yoda Posted October 11, 2018 Share Posted October 11, 2018 Hurricane Leslie Discussion Number 61 NWS National Hurricane Center Miami FL AL132018 1100 AM AST Thu Oct 11 2018 Leslie's structure has remained steady since last night. The hurricane has a ragged banding eye surrounded by a somewhat patchy central dense overcast. Recent Dvorak classifications from TAFB and SAB are unchanged, and still support an initial intensity of 70 kt. For days now, it has been clear that Leslie will accelerate east-northeastward on the south side of a mid-latitude trough moving across the North Atlantic. That acceleration is well underway now, and the initial motion estimate is 060/14 kt. It has been unclear, however, when (or if) Leslie could separate from this trough and begin to drift southward over the eastern Atlantic. The model spread has remarkably increased since yesterday, and nearly 1/3 of the members of the most recent GFS and ECMWF ensemble runs no longer forecast Leslie to separate from the trough at all, instead showing the cyclone approaching western Europe as an extratropical low. Even the deterministic model spread has increased, and the two NOAA regional hurricane models, the HWRF and HMON, are nearly 2300 miles apart at day 5. Through 48 h, the official track forecast is very similar to the previous advisory, but it has been adjusted eastward beyond that time, to bring it closer to the most recent deterministic multi-model consensus. Confidence in the track forecast is not high at 72 h and beyond, and it's possible that large changes could still be required to future advisories. Leslie should remain in a generally favorable environment for strengthening during the next 24-36 h, and slight intensification is still expected, though the official intensity forecast is now on the high side of the guidance through this period. By 48 h and onward, Leslie will be moving into a far more stable environment and over cooler waters, so steady weakening is anticipated. If Leslie follows a track similar to the NHC forecast, it will likely become a weak post-tropical low within 96 h. However, if Leslie undergoes extratropical transition, its worth noting that the maximum winds associated with the cyclone would likely be higher than indicated here. FORECAST POSITIONS AND MAX WINDS INIT 11/1500Z 29.1N 38.3W 70 KT 80 MPH 12H 12/0000Z 30.3N 35.5W 75 KT 85 MPH 24H 12/1200Z 31.7N 30.3W 75 KT 85 MPH 36H 13/0000Z 32.8N 24.6W 70 KT 80 MPH 48H 13/1200Z 33.2N 20.0W 60 KT 70 MPH 72H 14/1200Z 31.3N 17.3W 40 KT 45 MPH 96H 15/1200Z 29.1N 19.0W 30 KT 35 MPH...POST-TROPICAL 120H 16/1200Z 27.5N 24.0W 30 KT 35 MPH...POST-TROP/REMNT LOW $$ Forecaster Zelinsky Link to comment Share on other sites More sharing options...
Windspeed Posted October 12, 2018 Share Posted October 12, 2018 Leslie's track guidance has shifted north significantly due to deeper longwave trough interaction. Baroclinic influences by that interaction may also bring hurricane force gusts to Portugal coast as a post-tropical low. 10/12 12z GFS is now suggesting this as well. NHC 11 AM AST: Quote The intensity forecast shows Leslie only slowly weakening as a tropical cyclone during the next 24 hours due to a combination of cool SSTs and increasing shear from the trough. However, simulated satellite imagery and model fields suggest that Leslie will transition to a powerful post-tropical cyclone by 36 hours, likely still at hurricane intensity as shown by the global models. Link to comment Share on other sites More sharing options...
Windspeed Posted October 12, 2018 Share Posted October 12, 2018 This will probably be poor neglected Nadine's only mention here. lol.. Link to comment Share on other sites More sharing options...
Windspeed Posted October 12, 2018 Share Posted October 12, 2018 Thanks to Leslie and Michael, Accumulate Cyclone Energy (ACE) is now 119 for the Atlantic Basin, pushing the 2018 season above climateological mean of 111 considered for an above-normal season. 153 ACE is the mark for a hyperactive season like the one we experienced in 2017. So far 2018 has resulted in 14 storms, 7 hurricanes and 2 major hurricanes. Link to comment Share on other sites More sharing options...
KPITSnow Posted October 12, 2018 Share Posted October 12, 2018 This is the second year on a row we have had storms hold onto tropical characteristics extremely close to Europe. Ophelia last year and now Leslie. Just an observation, but I wonder if we are getting to the point where a fully tropical land falling system in Western Europe is possible? Link to comment Share on other sites More sharing options...
Windspeed Posted October 12, 2018 Share Posted October 12, 2018 ECMWF is now on board for a Portugal landfall as well. That stink jet though. Could be bad timing for landfall and PT transition. Link to comment Share on other sites More sharing options...
Windspeed Posted October 13, 2018 Share Posted October 13, 2018 Leslie is coming in fast and aquiring extratropical characteristics now. Looks like it will complete transition to a post-tropical storm just before landfall. That low-level jet streak on the southern side and sting jet may still force surface winds that pack quite a wallop however. Link to comment Share on other sites More sharing options...
Windspeed Posted October 13, 2018 Share Posted October 13, 2018 000 WTNT43 KNHC 131433 TCDAT3 Hurricane Leslie Discussion Number 69 NWS National Hurricane Center Miami FL AL132018 1100 AM AST Sat Oct 13 2018 Despite Leslie moving over 20C ocean and being embedded within strong shear, satellite data indicate that Leslie has maintained its deep warm core and is running ahead of a cold front. Although convection has weakened considerably, Dvorak estimates indicate that the winds are still 65 kt. All indications are that Leslie will acquire extratropical characteristics in the next several hours, and by the time it reaches the Iberian peninsula later today, the system will be a powerful post-tropical cyclone. After landfall, rapid weakening is anticipated, and Leslie is forecast to degenerate into a broad low pressure area over Spain in a day or so. Leslie is racing toward the northeast or 055 degrees at about 29 kt while embedded within the fast mid-latitude westerlies. A continued northeastward motion with gradual decrease in forward speed is anticipated in the next 12 to 24 hours. This is consistent with most of the track guidance, which unanimously brings the core of the post-tropical cyclone over the Iberian peninsula tonight. The meteorological services of Portugal and Spain are handling hazards information for their respective countries via local weather products. Key Messages: 1. Leslie is expected to bring near hurricane-force winds to portions of Portugal late today as a powerful post-tropical cyclone. Gale-force winds are also likely to affect portions of western Spain tonight and Sunday. 2. Leslie is expected to produce rainfall amounts of 25 to 75 mm (1 to 3 inches) with isolated amounts as high as 125 mm (5 inches) across portions of Portugal and Spain, which could cause flash flooding. 3. For more information on Leslie, interests in Portugal should refer to products from the Portuguese Institute for Sea and Atmosphere at www.ipma.pt. Interests in Spain should refer to products from the State Meteorological Agency at www.aemet.es. FORECAST POSITIONS AND MAX WINDS INIT 13/1500Z 38.0N 12.6W 65 KT 75 MPH 12H 14/0000Z 40.0N 8.0W 50 KT 60 MPH...POST-TROP/INLAND 24H 14/1200Z 41.5N 4.0W 30 KT 35 MPH...POST-TROP/INLAND 36H 15/0000Z...DISSIPATED $$ Forecaster Avila Link to comment Share on other sites More sharing options...
Windspeed Posted October 13, 2018 Share Posted October 13, 2018 000 WTNT43 KNHC 132036 TCDAT3 Post-Tropical Cyclone Leslie Discussion Number 70 NWS National Hurricane Center Miami FL AL132018 500 PM AST Sat Oct 13 2018 After a total of 70 advisories, long-lived Leslie has become post-tropical just west of the coast of Portugal, finally succumbing to the combination of cool waters, strong vertical wind shear, and interaction with an approaching cold front. The air mass ahead of the cyclone has moistened up in the low levels with Faro, Portugal, reporting a dewpoint of 70F/21C, but the dewpoints across central and northern Portugal ahead of Leslie are only in the low-60F range, which is not indicative of a tropical air mass. Thus, the cyclone is now a powerful post-tropical low pressure system that even has a partial eye noted in the most recent 2000Z Portuguese composite radar imagery. After landfall, rapid weakening is anticipated, and Leslie is forecast to degenerate into a broad low pressure area over or just north of Spain by late Sunday. Leslie is moving quickly toward the northeast or 050/30 kt. Post-tropical Cyclone Leslie should continue in a fast northeastward direction for the next 12-18 hours, making landfall near or just south of Porto, Portugal by 14/0000Z. This forecast motion is consistent with the previous advisory and the latest track model guidance. The meteorological services of Portugal and Spain are handling hazards information for their respective countries via local weather products. This is the last National Hurricane Center (NHC) advisory on this system. Key Messages: 1. Leslie is expected to bring near hurricane-force winds to portions of Portugal later tonight as a powerful post-tropical cyclone. Gale-force winds are also likely to affect portions of northwestern and northern Spain tonight and Sunday. 2. Leslie is expected to produce rainfall amounts of 25 to 75 mm (1 to 3 inches) with isolated amounts as high as 125 mm (5 inches) across portions of Portugal and Spain, which could cause flash flooding. 3. For more information on Leslie, interests in Portugal should refer to products from the Portuguese Institute for Sea and Atmosphere at www.ipma.pt. Interests in Spain should refer to products from the State Meteorological Agency at www.aemet.es. FORECAST POSITIONS AND MAX WINDS INIT 13/2100Z 40.5N 9.5W 60 KT 70 MPH...POST-TROPICAL 12H 14/0600Z 43.0N 4.9W 35 KT 40 MPH...POST-TROPICAL INLAND 24H 14/1800Z...DISSIPATED $$ Forecaster Stewart Link to comment Share on other sites More sharing options...
shaggy Posted October 14, 2018 Share Posted October 14, 2018 When you look at the amount of territory Leslie covered it's pretty awesome. She covered some ground out there. Link to comment Share on other sites More sharing options...
bluewave Posted October 14, 2018 Share Posted October 14, 2018 On October 12, 2018 at 6:31 PM, Windspeed said: ECMWF is now on board for a Portugal landfall as well. That stink jet though. Could be bad timing for landfall and PT transition. Gust to 109 mph in Figueira da Foz with the sting jet. Quite a bit of damage including blown out windows. http://www.ipma.pt/pt/media/noticias/news.detail.jsp?f=/pt/media/noticias/textos/leslie-3.html The IPMA station of Figueira da Foz / Vila Verde registered at 21:40 UTC (13:40 local time) on October 13, 2018, a gust of 49 m / s (about 176 km / h). This value is attributed to a phenomenon called sting jet . Sting jet is a strong downward current that sometimes develops on the western edge of extratropical depressions and can reach the surface. In these cases, the bursts may exceed 150 km / h in a reduced area, typically located southwest of the core of the depression. The formation of this meteorological phenomenon was first studied by the group of Professor Keith Browning of the University of Reading in the late 1980s. The gusts observed near the surface result from evaporative processes occurring at medium levels of the storm's hazy mass. These processes result in cooling and consequent downward transport of air to lower levels with progressive acceleration. The designation of sting jet stems from the fact that the signature of this phenomenon in satellite and radar images (image below) resembles that of the tail of a sting . In continental Portugal, a similar phenomenon was observed on December 23, 2009. However, at that time, the phenomenon was not associated to a depression resulting from the transition from tropical cyclone to extratropical depression, as presently it was verified. In fact, in 2009, the phenomenon resulted from a depression whose life cycle took place entirely in the middle latitudes. Then, the depression underwent a process of explosive cyclogenesis (rapid and intense decrease of atmospheric pressure in its center) to which a sting jet happened . The value of the 176 km / h gust, now observed, is the highest recorded in stations of the national meteorological network (previous high of 169 km / h on October 17, 2015) and is compatible with the short-term forecasts issued by IPMA, based on the European Center model and the AROME mesoscale model, operated by IPMA. Link to comment Share on other sites More sharing options...
jgf Posted October 23, 2018 Share Posted October 23, 2018 does anyone have any thoughts about this? Quote Tropical Weather Outlook NWS National Hurricane Center Miami FL 800 AM EDT Tue Oct 23 2018 For the North Atlantic...Caribbean Sea and the Gulf of Mexico: 1. A broad area of low pressure is expected to form in a couple of days several hundred miles east-northeast of the northern Leeward Islands. Some tropical or subtropical development of this system is possible by the weekend while it meanders over the central Atlantic Ocean. * Formation chance through 48 hours...low...near 0 percent. * Formation chance through 5 days...low...20 percent. Forecaster Pasch Link to comment Share on other sites More sharing options...
the ghost of leroy Posted October 23, 2018 Share Posted October 23, 2018 43 minutes ago, jgf said: does anyone have any thoughts about this? More garbage. Link to comment Share on other sites More sharing options...
yoda Posted October 24, 2018 Share Posted October 24, 2018 One more before the season ends looks like in the Atlantic Tropical Weather Outlook NWS National Hurricane Center Miami FL 800 AM EDT Wed Oct 24 2018 For the North Atlantic...Caribbean Sea and the Gulf of Mexico: 1. A large area of disorganized showers and thunderstorms over the central tropical Atlantic Ocean is associated with a broad area of low pressure located a little over 900 miles east of the northern Leeward Islands. This system is expected to move slowly northward over the next few days into an area where environmental conditions are forecast to be more conducive for development. A tropical or subtropical depression could form over the weekend while the system turns westward well to the northeast of the Lesser Antilles. * Formation chance through 48 hours...low...30 percent. * Formation chance through 5 days...medium...60 percent. Forecaster Roberts Link to comment Share on other sites More sharing options...
yoda Posted October 25, 2018 Share Posted October 25, 2018 Tropical Weather Outlook NWS National Hurricane Center Miami FL 800 AM EDT Thu Oct 25 2018 For the North Atlantic...Caribbean Sea and the Gulf of Mexico: 1. A low pressure system centered about 900 miles east-northeast of the northern Leeward Islands is gradually becoming better defined and the associated shower and thunderstorm activity is showing signs of organization. This low is expected to move generally northward over the next couple of days into an area where environmental conditions are forecast to be conducive for further development, and a tropical or subtropical storm is likely to form by early this weekend. After that time, the system is forecast to turn westward well to the north or northeast of the Lesser Antilles through early next week. * Formation chance through 48 hours...high...70 percent. * Formation chance through 5 days...high...80 percent. Forecaster Zelinsky Link to comment Share on other sites More sharing options...
the ghost of leroy Posted October 25, 2018 Share Posted October 25, 2018 not so subtle hype graphic Link to comment Share on other sites More sharing options...
yoda Posted October 26, 2018 Share Posted October 26, 2018 Tropical Weather Outlook NWS National Hurricane Center Miami FL 200 AM EDT Fri Oct 26 2018 For the North Atlantic...Caribbean Sea and the Gulf of Mexico: 1. Showers and thunderstorms are gradually becoming better organized in association with a low pressure system located about 1000 miles east-northeast of the northern Leeward Islands. However, recent satellite data indicate that the circulation is elongated and the center is not yet well defined. This system will likely become a tropical or subtropical cyclone later today while it moves generally northward over the central Atlantic. After that time, the low is forecast to turn westward well to the north or northeast of the Lesser Antilles through early next week. * Formation chance through 48 hours...high...90 percent. * Formation chance through 5 days...high...90 percent. Link to comment Share on other sites More sharing options...
jgf Posted October 26, 2018 Share Posted October 26, 2018 big difference between ECMWF and GFS for the track of Invest 95 - this is today's 6z GFS and 6z EC forecast for friday nov 2 GFS in blue, EC in black Link to comment Share on other sites More sharing options...
AfewUniversesBelowNormal Posted October 26, 2018 Author Share Posted October 26, 2018 So cool that storms are making European landfall now! Link to comment Share on other sites More sharing options...
JakkelWx Posted October 27, 2018 Share Posted October 27, 2018 Oscar has formed in the central Atlantic FORECAST POSITIONS AND MAX WINDS INIT 27/0300Z 26.7N 45.7W 40 KT 45 MPH 12H 27/1200Z 27.2N 47.2W 45 KT 50 MPH 24H 28/0000Z 26.6N 50.3W 50 KT 60 MPH 36H 28/1200Z 25.6N 53.2W 50 KT 60 MPH 48H 29/0000Z 25.3N 55.3W 55 KT 65 MPH...TROPICAL CYCLONE 72H 30/0000Z 26.5N 57.5W 60 KT 70 MPH 96H 31/0000Z 30.0N 55.5W 60 KT 70 MPH 120H 01/0000Z 34.0N 50.0W 55 KT 65 MPH $$ Forecaster Beven ...SUBTROPICAL STORM OSCAR FORMS OVER THE CENTRAL ATLANTIC... SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION ----------------------------------------------- LOCATION...26.7N 45.7W ABOUT 1255 MI...2020 KM ENE OF THE NORTHERN LEEWARD ISLANDS ABOUT 1210 MI...1945 KM ESE OF BERMUDA MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H PRESENT MOVEMENT...NNW OR 330 DEGREES AT 9 MPH...15 KM/H MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES Link to comment Share on other sites More sharing options...
bluewave Posted October 27, 2018 Share Posted October 27, 2018 For the first time on record (since 1970), all Northern Hemisphere tropical cyclone basins (North Atlantic, NW Pacific, NE Pacific and North Indian) will have above-average seasonal values of Accumulated Cyclone Energy in 2018.#Yutu #hurricane #typhoon pic.twitter.com/rNg9QAo19D 4:44 PM - 26 Oct 2018 Link to comment Share on other sites More sharing options...
Windspeed Posted October 27, 2018 Share Posted October 27, 2018 Oscar's vortex is actually not too horrible at the moment despite its sheared and tilted appearance of a persistent MCS. It has been interesting watching its circulation rotate around the northern half of the mid-to-upper cutoff trough on visible and IR imagery today. You can actually see the transformation to a more tropical low. As such, the NHC forecasts Oscar to become a purely tropical storm over night. Oscar is also forecast to become a hurricane in a few days after turning poleward, if upper level winds cooperate. Link to comment Share on other sites More sharing options...
Windspeed Posted October 28, 2018 Share Posted October 28, 2018 Oscar's transformation to a deep tropical system has been gorgeous. A nice eye band is establishing and a core with CDO. May have a hurricane before too much longer. Link to comment Share on other sites More sharing options...
Amped Posted October 28, 2018 Share Posted October 28, 2018 Adding more ACE to my already busted prediction for a low ACE season. Some models even get Oscar to CAT3 status. Link to comment Share on other sites More sharing options...
Windspeed Posted October 29, 2018 Share Posted October 29, 2018 Adding more ACE to my already busted prediction for a low ACE season. Some models even get Oscar to CAT3 status.HWRF has been intensifying Oscar down into the 950s with consistency. Based on SSTs and a cold upper troposphere analysis, convective instability should be great for a few days. A major seems most likely at this point. Link to comment Share on other sites More sharing options...
Chinook Posted October 29, 2018 Share Posted October 29, 2018 I saw this on twitter, as a reminder as just how powerful the storms have been that have affected the US and the US Territories Link to comment Share on other sites More sharing options...
AfewUniversesBelowNormal Posted October 29, 2018 Author Share Posted October 29, 2018 I knew this would be a big season despite El Nino, lots of unnamed seasonal trends. Next year probably too Link to comment Share on other sites More sharing options...
Windspeed Posted October 29, 2018 Share Posted October 29, 2018 I saw this on twitter, as a reminder as just how powerful the storms have been that have affected the US and the US TerritoriesMichael's band of > -80°C cloudtops at landfall was the most impressive I can remember at landfall for an Atlantic hurricane. Link to comment Share on other sites More sharing options...
Windspeed Posted October 29, 2018 Share Posted October 29, 2018 Oscar may be small, but not too shabby a hurricane. Wondering if the current westerly upper level flow is going to relax enough to allow Oscar to reach major status. I was confident of that last night. Now I am not so certain. Link to comment Share on other sites More sharing options...
Amped Posted October 30, 2018 Share Posted October 30, 2018 Nice pinhole eye even though the cloud pattern isn't very symmetric. Link to comment Share on other sites More sharing options...
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