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2023 Atlantic Hurricane season


Stormchaserchuck1
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1 hour ago, GaWx said:

Yes, the 12Z GFS has no H. The last on the list with a H is the 6Z GFS.

 Meanwhile:

Some pretty significant model news since the UKMET tends to be conservative: 

-The 12Z UKMET has TCG from the westernmost lemon in the W MDR on Fri (8/18) and it then hits the Leewards as a TS late on Saturday (8/19). 
-It then moves WNW to Hispaniola on Mon (8/21) still as a TS
-It ends up near SE Bahamas as a slowly strengthening TS on Tue (8/22) moving slowly WNW and in a potentially threatening position to the Bahamas/SE US.

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 78 HOURS
FORECAST POSITION AT T+ 78 : 14.2N 51.4W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
0000UTC 19.08.2023 84 14.7N 53.5W 1005 30
1200UTC 19.08.2023 96 15.4N 57.4W 1004 34
0000UTC 20.08.2023 108 16.3N 60.5W 1003 37
1200UTC 20.08.2023 120 17.5N 63.5W 1004 40
0000UTC 21.08.2023 132 17.8N 67.0W 1004 37
1200UTC 21.08.2023 144 19.4N 68.7W 1004 38
0000UTC 22.08.2023 156 20.3N 71.2W 1004 37
1200UTC 22.08.2023 168 21.0N 72.9W 1003 39

 

Edit: But the 12Z Euro like the GFS has just about nothing.

 What I mean by the 12Z Euro having just about nothing is that it has no surface circulation although it has trackable 850 mb vorticity further south. This even leads to a very weak low over FL at 240.

The JMA has only a weak reflection at the surface (no circ), but it is a little stronger than the prior 12Z run and pretty much takes the UKMET track from the LAs to the SE Bahamas. You can tell from the widespread 2" of qpf in and near the LAs from this that it has some "oomph" so to speak.

 Ever since the August 4th EPS runs, this feature has more or less had some model support and it absolutely bears watching! Yet, the NHC still has TCG chances at only 10%. I'd raise them to 30%.

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 More on the central MDR lemon:

 The 12Z EPS still is active with this AEW with ~half the members having TCG though there are fewer H vs the prior run. While having fewer H, it actually is more threatening further west because the tracks are on average further SW with many more going across the LAs and then a good portion of those going well into the Caribbean followed by either dissipation or moving over Hisp/Cuba followed by Bahamas. Some though move NW toward Virgin Islands/PR followed mostly by E of the Bahamas. A few still recurve sharply before the Caribbean and then threaten Bermuda.

 Bottom line for 12Z EPS vs 0Z: not as many H but centered closer to the US over Bahamas vs 0Z's mainly E of the Bahamas to Bermuda.

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42 minutes ago, WxWatcher007 said:

I honestly think I’d put a D7 lemon on whatever meanders into the Gulf. GFS has something close to a TC but more importantly, the ensemble signal has grown steadily as we get closer to what looks like a conducive environment for gradual development taking shape. 

Agreed. This is the one we should be focused on at this point

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Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Tue Aug 15 2023
3. Western Gulf of Mexico:
A broad area of low pressure could form in the central or western 
Gulf of Mexico by the beginning of next week. Some slow development 
of this system is possible thereafter as it moves generally 
westward, potentially nearing the western Gulf of Mexico coastline 
in about a week. 
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 7 days...low...20 percent.

 

two_atl_7d0.png

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5 minutes ago, Floydbuster said:

I'm a little surprised at the lemons from the NHC. Seems a little bullish to me. The models aren't THAT consistent yet with Gulf development, and this is a huge surge of dry SAL. 

 The SAL is forecasted to diminish substantially starting in ~5 days.

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Central MDR lemon; 18Z Euro stronger than 12Z and chances increased from 0/10 to 10/30:

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Tue Aug 15 2023

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

1. Central Tropical Atlantic:
A tropical wave, interacting with a larger trough of low pressure, 
continues to produce disorganized showers and thunderstorms a few 
hundred miles west-southwest of the Cabo Verde Islands.  
Environmental conditions appear to be conducive for some gradual 
development of this system during the next several days as it moves 
to the west-northwestward or northwestward between 10-15 mph across 
the tropical Atlantic through the weekend.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...low...30 percent.
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5 of the 18Z GFS ensemble members have very weak systems in the Gulf in the next week.  This is mostly a Euro family thing, and Euro seems to have been tweaking.  I think NHC could have waited a day or two to see if model support increased.  Speaking of tweaking, the GFS ensembles in 12 days...

Crystal.PNG

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I think a 0/20 makes sense for the Gulf. Again, it's not that there's anything particularly special right now with the wave, but that there should be a window for gradual development if it can get stay coherent and take advantage of cyclonic flow in the western Atlantic. It's not surprising IMO that the guidance has a marginal signal thus far, and that they've become more bullish as the wave traverses west. 

 

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For the central MDR lemon: 0Z UKMET

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 150 HOURS
              FORECAST POSITION AT T+150 : 20.5N  67.7W

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    1200UTC 22.08.2023  156  21.0N  67.9W     1006            35
    0000UTC 23.08.2023  168  21.7N  69.9W     1006            37

 

From 2AM EDT TWO: up to 20/40 from 10/30

1. Central Tropical Atlantic:
Disorganized showers and thunderstorms located over the central 
tropical Atlantic are associated with an elongated trough of low 
pressure centered about 600 miles west-southwest of the Cabo Verde 
Islands.  Environmental conditions appear conducive for gradual 
development of this system, and a tropical depression could form 
during the next several days while moving toward the west or 
west-northwest at about 10 mph across the central tropical Atlantic.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 7 days...medium...40 percent.
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 The 0Z UKMET has a new TS form in the far E MDR in a week moving WNW:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 156 HOURS
              FORECAST POSITION AT T+156 : 10.5N  16.9W

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    1200UTC 22.08.2023  156  10.5N  16.9W     1006            28
    0000UTC 23.08.2023  168  11.1N  19.4W     1006            35
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The 00Z GFS is terrifying, with what would appear to be:

Hurricane "Emily" moving out to sea in the Atlantic

Tropical Storm "Franklin" spinning in the far eastern Atlantic

Hurricane "Gert" making landfall in South Texas similar to Hanna 2020

Hurricane "Harold" making a devastating 939 mb landfall in the Mississippi Delta 

 

Thank goodness it's just a long-range run, but still. Geez...

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1 hour ago, Great Snow 1717 said:

The effects of El Nino and SAL on the Atlantic hurricane season

This MMA fighter will not remember getting knocked out, so ...

1. The overall magnitude of SAL is about to sharply decrease, which largely matches the typical decrease in mid August and is one of the  main reasons that there is a climatologically sharp increase in activity in late August.

2. One of the typical effects of a moderate+ El Niño is overall increased Caribbean shear coming in from the west. However, to this point overall, that has yet to take place. Of course, that may start dominating at any point as El Niño strengthens.

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Regarding the central MDR lemon, the 12Z UKMET again develops this into a TS. It hits the Leewards to PR followed by a recurve E of the Bahamas to a position that could later threaten Bermuda:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER  90 HOURS
              FORECAST POSITION AT T+ 90 : 16.2N  59.1W

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    1200UTC 20.08.2023   96  16.7N  60.2W     1005            34
    0000UTC 21.08.2023  108  17.3N  62.1W     1005            35
    1200UTC 21.08.2023  120  18.4N  64.4W     1004            36
    0000UTC 22.08.2023  132  19.8N  65.4W     1004            40
    1200UTC 22.08.2023  144  21.2N  67.5W     1004            45
    0000UTC 23.08.2023  156  22.2N  67.5W     1003            41
    1200UTC 23.08.2023  168  24.5N  68.2W     1004            40

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10 hours ago, GaWx said:

 The 0Z UKMET has a new TS form in the far E MDR in a week moving WNW:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 156 HOURS
              FORECAST POSITION AT T+156 : 10.5N  16.9W

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    1200UTC 22.08.2023  156  10.5N  16.9W     1006            28
    0000UTC 23.08.2023  168  11.1N  19.4W     1006            35

 1. The 12Z UKMET is similar to the prior run with a new TC in the far E MDR at 168:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 168 HOURS
              FORECAST POSITION AT T+168 : 12.1N  20.3W

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    1200UTC 23.08.2023  168  12.1N  20.3W     1006            30

 
 2. The UKMET still has no TC in the Gulf.

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12Z GFS almost closed the wave in the Gulf, the 18Z was a little further off.  Only a couple of the 18Z GEFS close a low.  12Z Canadian very weak low near the border is worst case scenario with 18 straight 100°F days in Houston and 7 weeks no rain.  18Z GFS wave does drop a widespread inch of rain.  Not enough to stop the inevitable fires a week or two later.  I think the big show this week is whether NHC will declare Hilary non-tropical before California.  Forecast shows that, but I'm hoping.

 

The wave near the CVs 'has the look' on MIMIC-TPW, even if it satellite presentation doesn't look that great.

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Not sure why the two oranges have the same development odds but only one is an invest. 

Still need to see development of course but it looks like the switch is flipping on with the monsoon trough breaking down into three areas of vorticity, the potential Gulf development, and what looks like a potential quasi-CAG in the western Atlantic/Caribbean. 

The GFS has a bunch of weenie solutions with that, but that may have the highest end potential long term for a strong system.

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The issue here is a western MDR TUTT. The GFS seems to drive a TC through it, north of the Greater Antilles; but obviously that scenario isn't ideal for westward moving TC into WNW steering flow. I wouldn't get too excited yet. The pattern is crap for any long range CV system. We're just going to have to see what early September brings. I am not confident for above normal activity. I already stated this. We'll see...


Yes, of course a home-grown frontal remnant system could develop or a CAG system in the western Caribbean. But that is very low probability. It's just going to take some serious patience to see how this all irons out.

To put it mildly, I think the whole setup is garbage. Regardless of the AMO state, I do not like the upper level environment and state of subsidence right now.

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47 minutes ago, Windspeed said:

The issue here is a western MDR TUTT. The GFS seems to drive a TC through it, north of the Greater Antilles; but obviously that scenario isn't ideal for westward moving TC into WNW steering flow. I wouldn't get too excited yet. The pattern is crap for any long range CV system. We're just going to have to see what early September brings. I am not confident for above normal activity. I already stated this. We'll see...


Yes, of course a home-grown frontal remnant system could develop or a CAG system in the western Caribbean. But that is very low probability. It's just going to take some serious patience to see how this all irons out.

To put it mildly, I think the whole setup is garbage. Regardless of the AMO state, I do not like the upper level environment and state of subsidence right now.

Good stuff—points well taken. I agree about the TUTTs that look poised to pepper the Atlantic and the subsidence in the MDR are an issue. For that reason I do think eastern/central MDR stuff will struggle, though not as much as before. Perhaps we get one of those three areas along the MT named? Two if there’s enough separation? Nothing spectacular.

I’m honestly more intrigued by prospects further west. Like a number of recent seasons, with a hostile MDR we’ve seen some AEWs find a window in the western Atlantic or Gulf for development. Away from the influence of SAL/Subsidence and maybe (?) a gauntlet of TUTTs we get something to pop—like you said though, that’ll require patience. A strong wave will need to survive the trek, and an August CAG is always low probability and even if one develops, the activity could focus in the EPAC. 

I continue to believe these next two weeks are critical to the overall season. Unlike prior seasons where an active September and even October provided a backloaded season, if the basin underperforms during this late August period, it becomes extremely hard to see even a normal season (particularly in the H/MH spaces) given the atmospheric response we’re seeing to the niño. 

I guess that’s a long winded way to say I’m not as bearish as you, but I’ve got my eyes on the towel in case I need to reach for it. 

 

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Regarding the mid/MDR tangerine, which has become Invest 99L:

TWO: now up to 40%/60%

0Z UKMET: yet again a TS in the Leewards, but this run then has it go NNW and later NNE track that aims well to the E of Bermuda:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 84 HOURS
FORECAST POSITION AT T+ 84 : 16.9N 58.9W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 20.08.2023 84 16.9N 58.9W 1006 28
0000UTC 21.08.2023 96 17.6N 60.3W 1005 34
1200UTC 21.08.2023 108 19.2N 60.9W 1005 42
0000UTC 22.08.2023 120 20.2N 61.4W 1003 39
1200UTC 22.08.2023 132 22.0N 61.8W 1003 44
0000UTC 23.08.2023 144 23.8N 62.3W 1004 35
1200UTC 23.08.2023 156 25.6N 61.8W 1005 31
0000UTC 24.08.2023 168 26.9N 60.9W 1004 27

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