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Hurricane Eugene Forecast Discussion Number 11

2017-07-10 10:50:47| National Hurricane Center (East Pacific)

Issued at 200 AM PDT Mon Jul 10 2017 000 WTPZ45 KNHC 100850 TCDEP5 Hurricane Eugene Discussion Number 11 NWS National Hurricane Center Miami FL EP052017 200 AM PDT Mon Jul 10 2017 Eugene's structure has changed during the past 6-12 hours, as the hurricane no longer has an eye in infrared satellite imagery. Microwave data and the derived MIMIC product from UW-CIMSS seem to suggest that dry air penetrated into the southern portion of Eugene's circulation and eroded the eyewall. In addition, center fixes off of ASCAT data indicate that the low-level center is displaced to the south of the mid-level rotation noted in geostationary satellite imagery, indicative of some unforeseen southerly shear. Subjective and objective Dvorak intensity estimates have decreased slightly from six hours ago, and a blend of the various numbers supports an initial intensity of 85 kt. Eugene will remain over water warmer than 26C for another 12 hours or so, and its intensity will either be steady or decrease slowly during that time. More pronounced weakening is anticipated after 12 hours when the circulation moves over much colder water, and Eugene will likely weaken to a tropical storm by tonight and then degenerate to a remnant low by Wednesday night. The updated NHC intensity forecast is fairly close to the ICON intensity consensus and tries to maintain as much continuity as possible with the previous forecast. However, it should be noted that HCCA and the Florida State Superensemble, both of which have performed well with Eugene, indicate a faster weakening rate than that shown by the official forecast. A weakness in the subtropical ridge located off the northern Baja California peninsula coast is causing Eugene to move northwestward with an initial motion of 320/10 kt. Even as Eugene weakens, low-level troughing near the California coast should maintain a northwestward or even north-northwestward track but at a slower forward speed through most of the forecast period. The track guidance remains in good agreement, and the only notable change in the NHC official forecast is a northeastward shift in the track during the remnant low stage compared to the previous forecast. Swells generated by Eugene will propagate northward along the west coast of the Baja California peninsula to southern California during the next few days, causing high surf and dangerous rip current conditions. Please refer to advisories issued by your local weather office for additional information. FORECAST POSITIONS AND MAX WINDS INIT 10/0900Z 18.1N 116.5W 85 KT 100 MPH 12H 10/1800Z 19.3N 117.6W 75 KT 85 MPH 24H 11/0600Z 20.7N 118.8W 60 KT 70 MPH 36H 11/1800Z 22.1N 119.9W 45 KT 50 MPH 48H 12/0600Z 23.3N 120.8W 35 KT 40 MPH 72H 13/0600Z 25.5N 122.6W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 14/0600Z 27.5N 124.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 15/0600Z 28.5N 125.5W 15 KT 15 MPH...POST-TROP/REMNT LOW $$ Forecaster Berg

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Hurricane EUGENE Forecast Discussion Number 10

2017-07-10 04:36:12| National Hurricane Center (East Pacific)

Issued at 800 PM PDT Sun Jul 09 2017 000 WTPZ45 KNHC 100236 TCDEP5 Hurricane Eugene Discussion Number 10 NWS National Hurricane Center Miami FL EP052017 800 PM PDT Sun Jul 09 2017 After steadily intensifying during the past couple of days, the strengthening trend of Eugene appears to have ended. The eye of the hurricane has become cloud-filled and ragged, and the convection in the eyewall is not quite as symmetric as it was earlier today. In addition, recent microwave images indicate that the eyewall has eroded on its east side. The Dvorak CI-numbers are 5.0/90 kt from TAFB and SAB and the latest UW-CIMSS satellite consensus estimate is 92 kt. Based on these values, the initial wind speed of Eugene is lowered to 90 kt. The current weakening of Eugene appears to be associated with some dry air that has wrapped into the circulation, as seen in total precipitable water images. The hurricane still has about another 12 hours over warm water and in a low wind shear environment, so little change in strength is expected overnight. Eugene is expected to cross the 26 deg C isotherm on Monday, and then move over progressively cooler waters later in the week. These unfavorable oceanic conditions combined with a drier and more stable air mass should cause steady, or even rapid, weakening beginning on Monday. The NHC intensity forecast is above most of the guidance in the short term, but then falls in line with the consensus models and brings Eugene below hurricane strength in 24 to 36 hours. The cyclone is expected to become a remnant low by 72 hours when it is forecast to be over water temperatures of around 20 C, which should cause the convection to dissipate. Eugene is moving northwestward at about 10 kt on the southwestern periphery of a mid-level high pressure system located over the southwestern United States. This high is expected to remain in place, which should keep Eugene moving northwestward during the next few days. After that time, a decrease in forward speed and a turn to the west-northwest is predicted when Eugene become a shallow system and is steered by the low-level trade wind flow. The NHC track forecast is in the middle of the guidance envelope for the next few days, and then favors the left side of the guidance when Eugene is predicted to be a remnant low. FORECAST POSITIONS AND MAX WINDS INIT 10/0300Z 17.6N 115.9W 90 KT 105 MPH 12H 10/1200Z 18.9N 117.1W 90 KT 105 MPH 24H 11/0000Z 20.5N 118.5W 75 KT 85 MPH 36H 11/1200Z 21.8N 119.6W 55 KT 65 MPH 48H 12/0000Z 23.0N 120.6W 40 KT 45 MPH 72H 13/0000Z 25.0N 122.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 14/0000Z 26.5N 125.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 15/0000Z 28.0N 128.0W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Cangialosi

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Hurricane Eugene Forecast Discussion Number 9

2017-07-09 22:31:41| National Hurricane Center (East Pacific)

Issued at 200 PM PDT Sun Jul 09 2017 000 WTPZ45 KNHC 092031 TCDEP5 Hurricane Eugene Discussion Number 9 NWS National Hurricane Center Miami FL EP052017 200 PM PDT Sun Jul 09 2017 Eugene continues to have a distinct eye surrounded by a ring of very deep convection. A blend of both objective and subjective Dvorak T-numbers from all agencies yield an initial intensity of 100 kt. The hurricane has the opportunity to strengthen a little more within the next 12 hours or so, before the circulation of Eugene begins to move over cooler waters of 24 degrees Celsius or lower. After that time, weakening should begin, and the cyclone should become post-tropical in about 3 days. This forecast follows both statistical models and the consensus. Eugene is moving toward the northwest or 325 degrees at 10 kt. The cyclone is embedded within a well established steering flow around a mid-level ridge over the western United States, and this pattern will keep Eugene on the same general track for the next 3 days. Once the cyclone weakens, it could turn more to the west-northwest with the low-level flow. The NHC forecast follows the consensus primarily during the next 3 days and does not depart much from the previous official forecast. FORECAST POSITIONS AND MAX WINDS INIT 09/2100Z 16.7N 115.3W 100 KT 115 MPH 12H 10/0600Z 17.9N 116.4W 105 KT 120 MPH 24H 10/1800Z 19.6N 117.9W 90 KT 105 MPH 36H 11/0600Z 21.0N 119.0W 70 KT 80 MPH 48H 11/1800Z 22.0N 120.0W 60 KT 70 MPH 72H 12/1800Z 24.0N 122.0W 35 KT 40 MPH...POST-TROPICAL 96H 13/1800Z 25.5N 124.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 14/1800Z 26.5N 127.5W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Avila

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Hurricane Eugene Forecast Discussion Number 8

2017-07-09 16:56:42| National Hurricane Center (East Pacific)

Issued at 900 AM MDT Sun Jul 09 2017 000 WTPZ45 KNHC 091456 TCDEP5 Hurricane Eugene Discussion Number 8 NWS National Hurricane Center Miami FL EP052017 900 AM MDT Sun Jul 09 2017 Eugene's eye is becoming more distinct this morning and cold cloud tops in the eyewall are wrapping more symmetrically around the center of the hurricane. Subjective Dvorak classifications from SAB and TAFB have increased, suggesting around 90 kt at 12Z. In the last couple of hours, Eugene's convective structure continues to improve and the objective Advanced Dvorak Technique currently indicates a substantially higher intensity. A blend of these estimates gives 100 kt at advisory time and Eugene is now a major hurricane. However, Eugene will be moving from warm to very cool SST, so it is likely that the hurricane will be peaking very soon. Steady to rapid weakening should ensue on Monday due to the hurricane ingesting dry and stable air into its inner core. It is anticipated that the system will lose its deep convection in about three days - if not sooner - and no longer be considered a tropical cyclone. The official intensity forecast is slightly lower than indicated in the previous advisory, and is based upon a blend of the SHIPS/LGEM statistical models and the COAMPS-TC dynamical guidance. Eugene has sped up some and is now moving toward the north-northwest at about 9 kt. The hurricane should continue moving in the same general direction and speed during the next 36 hours or so, due to the steering influence of a mid-tropospheric ridge over the southwestern United States. As Eugene weakens, it should be steered toward the west-northwest at a slower rate of speed by the lower tropospheric tradewinds. The official track forecast is based upon the HCCA corrected consensus technique through three days and upon a blend of the GFS and ECMWF models thereafter. This track prediction is very similar to that from the previous advisory, except slightly more to the west at days four and five. FORECAST POSITIONS AND MAX WINDS INIT 09/1500Z 16.0N 114.6W 100 KT 115 MPH 12H 10/0000Z 17.3N 115.6W 105 KT 120 MPH 24H 10/1200Z 18.8N 117.1W 95 KT 110 MPH 36H 11/0000Z 20.3N 118.5W 80 KT 90 MPH 48H 11/1200Z 21.6N 119.6W 65 KT 75 MPH 72H 12/1200Z 23.6N 121.8W 40 KT 45 MPH...POST-TROPICAL 96H 13/1200Z 25.3N 124.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 14/1200Z 26.5N 127.0W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Landsea

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Hurricane Eugene Forecast Discussion Number 7

2017-07-09 10:42:38| National Hurricane Center (East Pacific)

Issued at 300 AM MDT Sun Jul 09 2017 000 WTPZ45 KNHC 090842 TCDEP5 Hurricane Eugene Discussion Number 7 NWS National Hurricane Center Miami FL EP052017 300 AM MDT Sun Jul 09 2017 Although it hasn't cleared out entirely, an eye has persisted in infrared satellite imagery since the last advisory, and cloud tops colder than -70C have at times completely encircled the eye. Subjective Dvorak estimates from TAFB and SAB were T4.5/77 kt and T5.0/90 kt, respectively, at 0600 UTC, and an average of these numbers was mirrored by an objective ADT estimate of T4.8/85 kt. Eugene's rapid intensification phase continues, and the hurricane is now estimated to be category 2 with 85-kt winds. Eugene continues on a northwestward trajectory with an initial motion of 325/7 kt. Mid-tropospheric ridging is expected to remain anchored over the western United States for a few more days, while a progressive shortwave trough approaches the coast of California. This pattern should keep Eugene on a northwestward path for the entire five-day forecast period, with a faster forward speed anticipated from 12-36 hours. The track guidance remains tightly clustered, especially through 72 hours, and the NHC official forecast has been nudged westward toward the various consensus models. By the end of the forecast period, the official forecast favors the weaker, westward-leaning GFS and ECMWF models. Eugene has blown through all prior intensity guidance, so it's a little difficult to know how long this period of rapid intensification will last. The hurricane is expected to remain in a low-shear environment for much of the forecast period, and it will continue to traverse waters warmer than 26C for another 24-36 hours. Therefore, continued strengthening is likely, and Eugene could attain major hurricane intensity before it reaches colder water. The new NHC intensity forecast has been bumped upward and continues to be at the upper bound of the intensity models, closest to the SHIPS guidance through 36 hours. Weakening should be rather fast after 36 hours as Eugene moves over quickly decreasing sea surface temperatures, and the global models suggest that the cyclone will cease producing deep convection by 96 hours. At that point in the forecast Eugene is expected to be a remnant low. FORECAST POSITIONS AND MAX WINDS INIT 09/0900Z 15.2N 114.1W 85 KT 100 MPH 12H 09/1800Z 16.4N 115.1W 100 KT 115 MPH 24H 10/0600Z 18.0N 116.5W 105 KT 120 MPH 36H 10/1800Z 19.5N 117.9W 90 KT 105 MPH 48H 11/0600Z 20.9N 119.2W 75 KT 85 MPH 72H 12/0600Z 23.3N 121.4W 45 KT 50 MPH 96H 13/0600Z 25.0N 123.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 14/0600Z 26.5N 125.5W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Berg

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