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Windspeed

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  1. Should also add that shear is really taking its toll on Philippe. I mentioned in the previous post the outcome of Rina becoming the dominant TC. That might actually unfold. The low-level circulation flow of Philippe looks very broad now on visible. Forget TS status. It might even open up tonight if degradation of the low-level circulation continues.
    e05f77cf700948d727d37b887bc5b9f0.gif

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  2. Too much chaos to simulate between the globals due to the close proximity of both Philippe and Rina's vort maximums. Additionally, we have a hybrid low (remnents of Ophelia) and an upper trough that will split off the ECONUS with uncertainty between 500 hPa ridging and weakness.

    I think it's a very low confidence forecast between either TC and their eventual tracks right now. If Philippe were more intense, I would consider Rina being absorbed or dissipating. But if Philippe drives SW due to the synoptic setup and Fujiwara effect, it should remain sheared just NE of the Leewards.

    Haven't said much since the initial post, as nothing much has changed in idea here. If Philippe can shake off Rina and lift north, it could find a more favorable environment and intensify. That was a potential outcome with the original recurve guidance, though that is now more uncertain. Likewise, if Philippe were to remain sheared, get decapitated, or outright dissipate, then Rina could possibly become the dominant TC and intensify.

    I don't really think anyone can accurately know the outcome of these systems at present. It's going to take a few days to watch unfold and iron out. Furthermore, modeling will continue to struggle with this setup and spit out some ridiculous solutions.

    Updating thread to cover both systems since they're so closely tied together right now. There is no need to make a separate TC thread for Rina.

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  3. Tropical Depression 17 has formed in the MDR of the Atlantic. It is not yet forecast by the NHC to become a hurricane. This is due to a future that includes westerly shear at the 20°N latitude stretching from just WNW of the TC to along the northern Leewards. There, however, is some uncertainty bearing on the location and timing of a WATL trough versus ridge strength west of the Azores. A fast turn north with a deepening upper trough to the west might eventually place the system in a more favorable environment in the N Central Atlantic. The TC should have a recurving track and sheared while doing so until late next week.88c5319f52922d1434731ba281f3725d.jpg80ae742e450562960d1a8dd8d8d7bd1a.gif

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  4. With yet another long track storm possible next week, it’s worth noting that Atlantic ACE has exceeded 100 units this morning and with two active storms plus the future Nigel on the way, that value will continue to increase through next week. We are now running well ahead and likely to exceed normal seasonal values if early forecasts for Nigel verify. Pretty impressive for an El Niño year 
    It's phenomenal for an El Niño year, and it's not a even a weak one. The warm Atlantic basin really did a number to offset +ENSO. Plus, the subtropical jet has been displaced as such to make shear just manageable enough to get MDR hurricanes. Though I would argue that shear has still been an issue, such as Franklin getting kicked hard early in its life cycle and Lee getting over-modeled as a long duration high-end hurricane. Still, there wasn't an analog for what we've been witnessing. Fortunately, the MDR 'canes have cooperated with a recurving pattern in place. Though, not to downplay future impacts by a weakening Lee on Maine and Canada. Also, we did get lucky with the timing of an ERC and landfall location by Idalia, though this was not an MDR system. With late Sept. and early Oct., we have the usual transition back to GOM and WCARIB systems, which could still pose a threat. Furthermore, it isn't too late to have an MDR system still be a land threat for the Lesser and Greater Antilles down the road as well.

    Having considered if a strong +ENSO will even shut down the Atlantic prior to normal seasonal ASO decline at this point.
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  5. Wow.. Lee has had a massive expansion of hurricane force winds.


    Lee is very large hurricane. Hurricane-force winds extend outward up to 125 miles (205 km) from the center and tropical-storm-force winds extend outward up to 240 miles (390 km). Saildrone 1036, located about 70 miles (115 km) northwest of Lee's center, recently reported a wind gust to 92 mph (148 km/h).

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  6. After 84 years, Major Hurricane Lee has a dominant eyewall that is producing enough subsidence to clear out a rather large eye. As has been reiterated, Lee's gradient is loose for a sub 950s mb hurricane; as pressures fall, hurricane force winds are spreading out away from the center rather than increasing near the center. However, convection does have some >70°C tops for now. There should still be Category 3 winds in the eastern eyewall as Lee slugs NNW, and it could tighten a bit of gradient enough to increase the eyewall winds slightly. But not enough to increase a category.

    d063c56aca94d8bc1702512805282697.gif



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  7. I don’t think much has changed IMO. Long shot for NE (~5% SNE/15% Cape & ENE) with significantly greater risk for Atlantic Canada (40%) and OTS (40%) squarely on the table. 
    I know people want answers now or to put their flag in the ground, but the truth is it’s going to take more time to have true forecast clarity of all the critical elements determining the long term track. Can’t latch onto any one op run or even an individual model suite yet. 
    I think Maine has a good shot if the block and trough time correctly, but, of course, Canada remains the biggest landfall threat. We may start getting swings back and forth with the OPs, though, as they iron out the position of turn and trough versus ridge. These could show a western run into southern New England at times as this interaction gets ironed out. It may open the door for hype, but it is what it is...
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  8. Should be a Cat 2. Still think we'll see some impressive reintensification this evening through Sunday. I still think Lee will make Category 4 again with a big eye once it gets structural issues resolved and the shear is negated. An eyewall will have some work to do to tighten the gradient, but Lee will have a big outflow channel to help as well.

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  9. 400 hPa upper mid-level flow that had been undercutting the canopy and disrupting Lee's core is starting to ease up. It is still there; however, updrafts are strong as Lee remains an intense vortex with strong surface convergence. It doesn't take much backing down of this shear or having the flow come into more alignment with the vector of steering motion for Lee's eyewall to recover. You can make this out very clearly with lightning data as CBs regain a foothold on the core. The core will still battle some tonight. But shear will continue to lessen through Saturday, I would expect another round of RI by Sunday. I'm not saying Lee will reach its previous peak, but it will eventually be in a favorable environment for several days as it pushes WNW. It should look pretty impressive by Sunday afternoon and will likely bottom back out in the 930s. The gradient may not be as tight, so I don't know if it will achieve Category 5 windspeeds again. It may end up with a large eye, though.147464bc82d5e9d5c49a761705b7639a.gif

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  10. ^ Interesting to note that Lee outperformed all intensity guidance model runs, including the new HAFS suite. Keep in mind guidance didn't actually bomb the pressure until the weekend or just NE of the Leewards. It's quite possible that Lee's period of explosive RI in IRL occurred prior to the simulation of a time frame of southwesterly mid-level shear. This shear looks to back off tonight. In other words, Lee may get back that more classic satellite appearance overnight or on Saturday and bomb out again. It should have several days of good mid-to-upper level environment north of the Antilles.

  11. Keep in mind that inevitably, we will get an EWRC. But environmental conditions are going to remain sufficiently supportive of high MPI. So after the first completion, we could see another peak in intensity with the new eyewall. Perhaps even an impressive peak with the third eyewall. Should be an impressive hurricane through the weekend.

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  12. Lee is ahead of my forecast; and I thought I might've been too hasty. Think it will be a major by 5PM AST now. The eye is warming fast. Two CBs rotating around should drop pressures like a rock. Recon will find a hurricane undergoing rapid intensification when it reaches the core this evening.00afd9cc339705ebee586192868b68f5.gif

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  13. There's still a cold wake left by Franklin near and just W of Bermuda. Should it track there, hopefully this wake would weaken Lee some.
    It should weaken quite a bit prior to any potential interaction with Bermuda; however, both the ECMWF and GFS consistently want to model Lee into very large hurricane by then. It might not be a major due to the surface "cold pool," but large swells and a big expansion of the windfield could bring significant impacts there if indeed it heads that way.
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  14. That makes sense. But is there an alternative possibility, that of potential Margot helping to pump up the ridge to its NW and then leading to an omega block that forces Lee into the NE like was the case with Sandy? (See my post above showing the omega block that affected Sandy).
     I'll repost the Sandy omega block image:
    IMG_8067.thumb.png.e560a6959a9d5cfecedcc9fe28aa88a9.png


    Don't you think that would be a better possibility though if Margot actually drove westward and pumped heights to its NW, versus merely moving NW into the region west of the Azores? Seems like its position there erodes heights that would aid in keeping Lee from turning NE.
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