2024 Atlantic Hurricane Season

[GaWx]

From CHS NWS:
LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/     HIGH PRESSURE WILL CONTINUE TO EXTEND SOUTH INTO THE REGION EARLY   NEXT WEEK. MODELS INDICATE THAT AN AREA OF LOW PRESSURE COULD BE   LOCATED WELL OFFSHORE ALONG A STALLED FRONT. THE EVOLUTION OF THIS   FEATURE IS STILL UNCERTAIN, SO THERE IS LOWER CONFIDENCE IN THE   FORECAST AT THIS JUNCTURE, BUT THE LOW COULD TAKE A TRACK BACK   TOWARDS THE SOUTHEAST COAST LATER IN THE PERIOD. MAINTAINED CHANCE   POPS EACH DAY, GENERALLY IN THE 30-40% RANGE.    

[GaWx]

1 hour ago, NorthHillsWx said:

93L looks like it’s going to develop. It has the look. Lots of rotation evident as soon as it came off the African coast and it’s currently maintaining deep convection.

Im intrigued but the tropical-ish thing forecast to spin up off the southeast coast along the boundary. While this likely won’t get very strong and might not be purely tropical, trough axis could cause this to be a prolific rain maker in the Carolina’s. Might be more of a nor Easter but definitely has consistent model support

Not a land threat but a potentially significant ACE producer:
 

Eastern and Central Tropical Atlantic (AL93):
Updated: Recent satellite-wind data indicates that the system
located a few hundred miles to the west-southwest of the Cabo Verde
Islands has developed a well-defined circulation. In addition,
showers and thunderstorms continue to show signs of organization,
and if these trends continue, advisories will be issued on a
tropical depression later this morning. The system is moving to the
west-northwest at 10 to 15 mph and will be moving into the central
Tropical Atlantic by the end of the week.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 7 days...high...90 percent.

[GaWx]

Daily sunspot levels Sept MTD: general downward trend has continued. Perhaps the increased activity in the basin is partially related. Keeping an open mind because nobody knows.

2024 09 01 2024.668 182  14.5  27  35
2024 09 02 2024.671 195  21.1  25  32
2024 09 03 2024.673 179  22.2  20  23
2024 09 04 2024.676 174  26.1  21  26
2024 09 05 2024.679 181  13.1  15  20
2024 09 06 2024.682 189  13.3  19  24
2024 09 07 2024.684 167  17.0  22  26
2024 09 08 2024.687 173  17.5  19  24
2024 09 09 2024.690 156  19.9  21  24
2024 09 10 2024.693 149  11.4  20  26
2024 09 11 2024.695 152  15.7  20  23

@Seminole

[WxWatcher007]

Just looking across the basin this morning, all the invests (3!) look pretty solid, and the SE coast area that I’ve been talking about for a while is looking ripe. Think of 99L but much further south and with a ridge likely to develop over the top. Could bring a number of east coast impacts this weekend and early next week. 

[Windspeed]

NHC will initiate advisories on AL072024 or TD07 at 11AM AST. This was formerly Invest 93L near the Cabo Verdes. I don't think it warrants a new thread as it is too far into the eastern MDR and shouldn't be any near-term threat to land. Any light discussion will be fine here in the main thread. Modeling consense is for the TC to move into the central Atlantic into the midrange.

[WxWatcher007]

8 minutes ago, Windspeed said:

NHC will initiate advisories on AL072024 or TD07 at 11AM AST. This was formerly Invest 93L near the Cabo Verdes. I don't think it warrants a new thread as it is too far into the eastern MDR and shouldn't be any near-term threat to land. Any light discussion will be fine here in the main thread. Modeling consense is for the TC to move into the central Atlantic into the midrange.

What do you think of the other two invests out there? Not much of a signal on the models but each look decent this morning. 

[MANDA]

We're at the mid-point of the 2024 Hurricane season and here is where we stand.

Nothing hyperactive about it.

Potential system off the southeast coast next week would have various U.S. impacts.

Atlantic systems being watched:  No likely U.S. treats from any of them.

[Windspeed]

What do you think of the other two invests out there? Not much of a signal on the models but each look decent this morning. 

94L grabs the eye due to a vigorous exposed mesoconvective vortex (MCV) left spinning in the mid levels. That feature is exposed, and though easy to see on visible, associated convection is waning. I'm more interested in 92L. Persistent convection may eventually allow its mid level circulation to drill down. There is notable westerly flow to the low-level cloud motion south of the wave axis.

In short, I'm not really impressed by either, and both systems lack model support. We'll see if 92L can get its act together. It could still be a threat to the NE Antilles if it does develop.

[CurlyHeadBarrett]

Tropical Depression Seven Discussion Number   1
NWS National Hurricane Center Miami FL       AL072024
Issued by the NWS Weather Prediction Center College Park MD
200 PM CVT Wed Sep 11 2024

Tropical Depression Seven has formed in the eastern Atlantic 
today.  This formation is based on scatterometer depicting a 
closed circulation center, and organized deep convection based on 
TAFB/SAB satellite classifications. Satellite imagery also 
indicates that the low-level circulation has consolidated beneath 
the mid-level center based upon visible imagery  The initial 
intensity is set to 30 kt, based on the scatterometer data.

The depression is estimated to be moving 285/16 kt.  The system 
should move to the west or west-northwest over the next few days 
with the storm being steered by a subtropical ridge to the north of 
the Azores.  Confidence in the depression's track gradually lessens 
beyond forecast hour 72 as the synoptic scale flow becomes more 
complex. The depression will probably gradually slow down between 
hours 72-120 as it becomes caught between a pair of upper level 
ridges; one north of the Azores and another north of the Lesser 
Antilles. Meanwhile, an amplifying upper trough in the North 
Atlantic will attempt to deepen far enough south to steer the 
depression northward. How much the upper trough digs southward 
will determine if and when the storm takes on a more northerly 
track, or if it remains at a lower latitude longer. The forecast 
was placed just south of consensus this forecast period.

Wind shear is not expected to be a big hindrance in its 
development initially while SSTs along its forecast path will 
generally be around 27C.  Thus gradually intensification is shown 
for the first couple of days.  However, shear is forecast to 
increase thereafter along with more marginal dry air conditions. 
This forecast leans more heavily on the regional hurricane models 
which show more modest intensification than the statistical 
dynamical tools but could be conservative at the end depending on 
how much latitude the system gains.


FORECAST POSITIONS AND MAX WINDS

INIT  11/1500Z 16.0N  28.7W   30 KT  35 MPH
 12H  12/0000Z 16.6N  31.2W   35 KT  40 MPH
 24H  12/1200Z 17.5N  34.1W   40 KT  45 MPH
 36H  13/0000Z 18.6N  36.7W   45 KT  50 MPH
 48H  13/1200Z 19.3N  39.3W   45 KT  50 MPH
 60H  14/0000Z 19.9N  41.9W   45 KT  50 MPH
 72H  14/1200Z 20.3N  43.9W   45 KT  50 MPH
 96H  15/1200Z 20.6N  46.6W   45 KT  50 MPH
120H  16/1200Z 21.0N  48.8W   45 KT  50 MPH

$$
Forecaster Mullinax/Blake

[GaWx]

1 hour ago, WxWatcher007 said:

Just looking across the basin this morning, all the invests (3!) look pretty solid, and the SE coast area that I’ve been talking about for a while is looking ripe. Think of 99L but much further south and with a ridge likely to develop over the top. Could bring a number of east coast impacts this weekend and early next week. 

The ICON (arguably as good of a global model as any recently) on the new run (12Z) continues to be far different from the model consensus that has a surface low form just off the SE US this weekend into early next week. The ICON continues to develop it well offshore the E US.

[WxWatcher007]

7 minutes ago, GaWx said:

The ICON (arguably as good of a global model as any recently) on the new run (12Z) continues to be far different from the model consensus that has a surface low form just off the SE US this weekend into early next week. The ICON continues to develop it well offshore the E US.

It has definitely earned my respect this season.

[Seminole]

1 hour ago, GaWx said:

Daily sunspot levels Sept MTD: general downward trend has continued. Perhaps the increased activity in the basin is partially related. Keeping an open mind because nobody knows.

2024 09 01 2024.668 182  14.5  27  35
2024 09 02 2024.671 195  21.1  25  32
2024 09 03 2024.673 179  22.2  20  23
2024 09 04 2024.676 174  26.1  21  26
2024 09 05 2024.679 181  13.1  15  20
2024 09 06 2024.682 189  13.3  19  24
2024 09 07 2024.684 167  17.0  22  26
2024 09 08 2024.687 173  17.5  19  24
2024 09 09 2024.690 156  19.9  21  24
2024 09 10 2024.693 149  11.4  20  26
2024 09 11 2024.695 152  15.7  20  23

@Seminole

A heated Troposphere due to increased sunspot activity could definitely be a factor in the long lull of TC activity because of atmospheric stabilization between all layers of the atmosphere. The sunspot activity is now waning and we are now seeing a resumption in TC activity. Coincidence or not it still warrants consideration as a possible cause for the TC lull despite all the other favorable conditions for development.  

[GaWx]

More 12Z: GFS/CMC have a TS form offshore the SE that moves back into S NC to SC/NC border, similar to 0Z Euro, but far different from ICON

UKMET has no TC identified in its textual output

[StantonParkHoya]

27 minutes ago, GaWx said:

More 12Z: GFS/CMC have a TS form offshore the SE that moves back into S NC to SC/NC border, similar to 0Z Euro, but far different from ICON

UKMET has no TC identified in its textual output

NHC not convinced the low becomes tropical. Could be subtropical.

[GaWx]

6 minutes ago, StantonParkHoya said:

NHC not convinced the low becomes tropical. Could be subtropical.

Yeah, I was wondering about that but dewpoints on 12Z GFS are uniformly warm all around the surface low center. So, GFS looks tropical.

[Windspeed]

A heated Troposphere due to increased sunspot activity could definitely be a factor in the long lull of TC activity because of atmospheric stabilization between all layers of the atmosphere. The sunspot activity is now waning and we are now seeing a resumption in TC activity. Coincidence or not it still warrants consideration as a possible cause for the TC lull despite all the other favorable conditions for development.  

I am not trying to be argumentative in my response here, but I am lost on any correlation, much less causation with respect to sunspot activity and solar influences as inhibiting factors for cyclogenesis. During the same long-duration interseasonal quiet stretch in the Atlantic basin, we saw active stretches in the western and eastern Pacific basins. Solar influences should not discriminate between bodies of water. We have plenty of evidence of phenomenon contained within the troposphere to hypothesize why the Atlantic has struggled versus the WPAC and EPAC. Greater stability across the MDR due to +2-3°C warmer tropopause is among the evidence. But attributing that to sunspot activity seems more of a stretch than SPH placement, MJO, and meridional SSTs negative feedback to counter atmospheric lift versus subsidence.

[GaWx]

1 hour ago, Windspeed said:

2 hours ago, Seminole said:

A heated Troposphere due to increased sunspot activity could definitely be a factor in the long lull of TC activity because of atmospheric stabilization between all layers of the atmosphere. The sunspot activity is now waning and we are now seeing a resumption in TC activity. Coincidence or not it still warrants consideration as a possible cause for the TC lull despite all the other favorable conditions for development.  

I am not trying to be argumentative in my response here, but I am lost on any correlation, much less causation with respect to sunspot activity and solar influences as inhibiting factors for cyclogenesis. During the same long-duration interseasonal quiet stretch in the Atlantic basin, we saw active stretches in the western and eastern Pacific basins. Solar influences should not discriminate between bodies of water. We have plenty of evidence of phenomenon contained within the troposphere to hypothesize why the Atlantic has struggled versus the WPAC and EPAC. Greater stability across the MDR due to +2-3°C warmer tropopause is among the evidence. But attributing that to sunspot activity seems more of a stretch than SPH placement, MJO, and meridional SSTs negative feedback to counter atmospheric lift versus subsidence.

 There has been speculation about numerous possibilities. Pro mets as a whole weren’t able to predict the quiet despite the possible factors that you mentioned. Why not? Pro mets are in disagreement as they don’t know. It’s probably from a combo of factors. A very active sun is one possible contributor and a partial negative correlation between solar activity and atmospheric stability (via more heating of upper trop/lower strat) has been hypothesized. Many papers addressing the possible connection have been written since 2008, including those in my post below. Joe D’Aleo was who first brought it to my attention just a couple of weeks ago, but that wasn’t enough as I wanted to see papers. Now I’ve seen them. Thus, I’m now open-minded about this possibility.

 This graph was put together by Teban at Storm2K. It suggests to me that a ceiling on ACE does seem to be the highest when sunspot number is relatively low.

 

 

[GaWx]

1 hour ago, GaWx said:

More 12Z: GFS/CMC have a TS form offshore the SE that moves back into S NC to SC/NC border, similar to 0Z Euro, but far different from ICON

UKMET has no TC identified in its textual output

The 12Z Euro has only a hardly detectable very weak surface low just offshore SC/GA.
 So, the Euro and UKMET have nothing significant. The ICON is well offshore with a 1007 sfc low. The GFS/CMC have a TS or STS move back into ~S NC. So, no consensus.

[thunderbolt]

40 minutes ago, GaWx said:

The 12Z Euro has only a hardly detectable very weak surface low just offshore SC/GA.
 So, the Euro and UKMET have nothing significant. The ICON is well offshore with a 1007 sfc low. The GFS/CMC have a TS or STS move back into ~S NC. So, no consensus.

Hey GA do you have anything on the invest just west of the Cape Verdes

[GaWx]

6 minutes ago, thunderbolt said:

Hey GA do you have anything on the invest just west of the Cape Verdes

That’s now TD #7. Please see posts above addressing it.

[GaWx]

57 minutes ago, GaWx said:

The 12Z Euro has only a hardly detectable very weak surface low just offshore SC/GA.
 So, the Euro and UKMET have nothing significant. The ICON is well offshore with a 1007 sfc low. The GFS/CMC have a TS or STS move back into ~S NC. So, no consensus.

 12Z JMA has a weak low go into S NC but not til hour 168, which is ~48 hours after GFS/CMC. So very much a fwiw.

[purduewx80]

The ensembles are also all over the place in terms of location, timing and intensity. This is likely due to the Rex Block developing over eastern North America, with Francine's remnants and a few other shortwaves meandering/possibly merging under the ridge making it more difficult to model. Even the offshore tracks could be fairly impactful to the Outer Banks due to the long-duration onshore winds that should precede its development. That said, there is a naked surface low out there that could reform under any persistent convection over/near the Gulf Stream this weekend. 

[StantonParkHoya]

0z GFS with a subtropicalish looking weak low coming into SE NC. Couple inches of rain.

[GaWx]

0Z UKMET is its 1st run with a (S)TC forming offshore the SE; forms Sun night as TS or STS ~100 miles ESE of lower SC coast, moves WNW, and landfalls lower SC on Tue with CHS on the dirty side:

 NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 108 HOURS
              FORECAST POSITION AT T+108 : 31.5N  79.1W

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    1200UTC 16.09.2024  108  31.5N  79.1W     1008            38
    0000UTC 17.09.2024  120  31.4N  79.6W     1007            30
    1200UTC 17.09.2024  132  32.1N  80.3W     1009            30
    0000UTC 18.09.2024  144              CEASED TRACKING

—————————

Edit: So far I’m not seeing any surface low forming off the SE coast on 0Z Euro

[CurlyHeadBarrett]

AL, 07, 2024091212, , BEST, 0, 175N, 339W, 35, 1006, TS, 34, NEQ, 0, 0, 0, 0, 1011, 100, 20, 45, 0, L, 0, , 0, 0, GORDON, M, 0, , 0, 0, 0, 0, genesis-num, 020,

[yoda]

92L and 94L basically went to 0... so TD 7 is going to be the only game in town in the Atlantic for the foreseeable future 

[Normandy]

Disagree on 94L.  This should have already been a TC

[yoda]

92L is gone from the 2pm TWO... 94L is running out of time 

1. East of the Leeward Islands (AL94):
Showers and thunderstorms continue to show signs of organization in 
association with a small area of low pressure located a few hundred 
miles east of the Leeward Islands. However, the proximity of dry 
air near the system could limit additional development over the next 
couple of days. Environmental conditions are expected to become even 
less conducive over the weekend while the system moves slowly 
west-northwestward.  Regardless of development, this system could 
produce locally heavy rainfall and gusty winds across the northern 
Leeward Islands on Friday.
* Formation chance through 48 hours...low...30 percent. 
* Formation chance through 7 days...low...30 percent.

[GaWx]

Regarding the potential TC or STC forming just off the SE coast by early next week, here are some 12Z model runs:

-GFS 1003 TS that landfalls near Wilmington, NC

-CMC/UKMET/ICON no TC/STC

-Euro: a very weak low (1011) that landfalls at GA/SC border

-JMA: low moves NE to 350 miles E of NC/VA border at 1003 (ST or T); then stalls and is forced back SW to 300 miles E of Hatteras while strengthening to 998 at 192

[WxWatcher007]

30 minutes ago, GaWx said:

Regarding the potential TC or STC forming just off the SE coast by early next week, here are some 12Z model runs:

-GFS 1003 TS that landfalls near Wilmington, NC

-CMC/UKMET/ICON no TC/STC

-Euro: a very weak low (1011) that landfalls at GA/SC border

-JMA: low moves NE to 350 miles E of NC/VA border at 1003 (ST or T); then stalls and is forced back SW to 300 miles E of Hatteras while strengthening to 998 at 192

Looks like the signal has faded substantially but the general environment looks conducive for some kind of genesis—tropical or baroclinic.