GaWx

54 minutes ago, Windspeed said:

99L's low-level circulation appears to be tightening up under the moderate convective canopy. There is clearly mid-level spin parked over the LLC now. This should end the named storm drought this morning. How strong it can get before environmental conditions deteriorate by Monday-Tuesday remains questionable. Though you can see the shear axis is positioned dangerously close, just south of the system, made evident by the screaming upper cirrus flow on satellite, I could easily see this topping out around 50-60 kts if it can remain just north if it. SSTs are warm enough, combined with a cold pool aloft, to continue supporting convection in the short term.

Recent 3 day mean CFS’ have cut way back on the degree of cold in Feb:

9/16-18

Compare that to this from 8/7-9:

9 minutes ago, cptcatz said:

You've been posting lots of UK runs showing a tropical cyclone lately with nothing coming of it. UK has been just as bad as GFS with its fantasycanes. 

There indeed have been UK runs with false TCs though not false canes. But in this case, all models have a low off the NE coast as opposed to it being just on the UK. But would it be T, ST, or ET and would it stay offshore?

Watch off the E coast next week. Here’s a hint of that from 0Z Uk:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 150 HOURS
              FORECAST POSITION AT T+150 : 36.1N  70.8W

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    1200UTC 25.09.2026  156  36.9N  69.7W     1000            47
    0000UTC 26.09.2026  168  39.1N  67.9W      997            41

7 minutes ago, vortex95 said:

No I hadn't . What model is this?

I was looking at the various primarily model outputs  for intensity fcst (see attachment).

The operational GFS and ECMWF do very little w/ the system.  ECMWF brings it down to 1012 mb and makes it a TD.  Since the overall environment is marginal and fcst to gradually degrade, I am not optimistic at this time more than a TD.

That being said, the convection that has developed on the N side in the last few hours is more organized, but we need to see if it persists.  The dry air present makes it prone to pulsing up and down.  This makes it hard to pull the trigger and declare.  At 03z, it could look quite good and get declared, and then all the convection could collapse, and we are back at square one.  So NHC tends to hold off until clear trend or consistency exists.  These kind of high-latitude systems are often a challenge!

Google Deep Mind

12 hours ago, GaWx said:

 The AAM is now up to +3.7 and has a good chance to be off the chart tomorrow!

AAM +3.9 & rising to very extreme levels. Should be off the chart on next runs:

18 minutes ago, vortex95 said:

Convection has not been persistent enough.  For developing systems, you do not want irregular blobs pulsing.  There has been no curved banding evident yet for the system.  1016 mb c.p. shows a high environmental pressure field w/ synoptic gradient weak from the high centers to its NE and W

99L is in a very narrow margin area.  Look at the WV loop attached,  Strong shear evident t toe S, more starting to press in from the NW, and deformation zones N-W-S.  18z SHIPS output environment is not good.  Shear is high and 700-500 RH quite low..
https://hurricanes.ral.ucar.edu/realtime/plots/northatlantic/2026/al992026/stext/26091818AL9926_ships.txt
 

Intensity models usually for nascent systems are bullish in taking them to min TS quickly, but about half of them currently do not even do that.  A testament to this Atlantic season I suppose when nothing can go "right!"

TD status appears mdt-high, but TS is more of challenge.

Did you see this?

56 minutes ago, WEATHER53 said:

The signal that Katrina  was the sure sign of global warming causing ever increasing destruction to the USA was Gore style hype. 

 There may very well be a reduction in the # of storms due to GW because it has warmed the poles much more than the tropics. Because tropical systems bring heat out of the tropics to higher latitudes, it’s possible that the lower contrast means fewer storms albeit with perhaps stronger storms on average due to the warming oceans.
 

 Indeed, we’ve had stronger storms in the Atlantic basin with more cat 5 since 2016 per year than for the prior period. But OTOH, I do wonder if just having warmer oceans is enough to generate stronger storms. Isn’t it the contrast of the avg tropical ocean temp vs the avg global temp that matters most? The oceans in the tropical/subtropical regions are obviously warmer, but the rest of the globe is warmer, too. It used to be that ~79F was a crucial SST to support TCG. Is that crucial SST going to warm up due to GW?

Your thoughts?

3 hours ago, GaWx said:

 This CFSv2 seasonal prediction site, which includes the ENSO SSTa forecasts, hasn’t updated in over 4 days:

https://www.cpc.ncep.noaa.gov/products/CFSv2/CFSv2seasonal.shtml

This is the most recent 10 day mean forecast for RONI:

this has a peak at +2.9, compares to peaks of ~+3.5 on some runs from late July, and was suggesting further drops in the peak being likely on later 10 day means due to most of the blue lines being lower than the red ones:

Follow-up: I emailed the 2 contacts who are listed at this CFSv2 site. Just minutes later, the site was updated!

 Here’s the brand new latest 10 day mean RONI forecast: as expected, the progged peak dropped even further to +2.8. Compare that to the +3.5 runs of late July. It appears it could even drop to +2.75 later this month based on the red vs blue lines:

4 hours ago, WEATHER53 said:

Remember vividly the declarations of ever increasing disaster during the Katrina year.  Has not happened and various drivers of our patterns have changed a lot in last 25 years 

I don’t know about “ever increasing disaster”, but you must know that there have been some bad seasons since including 2008, 2012, and most of 2016-24. 2016-24 was one of the worst 9 year periods for the SE US overall. Fortunately 2025 as well as 2026 so far have given us a much needed break, especially after the horrible 2024. But that’s less than 2 seasons.

 Yesterday’s Euro Weeklies suggested a pretty active period in and near FL during the week of Sept 28-Oct 3rd. This suggests a recurving TC in that area is quite possible:

 This matches long-term climo well, which is at least close to the most active period for FL throughout the season:

 These 5 strong+ El Niño analogs with hits in FL during or near this active period shown on the Weeklies suggest to be wary especially in FL then although it’s interesting that these 5 were all 1902 and earlier as the subsequent 11 strong+ Ninos didn’t have a FL hit around then:

1902:

1899:

1896:

1888:

1877:

99L is now a cherry:

1. Eastern Subtropical Atlantic (AL99):
Showers and thunderstorms have changed little in organization since 
this morning in association with an area of low pressure located 
several hundred miles southwest of the Azores. However, just a small 
increase in organization is likely to result in the formation of a 
tropical depression as soon as later today. The system is expected 
to move slowly over the next couple of days remaining southwest of 
the Azores, followed by a turn to the southwest by early next week, 
when environmental conditions are forecast to become less favorable 
for additional development. 
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 7 days...high...70 percent.

 Is 99L going to be the first TC formation of the month? Edouard became a TC in August. When was the last Sept that didn’t have a TC formation by now? 2025 took til Sep 17th.

 1976 didn’t have one that later became a TS til the TD that formed on 9/26 and that became TS Gloria on 9/27. And there was a ST storm on Sept 13th. So, that doesn’t count as a TC. However, 1976 also had 2 TCs that maxed out as only TDs early in Sep. in the satellite era.

 So, even if a TD is declared today, 2026 has already beaten 2025 for the latest 1st TC declared in Sept. during the satellite era. Now, if it becomes a TS, that would mean that 1976 would remain the season with the latest first named TS in Sept. in the satellite era, which is Sept 27th.

 This CFSv2 seasonal prediction site, which includes the ENSO SSTa forecasts, hasn’t updated in over 4 days:

https://www.cpc.ncep.noaa.gov/products/CFSv2/CFSv2seasonal.shtml

This is the most recent 10 day mean forecast for RONI:

this has a peak at +2.9, compares to peaks of ~+3.5 on some runs from late July, and was suggesting further drops in the peak being likely on later 10 day means due to most of the blue lines being lower than the red ones:

1 hour ago, NorthHillsWx said:

Special update increased odds of 99L developing to 60% and that seems low given satellite. To me I’m not sure how this isn’t a depression at least but I think it is classified as such at 5 regardless 

12Z UKMET is at least the 2nd full run with it as a TD but the prior run didn’t do so until hour 36 (tomorrow at 8AM EDT) before dissipating it 48 hrs later; this run has it already doing that as of 2PM EDT today and then moving very little and never becoming a TS prior to dissipating at hour 96:

GLOBAL MODEL DATA TIME 1200UTC 18.09.2026

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 6 HOURS
FORECAST POSITION AT T+ 6 : 31.9N 34.2W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
0000UTC 19.09.2026 12 32.2N 33.6W 1016 20
1200UTC 19.09.2026 24 32.7N 33.2W 1014 22
0000UTC 20.09.2026 36 33.1N 33.4W 1015 22
1200UTC 20.09.2026 48 33.8N 32.9W 1014 27
0000UTC 21.09.2026 60 35.0N 32.6W 1014 25
1200UTC 21.09.2026 72 34.5N 31.9W 1015 27
0000UTC 22.09.2026 84 33.5N 32.7W 1017 25
1200UTC 22.09.2026 96 CEASED TRACKING

 The SOI has been negative for 37 days in a row.

 The area near the Azores is now Invest 99L.

1 hour ago, cptcatz said:

Pretty remarkable, we are now looking at a solid chance of going the rest of September with no tropical cyclone, let alone a hurricane. Now that GFS finally dropped its fantasycane, models show zilch into October.

Something may be forming near the Azores:

From 8AM TWO:

Eastern Subtropical Atlantic:
A trough of low pressure located several hundred miles southwest of 
the Azores is producing showers and thunderstorms that are 
showing some signs of organization. Environmental conditions appear 
marginally favorable for additional development over the next couple 
of days while the system moves slowly over the eastern portion of 
the Subtropical Atlantic. By early next week, environmental 
conditions are forecast to become less favorable for
development. 
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 7 days...low...30 percent.

 The AAM is now up to +3.7 and has a good chance to be off the chart tomorrow!

1 hour ago, so_whats_happening said:

It does start to become noticeable when you take a look at things in this perspective. Southern hemisphere and tropics still humming along as they have been.

The mean global AAM based on this is not much above 0…+0.5 at most, not at all jibing with the Sep 17th +3.3. I don’t get it.

6 hours ago, Winter Wizard said:

An interesting thing about the GLAAM is that when it's plotted on a latitudinal basis, it's actually shown to be strongly in the negative direction around the mid-latitudes. It almost looks like a glitch but it has been moderately to strongly negative at various other points since July. Perhaps some interference somewhere?

Indeed, the weighted avg of your graph, which looks like it is only ~+1.25 to 1.5, doesn’t at all jibe with the image below, which shows it ~+3.3:

12Z UKMET: again says no Gulf TC

5 minutes ago, Windspeed said:

1 hour ago, GaWx said:

 Despite the Euro having something in the Gulf late, ironically the crazy GFS has no Gulf TC on its 6Z for the 1st run since way back at 18Z of 9/14! It just has one moving just N of Cuba (not in Gulf) at 384.

It still does have a system / vorticity breaking off of the CAG 130'ish hours into the 6Z run, it just fails to develop a fully fledged TC and bring that into the GOM. That could just as easily come back on the 12z today. Again, chaotic. Though, yes, it also breaks off vorticity and develops a hurricane late in the run. Meh, these simulations will remain complete choas until something actually resolves. If anything can be taken from these runs at this point, it's to say we should have a warbling surface trough gyre establish itself by this weekend over central America and we just need to watch for any pieces of energy and vorticity that may break off on either side of the landmass (EPAC or WCARIB) for potential development over the next few weeks.

The MJO is heading toward favorable phases for TCG at this time of year, which Joe Bastardi has been appropriately emphasizing in his call for activity:

6 hours ago, Windspeed said:

Lol at tonight's GFS 00z operational. I made a post during the previous week that modeling of any potential CAG system was going to be rather chaotic until something actually resolved. That has definitely been the case. Still, if something develops and gets in the right position at the right time, potential exists for a powerful system given the potential favorable upper environment that should evolve over the GOM next week. If nothing else, it's something to watch. Mind you, though the UKMet and GFS suites continue flirting with a system, the Euro suites haven't been bothered yet. I should add it's not that Euro doesn't have the CAG there, it just transfers that energy or resulting vorticity into the EPAC instead of trying to resolve something in the WCARIB or GOM.

 Despite the Euro having something in the Gulf late, ironically the crazy GFS has no Gulf TC on its 6Z for the 1st run since way back at 18Z of 9/14! It just has one moving just N of Cuba (not in Gulf) at 384.

41 minutes ago, Windspeed said:

Lol at tonight's GFS 00z operational. I made a post during the previous week that modeling of any potential CAG system was going to be rather chaotic until something actually resolved. That has definitely been the case. Still, if something develops and gets in the right position at the right time, potential exists for a powerful system given the potential favorable upper environment that should evolve over the GOM next week. If nothing else, it's something to watch. Mind you, though the UKMet and GFS suites continue flirting with a system, the Euro suites haven't been bothered yet. I should add it's not that Euro doesn't have the CAG there, it just transfers that energy or resulting vorticity into the EPAC instead of trying to resolve something in the WCARIB or GOM.

The off again, on again UKMET is now off again with a Gulf TC fwiw.