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About Windspeed

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    ♪♫ Bucketbot ♪♫

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  • Four Letter Airport Code For Weather Obs (Such as KDCA)
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  • Location:
    Tri-Cities, TN/VA
  • Interests
    Geography, Climate and Geoarchaeology.

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  1. Windspeed

    Major Hurricane Michael

    Here is Hugo's wind distribution by the man himself, Dr. Fujita, courtesy of Texas Tech. His handdrawn maps were works of art. Posting this version despite the watermark, as the one available from NOAA is a very low resolution scan. Regardless, Hugo was perhaps the standard for long-lived inland hurricane intensity, remaining a major well inland into the South Carolina interior. Yet to no surprise, the peak wind assessment is in gusts as that best translates over land. Fujita knew this. Also, the highest reported gust on land by Hugo was 137 mph.
  2. Windspeed

    Michael Banter Thread

    Nice charted pressure vs distance relationship/comparison by Josh Morgerman [mention=19]hurricanejosh[/mention] between two of his Kestrel instruments, seperated by 3.7 miles. One left at his original chase location recorded 939.7 mb. It remained inside the eyewall. A second he had inside the hotel at his final chase position that measure 923.2 mb just inside the western periphery of the eye. A difference of 16.5 mb in 3.7 miles or 4.46 mb per mile. That is probably not exact as the pressure drop probably increased from point B to A. At any rate, that aligns pretty well to the last 919 mb center fix by recon at landfall, though central pressure may have actually dropped a mb or two lower as landfall was underway. Regardless, that is an impressively tight pressure gradient. Post analysis should definitely be interesting.
  3. Windspeed

    Major Hurricane Michael

    Additonally, task anyone with finding more comprehensive support of a stronger inland hurricane. I have read plenty of papers by Powell, Vickery, Kaplan, Reinhold, etc., on post-tropical landfalls. They won't. That OBS data is already amazing in its own right. I don't recall ever seeing inland wind gust velocities that high and that far inland in a preliminary report. But we need to comprehend the nature of those readings with regards to inland cyclone intensity. We need to understand that inland wind measurements are never going to be the same as over water, period. Frictional influences over land cause surface airflow velocities to be gustier. Energy transport becomes 20-30% less efficient even without the hurricane actually weakening above the 850 mb level. Airflow becomes less smooth/horizontal with greater vertical deviations due the influences of frictional drag. Simply put, the hurricane may be still be a Category 4, but surface airflow is rarely ever going to sustain wind speeds beyond 1-minute measurement like it would over open water or the immediate shoreline. It's only ever going to be represented in much shorter wind gusts. This is why the NHC will not drop a category over land based soley on sustained wind obs alone. They will continue using a mixture of remote sensing, radar velocities and maximum reported gusts. They are issuing a forecast with every advisory they make to inform people on the ground. The idea here is FORECAST until the NEXT advisory the highest maximum winds POSSIBLE. It would be highly irresponsible for them to forecast based on realtime inland station OBS alone, especially when it takes luck to ever have a station located perfectly where the highest winds might actually be occurring, much more the complications of instrument malfunction and failure. Edit: Here is a good article by Bob Henson about this very phenomenon: https://www.wunderground.com/cat6/hurricane-winds-landfall-why-it-they-seem-fall-short
  4. Windspeed

    2018 E. Pacific Hurricane Season

    Dusting off the cobwebs in this thread. Tara is in the process dissipating in 24 hr near the SW Mexican coast; however, there is a new area associated with the CAG and 94L that may interact with a northerly jet over the Gulf of Tehuantepec. A number of GEFS and EPS suites have suggested cyclogenesis occurring south of Guatemala and is climatologically favored in the current setup. Why it's worth watching is that some of the guidance shows signficant intensification in 3-5 days and also the possibility of a mid-to-upper weakness or trough being modeled late in 7-10 day range that could pull the TC into the S. Baja or Sinaloa region Mexico.
  5. Windspeed

    Major Hurricane Michael

    Nobody expected that final outcome. I think some of us layed out the opportunity of intensification near landfall and pointed out why a major hurricane was possible but not certain. The NE turn and intensity ranges from low 940s to 930s at landfall in model guidance was concerning. It gave us the possibility of rapid deepening and that verified. But a TC reaching maximum potential though? Nope. I should be clear that despite the possibility of a Cat 3, I thought the model runs deepening into the 930s by the HWRF and even the ECMWF OP were overdone.
  6. Windspeed

    Major Hurricane Michael

    For those who like classic NHC AVN imagery, Dr. Phillippe Papin @USNRL archived an entire 24 hour GOES-16 10/10/18 mesoscale loop of Major Hurricane Michael through landfall. You may download the 1392x1070 full resolution mp4 version here. Classic AVN is extremely useful for comparing and contrasting cloud tops of historical TCs of the past three to four decades.
  7. Windspeed

    Major Hurricane Michael

    The lack of an ERC or delayed ERC and Michael's rapid intensification near landfall has also been discussed and I understand the reasoning. I am a little apprehensive to hang my hat on it however mainly due to it all being so speculative. That isn't to say that had an ERC occurred, Michael would not have made landfall as a weaker or weakening hurricane as far as sustained wind. The problem is that ERCs are a highly unpredictable process and generally vary with respect to landfall intensity. We have seen them take mere hours to several days to complete. We have also seen concentric eyewalls persist and the inner eyewalls continue intensifying for a full day before succumbing to subsidence. Conversely, we have observed hurricanes where the ERC process fails to complete as a well-organized outter eye band breaks down or gets reabsorbed back into the eyewall, such as with Irma last year and its everlasting stable eye through the Antilles. I noticed one of the interesting aspects of Michael's development was its cyclogenesis out of a large gyre and broad surface trough. When the LLC reformed further east and a core consolidated near western Cuba, Michael's eyewall was originally reported by recon as 30 nm wide. That's a rather large eye for a hurricane to start its journey. Thanks to strong westerly mid level shear, the eyewall generally remained open in the SW semicircle and also weaker due to PV subsidence off seperate reoccurring mid-level MCS/MCVs. These would rotate around the northern semicircle of the circulation but seem to be strong enough to continue the pressure drops needed to maintain steady intensification of the core, despite said shear. This also kept the eye mostly or at least partially obscured by mid-to-high cloud debris and the eye temperature never really showed significant warming until the 12 hours prior to landfall. It is possible that both of these characteristics delayed the overall vortex from shrinking much, or a nearby outter band intensifying enough to advance the hurricane into an ERC. Still, had an ERC been allowed to occur and complete, we still aren't assured a weaker landfall.
  8. Windspeed

    Major Hurricane Michael

    Though I agree that nobody could have foreseen much less expected a 919 mb monster, I wouldn't say that the rapid intensification hit us blindly. Again, I was stunned by the maximum intensity, absolutely, but not shocked to see that Michael continued strengthening through landfall. All of the favorable environmental aspects were present aside from strong shear. That's a huge unfavorable negative. But given the positives, you abate it and you've got a problem. RI happened in two phases, but the second was modeled surprisingly well in hindsight. The initial 21 mb drop overnight on Sun was impressive on its own. But we also have to remember that the LLC relocated east just before that drop. At any rate, let's focus on the second phase near landfall that was modeled well. Several numericals and the intensity guidance, such as SHiPS, had repeatedly supported RI to a major hurricane as early as 00z Monday. That guidance further increased 06z Monday and, to no surprise, the Mon 09z suite from the NHC alluded to the possibility of a major hurricane intensifying into landfall. The very next package, they were forecasting it. We had repeated HWRF runs into the 930s, and though not being a focus for maximum intensity, even the generally conservative ECMWF op had multiple suites into the 930s. There were very important reasons for all this precursor however. Strong instability and poleward divergence was modeled unanimously and well ahead of time. SSTs were above normal right up to the coastline. If the overrider was being strong shear, it seemed North to Northeast forward motion would decrease it and allow the mid level flow in the steering column to align. We even discussed this early on in this very thread while Michael was still a tropical storm. And I believe we were already talking the possibility of a major hurricane. I was worried if the flow aligned, we might see something we had not experienced in many years -- an intensifying major into landfall on the N. Gulf coast. We just could not foresee such an explosion, as you put it. Edit: I should also emphasize that, as far as I am aware, no legitimate numerical or dynamical model guidance forecasted the intensity we observed. I stress legitimate. Please, do not bring up any one of the mesoscale outputs of that which shall not be spoken.
  9. Windspeed

    Major Hurricane Michael

    Oh absolutely historical data and climatology favor major hurricanes weakening due to all the aformentioned issues that Camille and Michael overcame. Intensity is still the most difficult aspect of tropical forecasting. Hopefully next time we have a hurricane forecasted along the N. Gulf coast, we are able to see if those issues that commonly result in weakening are there and not just assume or expect weakening will occur per usual.
  10. Windspeed

    Fall Banter 2018

    If we can just keep improving. I don't expect a miracle against Alabama, they show improvement and still get smashed; however, for the first time since before the Florida debacle, I am entertaining the possibility of 7 wins and a bowl. Feels good, man.
  11. Windspeed

    Major Hurricane Michael

    Yeah I saw your edit and deleted my post but not before you responded. Curious of your thoughts on the discussion. It seems Michael is a wake-up call that we shouldn't always expect shear or dry contentinal airmass to save our butts with regards to a weakening landfall on the N. GOM coast. The last 50 years seemed to have lulled us into those expectations and a false sense of security outside of perhaps say an Elena or Frederick. Edit: Can't forget Alicia either.
  12. Windspeed

    Major Hurricane Michael

    Based on the reanalysis work done by NCEP and FIU, Camille was imbedded in a much more favorable environment than Michael as it moved NNW across the East and Central GOM. The overall core circulation also seemed to remain small/tight enough to avoid the typical issues associated with entertainment of dry stable air, even after the core had undergone an ERC. Additonally, the axis of the deep layer trough and steering flow influencing Camille's motion was positioned such that mid-level southerly flow was aligned with the steering column; therefore, Camille never really encountered enough trough-induced windshear to encroach drier and stable continental airmass, typical of the western GOM during an advancing trough, into its interior core. It also passed over relatively untouched high SSTs in the shelf waters in August from the '69 mid-South heatwave. Camille always convinced me of the very real threat that Cat 5s landfalls on N. Gulf coast were not only possible, but would happen again, regardless of the frequency of major hurricanes that tend to weaken/degrade prior to landfall. It just took the right setup and positioning of cyclone. Interestingly, in Michael's case, it also appears struggling GOM systems can also be an upper-category threat when they finally are allowed to get their act together in the N. GOM. Even when Michael was struggling, it seemed to be positioned just enough outside the mid-level shear axis so it could slowly strengthen. Also, amazing upper level divergence and atmospheric instability allowed those reoccurring MCSs rotating around the north side of the larger circulation, which maintained pressure fall in the face of the stronger southwesterly mid level shear. That is, of course, until Michael's forward motion turned more N and NNE and then all hell broke lose. We only have estimates for Hurricane Camille's landfall from recon, pressure readings and damage surveys. Reanalysis dropped landfall intensity to 175 mph at landfall on the Mississippi coast, but since no anemometer survived on land, all we have are the pressure readings to go by onshore. There was an oil rig in the eyewall off the coast that reported a gust of 170 mph before it failed. Here is a good article about Camille's reanalysis from Dr. Jeff Masters: https://www.wunderground.com/blog/JeffMasters/new-reanalysis-sheds-lights-on-the-mysteries-of-hurricane-camille.html
  13. Windspeed

    Major Hurricane Michael

    Is this specifically in reference to Mexico Beach?
  14. Windspeed

    2018 Atlantic Hurricane Season

    000 WTNT43 KNHC 132036 TCDAT3 Post-Tropical Cyclone Leslie Discussion Number 70 NWS National Hurricane Center Miami FL AL132018 500 PM AST Sat Oct 13 2018 After a total of 70 advisories, long-lived Leslie has become post-tropical just west of the coast of Portugal, finally succumbing to the combination of cool waters, strong vertical wind shear, and interaction with an approaching cold front. The air mass ahead of the cyclone has moistened up in the low levels with Faro, Portugal, reporting a dewpoint of 70F/21C, but the dewpoints across central and northern Portugal ahead of Leslie are only in the low-60F range, which is not indicative of a tropical air mass. Thus, the cyclone is now a powerful post-tropical low pressure system that even has a partial eye noted in the most recent 2000Z Portuguese composite radar imagery. After landfall, rapid weakening is anticipated, and Leslie is forecast to degenerate into a broad low pressure area over or just north of Spain by late Sunday. Leslie is moving quickly toward the northeast or 050/30 kt. Post-tropical Cyclone Leslie should continue in a fast northeastward direction for the next 12-18 hours, making landfall near or just south of Porto, Portugal by 14/0000Z. This forecast motion is consistent with the previous advisory and the latest track model guidance. The meteorological services of Portugal and Spain are handling hazards information for their respective countries via local weather products. This is the last National Hurricane Center (NHC) advisory on this system. Key Messages: 1. Leslie is expected to bring near hurricane-force winds to portions of Portugal later tonight as a powerful post-tropical cyclone. Gale-force winds are also likely to affect portions of northwestern and northern Spain tonight and Sunday. 2. Leslie is expected to produce rainfall amounts of 25 to 75 mm (1 to 3 inches) with isolated amounts as high as 125 mm (5 inches) across portions of Portugal and Spain, which could cause flash flooding. 3. For more information on Leslie, interests in Portugal should refer to products from the Portuguese Institute for Sea and Atmosphere at www.ipma.pt. Interests in Spain should refer to products from the State Meteorological Agency at www.aemet.es. FORECAST POSITIONS AND MAX WINDS INIT 13/2100Z 40.5N 9.5W 60 KT 70 MPH...POST-TROPICAL 12H 14/0600Z 43.0N 4.9W 35 KT 40 MPH...POST-TROPICAL INLAND 24H 14/1800Z...DISSIPATED $$ Forecaster Stewart
  15. Windspeed

    Fall Banter 2018

    I'm seeing improvement. Yes, Tennessee won. But there appears to be a change or evolution occurring right before our eyes. The Vols had no business beating Auburn at their stadium. I didn't expect the win today, nor do I expect them to best Alabama. But they are focusing on their assignments and plays much better. Hell, it's a night and day comparison.