ERIN (40 KTS)

[BarryStantonGBP]

@jconsor lad posted this

https://hurricanehacker.substack.com/p/tropical-storm-erin-forms-in-eastern

[Kevin Reilly]

6 minutes ago, BarryStantonGBP said:

@jconsor lad posted this

https://hurricanehacker.substack.com/p/tropical-storm-erin-forms-in-eastern

Models should be interesting today.  Out ahead of Erin you can clearly see the push from NE to SW coming off the Sarhan Dust Fields of Africa.  This flow is trying to reassert itself as Erin moves generlly west.  I would think that this fairly robust NE to SW motion of drier air will do two things keep Erin in check possibly even a period of weakening and force Erin more south or even southwest for  a time as she heads generally westbound.  I think this is what to watch now and until nearing the Leeward Islands over the next two days. The models may need to adjust to this possibility over time. 

[40/70 Benchmark]

57 minutes ago, Kevin Reilly said:

Models should be interesting today.  Out ahead of Erin you can clearly see the push from NE to SW coming off the Sarhan Dust Fields of Africa.  This flow is trying to reassert itself as Erin moves generlly west.  I would think that this fairly robust NE to SW motion of drier air will do two things keep Erin in check possibly even a period of weakening and force Erin more south or even southwest for  a time as she heads generally westbound.  I think this is what to watch now and until nearing the Leeward Islands over the next two days. The models may need to adjust to this possibility over time. 

Paradoxically, a weakening trend in the near term is probably the most omninous sign possible for the US, as it would cause the system to remain lower in latitude while being steered by the lower level flow. Obviously this increases the risk of the system missing the westerlies should it reorganize down the road.

[BarryStantonGBP]

I literally implied Irma in my last post because of the SW dip. What the bloody hell happened lad 

[BarryStantonGBP]

[GaWx]

9 hours ago, GaWx said:

 The good news in the short-term for the US is that Erin climbed slightly from 17.4N to 17.6N since the previous advisory or at 275 degrees vs a prog to stay at 17.4N/270 degrees. Maybe this is a sign that the latitude will be mainly maintained instead of losing much. We’ll see.

 Edit: But the NHC is still progging the low point of 17.1N on Wednesday morning. That will be one key benchmark to compare the actual track to.

- Followup to above: Per the 5AM advisory, Erin dropped back down slightly to 17.4N with a 265 degree heading. The new track has a low point of 17.0N tomorrow instead of 17.1N. The 17.0N will be a key latitudinal benchmark to compare to tomorrow.

- The 6Z Icon at 120 is slightly W of that ominous looking for Conus 0Z run at 126.

-The 6Z GFS is similar to the 0Z GFS and again goes just NW of Bermuda with a hard hit there.

-The 6Z Euro 144 is barely SE of the 0Z Euro 150.

[MANDA]

1 hour ago, GaWx said:

- Followup to above: Per the 5AM advisory, Erin dropped back down slightly to 17.4N with a 265 degree heading. The new track has a low point of 17.0N tomorrow instead of 17.1N. The 17.0N will be a key latitudinal benchmark to compare to tomorrow.

- The 6Z Icon at 120 is slightly W of that ominous looking for Conus 0Z run at 126.

-The 6Z GFS is similar to the 0Z GFS and again goes just NW of Bermuda with a hard hit there.

-The 6Z Euro 144 is barely SE of the 0Z Euro 150.

Appreciate your model summaries for those of us on the run.  Nice to get a quick summary when I am on the road with minimal time to check the latest guidance.  Thanks!

[WxWatcher007]

55 minutes ago, 40/70 Benchmark said:

Paradoxically, a weakening trend in the near term is probably the most omninous sign possible for the US, as it would cause the system to remain lower in latitude while being steered by the lower level flow. Obviously this increases the risk of the system missing the westerlies should it reorganize down the road.

And once the system becomes convectively active again (as it did last night in the southern part of the system) we’ll have to see if that tugs the LLC in one direction or another temporarily.

[WxWatcher007]

You don't need to look far to see why Erin is struggling convectively this morning. 

First, it's still in a marginally favorable SST environment

Second and more important, it is plowing into an area of drier, more stable atmospheric conditions--something that was anticipated days ago. 

 

The microwave image I posted last night was illustrative of its organization, which still exists this morning. 

 

Note the well defined center and its symmetrical nature. Note also the more stable conditions to its northwest. This should keep Erin in check for a bit, but given the internal organization, if that doesn't fade once this finds a more favorable environment it should still be primed to ramp up. 

 

As for track, I still think it's highly unlikely to directly impact the US coast, but Atlantic Canada should be monitoring more closely. 

[WxWatcher007]

Tropical Storm Erin Discussion Number   5
NWS National Hurricane Center Miami FL       AL052025
1100 AM AST Tue Aug 12 2025
 
Erin still has a well-defined low-level circulation, but the
convective pattern has degraded since overnight, with only a band
of moderate convection located within the southern part of the
circulation.  A 1226 UTC ASCAT-C pass showed a maximum wind barb of
36 kt north of the center, and the intensity is held at a possibly 
generous 40 kt.  Most likely, this is a result of Erin's fast 
motion, which has been south of due west (265 deg) at about 20 kt.
 
The guidance suite indicates that Erin may continue to lose some 
latitude during the next 24 to 36 hours due to strong low- to 
mid-level ridging over the eastern and central Atlantic, but overall 
the general motion should be westward through early Thursday.  After 
that time, indications are that the ridge may weaken over the 
western and central Atlantic, causing Erin to turn 
west-northwestward, but there are model discrepancies on when
that might happen and where the break in the ridge actually forms.
The trend has been for a weaker Erin in the short term and possibly
a stronger ridge, and a number of track models, including HAFS-A and
-B, HWRF, the European, HCCA, and the Google Deep Mind, have shifted
south and west for much of the 5-day forecast.  The NHC forecast has
shifted in that direction accordingly, and it should be noted that a
significant number of deterministic models and ensemble members
still lie even farther south.
 
The environment of marginal water temperatures (26-27 deg Celsius) 
and low atmospheric instability and moisture appear to remain 
nearly constant for the next 24 hours or so.  Therefore, little to 
no intensification is expected through early Wednesday.  The 
environment and water temperatures become much more suitable for 
strengthening by 48 hours, and since the cyclone already has a 
well-defined structure, it could become a hurricane by late 
Thursday.  Continued strengthening is forecast after that time, and 
the NHC forecast continues to show Erin becoming a major hurricane 
by day 5 (early Sunday).  There is quite a lot of spread in the 
intensity models, and the NHC prediction is in the upper regime of 
the envelope, close to the SHIPS model, Florida State 
Superensemble, and ICON intensity consensus.
 
 
KEY MESSAGES:
 
1. Although it is still too early to know exactly what impacts Erin 
might bring to the northern Leeward Islands, the Virgin Islands, 
and Puerto Rico, the risk has increased for Erin to move closer to 
these islands over the weekend.  Interests there should monitor the 
progress of this storm.

2. There is even greater uncertainty in what impacts, if any, might 
occur in portions of the Greater Antilles, the Bahamas, the east 
coast of the United States, and Bermuda next week.  As we approach 
the climatological peak of the hurricane season, this is an 
opportune time to ensure your preparedness plans are in place.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  12/1500Z 17.2N  36.3W   40 KT  45 MPH
 12H  13/0000Z 16.8N  39.1W   40 KT  45 MPH
 24H  13/1200Z 16.5N  42.3W   40 KT  45 MPH
 36H  14/0000Z 16.6N  45.2W   45 KT  50 MPH
 48H  14/1200Z 17.1N  48.3W   55 KT  65 MPH
 60H  15/0000Z 17.8N  51.3W   65 KT  75 MPH
 72H  15/1200Z 18.5N  54.4W   75 KT  85 MPH
 96H  16/1200Z 19.8N  60.3W   90 KT 105 MPH
120H  17/1200Z 21.4N  65.0W  100 KT 115 MPH
 
$$
Forecaster Berg
  

[WxWatcher007]

For our friends in the Antilles, this is increasingly becoming a little close for comfort. Could be some indirect impacts there that become more direct if the south shift continues. To @40/70 Benchmark’s point earlier, that can muck things up if the ridge also ends up trending stronger or the big ULL in Canada is weaker in the long range. Still a lot to sort out here.

[Kevin Reilly]

1 hour ago, WxWatcher007 said:

You don't need to look far to see why Erin is struggling convectively this morning. 

First, it's still in a marginally favorable SST environment

Second and more important, it is plowing into an area of drier, more stable atmospheric conditions--something that was anticipated days ago. 

 

The microwave image I posted last night was illustrative of its organization, which still exists this morning. 

 

Note the well defined center and its symmetrical nature. Note also the more stable conditions to its northwest. This should keep Erin in check for a bit, but given the internal organization, if that doesn't fade once this finds a more favorable environment it should still be primed to ramp up. 

 

As for track, I still think it's highly unlikely to directly impact the US coast, but Atlantic Canada should be monitoring more closely. 

Great Post!!! This is exactly what I was talking about earlier this morning.  Erin is going to be ingesting in significant dry air looking at the push NE to SW from Sarhan Africa especially with that well defined broad circulation.  I do predict moderate level of keeping in check and its likely to weaken as it moves west bound and possibly redirected west-southwest for a time due to the nature of the flow. 

That is an absolute brick wall of dry air.  Erin's forward speed towards that brick wall is going to play a significant role as to what's going to happen from this very point clear on into the next 3-5 days because it is moving in tandem with this dry air layer from Africa moving west and southwest from Sarhan Africa. 

[GaWx]

30 minutes ago, WxWatcher007 said:

For our friends in the Antilles, this is increasingly becoming a little close for comfort. Could be some indirect impacts there that become more direct if the south shift continues. To @40/70 Benchmark’s point earlier, that can muck things up if the ridge also ends up trending stronger or the big ULL in Canada is weaker in the long range. Still a lot to sort out here.

As you posted, the 11AM position dropped from 5AM’s 17.4N to 17.2N. Also, the new track dips down to 16.5N tomorrow vs the prior advisory’s 17.0N:


FORECAST POSITIONS AND MAX WINDS

INIT 12/1500Z 17.2N 36.3W 40 KT 45 MPH
12H 13/0000Z 16.8N 39.1W 40 KT 45 MPH
24H 13/1200Z 16.5N 42.3W 40 KT 45 MPH

[Wannabehippie]

Erin has a good circulation, but zero convection near the core.

https://www.tropicaltidbits.com/sat/satlooper.php?region=05L&product=ir

[wthrmn654]

 

[GaWx]

12Z Icon 168 hr 150 miles NNE of that ominous 0Z Icon 180 hr map. Has less ridging and is moving NW to NNW instead of NW to WNW.

[BarryStantonGBP]

2 hours ago, WxWatcher007 said:

You don't need to look far to see why Erin is struggling convectively this morning. 

First, it's still in a marginally favorable SST environment

Second and more important, it is plowing into an area of drier, more stable atmospheric conditions--something that was anticipated days ago. 

 

The microwave image I posted last night was illustrative of its organization, which still exists this morning. 

 

Note the well defined center and its symmetrical nature. Note also the more stable conditions to its northwest. This should keep Erin in check for a bit, but given the internal organization, if that doesn't fade once this finds a more favorable environment it should still be primed to ramp up. 

 

As for track, I still think it's highly unlikely to directly impact the US coast, but Atlantic Canada should be monitoring more closely. 

translation: the weaker she stays, the further west and south she drifts

[BarryStantonGBP]

 

[WxWatcher007]

That HCCA trend is interesting 

[GaWx]

12Z UKMET: dips down to 16.4N vs 17.0N on 0Z; recurves at 68.7W vs 66.5W on 0Z; so still a safe recurve for Conus:

    TROPICAL STORM ERIN       ANALYSED POSITION : 17.3N  35.4W

     ATCF IDENTIFIER : AL052025

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    1200UTC 12.08.2025    0  17.3N  35.4W     1008            31
    0000UTC 13.08.2025   12  16.7N  39.3W     1008            29
    1200UTC 13.08.2025   24  16.4N  42.2W     1008            27
    0000UTC 14.08.2025   36  16.7N  45.0W     1007            29
    1200UTC 14.08.2025   48  17.6N  48.5W     1008            31
    0000UTC 15.08.2025   60  18.6N  51.8W     1008            31
    1200UTC 15.08.2025   72  19.8N  55.4W     1006            31
    0000UTC 16.08.2025   84  20.7N  58.6W     1005            32
    1200UTC 16.08.2025   96  21.6N  61.6W     1001            37
    0000UTC 17.08.2025  108  22.3N  64.2W      998            44
    1200UTC 17.08.2025  120  23.3N  66.3W      998            48
    0000UTC 18.08.2025  132  24.8N  67.7W      996            42
    1200UTC 18.08.2025  144  26.9N  68.6W      992            52
    0000UTC 19.08.2025  156  28.8N  68.7W      988            48
    1200UTC 19.08.2025  168  30.7N  68.0W      980            58

[40/70 Benchmark]

2 hours ago, WxWatcher007 said:

For our friends in the Antilles, this is increasingly becoming a little close for comfort. Could be some indirect impacts there that become more direct if the south shift continues. To @40/70 Benchmark’s point earlier, that can muck things up if the ridge also ends up trending stronger or the big ULL in Canada is weaker in the long range. Still a lot to sort out here.

I'm sitting this one out regardless due to an impending trip to Africa, but I do not foresee a big US threat.

[WxWatcher007]

5 minutes ago, 40/70 Benchmark said:

I'm sitting this one out regardless due to an impending trip to Africa, but I do not foresee a big US threat.

Same. Maybe impacts in the Antilles. Perhaps a more direct impact for Bermuda and Atlantic Canada. This does not look like a steering pattern for a direct US impact. 

[WxWatcher007]

Euro recurves well east of the U.S. coast, but with the trough to the north it pulls Erin into Newfoundland. Again, long way out, but highlights the risk to Atlantic Canada. 

 

[GaWx]

12Z JMA: Bermuda at 192