Hurricane Francine

[salbers]

What we've been following in the NW Gulf since Aug 30 in the "2024 Atlantic Hurricane Season" thread.

Looks like an energetic circulation on visible satellite here: https://col.st/i3X9I

One coastal / buoy station (LUIT2) recently had sustained NE winds around 22kt.

[wthrmn654]

The Gulf, thing looks like a lot of blah right now while the Atlantic one looks a little bit better actually. 

[WxWatcher007]

Each night the convection has waned significantly but the model signal has increased a touch. Best chance of genesis would be the ICON if this shifted south this weekend before getting pulled north. Clearly it needs space and time. 

[WxWatcher007]

Model signal looking a little more legit at 12z as the energy from 90L merges with the western Caribbean wave we’ve had on our radar forever. The BoC topography may help organize this over the weekend.

[salbers]

Discussion of this system in the Spire video with the SRFS:

https://www.linkedin.com/feed/update/urn:li:activity:7237851905635299330/

[FredRed]

Storm Track: INVEST (AL902024) 9/4-9/6 (atcf-model-track-viewer.replit.app)

 

[salbers]

Is there a parent web site to the ATCF page? I'm having some challenges with the direct link.

35kt is enough for a tropical depression though it may have yet to be classified as such.

[yoda]

34 minutes ago, salbers said:

Is there a parent web site to the ATCF page? I'm having some challenges with the direct link.

35kt is enough for a tropical depression though it may have yet to be classified as such.

Looks like nothing at 5pm from NHC 

[purduewx80]

18Z GFS and ICON ensembles both show an uptick in members with hurricanes, especially with a farther offshore track. There are good jet exit region dynamics for ventilation but with increasing shear prior to landfall, and dry air still looks to be an issue into early next week. It will be an interesting system to watch meteorologically due to the likely merger of the frontal-origin and AEW-origin surface waves. HAFS and other hurricane models are probably not to be trusted until this process is sorted out. 

[WxWatcher007]

I expect this thread to get more active in a few days. It’ll need a title change though as the NHC will likely designate a new invest (if the merged area becomes invest worthy).

Very interesting how the model signal has evolved over the last week—from focusing solely on the western Caribbean wave to focusing solely on 90L to now kind of combining the residual vorticity of the two. 

[WxWatcher007]

The 00z op GFS continues the signal that started in large part with the ICON.

What was 90L dives down into the Bay of Campeche as our western Caribbean wave (which started as part of the monsoon trough a week ago) reaches the BoC. Vorticity merges and organizes into a weak low. A trough/front pulls the coalesced low NW and then NNE into the northern Gulf next week. 

 

This is far from a lock to develop and a higher end system is even less likely at this time, but I think the key at least on recent guidance is that the potential low gets pulled north before running out of time to organize. Anywhere from the Gulf coast of Mexico to Louisiana should watch this one imo. 

[WxWatcher007]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Sat Sep 7 2024

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

1. Southwestern Gulf of Mexico:
A tropical wave over the Bay of Campeche is producing disorganized 
showers and thunderstorms. An area of low pressure is forecast to 
develop while the wave interacts with a frontal boundary during 
the next couple of days. Environmental conditions are forecast to 
be conducive for development, and a tropical depression could form 
during the early or middle part of next week while the system moves 
slowly northwestward to northward over the southwestern Gulf of 
Mexico.
* Formation chance through 48 hours...medium...40 percent. 
* Formation chance through 7 days...medium...60 percent.

[WxWatcher007]

 

[WxWatcher007]

Now designated as Invest 91L

[salbers]

The RAP shows this merger:

https://www.pivotalweather.com/model.php?rh=2024090715&fh=loop&dpdt=&mc=&r=gom&p=sfcwind_mslp&m=rap

I'll update the thread title to mention 90L & 91L.

Both of these are still distinctly visible on satellite so it will be interesting to see how they can merge.

https://col.st/hoN7H

[WxWatcher007]

14 minutes ago, NorthHillsWx said:

GFS is screaming a hurricane Nicholas redux with the BOC wave/trough interaction 

Verbatim it’s a good environment for intensification on the GFS. Has to stay offshore though. I’m sure the Euro will show nothing.  

[salbers]

ICON also has vigorous development after the merger:

https://www.pivotalweather.com/model.php?m=icon&p=sfcwind_mslp&rh=2024090715&fh=loop&r=gom&dpdt=&mc=

GFS is initializing the low at 12z south of where the satellite circulation center is for the former 90L.

[WxWatcher007]

14 minutes ago, salbers said:

The RAP shows this merger:

https://www.pivotalweather.com/model.php?rh=2024090715&fh=loop&dpdt=&mc=&r=gom&p=sfcwind_mslp&m=rap

I'll update the thread title to mention 90L & 91L.

That’s a really good illustration. Thanks for sharing. You can see how the concave nature of the BoC may be assisting with organization as 90L’s residual vorticity shifts south.

https://tropic.ssec.wisc.edu/real-time/atlantic/movies/wg8vor5/wg8vor5_loop.html

[WxWatcher007]

12z Euro is weaker, but finally in line with other guidance. Doesn’t matter as much at this point, but it has intensification through landfall. 

 

 

 

[WxWatcher007]

I do wonder how much room there is for an eastward trend or sharper hook. The track forecast looks like it could be pretty sensitive until we have a well defined system. I’d imagine faster/stronger will get carried more efficiently, which could also make the upper air conditions more favorable as well. 

[purduewx80]

Despite SSTs cooling in the Gulf recently, ocean heat content is at record highs. 91L may be able to take advantage of that loop current eddy in the western Gulf if it gets its act together in time. 

[Normandy]

Think they need to pull the trigger on this one.  Very evident circ with deep convection now. 

[Normandy]

1 hour ago, WxWatcher007 said:

I do wonder how much room there is for an eastward trend or sharper hook. The track forecast looks like it could be pretty sensitive until we have a well defined system. I’d imagine faster/stronger will get carried more efficiently, which could also make the upper air conditions more favorable as well. 

If I’m a betting man I’m thinking eastern LA. I like the idea of a sharper hook east

[salbers]

Here's the story over the next couple of days with the RAP:

https://rapidrefresh.noaa.gov/RAP/jsloopUpdated.cgi?dsKeys=rap_ncep_jet:&runTime=2024090721&plotName=totp_full_sfc&fcstInc=60&numFcsts=52&model=rr&ptitle=RAP and RRFS Model Fields - Experimental&maxFcstLen=51&fcstStrLen=-1&domain=full&adtfn=1&resizePlot=1

[Boston Bulldog]

Fascinating and dynamic satellite view of the Western Gulf tonight. Look at that circulation around 27N start to accelerate south and get pulled closer to the wave axis

[GaWx]

0Z UKMET: TS landfall Wed (9/11) evening C LA; moves NE to far E TN, where it dissipates Fri night (9/13-4)

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER  36 HOURS
              FORECAST POSITION AT T+ 36 : 20.5N  94.4W

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    1200UTC 09.09.2024   36  20.5N  94.4W     1005            40
    0000UTC 10.09.2024   48  21.8N  93.5W     1006            36
    1200UTC 10.09.2024   60  23.1N  95.0W     1005            31
    0000UTC 11.09.2024   72  24.7N  94.0W     1001            30
    1200UTC 11.09.2024   84  26.9N  93.3W      998            38
    0000UTC 12.09.2024   96  29.2N  91.6W      996            36
    1200UTC 12.09.2024  108  31.8N  89.6W      999            32
    0000UTC 13.09.2024  120  32.9N  88.8W     1002            20
    1200UTC 13.09.2024  132  34.4N  87.9W     1006            16
    0000UTC 14.09.2024  144  36.6N  84.0W     1008            14
    1200UTC 14.09.2024  156              CEASED TRACKING

———————————-

0Z Euro: landfall W LA at 1001 mb TS on Thu 9/12; significantly weaker than 12Z but much stronger than yesterday’s 0Z, which had very little

———

TS landfall in LA at is my best guess as of now

[WxWatcher007]

Not much time to write but this morning we’re likely seeing 91L begin to organize at a more deliberate pace.

 

For the first time in a while given the stability issues we’ve had across the basin, this invest is producing deep and persistent convection, a critical element for future development and structural organization. 

The residual energy from 90L continues to dive down into the BoC and is merging with what was the weak Caribbean wave we were tracking for a week. 

https://tropic.ssec.wisc.edu/real-time/atlantic/movies/wg8vor5/wg8vor5_loop.html

Although it is trying to organize, I’m not sure we have a TC quite yet. Recon is scheduled for later and by then we may have something if the convective trends continue.

I would caution however, that this system while currently in a conducive environment will need to battle more potentially hostile conditions including shear and dry air at some point.

 

 

For now, however, in the race with 92L to break the historic inactive streak, 91L is closest to getting a name. NHC telegraphing that advisories are coming at some point today. 

[Normandy]

^not sure about the inhibiting factors.  The models are showing the deepening fast as it accelerates NE.  The fast NE motion might yield a more positive interaction with the jet streak to its north (less shear)

[Normandy]

I don’t have the charts to prove this, but this feels a hell of a lot like the setup of hurricane opal (but further west).  Cyclone forms deep in the BOC and gets pulled north/northeast.  I’m bullish on this one.  I actually like the chances of a major out of this.  The quality train continues

[Seminole]

1 minute ago, Normandy said:

I don’t have the charts to prove this, but this feels a hell of a lot like the setup of hurricane opal (but further west).  Cyclone forms deep in the BOC and gets pulled north/northeast.  I’m bullish on this one.  I actually like the chances of a major out of this.  The quality train continues

The 12z GFS seems to agree with you.