2017 TCRs

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cycloneye
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Re: 2017 TCRs

#41 Postby cycloneye » Tue Jan 02, 2018 2:57 pm

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Re: 2017 TCRs

#42 Postby cycloneye » Wed Jan 10, 2018 11:08 am

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Re: 2017 TCRs

#43 Postby CrazyC83 » Wed Jan 10, 2018 11:14 am

Interesting how Rina formed with a complex interaction of a late-season tropical wave and a mid-latitude trough.
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Re: 2017 TCRs

#44 Postby Shell Mound » Sun Jan 14, 2018 12:03 pm

CrazyC83 wrote:Interesting how Rina formed with a complex interaction of a late-season tropical wave and a mid-latitude trough.

When Rina formed, I immediately thought about its origins from an African easterly wave. Considering its location and early-November genesis, it must be one of the latest Cape Verde-type systems to form over the Atlantic on record.
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Re: 2017 TCRs

#45 Postby galaxy401 » Fri Jan 19, 2018 6:14 pm

These reports have certainly been coming out a slower pace compared to previous seasons. I assume they are currently working on the bigger reports such as Harvey and Irma and it contains a lot of information.

I'm sure as I said that, a lot of reports will come out in the next few days.
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Re: 2017 TCRs

#46 Postby CrazyC83 » Fri Jan 19, 2018 6:19 pm

galaxy401 wrote:These reports have certainly been coming out a slower pace compared to previous seasons. I assume they are currently working on the bigger reports such as Harvey and Irma and it contains a lot of information.

I'm sure as I said that, a lot of reports will come out in the next few days.


I agree, they are probably working on some tougher reports. Bret is probably the shortest of the remaining ones, followed by some combination of Emily, Franklin, Gert and (possibly) Philippe (depending on if they consider the semi-related extratropical stage as part of the storm or as a separate system). The EPAC ones, for the most part, should be fairly quick too so if they move to them they could produce them in short order.

Those for Harvey and Irma will likely be over 100 pages each, while I'd think Maria and Nate will be around 50 pages with the land data collected. I don't think we will be done before late March at the earliest - around when the WMO TCP meets.
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Re: 2017 TCRs

#47 Postby cycloneye » Fri Jan 19, 2018 6:37 pm

CrazyC83 IMO,Maria will have more than 50 pages but less than 100.(Between 60-65)
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Re: 2017 TCRs

#48 Postby Shell Mound » Sun Jan 21, 2018 12:20 pm

CrazyC83 wrote:
galaxy401 wrote:These reports have certainly been coming out a slower pace compared to previous seasons. I assume they are currently working on the bigger reports such as Harvey and Irma and it contains a lot of information.

I'm sure as I said that, a lot of reports will come out in the next few days.


I agree, they are probably working on some tougher reports. Bret is probably the shortest of the remaining ones, followed by some combination of Emily, Franklin, Gert and (possibly) Philippe (depending on if they consider the semi-related extratropical stage as part of the storm or as a separate system). The EPAC ones, for the most part, should be fairly quick too so if they move to them they could produce them in short order.

Those for Harvey and Irma will likely be over 100 pages each, while I'd think Maria and Nate will be around 50 pages with the land data collected. I don't think we will be done before late March at the earliest - around when the WMO TCP meets.

I also think that the 1961-65 reanalysis for the Atlantic should come out shortly after the final TCRs are completed, which should be icing on the cake to top off an epic 2017 season. Some big changes could be in the works, including some surprises, perhaps even a new U.S. major hurricane (Cleo [1964] in SE FL, based on surface observations in the Miami-Fort Lauderdale metro area). I am already willing to take some preliminary guesses as to what the final, Best Track Committee-approved data might contain. I'll start off by mentioning some of the notable storms, adding in some interesting sideshows. Again, these are only my guesses, and do not reflect inside information, which I wouldn't share publicly until the formal release of the reanalysis (revised HURDAT) online. For reference, I used Sandy Delgado's preliminary reanalysis of the 1955-63 seasons.

Carla (1961) will likely be downgraded to 120 knots at its initial peak over the Gulf of Mexico, if not lower, due to its large size/RMW and slow movement. However, the landfall in TX might prove a different story. The anemometer data and pressure reports from Port Lavaca, TX, plus pre-landfall recon data and the (spectacular) radar presentation, suggest that the TX intensity will be very close to what is currently implied in HURDAT. If the report of 124 knots from the oil-drilling site in Port Lavaca was sustained and close to the standard 10-m elevation, then that would hold intriguing implications for the winds at landfall, for the anemometer was in the NW (or at least N) quadrant and failed after recording the 124-knot value (measured gusts were in the Cat-5 range, ~150 knots). Also, recon fixes suggest the pressure was deepening in the hours before landfall, and radar fixes suggested the eye was contracting at that time. Pressure reports, including 936 mb in Port Lavaca, were taken somewhat inland from the immediate coastline, and are fully consistent with a landfall pressure of at most 931 mb, if not a few mb deeper. I think Carla could have conceivably been in the 928-930 mb range at landfall. All the data, to me, suggest that Carla was likely a full 125 knots at landfall in TX, rather than the 115-120 knots many people suggest. The measured storm-surge values and wind damage are all consistent with the scientific data, too. My personal, preliminary estimate for the intensity in TX: 125 knots / 929 mb.

Debbie (1961) may have been still been a major hurricane, as indicated in HURDAT, but on 7 September, not 11 September. At 19:13 UTC on 7 September, crude, tilted, TIROS satellite imagery shows a well-developed anticyclone over a bright, white CDO and well-defined "stadium" eye, with well-developed outflow on the western semicircle. There was no recon so early in the life cycle of Debbie, and the first aircraft entered the storm several days later, when it was clearly much weaker, sheared, post-EWRC, and sprawling (as on this 18:30 UTC image), probably a Cat-1 system at most, and certainly not a major hurricane. However, since there are absolutely no in-situ data for Debbie so early as 7 September, the BTC cannot make a huge change to that segment of the track, which is listed at Cat-1 status in HURDAT. However, the BTC could, perhaps, compromise between the old (current) peak in HURDAT, 105 knots, and the suggested peak on 11 September, 75-80 knots (when the first aircraft reached Debbie), and extrapolate backward to a revised intensity of 90 knots on 7-10 September. This would nicely balance the uncertainties, showing an earlier peak, holding that intensity for several days, and then slowly weakening to 75-80 knots on 11 September. I would also note that Debbie could have easily been a major hurricane on 7 September, perhaps by 12:00 UTC; as the system was then near 28°W, it would be a candidate, along with Frances (1980), to potentially replace Ophelia (2017) as the easternmost major hurricane on record in the Atlantic. My personal hunch is that, had modern sensors and GOES-16 been available back then, Debbie most probably would count as a major hurricane on 7 September, but as it is, we have no way to know for sure.

My suggested best track for Debbie on 5—11 September, including genesis (same coordinates as in Sandy Delgado's reanalysis, but some adjusted intensities—my values first, then Sandy Delgado's, then current HURDAT's):

1200Z/5 Sept — 30 (30)
1800Z/5 Sept — 30 (30)
0000Z/6 Sept — 30 (30)
0600Z/6 Sept — 40 (35)
1200Z/6 Sept — 50 (40)
1800Z/6 Sept — 60 (50[50])
0000Z/7 Sept — 70 (65[65])
0600Z/7 Sept — 80 (70[70])
1200Z/7 Sept — 90 (70[70])
1800Z/7 Sept — 90 (70[70])
0000Z/8 Sept — 90 (70[70])
0600Z/8 Sept — 90 (70[70])
1200Z/8 Sept — 85 (70[70])
1800Z/8 Sept — 85 (70[70])
0000Z/9 Sept — 85 (70[70])
0600Z/9 Sept — 85 (70[70])
1200Z/9 Sept — 80 (70[70])
1800Z/9 Sept — 80 (70[70])
0000Z/10 Sept — 80 (70[70])
0600Z/10 Sept — 80 (70[70])
1200Z/10 Sept — 75 (75[75])
1800Z/10 Sept — 75 (75[75])
0000Z/11 Sept — 75 (75[80])
0600Z/11 Sept — 75 (75[90])
1200Z/11 Sept — 80 (80[100])
1800Z/11 Sept — 80 (80[105])

Esther (1961) was almost certainly a Cat-5 sometime on 17—18 September, probably between 1200Z—1800Z on 17 September. That would have taken place between aircraft fixes. The RMW was not only more compact than is typical for Esther's location at the time, but Esther was also situated beneath a strong subtropical ridge as it passed north of the Lesser Antilles. The evidence isn't strong enough to go higher than 135 knots, but Esther most likely was 140-145 knots at its peak, if not a bit stronger, based on what we know about high environmental pressures and westward-tracking tropical cyclones. Further evidence is the fact that the central pressure was at or below 935 mb for a full day, indicating very conducive upper-air conditions. GOES-16 alone, to not mention today's recon, would have confirmed Esther as a Cat-5, had it been available in 1961. On the whole, Esther's longevity, Cabo-Verde origin, and sustained intensity is rather similar to Edouard (1996), and the two might be analogous, except that Esther occurred later in the year, during the seasonal apex (mid to late September).

Hattie (1961) probably was no stronger than 135 knots at its peak, given its larger-than-average RMW, slow movement, and good aircraft and land coverage. On 31 October, aircraft documented an RMW of 15 n mi and a pressure of 923 mb at 17:00 UTC. Four hours later, another fix indicated an RMW of 17 n mi (weaker pressure gradient, weaker winds) and a slightly deeper pressure (normally favours stronger winds) of 920 mb. On balance, the data suggest that Hattie came close but did not quite reach Cat-5 status. It was clearly a high-end Category 4, both at its peak and at its devastating Belizean landfall, but the most likely candidate for Cat-5 status in 1961 would be Esther, not Hattie, in my humble opinion. My verdict: Carla and Hattie should be downgraded to high-end Cat-4s; Esther should at least be *considered* for an upgrade to Cat-5 status.

As for the 2017 TCRs, here are my final guesses on what the Hurricane Center may determine:

Gert is a good candidate to be *considered* for upgrade to major-hurricane status (100 knots), based on peak satellite estimates. If not, expect a slight upward bump from 90 to 95 knots, which is probably more likely than an upgrade to major status, but I wouldn't *totally* preclude the former.

Harvey, if anything, will probably be assessed as slightly *more* intense at landfall in TX. Aircraft did not sample the strongest winds as the eye moved onshore, but found enough evidence (either flight-level or SFMR, I can't recall, but not both) for ~120 knots. The lowest pressures observed on land were in the 940-942 mb range (suggesting 938-939 mb at their location), but even in the eye, there were many fluctuations, owing to mesovortices, so even chasers in Rockport may have not sampled the lowest pressure. Rockport is also a bit inland from the immediate coastline and barrier islands. My guess for the landfall intensity: 125 knots / 937 mb. Of course, those peak winds and highest storm surge impacted uninhabited parts of the barrier islands, so no one witnessed or sampled those impacts.

Irma has been a bit of a toss-up for me. At first, I was rather strongly in favour of downgrading its landfall in the lower FL Keys to high-end Cat-3 (110 knots), based primarily on the filling trend, the impact of increasing shear and dry-air intrusion, and the fact that shoaling could have impacted high SFMR readings. However, I have since reconsidered a number of things, and very recently I have *finally* altered my assessment. The most important factors were:

1) the observed winds on Marco Island and at Naples Municipal Airport. Based on their locations relative to the RMW, both sites likely missed Irma's peak winds. Nevertheless, the 77-knot sustained value (with a peak gust of 123 knots) at Naples Municipal Airport strongly suggests that low-end Cat-2 winds affected at least part of Naples proper, somewhere nearby. The airport was on the N or even NNW side of Irma's eye, so it likely missed the peak winds in the core. Also, a storm chaser measured a 97-knot sustained wind on Marco Island via mesonet over short exposure-time. Again, based on its location and brief exposure, that mesonet station likely did *not* sample the peak winds in Irma's eyewall, which occurred over the mangrove-covered islands, coves, and channels of Everglades National Park, near and east of Goodland.

2) The consistent underestimation of Irma's surface winds on the basis of aircraft data. After its passage through the Keys, Irma passed west of Everglades National Park, and there were two aircraft fixes post-Keys. Prior to Irma's landfall on Marco Island, the last couple of aircraft fixes did not find SFMR or flight-level winds that would have suggested anything stronger than 90-100 knots at most. As noted elsewhere, the observations from Naples and Marco Island strongly suggest that Irma was up to ten knots stronger than the final aircraft data implied. The winds from those two sites, in context, suggest that Irma's peak winds were likely close to 105 knots at landfall on Marco Island.

3) Even the flight-level winds closest to the time of landfall on Cudjoe Key were consistent with surface winds of 110 knots, in agreement with SFMR, and the NHC noted that aircraft may have not sampled the strongest winds, which would have occurred in a very small area, just as they did at the time of Irma's second landfall, on Marco Island. (Note that even Irma's pressure on Marco Island was likely deeper than the NHC operationally estimated; storm-chaser data suggest that the final pressure will be close to 937 mb for the landfall on Marco Island.)

All this leads me to conclude that Irma was *indeed* a low-end Cat-4 over the Keys, and even slightly stronger than operationally estimated at its second landfall. My guesses: 115 knots / 932 mb in the Keys, 105 knots / 937 mb at Marco Island.

As has been extensively discussed here, Maria's landfall intensity looks set. I think 130 knots / 923 mb is a very good guess for the landfall in Yabucoa, PR.

If Jose is upgraded to Cat-5, expect the SFMR readings (as in Irma) to play a role, besides satellite. If so, then 145-150 knots seems more likely than a peak of 140 knots.
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