Hurricane Hermine Discussion

In order to minimize confusion with the Tropics, here is a thread to talk about 99L. They are sending in recon data to have in tonight's 00z model runs (see link). The latest EURO looks like the GFS with a very weak tropical low hitting NW Florida. This is a big change for the EURO because prior runs had it strengthening into a low-end Hurricane or strong Tropical Storm.

https://flightaware.com/live/flight/NOAA43

The Canadian and some of the hurricane models are the only guidances' strengthening 99L into Hurricane Helene.



Regardless of its intensity, I do NOT expect tropical rains associated with this system to make it into our area. The DC area and southern NJ may see some rain, but I think we remain dry all of this week into the weekend.

If 99L remains unnamed, that means the African wave we are tracking for September 10th period will be Helene.

Joe Bastardi tweeted he has never seen the EURO this bad. Going from a strong Hurricane to a weak invest in a 12 hour span. Until we get the Hurricane Hunter data recon, we really have no clue. Must be frustrating living in Florida or AL/GA and not knowing what's happening 2 days from now...

I am hearing HH are finding 1008mb pressures in 99L.

Frank_Wx wrote:Joe Bastardi tweeted he has never seen the EURO this bad. Going from a strong Hurricane to a weak invest in a 12 hour span. Until we get the Hurricane Hunter data recon, we really have no clue. Must be frustrating living in Florida or AL/GA and not knowing what's happening 2 days from now...

No kidding right, you would think with the technology and proximity to land we would know more, I mean if this did explode that would be really bad for any planning.

Honestly Ive been following 99L from its inception and wind shear to the north and NE has plagued it for the last 5-7days.  The shear forecasts in the s/r and md/r have consistently forecast the shear to diminish but it really never has to this point.  The result has always been to have the lower level circulation and the mid level circulations decoupled.   Earlier today the shear was down to 20-25kts, but currently the shear has increased again to 25-30kts out of the NW over Fla.  It can be clearly seen on the sat loop.  




Latest recon is now showing what looks to me to be a clearly closed low level circulation with west winds on the south side of the LP center. This could be big because in the next 24hrs both GFS and Euro forecasts an upper level anticyclone over top of the LP center as it moves into the GOM.  If the shear lets up at all this could still ramp up quickly.  I don't care what models say today I agree with JB.  This whole thing screams rapid development still.  The only thing to hold it back has got to be the shear if it persists stronger than forecast, which it has done all along.  Should be very interesting to see if they upgrade to a TD with current recon data showing a closed LLC and what the 00z's tonight show with the new data.  

Actually upon closer inspection of the shear forecast of both 12z euro and GFS shear forecasts still call for at least mode shear to the N and NE of the system. It has to be the only reason for it not to develop rapidly. It will be really interesting if that shear ends up less than forecast because the rest of the conditions look primed for rapid development.

5pm update will upgrade to TD 9, they found a closed LP. Good lord that took a long time lol

TD 9


5:00 PM EDT Sun Aug 28
Location: 23.7°N 81.7°W
Moving: W at 9 mph
Min pressure: 1009 mb
Max sustained: 35 mph

Someone change title of the thread to TD 9 maybe?

huge cone,

Holy crap it's finally a TD. Felt like years.

There's an upper level low over FL that is inhibiting TD 9 with dry air and shear on the northern quadrant (like Scott said). There's another ULL over western GOM. It's no wonder models are struggling with how strong TD 9 may get. Some have the wave interacting too much with these upper lows. Some have it avoid the interaction and it strengthens under the anticyclonic flow.

18 z appears to have it gping up coast and actually backs into area a bit. Plausible or u still feel strongly this won't have any effect up this way?

Anything beyond two days is plausible. Starting this evening we really should see the soln come into true focus. We finally have a LLC for the models to initialize properly.

Frank_Wx wrote:Holy crap it's finally a TD. Felt like years.

I have to say 99L had a lot of heart it hung in there, as the saying goes Never Quit!!!

Now lets see if it can let loose and make for some excitement, lol or will it just die off....

This is the Current Radar from Key Biscayne

Joe Snow wrote:


This is the Current Radar from Key Biscayne

Doesn't look like much, having a hard time seeing anything but a big mess on sattelite. I have seen better invests. LOL

Hmm sgetti models starting to want to bring this up coast more and closer, a big mess once nears carolinas.

Intensity hmmm, maybe this will become at least a Cat 1.

Looks like a ridge keeps everything brickwalled south of our area, should be out of a action for a while up here. East US south of the carolinas threatened by a possible train of systems.

Quick update:  Its becoming very clear that wind shear conts to hinder TD 9.  And will likely cont to do so.  As you can see by this mornings water vapor satellite the two upper level lows that Frank pointed out yesterday cont to spin on either side of TD 9.  One in the NW GOM and the other just off the SE coast.  The one off the SE coast cont to provide at least moderate shear out of the N to NW, but does appear to be pulling N ever so slight on the last few fames of the loop.  This cont to prevent the main area of convection from firing over the low level center which is absolutely vital if this is to ramp up at all; instead it can be clearly seen south of the low level center centered over western Cuba.  In addition the low level center and mid level center remain de coupled which is also important for intensification.   Dry air to the west in association with the ULL in the NW GOM is also not helping.







Models are in pretty good agreement showing how the mid levels cont to be influenced by first the ULL in the NW GOM, and then a bigger positively tilted trough digs deeper into the NE which eventually triggers the N then NE turn.  This deep pos tilted trough will more than likely prevent TD 9 from making it any further north than around Cape Hatteras.  Euro is similar at 500mb so I will use the GFS to show the initial influence by the ULL in the NW gulf then show how the digging trough pulls it up and out of the GOM.  FWIW I looked back at the euro runs that showed a much more intense soln and found that when the center of the vorticity and spin of the ULL in the NW GOM was backed in over SE texas it allowed TD 9 the space it needed to develop.  However it has not backed into SE Tx but the center has remained over the NW GOM and conts to be forecasted to remain there instead which is what the GFS has shown all along.  

Notice how every other frame TD 9 closes then open then closes then opens.  follow the 588 line:






Pay attention to the trough digging in southward out of the Hudson Bay Canada, N of the great Lakes.




You can see by hr 54 the 588line now reaches up to the digging trough meaning it is now taking over the steering by pulling it up.  By hr 84 its fully captured in the trough leading a weak, 1005-1009mb LP under the vorticity, land falling somewhere into the big bend area of the GOM and eventually NE from there.
 


Im not officially writing anything off, but it does look like the picture, at least with respect to the next few days, is becoming clear that a major hurricane is highly  unlikely.  This still of course could ramp up to a TS or even weak Cat 1 while still in the GOM, but odds are even against this as well ATT.  Levi Cowan in last nights video mentions the possibility of some intensification as it exits just off the SE coast due to divergence aloft created to the NE of the system by a 250mb jet streak embedded within the eastern side of the trough.  Something to cont to monitor I suppose.

It is really looking much more circular now and you can kinda tell its something tropical for once lol

Euro intensifies td9 the most after fl. goes off Carolinas ots. They may b get a double wammy.