea in the central 

Atlantic.

 

The conundrum I see is that if such a transition occurs, it may be while significant

non-tropical land impacts from wind/rain/coastal flooding are ongoing.  So that 

implies non-tropical wind warnings would have to be switched to tropical wind 

warnings.  This presents a problem in messaging, among other things.

 

We have policy/procedures in place when a tropical system transitions to PT/ET  --

the capability to continue pre-existing tropical wind warnings, but what about when

you have an ET low going to subtropical/tropical?  There is no sensible weather

difference between gale/storm warnings and tropical storm warnings, but a 

significant amount of the public does not realize or understand that.  Going from

an unnamed system to a named system?  Well, I don't have to say how the

media (social and otherwise) reacts when a subtropical/tropical system is named.

But the meteorology operationally just can't be ignored either.  A system is what

it is.

 

This is further complicated by the fact that days before non-tropical low develops, a 

strong pressure gradient from high pressure over southeastern Canada will result in

gale force E and NE winds as early as late today over the marine zone waters off the 

Mid-Atlantic and New England coast.
 

In my opinion, the above is a non-trivial from a logistical and social point-of-view if

such a non-tropical to ST/T transition occur in said region.  A similar modern day 

event that did not fit or work within any current policies/produces at the time occurred 

with Hurricane Sandy in October 2012, which was also this very same region.  The 

ante this time is not forecast to be on the level of Sandy, but nevertheless is significant.

[Typhoon Tip]

There's some sensitivity to deterministic solutions coming from the amount of positive vorticity ( how much?) getting pulled out of the Caribbean and injected between 42 and 90+ hours or so.  This window of interaction is being slightly differently handled in the Euro vs GFS.  The Euro is sweaty love-making. The GFS isn't sure what its feelings are ..heh

Recent Euro runs are quite proficient/bullish with the result, because it is massively infusing this junk/failed zygote tropical entity into the agglomeration of weak S/W aspect that is wobbling through that lat/lon of the MA by the end of that time range.  This transition of annotated charts over the course shows what happens when even weak N stream gets injected with a pithy diabatic heat source...

 

 

 

The GFS is occasionally not as proficient with/in the integrating idea. 

The Euro has been rather persistent in forecasting a proficient phase at a range when modeling et al typically has higher average error when handling delicate matters. 

I took a look at the ensemble means of both ... it appears the idea of vestigial tropical infusion and subsequent unusual feedback due to that source is what I was personally missing yesterday in my analysis at that time.  That does not mean it will happen like the Euro, per se... the 00z GGEM was less, as was the 06 GFS... We'll pick and choose ( ha, I can imagine which this particular group will pick!).  But there's enough support from the orbit of the ens means of both camps to suggest a Euro idea isn't impossible.  It is, however, one of the stronger members out of the whole EPS cluster, whereas the GFS is in the apparent interquartile mean of its own group. 

This is why suggest the scenario is a bit touchy.  Smaller percentages less of the lower latitude diabatic source-inclusion into the holistic set up... will probably manifest something more like the a flatter/weaker less entertaining surface result.

For now ..I'm willing to go less than the Euro's bigger dawg with this thing, but give it a nod should we get into a better deterministic range and the other models start getting more proficient/synergistic like that.

[CoastalWx]

6 minutes ago, vortex95 said:

You forget how we are at peak SSTs for the season, and they are running 2-4 C above avg S not that far S of the region, so better mixing down of 925 winds likely.

SSTs are 61-63 offshore. Already cooling. 

[weatherwiz]

5 minutes ago, Typhoon Tip said:

There's some sensitivity to deterministic solutions coming from the amount of positive vorticity ( how much?) getting pulled out of the Caribbean and injected between 42 and 90+ hours or so.  This window of interaction is being slightly differently handled in the Euro vs GFS.  The Euro is sweaty love-making. The GFS isn't sure what its feelings are ..heh

Recent Euro runs are quite proficient/bullish with the result, because it is massively infusing this junk/failed zygote tropical entity into the agglomeration of weak S/W aspect that is wobbling through that lat/lon of the MA by the end of that time range.  This transition of annotated charts over the course shows what happens when even weak N stream gets injected with a pithy diabatic heat source...

 

 

 

The GFS is occasionally not as proficient with/in the integrating idea. 

The Euro has been rather persistent in forecasting a proficient phase at a range when modeling et al typically has higher average error when handling delicate matters. 

I took a look at the ensemble means of both ... it appears the idea of vestigial tropical infusion and subsequent unusual feedback due to that source is what I was personally missing yesterday in my analysis at that time.  That does not mean it will happen like the Euro, per se... the 00z GGEM was less, as was the 06 GFS... We'll pick and choose ( ha, I can imagine which this particular group will pick!) 

This is why suggest the scenario is a bit touchy.  Smaller percentages less of the lower latitude diabatic source-inclusion into the holistic set up... will probably manifest something more like the a flatter/weaker less entertaining surface result.

This is where you have to wonder whether the Euro's parameterization scheme just remains far superior to the GFS. I mean compare H5 of the Euro to the GFS from the 0z run at initialization. Now one could argue it's "noise" or subtle differences but IMO those differences for an initialization are rather large. I would also re-suggest the argument of the lack of upper-air observations within the region the s/w is traversing but the counter-argument to that would be - why is that not impacting the Euro...perhaps an answer to that would be...the euro is just more superior with initializing processes haha. 

Anyways, this post comes across as Euro is right and GFS is wrong - obviously we don't know that but lets say the Euro ends up scoring the scoop on this and blows the GFS away...may as well just put the GFS away. 

[WinterWolf]

12 minutes ago, Damage In Tolland said:

Seems like 45-60 mph gusts inland and 50-70 mph coasts right ? 

I’d go 25-40 mph inland at the moment. If this thing wraps more over the next couple days…then we up the ante.  Stay conservative for time being. 

[Typhoon Tip]

13 minutes ago, CoastalWx said:

SSTs are 61-63 offshore. Already cooling. 

Makes sense ...

I was attempting to be in the water near the end of July up near Rye Beach/NH coast, and the 57ness of it was too much for the balls to handle... Couldn't really go in deeper than knees.  

3 years ago around that same time I was there, and the 73 F water was warm enough that we were able to spend over an hour on boogie boards with no wet suits...  Granted, this was an excessive warm anomaly for that area. 

Now, this is just one bloke's take on it, but I do check the summer progression of SST around here as a matter of course. And world over for that matter. As an ongoing observation I was never very impressed with the buoy numbers this summer.  Seemed this was a regression year for local SSTs ... whether normal or not, notwithstanding.  Just less in the way of residual heat to keep things elevated into autumn?

[Damage In Tolland]

3 minutes ago, WinterWolf said:

I’d go 25-40 mph inland at the moment. If this thing wraps more over the next couple days…then we up the ante.  Stay conservative for time being. 

Maybe in your area that doesn’t do wind well. But many windy areas are gonna roar for days and days.

[TauntonBlizzard2013]

26 minutes ago, kdxken said:

Let's do this. 

 

This will be close to reality IMO.

Hope it’s wrong because we desperately need the rain, but sell 

[Typhoon Tip]

10 minutes ago, weatherwiz said:

This is where you have to wonder whether the Euro's parameterization scheme just remains far superior to the GFS. I mean compare H5 of the Euro to the GFS from the 0z run at initialization. Now one could argue it's "noise" or subtle differences but IMO those differences for an initialization are rather large. I would also re-suggest the argument of the lack of upper-air observations within the region the s/w is traversing but the counter-argument to that would be - why is that not impacting the Euro...perhaps an answer to that would be...the euro is just more superior with initializing processes haha. 

Anyways, this post comes across as Euro is right and GFS is wrong - obviously we don't know that but lets say the Euro ends up scoring the scoop on this and blows the GFS away...may as well just put the GFS away. 

It's not really noise though if one can identify the cause of the differences...  Not meaning to be priggish ...just that it seems pretty clear - to me - that if the smear cross Cuba and gets pulled in en masse like the Euro, it's getting a huge physical feedback from that.  I think Scott mentioned feedback yesterday - no arg there but 16 dm of?!   "Noise" seems like a spray of offsetting probabilities...

Well, this explains where.   The GFS is less proficient with that infusion... The Euro, more.  Results follow -

But I agree, higher resolution is worth wondering -

[weatherwiz]

2 minutes ago, Typhoon Tip said:

It's not really noise though if one can identify the cause of the differences...  Not meaning to be priggish ...just that it seems pretty clear - to me - that if the smear cross Cuba and gets pulled in en masse like the Euro, it's getting a huge physical feedback from that.  I think Scott mentioned feedback yesterday - no arg there but 16 dm of?!   "Noise" seems like a spray of offsetting probabilities...

Well, this explains where.   The GFS is less proficient with that infusion...

But I agree, higher resolution is worth wondering -

Agreed with that.

But to be clear (though this may not matter) I was referring to H5 in general (across CONUS) - not just the specific feature. But I get what you're saying. 

[ineedsnow]

BOOM!!!! 

[CoastalWx]

6z deep mind more clustered south of ACK and MVY then bending west. 

[Torch Tiger]

bend that crap ots thanks. No one wants that

[MarkO]

It looks like it is still warm enough to be a warm core storm that will transition as it moves north with the wind field expanding like Sandy did. But all that churning and slow moving is going to cool the surface. 

My niece is getting married on Friday afternoon in Newport in a fancy ceremony. I feel bad, but it might be interesting.

[ScituateWX]

26 minutes ago, CoastalWx said:

6z deep mind more clustered south of ACK and MVY then bending west. 

Scott is deep mind something you have to pay for?

[WxWatcher007]

I started a thread for posterity. This looks like it's going to be pretty impactful. 

[HIPPYVALLEY]

37 minutes ago, Torch Tiger said:

bend that crap ots thanks. No one wants that

What do you have against miserable weekends?

[CoastalWx]

17 minutes ago, ScituateWX said:

Scott is deep mind something you have to pay for?

Can look at it on Weathernerds. It’s labeled GFM and then the one that has been superior is called weathernext. It’s labeled as GDMWNV3

[Damage In Tolland]

46 minutes ago, CoastalWx said:

6z deep mind more clustered south of ACK and MVY then bending west. 

Thats a bigtime impressive damager pike  South 

[CT Rain]

Pretty well mixed in the boundary layer. 

This would be problematic for sure. 

[CoastalWx]

11 minutes ago, Damage In Tolland said:

Thats a bigtime impressive damager pike  South 

In this case you want to be on the north and northwest side of this storm. 
 

it’s way different than Sandy which was moving WNW and had a high to the east causing strong SE flow.

[CoastalWx]

1 minute ago, CT Rain said:

Pretty well mixed in the boundary layer. 

This would be problematic for sure. 

That’s funny you posted that. In between bands it definitely seemed more mixed. 

[ineedsnow]

Not around here but what a monster storm Polo turned into and insanely fast

[SJonesWX]

1 hour ago, WinterWolf said:

I’d go 25-40 mph inland at the moment. If this thing wraps more over the next couple days…then we up the ante.  Stay conservative for time being. 

i am pretty sure that DIT has no idea how to stay conservative.

[Damage In Tolland]

29 minutes ago, CT Rain said:

Pretty well mixed in the boundary layer. 

This would be problematic for sure. 

We’ve been trying to tell them . Hopefully they start listening to the seriousness of this