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NorthGeorgiaWX

Hurricane Dorian (05L)

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I hadn't realized how little support the 12z GFS had from its ensembles. They actually shifted towards the Euro solution. GEFS mean and Euro are very similar, same with the 12z HWRF. 

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UKMET very similar to Euro as well just a bit slower. A lot more support for the Euro solution than the GFS for the time being, but still a long ways to go. It might not be so good for the Fv3 GFS that it and the old one are so similar. Question, does anyone remember what led to the change in Katrina's track when it got into the Gulf? I know it was initially forecast to landfall on the Florida panhandle but then shifted dramatically west putting New Orleans in the cross-hairs.

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4 days ago a little tropical depression formed out in the Atlantic that no one thought had a chance. Too much dry air, lots of shear, Saharan dust all over, if it goes south it dissolves... I don't recall too many people giving that little depression a chance. 

Here's the first image I saved from that TD genesis

144923.png.216a8e949547cd6aa026a17bc87d0c53.png

 

Here we are 4 days later, that little tropical depression grew up, got a name, and decided it was ready for the big time. And big time it is going to be. I don't believe the models have the intensity figured out yet. They have been playing catch up from the beginning with this little storm that could. It's been amazing to watch how Dorian fought off challenge after challenge to defy the odds and continue to grow. 

We will have about 4 days to watch Dorian before she decides to hang a left and crawl to the coast of Florida. As with other Florida tourist, she won't be in a big hurry to get across the state to the Gulf of Mexico, so severe wind and rain damage will occur along with very damaging beach erosion. And with weakening steering currents, she won't be in a big hurry to move to the northern Gulf coast either. Oh, I didn't mention a 2nd Florida landfall did I? Yes, a likely scenario.

As with any deep low in in the central Gulf, a strong moisture plume will be transported north toward Alabama and Georgia. As this hurricane moves north toward the Gulf coast, high levels of precipitable water will be pumped northward creating rounds of heavy tropical rainfall.

Will it get this far? Can't say. Can't even say that all of this will happen the way I describe it. But it appears to match up fairly nicely with the models AT THE MOMENT. But... if you've been following this over the last four days you've seen a lot of changes, and you'll probably see a lot more changes over the next four days. 

The timing of the forward motion of Dorian and how quickly the high pressure starts building in (as well as how strong) and pushing west, will determine when and how much Dorian turns west. This is key. Regardless of the turn, Dorian will be a major hurricane at landfall. Everyone on the east coast (or even central) of Florida needs to be stepping up the hurricane plans to completion. 

It's going to get interesting and it's going to get busy. I'll do my best to keep up but I have to eat and sleep too! 🙂 Feel free to add anything to the discussion.

See you at 5 pm... 🙂

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29 minutes ago, KingOfTheMountains said:

UKMET very similar to Euro as well just a bit slower. A lot more support for the Euro solution than the GFS for the time being, but still a long ways to go. It might not be so good for the Fv3 GFS that it and the old one are so similar. Question, does anyone remember what led to the change in Katrina's track when it got into the Gulf? I know it was initially forecast to landfall on the Florida panhandle but then shifted dramatically west putting New Orleans in the cross-hairs.

I don't remember what changed it. And that's part of the problem here. With weak steering currents, small changes of surrounding air masses can have a big effect on track.  I feel pretty confident about a (roughly) middle FL landfall. After that, all bets are off for me, although I'm gaining more confidence in the Euro solution at the moment.

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Thanks, Steve - what is the Euro's track after it enters the Gulf?  I've seen a westward move towards MS/AL that passes to Georgia's west, and a crazy reverse course through south Georgia and up SC/NC/the coast.

I know it's too far out and the steering is broken down so it may just noise around down in the gulf, getting steadily drunker on bathwater fuel, so obviously any answer is extremely speculative.  Just curious.  The maps I see end just west of Florida's gulf coast.

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Wednesday, August 28 - 5 PM Update

Hurricane Dorian Discussion Number  18
NWS National Hurricane Center Miami FL       AL052019
500 PM AST Wed Aug 28 2019

The cloud pattern has become better organized with a hint of an eye
on high resolution satellite imagery and plenty of convective bands.
In addition, earlier data from a reconnaissance plane and surface
observations from St. Thomas as Dorian moved by yield an initial
intensity of 70 kt.  Now that the hurricane has developed an inner
core with a 15 to 20 n mi eye, strengthening is more likely. Given
the favorable environment of warm waters and low shear prevailing in
the western Atlantic, the NHC forecast calls for a marked
intensification, and brings Dorian to category 3 intensity in 72
hours, and keeps it at that intensity until landfall.
This
forecast is very close to the intensity consensus, the HCCA model,
and the SHIPS guidance.

Satellite and earlier reconnaissance plane fixes indicate that
Dorian has been moving toward the northwest or 320 degrees at 12
kt.  The cyclone is heading toward a weakness in the Atlantic
subtropical ridge, and this northwest motion should continue for the
next 24 to 48 hours. However, after that time, all the global models
continue to build a strong ridge over the western Atlantic, and this
flow pattern should force Dorian to turn more to the west-northwest
toward Florida. All indications are that by this Labor Day weekend,
a powerful hurricane will be near or over the Florida peninsula. The
new NHC track forecast is a little bit to the south of the previous
one, given that global models have a stronger ridge to the north and
the track models show more of a westward motion.
 Users are reminded
not to focus on the exact forecast track, as the average 5-day track
error is around 200 miles.

Key Messages:

1. Dangerous winds will continue in the Virgin Islands, Culebra,
Vieques, and portions of Puerto Rico during the next few hours.
Heavy rainfall over portions of Puerto Rico and the Virgin Islands
could produce flash flooding through Thursday morning.

2. The risk of dangerous storm surge and hurricane-force winds later
this week and this weekend continues to increase in the central and
northwestern Bahamas and along the Florida east coast, although it
is too soon to determine where these hazards will occur. Residents
in these areas should ensure they have their hurricane plan in place
and not focus on the exact forecast track of Dorian's center.

3. Heavy rains are expected to occur over portions of the Bahamas,
Florida, and elsewhere in the southeastern United States later this
week and into early next week.

FORECAST POSITIONS AND MAX WINDS

INIT  28/2100Z 18.8N  65.5W   70 KT  80 MPH
 12H  29/0600Z 20.1N  66.6W   75 KT  85 MPH
 24H  29/1800Z 22.0N  68.0W   80 KT  90 MPH
 36H  30/0600Z 23.8N  69.3W   85 KT 100 MPH
 48H  30/1800Z 25.2N  71.1W   90 KT 105 MPH
 72H  31/1800Z 26.8N  75.0W  100 KT 115 MPH
 96H  01/1800Z 27.7N  79.0W  100 KT 115 MPH
120H  02/1800Z 28.2N  81.5W   85 KT 100 MPH...INLAND

204641_5day_cone_with_line_and_wind.png.4e03263846fcb0a924f5e81fd8cc109e.png

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This image is the Euro ensembles for Tuesday, September 3 at 8 am

Notice the wide spread in the ensemble members at this point in time. I think it's also important to note that the members are are weaker, move faster and go further north. 

Those that are stronger, go further south and move slower. 

Either way, lots of possibilities.

ecens_2019-08-28-12Z_132_32.993_271.756_23.285_284.286_MSLP_Surface_tracks_lows.thumb.png.c7e2b90cb1dc42317101c2ee06d91d5d.png

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How did atl come away with that idea?  Are they talking of landfall , as in through Florida/al into s Ga?

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30 minutes ago, NorthGeorgiaWX said:

Out on a limb, and I'm no expert... I see CAT 4 at landfall.

Which landfall...😉 

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1 hour ago, NorthGeorgiaWX said:

This image is the Euro ensembles for Tuesday, September 3 at 8 am

Notice the wide spread in the ensemble members at this point in time. I think it's also important to note that the members are are weaker, move faster and go further north. 

Those that are stronger, go further south and move slower. 

Either way, lots of possibilities.

ecens_2019-08-28-12Z_132_32.993_271.756_23.285_284.286_MSLP_Surface_tracks_lows.thumb.png.c7e2b90cb1dc42317101c2ee06d91d5d.png

Of note also the weaker faster solutions mostly started on the western side of the envelope and stronger south solutions started further east. To this point the storm has consistently been east of modeling, may be significant or it may not but interesting nonetheless. GFS sticking to its guns at 18z.

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Still a nice radar presentation as it moves away from Puerto Rico. This is the last decent radar view well have until Dorian approaches the US coast. 

1854812240_20190829_0005_tjua_BR_0.5.thumb.png.13a6d4740f1a825767c7afcd8b424eb3.png

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