Moderately Unstable

Anyone still complaining about a low ACE score now?

Yes I like cod as well. I also use trackthetropics to get my bigger picture data since that includes ohc, current wind shear, more plots and patterns, ssts etc. I also use the ewall bc Penn State alum *hand raise*, but more for mid latitude storms. I miss the real wall in the weather center! For non penn staters, there's a giant weather lounge on the 5th floor of the meteo building where all the students go to study and such. There's a wall of computer monitors, ~40, rotating through all the things you see on the ewall.

Per the nhc's official track, substantial. But it should be noted to take the current long term solutions such as the fujiwara effect and low splitting phenomena with a grain of salt. They are likely just model artifacts. I hope they are model artifacts! Let's not get ahead of ourselves. The nhc issues a 5 day and not a 10 day forecast for a reason. It's a good reason.

Nah. I mean, if I were them I'd have played it out more consistently just to keep congruence with the earlier forecasts (don't want to change things too quickly). But they probably had some data that made them want to take a tiny step back. They only dropped the peak winds by 5mph from 115 to 110 but since that's the cutoff it was the difference btwn major and not.

See my page 1 or 2 analysis I wrote up yesterday am that answered this question. Short answer is yes. The ohc right now supports a peak storm strength of 900-910mb, which is a cat 5. Statistically it's hard to forecast a cat 5 due to potential ercs.

Yes they did. 11pm discussion explicitly stated they expected a major hurricane. 5am discussion said probably would be a major hurricane. 11pm discussion showed a major inland below peak strength. 5am showed a non major right before land at peak strength. The discussions themselves bear that out. It's splitting hairs but my comment was correct. I don't blame them for it. Reading this forum sometimes is like being on a rollercoaster. Cat 5, cat 1, cat 5, tropical storm, it sucks, its great, where's the plane, there's the plane!! Twitter is on fire as well about this storm. I think they saw the data that overnight the storm wasn't intensifying quite as fast as the fanatics were all screaming it would so they dropped back. Then, you had that classic wobble motion with the storm and the eye popped out and, poof there's your high end 4.

Also, folks, you can view the current feed by selecting the western Atlantic as mayor regional view either on tidbits or on the goes sat site. Not as zoomed in but you can zoom in yourself.

You're right, but the storm has 24+ hours to go. They have 4 flights scheduled not all with the same division. There is a 0% chance of not having another plane in before landfall. I know what you mean in terms of hoping they don't have more tech issues--I am in the same camp. More just saying, it would be absolutely shocking if they didn't actually send another one in. Nhc would ask noaa hunters and air force to go at same time so that if one had an issue we still got the data.

It appears that the issue is with the feed itself, goes 16 meso 1. Hence not an issue with where you get the feed, it is the feed. On a creepy note it appears to be centered on my location now. HIIIIIIIIIIIIIIII. Yes, another plane will be arriving soon. They post the plan of day you know. Search Google. Nhc plan of the day. They say when they're launching the planes. What a beautiful storm structure. Stuff like this can hold my attention for hours.

I agree on appearing a bit like a WPAC storm. When I yesterday made the remark about the western band I did so because of Goni and Haiyan, both of which sported such a feature as they strengthened. The structure does sort of remind me more of a super typhoon than your classic Atlantic hurricane which is interesting. Today's structure is solid and very impressive, the 140mph peak the nhc just released seems likely to verify. I'm glad it may landfall in a sparsely populated area. I got a bit of a laugh over whomever reduced the peak intensity forecast last night after Stewart's and then the probable "oh crap" moment this morning.

The shelf is a lie! Jk. But in all seriousness that's an artifact you're seeing there because of the shallow waters. Ocean heat content is lower in shallow water, because, well, yeah. Or more scientifically...there is less water to heat. The actual water temps are homogenous up to the coastline. My hwrf comment was wrt amped's comment. I really appreciated the 11pm advisory, excellent discussion and very informative. Thank you Stacy Stewart! Edit: Wrt timing, yeah, it's slowing down, but the models said it would do that and most still take it inland in 2 days. If the 00z gfs, euro, hmon, hwrf etc all stall the storm I'll pay attention. The estimate for high end cat 3 accounts for that. When this storm formed, I flashed to Wilma, and I keep flashing to it now. Not because of location and track but due to time of year, the environmental conditions, and the propensity for a storm in this environment to just be a bomb. Wilma strengthened from a cat 1 to cat 5 in 24 hours and shattered all the records, in the 2005 record breaking season with which we are now tied. I just get so many similarities with this intense convection forming a pinwheel eye that goes nuts. I think Stacy was right in saying the question isn't will it ri, or will it be a major. It's "how much". The upper bar right now is *very* high. The lower bar is a cat 3, and I think statistically cat 3 is most likely based on time over water. Yeah, I agree, more time over water we flirt with a cat 4 or 5 without an erc. As they said, excellent dual outflow channels. That's also usually a good sign.

Sometimes I wonder if the nhc reads this forum based on their discussions.

As much as I like weenie solutions, I think the HWRF is overdone. The wrf is a friend of the nam, which is often wet n' wild. Even if you go with rapid intensification you wouldn't really think sub 980, right now. 980-985 on the nose and starting to drop at a 2mb rate, is my educated guess. Strengthening usually works on a curve. In other words, 0.5mb per hour becomes 1mb per hour becomes 1.5 mb per hour becomes 2mb/hr as the storm deepens. I still think it's trending towards a major hurricane, and yeah, cat 4 is possible, but I would say cat 3 is more likely just from a numbers standpoint. The 00z intensity guidance which just came out has trended stronger but is clustered around a cat 3 solution. Cat 4 becomes more plausible with more time over water, e.g. system stalls out more. Edit: by friend, I mean, they are versions of the same model.

70/989mb. Leroy has a wide array of fellow ghosts to lean on for support in referencing past significant hurricanes. He offers his medium services every third Wednesday, for a fee. 12x mean is impressive but not as headline making as it sounds. You can make anything sound impressive by comparing it to a low probability event. For example, if an event had a 0.1% chance of occurring, 10x the mean is 1%. Not trivialializing the statistic but not foaming over it. I was more impressed by the nhc mentioning a SEVENTY ONE percent chance of a 30 knot increase in winds according to DTOPS in the next 24 hours. Plus the 51-55% ships guidance. I care more about raw percentages than percent of means, because that is what the probability it actually happens is. Translation: the consensus expects rapid intensification and it would be unusual if that didn't happen at this point. Hence no one should be, or act, surprised by it, and should not adjust their intensity forecast based on minute by minute analyses. I expect we will have a major hurricane tomorrow. The environment favors it (see my morning analysis). It is already rapidly intensifying, it has been since the early afternoon. How can you tell? Pressures are already dropping fast NOW, not in the future. 1000-->992-->989 (1mb/hr). Accelerating as eyewall closes soon, yes, probably 2-2.5-3mb/hr on average w/some fluctuations. But-- already intensifying. You can also tell through the storms structure. Vigorous convection, very well defined, rapidly rotating curved bands around the tight cdo that are progressively rotating faster (implies strong angular velocity and tightening circulation...think figure skater pulling their arms in). The next reconnaissance flight is scheduled for 530Z/02, e.g. 1230am EST, by the Air Force hhunter division. Flight 3 is at 1130Z/02, e.g. 630am, also air force, and nhc expects to fly someone in every 6 hours thereafter. Aircraft, while useful, aren't required to be in the storm 100% of the time (as much as weather geeks enjoy discussing it). They fly a bit more often into storms headed for the us coastline. Edit: the Air Force has launched an aircraft now, at 130Z, 830PM EST. This flight was not on the plan of the day. Various grammatical and clarity edits.

Edit: 4pm discussion: 000 WTNT44 KNHC 012053 TCDAT4 Tropical Storm Eta Discussion Number 5 NWS National Hurricane Center Miami FL AL292020 400 PM EST Sun Nov 01 2020 Eta has continued to quickly become better organized today with an increase in banding and the development of a central dense overcast feature. A NOAA Hurricane Hunter aircraft that has provided a couple of center fixes this afternoon has found a strengthening tropical storm. The aircraft has reported a minimum pressure of 992 mb and a 30 n-mi-wide eye that is open to the southwest. A blend of the SFMR and flight-level wind data support an initial wind speed of 55 kt for this advisory. Given the much improved inner-core structure as reported by the reconnaissance aircraft and the favorable environmental conditions of low vertical wind shear and high ocean heat content, additional strengthening is likely. The intensity guidance is much higher this cycle, and the various rapid intensification models show a much more significant chance of rapid strengthening over the next 24 to 36 hours. The DTOPS model indicates a 71 percent chance of a 30-kt increase in wind speed over the next 24 hours, while the SHIPS Rapid Intensification Index shows a 53 percent chance of a 45-kt increase over the next 36 hours. Based on the higher initial intensity and the more bullish guidance, the NHC intensity forecast has been increased and essentially calls for rapid strengthening until Eta reaches the coast of Central America. Once inland, Eta should quickly weaken over the mountainous terrain of Nicaragua and Honduras. Eta is still moving steadily westward or 270 degrees at about 14 kt. A westward motion at a somewhat slower forward speed is expected tonight. On Monday, Eta is forecast to turn southwestward at a slower forward speed when a mid-level ridge builds to the north and northwest of the cyclone. Eta is forecast to move inland over northeastern Nicaragua within the Hurricane Warning area Monday night or early Tuesday. The dynamical models are in relatively good agreement through about 72 hours, expect for the HWRF which shows a more northern track and keeps Eta offshore for much of the period. This solution is considered an outlier at this time, and the NHC track is in good agreement with the various global models and the HFIP corrected consensus model. Some model solutions still suggest Eta or its remnants will re-emerge over the northwestern Caribbean Sea at or beyond day 5. The new NHC 5-day position is still inland near the Gulf of Honduras close to the various consensus aids, but large uncertainty exists in the forecast at that time range due to the large spread in the track guidance. Key Messages: 1. Eta is forecast to strengthen into a hurricane tonight, and additional strengthening is forecast before it reaches the northeastern coast of Nicaragua Monday night or early Tuesday, where a Hurricane Warning is in effect. A Tropical Storm Warning is in effect for a portion of the northeastern coast of Honduras. 2. Through Friday afternoon, heavy rainfall from Eta will lead to significant, life-threatening flash flooding and river flooding across portions of Central America, along with landslides in areas of higher terrain. Flash and river flooding is also possible across Jamaica, Southern Haiti, and the Cayman Islands. 3. A life-threatening storm surge, along with damaging waves, is expected along portions of the northeastern coast of Nicaragua near and to the north of where the center makes landfall. Water levels could reach as high as 10 to 15 feet above normal tide levels in some parts of the hurricane warning area. Preparations to protect life and property should be rushed to completion. FORECAST POSITIONS AND MAX WINDS INIT 01/2100Z 14.9N 78.9W 55 KT 65 MPH 12H 02/0600Z 15.0N 80.5W 65 KT 75 MPH 24H 02/1800Z 14.7N 82.1W 80 KT 90 MPH 36H 03/0600Z 14.2N 83.1W 95 KT 110 MPH 48H 03/1800Z 14.0N 83.8W 75 KT 85 MPH...INLAND 60H 04/0600Z 14.0N 84.7W 50 KT 60 MPH...INLAND 72H 04/1800Z 14.1N 85.7W 35 KT 40 MPH...INLAND 96H 05/1800Z 14.7N 88.0W 25 KT 30 MPH...INLAND 120H 06/1800Z 15.5N 88.5W 25 KT 30 MPH...INLAND $$ Forecaster Brown I agree with them on HWRF as an outlier on track. The vast majority of the guidance landfalls the storm. What is NOT an outlier (for the folks reading this who are more casual readers), is the trend in the medium term for the global and hurricane models to curve the storm back over the Caribbean at the 5-6 day range. Because models are notoriously poor at long range tropical forecast tracks and intensities, I don't take the various solutions too seriously as they vary run to run (blizzard-cane in New England, baroclinic-induced strengthening cuban-florida-gulf coast storm, out to sea in the middle of the Atlantic). The consistent message however seems to be that should the system maintain enough organization--either through minimal time on land, or just staying a weak depression and re emerging, it has a high chance of regaining some strength and posing a threat to some yet undetermined part of the US. This is just a signal, but it's persistent enough to be cognizant of the potential as we enter the second week of November. Edited to remove incorrect statement.

Second pass VDM: 643 URNT12 KWBC 012029 VORTEX DATA MESSAGE AL292020 A. 01/19:45:58Z B. 14.79 deg N 078.67 deg W C. 850 MB 1372 m D. 992 mb E. 030 deg 06 kt F. OPEN SW G. C30 H. 39 kt I. 134 deg 9 nm 19:43:45Z J. 217 deg 34 kt K. 132 deg 15 nm 19:42:09Z L. 58 kt M. 300 deg 12 nm 19:49:06Z N. 068 deg 55 kt O. 321 deg 54 nm 20:00:58Z P. 19 C / 1537 m Q. 24 C / 1537 m R. 18 C / NA S. 12345 / 8 T. 0.01 / 2 nm U. NOAA2 0129A ETA OB 14 MAX FL WIND 55 KT 321 / 54 NM 20:00:58Z Revenge of the greeks!

VDM: 725 URNT12 KWBC 011903 VORTEX DATA MESSAGE AL292020 A. 01/18:32:04Z B. 14.85 deg N 078.46 deg W C. 850 MB 1376 m D. 993 mb E. 035 deg 08 kt F. OPEN W TO SW G. C30 H. 48 kt I. 072 deg 72 nm 18:11:22Z J. 120 deg 42 kt K. 071 deg 76 nm 18:10:18Z L. 34 kt M. 212 deg 13 nm 18:38:15Z N. 336 deg 34 kt O. 218 deg 26 nm 18:41:30Z P. 18 C / 1538 m Q. 23 C / 1536 m R. 18 C / NA S. 1235 / 8 T. 0.01 / 1 nm U. NOAA2 0129A ETA OB 07 MAX FL WIND 42 KT 071 / 76 NM 18:10:18Z

It's an active area of research actually, but they do a decent job. The main issue has to do with the lapse rates. There is a low-bias in extrapolated mslps because the warm core of tropical cyclones has a lower lapse rate than the average 6.5C/km. Warm core cyclone lapse rates vary from 1-4 C/km due to latent heat release in the eye. To calculate a measured lapse rate however you need a dropsonde that gives you the surface temperature. You can then use that data, compare it with the flight level temperature and divide by the geopotential altitude. However...that itself requires a dropsonde. P=rho*rT. So, to get the better value you need the thing that you're trying to avoid having to use. In the near future a better empirical formula may be able to be substituted using an average lapse rate that applies across cyclones in a particular basin. In general though, this is more of an esoteric concern for large-scale data input than it is important for central pressures. When the hurricane hunters fly to the eye of a storm, they drop a sonde. It would be a bit pointless to fly hundreds of miles, put an aircraft and crew through the eyewall, just to, ya know, estimate pressures from the air. As such, you can expect an objective measurement from recon aircraft, and don't need to rely on subjective calculations. They're helpful, and can be useful in interpolating the large scale pressure field in areas where you're NOT dropping a sonde, but at least in the eye, and usually several other places, you're performing the gold standard: measuring it directly.

Eta is strengthening. While I tend to be on the more bullish side when it comes to intensity forecasts, the following factors are useful to know: -Current SSTs under Eta 29C. -Current shear: 10-15 knots. Shear forecast: 5-15 knots. Shear tendency: -5kts/24hrs. -Current regional SST anomaly: +0.5-1C. -Current OHC: 100-125 kJ/cm^2. -Current maximum potential TS intensity based on OHC: Category 5/900-910mb. -Upper level anticyclone ESE of CoC. -MJO: Phase 5. -Current steering winds take the storm over land in the 48hr time frame. // Objective: -Current microwave data suggests a core is forming. // Analysis (Subjective): -OHC is decent but not off the charts. -Wind shear is low. -Visible & IR sat imagery indicate the system is quickly organizing. It will run out of ocean in slightly less than 2 days. The probability of attaining maximal potential intensity is reduced by this factor. Achieving major status seems plausible but not certain. If hurricane hunters find a massive jump in winds to 65-70 a major is more likely. I base this educated guess on the satellite presentation, intuition, and past storms, more than I do the intensity guidance. -SHIPs is bullish on potential for RI; SHIPs is often bullish so, I find it notable, but don't want to cherrypick data. -It appears to currently be strengthening rapidly, and I expect hurricane hunters to report that. The band to the west in particular was notable to me in being a hallmark of past strong hurricanes and strengthening systems. -It will be strengthening as it hits the coast regardless of intensity, thereby increasing wind hazards. Mountainous terrain will enhance gusts as well. Less prosperous nations such as Honduras and Nicaragua face an outsized risk from landfalling hurricanes due to on average less robust infrastructure and building materials.

You have a *strong* track record this season in terms of forecasting, so I don't think you should discount your input as nonsense. We are ALL looking at the same data which doesn't all agree and trying to figure out what to believe and what factors support our thinking. You have a high likelihood of being right on models changing and missing something by shear nature of the way hurricanes and models work. Short time frame models tend to have a good handle on what will happen. Longer term they aren't. That's always how it works. This is where analogs, the large scale pattern, model performance in given large scale patterns (too progressive too slow over enthusiastic) come into play. My memory is that with a few exceptions with very clear data, the nhc doesn't project a major hurricane often when any storm first forms. If conditions are favorable, a hurricane is forecast in the 5 day range. There are exceptions. Hence the fact they don't numerically predict a strong hurricane in their forecast doesn't mean that won't happen, and they state as much in their discussion. In summary--you aren't being paid for your opinions on here so no need to bash them. It's a weather forum. Right or wrong you learn something, and you aren't auditioning for a job. I've been here for 3 months and I feel more confident in posting now for that reason; if I'm saying something nonsensical someone will say something or gloss past my post entirely and I learn from that. From a statistical perspective, this part of the Caribbean is the locus for intensifying tropical systems at this time of year. Take that fwiw.

My thoughts are likely that they needed some type of objective measurement (e.g. ASCAT) which missed the system several times in a row. Without objective data, they can't truly determine if (a) the circulation was elongated or tightly closed, (b) the intensity of the storm. Since it's been clear for perhaps 48 hours now that this storm would eventually form a surface circulation and the time frame in which the system really poses a land and life threat is a few days out, they probably felt it prudent to wait for objective data to both better make a forecast, improve model predictability, and provide a better starting intensity. A minor but present issue--lets say they initiated and subjectively went with 30mph winds. But then, objective data came in and showed 3 hours later the storm was at 50mph. Over the following 24 hours, the storm RIs into a 100mph monster. One could then infer the storm was on pace to become a cat 5 monster. If instead the first advisory sampled 50 mph winds (making it a ts), then that rise, while substantial, isn't quite as "wilma-esq". In addition, weak and developing systems are less stable than stronger ones. Some unknown shear or dry air or what have you could weaken the storm or change the position of the surface low by a large distance. It boils down to--what data can objectively prove a closed low? I'd bet money that if ASCAT had provided data this am, they'd have classified it this morning. The sat presentation at this point, in my subjective opinion, is too strong to ignore even in absence of more objective measurements.

The nhc has announced they will initiate advisories on TD 29 at 5pm.

Looking at visible sat, they have to classify this thing soon. They're looking for a closed, low-level, non-elongated circulation... I have a hard time believing a storm could have that current structure on visible and lack such a circulation. Based on the ensembles, it looks like none of the pertubations think it won't head west towards Central America. The medium term has a few possibilities for curving north and northeast and hit Florida via Cuba. The suite of hurricane specific track models is also fairly consistent with an initial westward track. Looking at the upper level progs, it appears the reason for the directional shift is a Mexican surface low coupled with a departing deep trough over the southern US and something I don't have a handle on to the SE of what will likely by then be Eta.Those two things change the steering currents according to the gfs and draw the storm north. The issue with the gfs right now is it's relatively slow to strengthen and organize the storm. Most of the other guidance has it getting stronger more quickly. I think the bulk of the hurricane specific guidance RIs the storm, and then assumes that if so, it should slam into Central America. There's a secondary possibility of a glancing blow to Central America and then a turn north supported by a few ensemble members. What's important is that this storm is organizing quickly, and that is more in line with HMON/HWRF than either the gfs or the other hurricane track models. So, I suspect that the global guidance will shift dramatically when the low consolidates and hence steering based on that can be better defined. At the rate it's going its going to be a hurricane when it gets classified!

Hm. 29 degree SSTs, well developed convection, 10 knots of shear relaxing by Monday morning, dynamical and statistical models bullish and in agreement, favorable MJO. Probably a non-event.

Yes, agree sat presentation is now finally degrading. Like the rest of this storm it has taken its time in doing so. Short range guidance did well on that. Then again, you can always find models in any situation that did well and didn't. Statistical intensity guidance in this case was crap, dynamic was solid. Probably better modeled the baroclinic factors than the statistical. Very interesting storm to watch. The signal the last several days of yet another tropical system in a couple weeks in the Caribbean is just adding insult to injury at this point. Wayyyy too far out to talk track or intensity or what have you but the models have clearly locked onto a potent tropical wave that tries to do something in the second week of November. Very long range but good model agreement on that possibility. I hope we make it to theta. I really want to be able to make horrible jokes that none of my friends understand about the theta in theta.