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Tropical Major Hurricane Irma (Part 1)

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Well, what's happening with Irma is that it's losing coriolis. What's causing that is the upper level high that is pushing off to the east which will eventually steer Irma off to the WSW. Irma may lose it's major hurricane status briefly during the transition from the west track to the WSW track.

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GEFS ; /
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Shawn said:
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This basically means no strong intensification but no weakening for a while correct? Until it hits the warmer waters..?
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Essentially yes, Irma is already near its theoretical maximum potential intensity for a TC in this part of the Atlantic, given the underlying SSTs and if it were to become completely annular, it probably wouldn't fluctuate in intensity much and could strengthen perhaps a tad considering that annular hurricanes are often much closer to MPI (~85% or more) vs a stereotypical hurricane. Once it nears 50W where SSTs and tropical cyclone heat potential increases considerably, I'd expect Irma to begin intensifying in earnest once again, becoming a category 4 or 5 hurricane as it approaches passes just north of the Lesser Antilles and Puerto Rico. Eyewall replacement cycles may be increasingly frequent thereafter as well as the environment becomes relatively more moist.
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It's definitely worrisome to see this many EPS members with a category 4-5 hurricane just north of the Greater Antilles in a week or so from now.
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sometimes I really hate how slowly the Euro loads :p

Through 144 its similar then at 168 its north above Hispanola
 
H5 is completely different over the US vs 12z. Either the trough grabs it or the ridge rebuilds and its on the way to Texas,
 
wow this run is much different... may actually recurve?!

192 looks much more like the GFS
 
Brent said:
HWRF is a beast on the Euro's southerly route to hit the Antilles
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That is extremely scary for those people. It'd likely be at least a higher end Category 4 by that point.
 
925 off the SE coast.. looks like Euro may toss it OTS this run.

500MB is much different versus previous Euro runs. Almost too different....
 
Lol euro curveball, where did the cutoff go? The GFS/Euro are much closer now at least...

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Missed the trough, sits as a loaded gun for anyone at 240hr. Could go OTS or the ridge could build and push it west.
 
High res Euro shows 915mb category 5 cane crawling N-NNE as the first s/w leaves and heights build to its north. Wouldn't look much beyond 4-5 days for an accurate z500 forecast evolution for the E US esp given how poorly NWP has been handling the intensity of Sanvu in the western Pacific...
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00z EPS spaghetti still all over the place.. maybe a slight trend to a curve out, but still.. everyone is in play based on it.
 
Yeah that slight NE shift in the EPS is a welcome sight this morning but still way too early to feel better or panic along the US Coast.... real interested in seeing how the Euro handles H5 with the 12z run today, after being so consistent over the last few days that was a significant change for the Euro at those levels. The most fun part about weather.... wait and watch lol
 
On the current NHC track Irma will pass real close if not through Herbert Box 1, anyone in Florida I bet can tell you a thing or two about that.... paging Phil.
 
We're really just going to have to wait for Sanvu's recurvature and phasing with a mid latitude trough and extratropical transition to complete and monitor trends in the speed, amplitude, and direction of the Rossby Wave packet that's forecast to reach North America by late next week... Model skill in these types of situations is often lower than normal so extreme caution should be urged when interpreting z500 pattern details more than 4-5 days out near eastern North America
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metwannabe said:
On the current NHC track Irma will pass real close if not through Herbert Box 1, anyone in Florida I bet can tell you a thing or two about that.... paging Phil.
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I'm here and not excited about prospects, however they unfold ... :(

Edit - I am not in south FL (thank the Good Lord); but anywhere is no good when a 'Cane is involved.

Here's a synopsis on the Herbert Box, btw:

1. North Carolina has as much of a chance to get hit as Florida.
2. 20.58% or most go out to sea without hitting land.
3. Only 8.82% make it into the Gulf of Mexico when they pass through the box as a hurricane.
4. Puerto Rico will get hit 20.58% of the time (the highest outside of n Antilles).
 
Irma has become more ragged looking this morning, we've lost the eye on satellite and the CDO has become less symmetric, if organization doesn't improve between now and 11am I could see the NHC bumping its intensity down a tad.
 
pcbjr said:
I'm here and not excited about prospects, however they unfold ... :(

Edit - I am not in south FL (thank the Good Lord); but anywhere is no good when a 'Cane is involved.

Here's a synopsis on the Herbert Box, btw:

1. North Carolina has as much of a chance to get hit as Florida.
2. 20.58% or most go out to sea without hitting land.
3. Only 8.82% make it into the Gulf of Mexico when they pass through the box as a hurricane.
4. Puerto Rico will get hit 20.58% of the time (the highest outside of n Antilles).
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Good stuff and the GFS actually just misses it and Euro is in the NE section of it.....
Btw NC sits out like a sore thumb so yeah we rate right up there with Florida of being in the way of TC's
 
Webberweather53 said:
Irma has become more ragged looking this morning, we've lost the eye on satellite and the CDO has become less symmetric, if organization doesn't improve between now and 11am I could see the NHC bumping its intensity down a tad.
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Per Dvorak estimates, I wouldn't be surprised if we see a downgrade at 11. However, it looks like the strength per the same estimates have stopped weakening, so it should ramp back up into a major hurricane by tomorrow or tonight, unless weakening continues.
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Webberweather53 said:
Irma has become more ragged looking this morning, we've lost the eye on satellite and the CDO has become less symmetric, if organization doesn't improve between now and 11am I could see the NHC bumping its intensity down a tad.
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Could be letting it take the SW jog or keep it from curving North? The slight weakening?
 
Storm5 said:
Another look at the 00z EPS . The mean shifted a little NE bjt the spread expanded lol. Clearly two camps, a US hit and offshore/OTS
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OTS is my guess but we'll see.


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Tarheel1 said:
Could be letting it take the SW jog or keep it from curving North? The slight weakening?
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The weakening won't hinder that, while the deeper layer steering in this case is actually more southwesterly as compared with the low level steering flow from the subtropical high, Irma will still be strong enough to feel the impact of the Potential Vorticity Streamer to its northeast. The stronger Irma becomes the slower it's forward movement will become and the longer it will be influenced by this PVS although as it intensifies it will throw more heat into this upper level trough and thus act to weaken it. By Tuesday Irma should be far enough removed from this PVS to allow deep layer ridge to its north to dominate the large scale steering pattern.
 
One thing that sticks out in my mind is our woe in Winter, the models love to over pump the PNA Ridge and over deepen the eastern trough. It's pretty much a given that both of these features are over done.

That said if they end up right, I'm suing for all the emotional distress they have caused in winter.
 
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