WxWatcher007

We’re still paying attention. Will probably throw up a thread with the 2pm outlook unless someone else wants to start it.

Hurricane Kirk Discussion Number 19 NWS National Hurricane Center Miami FL AL122024 1100 PM AST Thu Oct 03 2024 Kirk continues to prosper. The earlier eyewall replacement cycle appears to have completed, and Kirk is back on a strengthening trend. Satellite images indicate that Kirk has a circular and clear 15 n mi eye surrounded by a solid ring of intense deep convection. The latest satellite intensity estimates range from 115 to 135 kt, and based on that data, the initial wind speed is increased to 125 kt. The hurricane is moving northwestward at 9 kt, and this general motion should continue through Friday as Kirk continues to move along the southwestern periphery of a high pressure ridge over the central and eastern subtropical Atlantic. A turn to the north is expected on Saturday when Kirk reaches the western periphery of the ridge and as a shortwave trough approaches the system. This trough and a reinforcing one should cause the hurricane to accelerate northeastward on Sunday and early next week. The models are in fairly good agreement on this overall scenario, and the NHC track forecast has been nudged westward to be in better agreement with the latest model runs. Kirk could strengthen a little more during the next 12 hours or so, but increasing vertical wind shear and intrusions of dry air should cause a steady weakening trend to begin shortly after that. Kirk will likely complete extratropical transition when it moves over cool waters sometime between day 4 and day 5, but it is expected to remain a powerful system throughout the forecast period. The NHC track forecast is in best agreement with the HCCA and IVCN consensus models. Even though Kirk is expected to stay over the open Atlantic, its strong intensity and increasing size will cause large ocean swells to propagate far away from the hurricane. These swells will likely increase the risk of dangerous surf and rip currents across the Leeward Islands beginning Friday, Bermuda and the Greater Antilles by Saturday, and much of the U.S. East Coast, Atlantic Canada, and the Bahamas by Sunday. For more information on this hazard, see products issued by your local weather office. FORECAST POSITIONS AND MAX WINDS INIT 04/0300Z 21.5N 47.5W 125 KT 145 MPH 12H 04/1200Z 22.5N 48.6W 135 KT 155 MPH 24H 05/0000Z 24.4N 49.7W 130 KT 150 MPH 36H 05/1200Z 26.8N 50.3W 120 KT 140 MPH 48H 06/0000Z 30.0N 49.9W 110 KT 125 MPH 60H 06/1200Z 33.6N 48.3W 100 KT 115 MPH 72H 07/0000Z 37.3N 44.7W 90 KT 105 MPH 96H 08/0000Z 43.5N 33.2W 75 KT 85 MPH 120H 09/0000Z 47.0N 16.8W 60 KT 70 MPH...POST-TROP/EXTRATROP $$ Forecaster Cangialosi

Unfortunately I think the rainfall signal does look higher end irrespective of what kind of low forms.

Yeah—I think we don’t have a thread yet because the signal is still unclear on development and impact, though I think both are trying to come into better focus. I think the genesis potential is a bit higher than the NHC currently has. And while pre-Helene discussion also weighed toward a broader/messier system coming out of the CAG, even at the start there was a recognition that higher end solutions were reasonably on the table. We have a very different outcome for many imo if the nascent center of Helene went 50-100 miles west and over the Yucatán. Sometimes that’s just how it goes, as you know. I’m intrigued that the Euro is more robust than the GFS. 12z maybe gets it to a hurricane. Aside from that it meanders, which means hydro trouble. Probably much more than you asked for, but here’s a good resource. https://severeweather.wmo.int/TCFW/RAIV_Workshop2019/09a_Ensemble-Prediction-Systems_EricBlake.pdf Now if you’re just wondering what the image above is, it’s all of the separate ensemble member projections for that particular time stamp. Some may not even appear because they may not actually have an actual low formed. Seeing a lot more EPS members show a low tells me that there’s a stronger signal for something to be there than on the GEFS. Looking closer however, you see that there are very few members at least at that time stamp that are below 1000mb, telling me that there’s a signal for something, but that something appears weak. This can be visualized a number of ways. If you’re looking for just the mean, that’s not the image I’d use. You would want to use something like this. An individual ensemble run can be wrong and often is when it comes to pinning down a specific forecast, but it does a good job of giving you the envelope of reasonable possibilities. Sometimes the op run telegraphs a shift in ensembles. For example, I’d expect the 12z EPS to be a bit more robust given how favorable the environment looked on the 12z Euro. Hope this helps.

Now THAT’S good stuff. Wow.

Hurricane Kirk Discussion Number 15 NWS National Hurricane Center Miami FL AL122024 1100 PM AST Wed Oct 02 2024 Kirk has undergone an impressive period of rapid intensification over the past 24 h. Recent satellite imagery showed a ragged eye, with multiple deep bursts of convection rotating in the eyewall. Overshooting tops are obscuring the eye now, but it would not be surprising if it clears again soon. As noted in the special advisory, the subjective Dvorak satellite estimates have climbed but were constrained. The initial intensity is nudged up to 110 kt for this advisory, closest to the T6.0 data-T number from SAB. The hurricane has strengthened 55 kt since 0300 UTC last night, which means Kirk lands at a Category 3 on the Saffir-Simpson scale. The hurricane continues to be steered by the subtropical ridge to the northwest at an estimated 310/9 kt. Little has changed in the track forecast reasoning. On Friday night or Saturday, Kirk is expected to gradually turn north-northwestward to northward and accelerate in the flow between a deep-layer trough and the weakening subtropical ridge. Later in the weekend, Kirk is expected to continue accelerating north-northeastward to northeastward. Few changes have been made to the latest official track forecast, which lie close to various consensus aids. Given Kirk's recent rapid intensification, conditions appear conducive for further strengthening during the next day or so. The short-term forecast is therefore above all of the guidance now, peaking at 130 kt in 24 h. By Friday, the vertical wind shear is expected to increase and gradually weaken Kirk through the remainder of the forecast period. As the hurricane moves more poleward, Kirk's tropical-storm-force winds are predicted to grow and send large swell westward to the northern Leeward Islands and the Bahamas over the weekend. FORECAST POSITIONS AND MAX WINDS INIT 03/0300Z 19.5N 44.5W 110 KT 125 MPH 12H 03/1200Z 20.4N 45.6W 125 KT 145 MPH 24H 04/0000Z 21.7N 47.1W 130 KT 150 MPH 36H 04/1200Z 23.1N 48.7W 125 KT 145 MPH 48H 05/0000Z 24.8N 49.9W 120 KT 140 MPH 60H 05/1200Z 27.0N 50.5W 110 KT 125 MPH 72H 06/0000Z 30.0N 50.1W 105 KT 120 MPH 96H 07/0000Z 36.8N 45.5W 90 KT 105 MPH 120H 08/0000Z 43.9N 35.2W 80 KT 90 MPH $$ Forecaster Bucci

Tropical Storm Leslie Discussion Number 3 NWS National Hurricane Center Miami FL AL132024 1100 PM AST Wed Oct 02 2024 Geostationary satellite and microwave images indicate that the system has become better organized with convective bands wrapping about two-thirds of the way around the center. A partial ASCAT pass from around 2230 UTC showed winds very close to tropical storm force northeast of the center. Since the system has continued to become organized since the ASCAT pass, the initial intensity is increased to 35 kt, making the cyclone Tropical Storm Leslie. This intensity estimate is also in agreement with a 2.5 Dvorak classification from TAFB. Leslie is moving slowly to the west at about 5 kt. A continued slow westward to west-northwestward motion is expected during the next 2 to 3 days as Leslie remains steered by a weak mid-level ridge to its north. Beyond that time, a slightly faster motion to the northwest is predicted as the storm moves on the western periphery of the ridge and approaches a broad trough over the central Atlantic. The models are in fair agreement overall, and the NHC track forecast lies near the middle of the guidance envelope. Leslie is currently in a moderate wind shear environment due to the outflow from major Hurricane Kirk to its northwest. However, the shear is expected to lessen while Leslie remains over warm waters and in a moist environment. These condition should support steady strengthening during the next few days, and the official intensity forecast is a little higher than the previous one. Beyond a few days, Leslie is predicted to move over Kirk's prior track and associated cool wake, and into a slightly drier air mass. These conditions could cause the intensity to level off. The new forecast is in best agreement with the latest HCCA guidance. FORECAST POSITIONS AND MAX WINDS INIT 03/0300Z 10.4N 30.1W 35 KT 40 MPH 12H 03/1200Z 10.2N 30.8W 40 KT 45 MPH 24H 04/0000Z 10.2N 31.9W 50 KT 60 MPH 36H 04/1200Z 10.4N 33.1W 60 KT 70 MPH 48H 05/0000Z 10.8N 34.5W 70 KT 80 MPH 60H 05/1200Z 11.4N 35.8W 80 KT 90 MPH 72H 06/0000Z 12.2N 37.0W 85 KT 100 MPH 96H 07/0000Z 14.3N 39.6W 85 KT 100 MPH 120H 08/0000Z 17.0N 42.9W 85 KT 100 MPH $$ Forecaster Bucci/Cangialosi

That one may have a chance at major status too if it can stay south enough of the behemoth Kirk is likely to become.

Kirk & Leslie

Note how the EPS has some stronger members in the Gulf too.

Doubt it matters in the whole scheme of things but it’s interesting.

It still looks like a messy signal to me. Surprisingly the GEFS is less robust even though the op model is aggressive from time to time. The Euro/EPS has seemed fairly consistent to me. I still think something will develop, but it looks much more broad. The jury is still out on what if anything develops.

000 WTNT43 KNHC 021445 TCDAT3 Tropical Depression Thirteen Discussion Number 1 NWS National Hurricane Center Miami FL AL132024 200 PM CVT Wed Oct 02 2024 The system we have been monitoring several hundred miles to the southwest of the southernmost Cabo Verde Islands has become gradually better organized this morning with some curved bands organizing to the west of the estimated center. Visible satellite images show that at least a broad closed circulation has developed. Based on the latest subjective Dvorak fixes of T2.5/35-kt from TAFB and T1.5/25-kt from SAB, advisories are being initiated on Tropical Depression Thirteen, with an initial intensity in between these estimates at 30 kt. The depressions initial motion appears to be slowly due west, at 270/6 kt. Over the next day or two this motion should continue, though some of the track guidance actually shows a south of due west motion, partially related to the steering flow and also the possibility that the center might try to reform underneath deep convective bursts in the southern semicircle. After 48 h, the guidance shows TD13 turning west-northwestward and then northwestward by the end of the forecast as mid-level ridging becomes more eroded on its northwestern side while a large long-wave trough becomes established over the Northwest Atlantic. The initial NHC track forecast has opted to favor a track close to the consensus aid TVCN. Interestingly, both the GFS and ECMWF are on the east side of the guidance, while HCCA is on the western side by the end of the forecast period. Intensity wise, initial strengthening could be on the slower end, as the system has to deal with some northwesterly shear related of the outflow from the much larger Hurricane Kirk impinging upon the system. However, the guidance insists this shear will soon decrease, especially after 24-36 h where the upper-level flow seems to split off into a cutoff low to the southwest, and a upper-level trough that shifts east of the depression, leaving the depression in a more favorable upper-level diffluent pattern. After TD13's inner core become better defined, the rate of intensification could increase after 36 h, and the latest NHC intensity forecast forecasts the depression to become a hurricane in 3 days. Additional intensification is forecast after that point as long as the cyclone tracks far enough away from the cold ocean wake left behind by Kirk. This forecast is roughly in the mean of the intensity guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 02/1500Z 10.6N 29.1W 30 KT 35 MPH 12H 03/0000Z 10.5N 29.8W 35 KT 40 MPH 24H 03/1200Z 10.2N 30.8W 40 KT 45 MPH 36H 04/0000Z 10.2N 31.9W 45 KT 50 MPH 48H 04/1200Z 10.4N 33.3W 55 KT 65 MPH 60H 05/0000Z 11.0N 34.6W 60 KT 70 MPH 72H 05/1200Z 11.7N 35.8W 65 KT 75 MPH 96H 06/1200Z 13.5N 38.1W 75 KT 85 MPH 120H 07/1200Z 16.5N 41.0W 80 KT 90 MPH $$ Forecaster Papin

Peak Season Forecast (Aug 20-Oct 20) Named Storms: 15 (6) Hurricanes: 10 (4) Major Hurricanes: 5 (1) Francine (H), Gordon, Helene (MH), Isaac (H), Joyce, Kirk (H)

Euro has explosive intensification over the next few days. Everything continues to point to another MH going on the board soon.

Just reposting so folks can see. Paging @CoastalWx

I smiled when I saw the new avatar this morning.

It really does look like a delayed peak, and maybe one that’s higher end with CV season heating up? Although weaker, the genesis signal in the Gulf still looks pretty robust. Definitely worth watching. I’m still way off my peak season forecast but some of each category will be added to the board soon. Peak Season Forecast (Aug 20-Oct 20) Named Storms: 15 (6) Hurricanes: 10 (3) Major Hurricanes: 5 (1) Francine (H), Gordon, Helene (MH), Isaac (H), Joyce, Kirk

I think two of the other challenges are that 1) we’re seeing events that are outside of our frame of reference. How do you adequately communicate the worst case scenario when a region has literally seen anything close into it? Worst on record doesn’t cut it when the impacts are almost biblical or an order of magnitude worse than the worst. 2) I think media/NHC really need to reconsider how TCs and impacts get categorized. I think the NHC has done tremendous work over the years talking more about hydro impacts, but categorizing TCs based strictly on winds seems increasingly inadequate given what we’re seeing even with non-hurricanes. Much of the media is still too focused on wind and coastal impacts imo. Not all to be sure, but many.

What a monster Camille was. Completed an ERC just offshore and quickly reintensified to 175mph/900mb. Just unreal. All of our 5’s rapidly intensified within 3 days of landfall. It’s about timing and “luck” as much as anything else.