jpeters3

Meteorologist
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Everything posted by jpeters3

  1. I'll agree with Quincy that the prevalent low-level saturation that has shown up in most convection allowing models makes me every so slightly concerned. On the other hand, there isn't extremely strong WAA/synoptic ascent through the warm sector. Also agree that low-level lapse rates could be a tad steeper.
  2. The region of best instability that day was much further south, and predominantly south of the crazy hodographs in central and northern LA, so i don't think the comparison is entirely fair. Somewhat better overlap between great low-level profiles and instability projected for tomorrow tomorrow.
  3. Also good to remember that while 3 km models are commonly referred to as "convection resolving" or "convection allowing," they do not have sufficient resolution to properly portray many attributes of convection. For instance, typical supercell updrafts are on the order of 8-12 km wide. A 3 km model will only have a few grid points across the extent of an updraft. The result of this insufficient resolution is that 3-4 km models tend to produce updrafts and storms that are unrealistically large, and may "unfairly" show more connection/congealment between cells during events like this. Given the magnitude of the deep-layer shear and what we know about supercell dynamics, what has happened in past similar events, and the fact that there isn't strong synoptic scale forcing overriding the warm sector, I would bet money that we see something more like widespread scattered supercells rather than a QLCS with embedded circulations.
  4. I'm not convinced that cell interference will be a problem. Firstly, 4-2-17 had slightly weaker deep-layer and low-level shear. The shear magnitudes in these profiles are more akin to 4-27-11. Remember that day didn't have much of a CAPE either, but cells stayed discrete. Stronger deep-layer shear and substantial boundary-perpendicular deep-layer shear should keep things discrete, IMO.
  5. Yeah, I just checked and they have only done it twice. So you're right, it's probably unlikely. For some reason I thought both 4-27-11 and 5-24-11 were day-2 HIGH, but not the case.
  6. It has been a while, but it does happen. Either way, if the current model projections pan out, there WILL be a day 1 HIGH. EDIT: I just checked and it has only happened twice, on 7-Apr 2006 and 14-Apr 2012, so it's probabilistically unlikely.
  7. It is certainly possible, given the general agreement between models on the environmental parameters and discrete convective mode. I would probably go high risk if I were in the forecast seat... Probably the best looking day 1 setup I've seen since 2012.
  8. Yeah... so Brett Adair chased this thing with a drone... Never seen someone do that before. https://www.youtube.com/watch?v=COuETqZz-rg
  9. 140 kt / 925 hPa cat 5 in the 900 MDT update. 000 WTPZ44 KNHC 221447 TCDEP4 Hurricane Willa Discussion Number 10 NWS National Hurricane Center Miami FL EP242018 900 AM MDT Mon Oct 22 2018 Willa is an extremely impressive hurricane in infrared and visible satellite imagery this morning. The small, but very distinct, eye is embedded within a symmetric central dense overcast with cloud tops of -70 to -80 degrees Celsius. A very recent SSMIS microwave overpass is the first to indicate that an outer eyewall has formed, suggesting that an eyewall replacement cycle has started. The latest objective T-numbers from UW-CIMSS are T7.0/140 kt, and subjective Dvorak intensity estimates from TAFB and SAB are 140 kt and 127 kt, respectively. Based on these data the initial intensity has been increased to 140 kt. An Air Force Reserve Hurricane Hunter aircraft is currently en route to Wilma and should provide a better assessment of the storm's intensity by early this afternoon. Willa is moving northward 6 kt. The hurricane is forecast to continue to move northward today around the western flank of a deep-layer ridge that is located over the Gulf of Mexico. A short wave trough that is seen in water vapor imagery near 130W longitude is forecast to deepen as it moves eastward toward Baja California. This should cause Willa to turn north-northeastward tonight, then accelerate northeastward on Tuesday, bringing the center of the hurricane onshore along the west-central coast of Mexico Tuesday afternoon or evening. As mentioned in the previous advisory, the track guidance is good agreement on the overall scenario but there are still some notable differences in the predicted forward speed of the hurricane. The NHC track forecast leans toward the faster solutions of the GFS and GFS ensemble mean, which have been handling Willa's track the best so far. The environment of low wind shear and water temperatures of 28 to 29.5 degrees Celsius suggest some additional strengthening is possible but with the evidence that an eyewall replacement has begun, some fluctuations intensity are possible during the next 12 to 24 hours. After that time, increasing southwesterly shear is forecast to induce weakening, but Willa is likely to remain an extremely dangerous major hurricane when it makes landfall along the west-central coast of Mexico. After landfall, shear and the mountainous terrain of Mexico will cause rapid weakening and dissipation of the cyclone. Key Messages: 1. A life-threatening storm surge is expected Tuesday along the coasts of the Isla Marias, and west-central and southwestern Mexico near the path of Willa. Residents should rush preparations to completion to protect life and property and follow any advice given by local officials. 2. Everyone in Isla Marias, and within the hurricane warning area along coast of west-central Mexico should prepare for life- threatening major hurricane winds associated with the core of Michael. Hurricane force winds will also extend inland across the mountainous areas of west-central Mexico as Willa moves inland. 3. Heavy rainfall from Willa is likely to produce life-threatening flash flooding and landslides over much of southwestern and west-central Mexico. FORECAST POSITIONS AND MAX WINDS INIT 22/1500Z 19.1N 107.2W 140 KT 160 MPH 12H 23/0000Z 20.1N 107.2W 140 KT 160 MPH 24H 23/1200Z 21.4N 106.9W 135 KT 155 MPH 36H 24/0000Z 23.1N 105.6W 90 KT 105 MPH...INLAND 48H 24/1200Z 25.4N 102.5W 30 KT 35 MPH...INLAND 72H 25/1200Z...DISSIPATED $$ Forecaster Brown
  10. Beautiful this morning. Best looking satellite presentation yet.
  11. In regards to sakau2007's comments about Category 4 winds at/north of I-10, I have to agree with his argument. As I stated in an earlier post, TC winds are dramatically reduced relative to their open water speeds by the increase in surface roughness over land. Based on this well-supported phenomena, I believe it is highly unlikely that category 4 force winds were sustained anywhere beyond the few miles near coast. Boundary-layer parameterizations mimic this in hurricane models. See the attached GIF of one of the HWRF forecasts of 10 m winds. Wind speeds dramatically fall off - well beyond major hurricane status - over land. This is something that happens for most, if not all, TCs that make landfall. This is different than the asshat in the banter forum who keeps arguing that the intensity was only Cat 2 at landfall. This was probably as much a cat-4 open-water storm as Charlie or Harvey was. Edit: it appears that you have to click to view the animation.
  12. Dude that only looks like strong TS force wind damage. I doubt this thing was even a hurricane at landfall ;-). (I'm obviously making fun of the idiot who thinks this was only Cat 2).
  13. Yeah seriously, this bickering over the landfall intensity needs to stop. There is absolutely insufficient information to make damage comparisons either way to Andrew.
  14. Just for reference, this is what category 4 wind probably look like on video (the Charlie gas station video, particularly at 2:50 onward):
  15. Just a sanity check for everyone here. Official intensity estimates are for open water sustained winds. Once an eyewall has come onshore, the associated increase in surface roughness substantially dampens near-surface winds speeds. This means that a TC analyzed at 155 mph during landfall will probably only deliver winds of this magnitude to a very small section of land that is near coast, and on the right-front quadrant of the storm where the wind has crossed directly from water onto land. Substantially slower winds should be expected elsewhere inland because of the larger surface roughness on land, compared to over open water. This goes for all TCs that make landfall, not just Michael. So with that being said, the 150/140 mph assessments when the storm was well inland may have been inappropriate. These speeds probably reflect the intensity the storm would have had if it were open water - not the actual near-surface wind speeds on land. This does mean that comparisons between two TCs at landfall are apples-to-apples. For instance, winds during Andrew and other very intense storms were probably far slower than their official landfall intensities over most regions beyond a mile or two inland on the right-front quadrant of the storms.
  16. Not that they really matter when there is a recon in the storm, but the ADT numbers are pretty insane. Final T# Adj T# Raw T# 7.2 7.4 7.4
  17. Not surprising given that there is still ~ 20 kt of analyzed shear:
  18. Raw T values up to 7.0! http://tropic.ssec.wisc.edu/real-time/adt/odt14L.html
  19. Looks like 15-20 kt. Look at the top plot, which shows the 200-850 hPa wind difference averaged an area centered on the vortex. But agreed, I think poorly forecasted shear was the culprit today, which inhibited further intensification.
  20. I'd say it was pretty well analyzed: For some reason though, it wasn't mentioned at all in the NHC forecast.
  21. CDO is starting to look a lot more symmetric. Looks like the brief uptick in shear this AM is abating (per the CIRA product). Edit: that's odd, it seems to have embedded an older version of the shear product than what is currently displayed on the website. There has been a downtick in the 200-850 hPa shear over the past 6 hours. The latest microwave pass shows improvement in the inner core structure as well:
  22. I suspect there might have been a slight uptick in southerly or southeasterly shear over the past 12 hours. There was a bit of an increase (to roughly 15 kt) in shear in the CIRA area averaged product: Also not the cloud tops to the southeast of the system that are being blown toward the core, rather than parallel to or away from the core, and outflow is a bit restricted on the southern and southeaster quadrant.
  23. This is an educated hypothesis, but I'd say a smaller eye implies that the pressure difference between the eye and surroundings happens over a shorter distance, the pressure gradient force is stronger, and the winds are also probably stronger. This logic seems to be supported by the fact that the TCs with the fastest recorded winds had pinhole eyes. It does seem like a lot of TCs end up with pinhole eyes after their initial RI (i.e. wilma, patricia, rita), but not all (Katrina had a huge eye after RI, and Irma peaked with a larger eye). So to answer your question, a smaller eye might mean things will crank up faster. Though, storms might also have small eyes after RI because of the RI process (i.e. the RI was not necessarily caused by the small eye). Not really sure.
  24. This is definitely not a "pinhole" eye. It's pretty clear that most of the eye is obstructed by anvil associated with hot towers in the eyewall, and you're seeing the little sliver that is exposed. Eyewall is still partially open. It's going to take another 12-24 hours before the eyewall becomes steady, and then we should start taking about eye size.