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About ncforecaster89

  • Birthday 05/03/1970

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  • Four Letter Airport Code For Weather Obs (Such as KDCA)
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    Wilmington, NC
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    Hurricanes and blizzards are my primary interests relative to a specific atmospheric phenomenon. Tropical meteorology was, and has been, my focus since my first hurricane experience at the impressionable age of 14. It was this fateful encounter that led me to pursue a degree in atmospheric sciences. While in college, I was most fortunate to have interned at the NHC (by way of a student internship) with the late Bob Case as a mentor. Although I no longer work in the meterological field professionally, I still enjoy helping others by sharing the knowledge others have so generously given me. Thus, one is most likely to see the vast majority of my posts being centered on tropical meterology.

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  1. That's not how the translational speed affects the maximum sustained winds (MSW) in the NE quadrant of the storm. In your theoretical scenario, the 90 mph MSW is the maximum 1 minute average wind anywhere in the hurricane. The translational speed is the main reason the MSW is typically found in the aforementioned right-front quadrant. That said, a fast-moving hurricane will generally have a reduced MSW in the NW quad, as a result of the translational speed working against the winds moving in an opposing direction.
  2. Four "major" hurricane landfalls in one season, occurred in 2005: Dennis, Katrina, Rita, and Wilma. I believe there have been 2 or 3 other years with three "major" H landfalls in the USA.
  3. As I posted in the main "Maria" thread, hurricane Earl delivered HF wind gusts to the outer-most Outer Banks in September of 2010. It was very similar in size (HF winds reached 70 nm from the center) and the forecast intensity of Maria as it reaches its closest approach. To be specific, it got within 90 nm of Hatteras Island and Nags Head, while moving from 35.3 N 74.0 W to 35.8 N 73.7 W. It was a 100 mph category-two at 35.3 and a 85 mph category-one at 35.8 N. I mentioned this to provide a general barometer/guideline as to what coordinates Maria must reach in order to deliver possible HF wind gusts to the NC Outer Banks; all things being equal.
  4. My analog for this system is hurricane Earl of 2010. It caused sustained 70 mph winds, and gusts to 89 mph, at Nags Head, as it passed due E at longitude 73.7 w. It was at 35.3 n and 74.0 w, as well. H Maria is of similar size, and Earl's proximity to the coast provides a good barometer of what may occur on the outer-most Outer Banks of NC.
  5. Hi cheeseland! The technology and data available is greatly improved from 1992, as you alluded to, which would have certainly helped. OTOH, the main reason Andrew rapidly intensified shortly before and through landfall was the completion of an EWRC that had caused it to weaken, beforehand. The underestimate of the MSW, at the time, was due to the more limited knowledge of the proper ratio between FLvl to surface winds.
  6. I agree. Excellent footage! Definitely one of Josh's best/most intense chases (maybe top 3 after Hyian and Patricia?). The extreme wind damage and incredible flooding, as you noted, make this a rather catastrophic event for too many on the island. Thoughts and prayers are with them all.
  7. Hi Steve! Thanks for posting this velocity data. Please let me clarify that my post was intended to rebutt the suggestion that Maria was anything less than a very powerful category-four hurricane, at landfall. The part about possibly having weakened below 135 kts is based on the Recon data, continued rise in the central pressure, and satellite presentation at landfall. My best guess is 130 kts.; the same estimate I had for Patricia. However, it's just as conceivable that it retained that extra 5 kts, as well. Either way, a very intense upper-end category-four hurricane, which was the intent of my post.
  8. Hi Paragon, I am only aware of the empirical wind data contained in the NWS post-storm report that actually features a wind gust measurement of 122 kt (140 mph). Given that it's highly unlikely that the maximum wind gusts will be measured at a single station, I'd suspect it's probable that peak gusts were as high as 150 mph. As far as Rockport, it appears an estimate of 140 mph gusts seems most reasonable, maybe slightly higher, but not the locality of the highest winds experienced on land. In many cases, your rule of thumb would be applicable, but in the aforementioned cases of Katrina and Irma, it would significantly overestimate the MSW. Although Irma generated extreme wind gusts =/> 142 mph in the Naples area, the cumulative data clearly suggests it was not a 140 mph category-four at that time. Edit: The NWS report also lists a 1-sec gust of 126 kt (145 mph) at virtually the same location (between Fulton and Lamar) as the 122 kt measurement mentioned above. Important to emphasize that these are both 1-second gusts, rather than the 3-sec standard, which makes it a slightly inflated value.
  9. Concerning all this discussion regarding estimated/presumed wind speeds and categorical damage relative to Maria's intensity, I would add that each hurricane is unique and there's not necessarily a one to one correlation between Recon estimated MSW at the surface and the actual winds that occur on land. In most cases, and in general, one should expect to see wind gusts equal to the MSW value contained in the NHC advisory in the area of the RMW, as the advisory intensity is the absolute maximum estimated surface wind found anywhere in the storm; which is a single point. OTOH, there have been much weaker hurricanes (such as Katrina and Irma), which were also weakening at their respective landfalls, but generated extreme wind gusts that far exceeded the typical sustained to wind gust ratio. Taking into consideration various factors such as how an EWRC might effect wind transport from FLvl to the surface, land friction, influences of orography and topography, an objects exposure to the strongest winds, and the quality and durability of said onjects, are just a few reasons why we shouldn't presume a one to one correlation between the NHC advisory MSW and the damage that occurs or similar assumptions comparing storms of similar intensity. Although one can reasonably argue that Maria may have weakened below 135 kt at landfall (for which I agree), I think all the respective data strongly suggests that Maria was most certainly still a very powerful category-four hurricane, regardless of the extent or severity of the damage that has been left in its wake.
  10. To the very best of my knowledge, the figures you listed for highest recorded wind gusts in the USA are accurate. As far as the localities outside the USA, I honestly haven't put much effort into researching that data. That said, I believe there was a confirmed wind gust measurement of 155 mph on Barbuda before the anemometer was destroyed. Unlike in the USA where it's likely that the 142 mph gust is close to the peak wind gust produced by Irma at that time, there's very little doubt that the aforementioned 155 mph gust was greatly exceeded by the unmeasured max gust generated on the eastern Caribbean Islands. Maybe another member is aware of a higher recorded gust than the 155 mph mentioned above? Of course, it's essentially impossible for any anemometer to survive long enough to actually record a wind gust =/> 200 mph...which is theoretically assumed to have been produced by hurricane Irma.
  11. Can't speak to the rest of this post, as I was busy documenting #Irma in SW Fl, except to say that the officially recorded 142 mph gust most definitely matches the peak winds myself, Michael Laca, and other highly experienced chasers experienced at the city parking garage in #Naples. In fact, its peak winds are at least top 3 (along with Katrina and Harvey), maybe even#1, in my own chase career! The biggest difference I observed, with regard to the two others, is the relative short duration of those extreme winds; which appears to have limited the more severe wind damage that otherwise would have occured, although certainly bad enough. I'm still stranded at the Jacksonville, Fl airport awaiting a flight back home, after my car rental broke down on me. As a result, I'm still trying to catch up posting damage pics taken the days following the storm in Naples...which can be viewed on Twitter @tbrite89.
  12. Time will tell, honestly, as there is never a guarantee that an intense hurricane will ultimately regain it's previous intensity following an EWRC. It only takes a subtle difference in either the atmospheric or oceanic environment to induce weakening. In the case of H Andrew, an EWRC dropped the MSW to category-four strength as it passed through the Bahamas, but Andrew rapidly reintensified to category-five intensity on approach and through landfall, after completing that EWRC. Perfect conditions were the primary reason. In contrast, H Katrina weakened from a category-five to a strong category-three H following the emergence of an EWRC that combined with a less favorable environment through landfall. However, Katrina's double-eyewall structure at landfall helped enhance a large storm surge over an immense area of the Gulf coast, as well as powerful wind gusts well inland, than otherwise would've been the case.
  13. In simpliest terms and in general, a smaller eye is typically associated with a higher intensity. Since wind speed itself is dictated by the pressure gradient over a given distance, a tighter eye generally produces a higher maximum sustained wind. With Irma going through an EWRC, the outer eyewall ultimately replaces the deteriorating inner one...causing a lessening of the PG, and a corresponding decrease in the MSW, as well as a larger eye. If conditions allow, the new larger eye will attempt to contract once again, and tighten the PG and reintensify, accordingly. The main concern of the larger eye resulting from the aforementioned EWRC is an expansion of the hurricane-force wind field, and potentially an increased surge at landfall.
  14. As just noted by another poster, an ERC is typically complete within a 24 hour period, and is usually followed by restrengthening if conditions allow. Thus, it's currently so far away, it's highly likely there will be a minimum of at least one more ERC prior to reaching the USA. Although ERC's can help moderate intensity somewhat, in the aforementioned short term, it also helps expand the hurricane force wind field. In cases such as Matthew and a potential track just offshore of the Fl Peninsula, an ERC can actually be the difference between a hit by the W eyewall and a near miss. Moreover, a larger hurricane could be more devastating than a somewhat smaller, yet slightly more intense one; relative to MSW.
  15. Forgive me if I'm elaborating on something you already know. You are correct that the public advisories list the maximum sustained surface wind speeds (MSW) in mph. However, the NHC calculates that figure based on the unit of knots. Correspondingly, 135 knots is 155 mph (highest-end category 4 intensity), while 140 knots is rounded to the nearest 5 mph increment of 160 mph. Since the NHC uses knots to convert to the unit of mph, one will no longer see an advisory listing a MSW of 95 or 135 mph, respectively. As such, 140 knots x 1.15 = 161 mph (thus, rounded down to an even 160 mph).