Random Chaos

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  • Four Letter Airport Code For Weather Obs (Such as KDCA)
    KBWI
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    KMDANNAP25

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  1. The storm is looking a lot better on IR than it was even 6 hours ago, but the proximity to land and the shallow shelf waters are going to have a negative impact. I can see it strengthening a little before running low on juice, but storms that basically stall don't end up strengthening. The other question is landfall location. Again, I'm going to say that everywhere that's getting at least TS gusts needs to be prepared for landfall. Stalled systems have a propensity to move in unpredictable directions for short periods of time. The models do best at predicting strong steering situations and worst at predicting weak steering situations.
  2. MIMIC is not a good reference source for hurricane form. It's based on the 85GHz microwave passes from satellite that occur every 6-15 hours on average, with often large gaps between them, then a computer "morphs" those images together to create a pseudo-continuous look at what the storm probably is. Use the raw microwave passes available at the NRL Tropical Cyclone site rather than the MIMIC if you want to reference the 85GHz-observed internal structure. That said, microwave data is most useful well away from shore where you have no radar coverage to tell internal structure. It is less detailed than radar and shows similar information about the storm's structure. Sally has luckily been in range of radar extensively during her development, meaning we have very good information on the central structure of the storm. I agree that an eye did try to pop out earlier on IR, and has been well visible on radar for quite a while. That said, it is still not a well wrapped storm with the eye not yet fully closed. Give it another 6-12 hours and we'll probably have a closed eye, so long as land interference and shear don't cause issues. Once it pops out on radar in a good, well wrapped state you'll know very clearly that we have an eye, and no one will dispute it. Right now the updraft just isn't yet strong enough to clear away the hot towers convective structures from overshooting the eye, even though radar shows the eye about 60% to 70% wrapped. Once it gets fully wrapped the outflow will only be via the central core: the eye will clear and the pressure will drop. It will be clear to everyone that we have a well formed eye.
  3. I've been tracking hurricanes for twenty years. One thing everyone seems to forget it takes time for a hurricane to wind up, generally 36-48+ hours minimum for a non-sheared storm after it hits "curved band" status (usually reached as a strong Tropical Storm) before a storm becomes what I consider "well formed" - that is, have a definite eye visible on IR (typically appears as a stronger cat 2 storm). Storms this year have been having wind speeds jump up before the core finishes forming, and I'm not sure why that's happening; usually you need a fully wrapped eye (radar based; may not be visible on IR yet) before the winds start moving above Category 1 strength. This is my rule of thumb, some storms are faster, but it's rare. Many storms are slower, especially if sheared or over cooler water. Sally has one big limiting factor: it's proximity to land. This is going to be a big negative impediment to intensification. If the storm was a couple hundred more miles offshore, we could easily see a cat 4 by landfall with the high gulf heat content, but land impacts will probably limit it's strength to cat 2, maybe weak cat 3 if it can finish wrapping its core before landfall (it sure is trying).
  4. Anyone that looks at TT and sees wacky low pressure drop sonde for Sally from NOAA2, note the date on it: September 27, 2020. It's from 13 days in the future. All I can say is: wtf? I'm guessing someone forgot to turn off reporting for a test. Just noting this before someone goes posting it and thinks it's real.
  5. Outer edge of the eyewall starting to come ashore in Cameron, per radar.
  6. A few final comments before I sleep... 1. Radar is looking better at the moment than it has looked in the last 1-2 hours. Very robust SW through N to E. The one concern, visible from both KLCH and KHGX radars is a more open portion of the spiral in the south. This appears to be filling in with the last couple radar images.This is likely what is leading to #2: 2. IR is showing some slight non-symmetry to the eyewall (not mesovorticies) that is generally indicative of a slightly weaker (but still major) hurricane. 3. Time is running out before landfall. Both recon (SFMWR and dropesondes) and radar is showing very powerful winds aloft, though mixing to the surface is still not fully occurring. Center pressures are falling again, indicating to me that the south issue with the eyewall may be closing up again. I am not sure there is enough time to strengthen, but it doesn't need much to meet the Category 5 threshold. I never discount any storms in the Gulf from doing crazy stuff since I've seen too many storms break every rule in the book before. My guess is at most 5-10 mph strengthening left before landfall, and likely little change, depending on how much winds at altitude are able to mix to the surface. 4. Landfall location often is slightly clockwise of the radar depicted path. This is due to drag on land vs open water. Doesn't always happen, but I've seen it enough to know that west of the hurricane is going to be "safer" than east of the hurricane from sudden last minute wobbles.
  7. i’m seeing a lot of 180+ mph velocities on radar both east and west side, plus occasionally 190+ mph readings that are more suspect. That’s up 15+ mph from a couple hours ago. Storm seems to still be strengthening as also seen on recon.
  8. ADT's really picking up this intensification. 2020AUG25 225020 3.6 985.5 57.0 3.6 3.7 3.7 NO LIMIT OFF OFF OFF OFF -62.04 -63.57 UNIFRM N/A 9.9 24.91 88.73 FCST GOES16 32.8 2020AUG25 232020 3.6 985.5 57.0 3.6 3.7 3.7 NO LIMIT OFF OFF OFF OFF -35.00 -63.51 UNIFRM N/A 9.9 24.97 88.84 FCST GOES16 32.9 2020AUG25 235020 3.7 984.2 59.0 3.7 4.1 5.7 0.5T/hour OFF OFF OFF OFF -24.01 -66.64 EYE -99 IR 9.9 25.02 88.96 FCST GOES16 33.0 First pass that shows an "Eye" detection. Rapid strengthening limiter is on. Raw ADT number jumped 2.0 so expect the storm to "catch up" to this T-rating over the next several hours. It's on!
  9. Only off the table because the chart doesn't give probabilities in excess of 40kt/24hr and we are land falling in just over 24 hours. Remember Hurricane Michael last year that had RI right up until landfall. Never assume it's off the table, just assume it's very unlikely.
  10. I know it’s the NAM, but i gave to make a weenie post: NAM has sub-900mb pressures for 14 hours straight before landfall with a low of 885mb. On the other hand, HMON keeps it a weak, disorganized tropical storm through landfall.
  11. It is really hard to tell from IR imagery where the center is located between interaction with mountains, what appears to be a certain amount of dry air in the core, plus sheer the low level vortex is over the western side of south Cuba, not too far from Bayamo on google maps. However I'm concerned that we might see again what happened with Puerto Rico with the radar-fixed center tracking over the mountains but the mid level center staying to the south, with the LLC relocating under the mid-level center after the storm exited Puerto Rico. If something similar happens with Laura, we could see the storm more significantly over the warm waters south of Cuba. This is what Levi Cowan aluded to in his tweet (several posts earlier) with a displacement of the mid-level center south of the LLC. Again, this is at this time all speculation as to what could happen; until the LLC actually relocates we have to assume it will not relocate. Something I have noticed about this storm for the past two days is it seems to often have what appear to be multiple vortices. This makes the system especially difficult to locate sometimes via IR. Shear is a factor, but I also feel that land interaction is helping keep the core from organizing. The system has essentially been impacted by land since about the time it was upgraded to Tropical Storm, and its core has been continually disrupted by mountainous terrain - Puerto Rico, Hispanola, southern Cuba. A longer time as a tropical storm can mean two possible things: (1) it stays weak with little pressure falls or (2) it obtains a much broader region of Tropical Storm force winds with more significant pressure falls. Given the high heat content south of Cuba (reference SST maps) combined with land interaction continually disrupting the core while over this bath water, we may end up with a much larger storm than typical when it enters the gulf. This has both advantages and disadvantages: it will take longer to organize a bigger storm, but when it does organize it can be far more destructive. Only time will tell and the models are doing a fairly poor job of figuring out exactly where this storm is heading (and much of that is due to land interaction and interaction with Hurricane Marco). P.S. Anyone else wish that Laura was actually named Polo? Then we could have storms Marco followed by Polo.
  12. Looking at the Guantanamo Bay radar, the COC looks to be south of the NHC location. The displacement from the visible satellite location may mean the LLC and mid and upper-centers aren't well stacked yet. https://www.metoc.navy.mil/fwcn/animate.html?icao=mugm&type=PPIZH240
  13. The most important, the most critical, to what this storm does over the next 2-3 days is whether the low level COC passes over Hispanola and the mountains there, or if the COC stays off shore. PR radar definitely looks like the radar identified COC is going to skim the northern edge of Hispanola. The disruption from passing over PR's mountains are minor compared to what Hispanola's mountains can do to a tropical system. I've seen well intact hurricanes completely ripped apart, never recovering, from Hispanola. Watching both radar and IR the system looks to have convection displaced mainly south of the COC. Radar showed the low level COC being disrupted somewhat by the mountains of PR, but still intact, and on track in the northern portions of the CDO near the eastern tip of Hispanola. As long as this track continues, the system, I feel, will not be significantly impacted by Hispanola, with the low level COC just barely missing the mountains. -- Longer term (1-3 days) we need to watch for interaction between Marco and Laura. This is one of the rare cases where we may actually witness the Fujiwara effect near land, and that may throw off forecast track somewhat.
  14. Looking at the HWRF, the tracks for both Laura and Marco cannot both be right. This is 108 hours for each storm. There is no way they can both be in the same spot. Clearly one, if not both, are wrong.