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Hurricane Dora Forecast Discussion Number 9

2017-06-27 04:46:45| National Hurricane Center (East Pacific)

Issued at 900 PM MDT Mon Jun 26 2017 000 WTPZ44 KNHC 270246 TCDEP4 Hurricane Dora Discussion Number 9 NWS National Hurricane Center Miami FL EP042017 900 PM MDT Mon Jun 26 2017 Dora continues to exhibit a very symmetric cloud pattern with a well-defined 25 to 30 n mi wide eye. The convective cloud tops have gradually warmed today, but subjective Dvorak intensity estimates from TAFB and SAB still support an initial intensity of 80 kt. The hurricane will be moving over cooler waters as it crosses the 26 degree Celsius isotherm very soon. Since the shear is expected to remain quite low throughout the forecast period, this may result in a somewhat slower than typical rate of weakening during the next day or so. After that time, Dora will be moving over waters colder than 24 degrees Celsius which should cause a faster rate of decay. Dora is forecast to become a tropical storm in about 24 hours, and degenerate into a remnant low in 2 to 3 days. The NHC intensity forecast is initially close to the SHIPS/LGEM guidance but leans toward the intensity consensus at 24 h and beyond. Dora is moving west-northwestward or 295/11 kt. A large deep-layer ridge to the north of the hurricane should keep it moving on a west-northwestward track during the next 24 to 36 hours. After that time, a weaker and more shallow Dora should turn generally westward in the low-level flow. The new NHC track forecast is essentially an update of the previous advisory and is close to the latest multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 27/0300Z 18.4N 108.3W 80 KT 90 MPH 12H 27/1200Z 18.9N 109.7W 75 KT 85 MPH 24H 28/0000Z 19.4N 111.5W 60 KT 70 MPH 36H 28/1200Z 19.8N 113.1W 50 KT 60 MPH 48H 29/0000Z 20.2N 114.7W 40 KT 45 MPH 72H 30/0000Z 20.7N 117.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 01/0000Z 20.5N 120.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 02/0000Z...DISSIPATED $$ Forecaster Brown

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Hurricane DORA Forecast Discussion Number 8

2017-06-26 22:41:16| National Hurricane Center (East Pacific)

Issued at 300 PM MDT Mon Jun 26 2017 000 WTPZ44 KNHC 262041 TCDEP4 Hurricane Dora Discussion Number 8 NWS National Hurricane Center Miami FL EP042017 300 PM MDT Mon Jun 26 2017 Since the previous advisory, Dora's cloud pattern has noticeably eroded, with cloud tops having warmed considerably and the earlier embedded eye feature having devolved into more of a banding eye structure. Satellite intensity estimates remain a consensus T4.5/77 kt from TAFB and SAB, and NHC automated Dvorak intensity estimates have been steady at 80-82 kt. Therefore, the initial intensity has been increased slightly to 80 kt. The initial motion estimate remains a steady 295/11 kt. The global and regional models maintain the deep-layer ridge to the north of Dora throughout the forecast period, keeping the hurricane on a west-northwestward track for the next 48-72 hours, followed by a turn toward the west thereafter until dissipation occurs by 120 hours. The latest NHC model guidance is more tightly packed around the previous advisory track now that the ECMWF has shifted farther to the north. As a result, only minor tweaks had to made to the forecast track, which lies close to the consensus track model TVCE. Dora has likely peaked in intensity, and is now starting to feel the negative effects of cooler water and more stable air just to its north. The hurricane should move over sub-26 C SSTs within the next 6-12 hours, which will induce gradual weakening. However, proximity to warm, unstable air just to the south of Dora's track, along with very favorable shear and outflow patterns, should act to temper the weakening rate somewhat. Dora is expected to become a tropical storm by 36 hours and degenerate into a remnant low by 72 hours, if not sooner. The new intensity forecast is similar to the intensity consensus model IVCN. Although the center of Dora is forecast to move farther away from mainland Mexico, the outer bands of the cyclone could bring brief locally heavy rainfall to portions of coastal southwestern Mexico into this evening. FORECAST POSITIONS AND MAX WINDS INIT 26/2100Z 17.8N 107.3W 80 KT 90 MPH 12H 27/0600Z 18.4N 108.7W 75 KT 85 MPH 24H 27/1800Z 19.0N 110.4W 65 KT 75 MPH...NEAR SOCORRO ISLAND 36H 28/0600Z 19.5N 112.3W 55 KT 65 MPH 48H 28/1800Z 19.8N 113.7W 45 KT 50 MPH 72H 29/1800Z 20.3N 116.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 30/1800Z 20.5N 119.4W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 01/1800Z...DISSIPATED $$ Forecaster Stewart

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Hurricane DORA Forecast Discussion Number 7

2017-06-26 16:32:42| National Hurricane Center (East Pacific)

Issued at 900 AM MDT Mon Jun 26 2017 000 WTPZ44 KNHC 261432 TCDEP4 Hurricane Dora Discussion Number 7 NWS National Hurricane Center Miami FL EP042017 900 AM MDT Mon Jun 26 2017 Dora has continued to rapidly intensify with a 20-nmi-diameter, cloud-filled eye now evident in visible satellite imagery. The upper-level outflow pattern remains quite impressive and continues to expand in all quadrants. Satellite intensity estimates are a consensus T4.5/77 kt from TAFB and SAB, and T4.7/82 kt from CIMSS ADT, which supports an initial intensity of 75 kt. Dora could be a little stronger, but recent infrared imagery indicates that the inner-core convection has eroded significantly since the 1200 UTC fixes, so the initial intensity will remain on the low end of estimates for this advisory. Dora has been holding on a steady west-northwestward course or 295/11 kt for the past 12 hours. A strong deep-layer subtropical ridge entrenched to the north of the hurricane is expected to keep Dora moving in a general west-northwestward motion for the next 3 days or so. By 72 hours, the cyclone is expected to weaken significantly and become a more vertically shallow system, steered westward by the low-level trade wind flow until Dora dissipates by day 5. The new NHC track forecast is essentially just an update of the previous advisory track, and lies a little south of the consensus track model TVCE out of respect for the more southerly ECMWF solution. Dora has about another 12 hours or so to strengthen. However, the rapid intensification event that the hurricane has undergone for the past 30 hours has likely ended. The aforementioned erosion of the inner-core convection is possibly due to the entrainment of cooler and more stable air into the western semicircle now that Dora is beginning to encroach upon 26-deg C SSTs. The vertical wind shear is expected to remain low at less than 5 kt and the favorable upper-level outflow pattern is forecast to persist for the next few days as well. The only hindering factor will be the decreasing thermodynamics due to the hurricane moving over sub-26C SSTs within 12-18 hours. Steady weakening should begin by 24 h, but the rate of the weakening trend should be lessened due to proximity to warmer water just south of the path of Dora and the aforementioned favorable dynamic conditions. The NHC official intensity forecast is similar to the previous advisory, and closely follows the consensus model IVCN. Although the center of Dora is forecast to remain well offshore, the outer bands of the cyclone could bring brief locally heavy rainfall to portions of coastal southwestern Mexico into this evening. FORECAST POSITIONS AND MAX WINDS INIT 26/1500Z 17.3N 106.3W 75 KT 85 MPH 12H 27/0000Z 17.9N 107.7W 80 KT 90 MPH 24H 27/1200Z 18.6N 109.5W 70 KT 80 MPH 36H 28/0000Z 19.1N 111.1W 60 KT 70 MPH...NEAR SOCORRO ISLAND 48H 28/1200Z 19.5N 112.7W 50 KT 60 MPH 72H 29/1200Z 20.2N 115.7W 35 KT 40 MPH...POST-TROPICAL 96H 30/1200Z 20.4N 118.6W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 01/1200Z...DISSIPATED $$ Forecaster Stewart

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Hurricane Dora Forecast Discussion Number 6

2017-06-26 10:44:41| National Hurricane Center (East Pacific)

Issued at 400 AM CDT Mon Jun 26 2017 000 WTPZ44 KNHC 260844 TCDEP4 Hurricane Dora Discussion Number 6 NWS National Hurricane Center Miami FL EP042017 400 AM CDT Mon Jun 26 2017 Dora has continued to intensify overnight with a well-defined eye on microwave data and occasional hints of an eye on conventional satellite imagery. The cloud pattern has also become more symmetric than 6 hours ago, with outflow expanding in all quadrants. Satellite estimates supported an intensity of 65 kt at 0600 UTC, but with the improving satellite presentation since that time, the initial wind speed is set to 70 kt. Dora has about 12-24 hours to further strengthen before a combination of cooling SSTs and a more dry and stable environment likely causes the hurricane to start to decay. Interestingly, the models are in poor agreement on the weakening rate of Dora, with the regional hurricane models showing the cyclone losing strength much faster than the statistical aids. Since the shear is expected to remain low, which would normally inhibit dry air intrusions, the NHC forecast is a little higher than the model consensus, closer to the SHIPS/LGEM solutions and the previous NHC forecast. Given the spread in the guidance, this is a low confidence forecast. Dora is moving west-northwestward or 295/11 kt. A strong mid-level ridge to the north of Dora is expected to steer the tropical cyclone west-northwestward over the next couple of days. Dora should turn westward in about 3 days as it loses deep convection and becomes a more shallow low. Models have shifted a bit southward since the previous advisory, and the official NHC track forecast follows suit. The global models also show Dora weakening into a trough by day 5, and this is reflected in the dissipation forecast for that time. Although Dora is forecast to remain offshore, the outer bands of the tropical cyclone could bring locally heavy rainfall to portions of coastal southwestern Mexico through this evening. FORECAST POSITIONS AND MAX WINDS INIT 26/0900Z 16.7N 105.3W 70 KT 80 MPH 12H 26/1800Z 17.4N 106.8W 80 KT 90 MPH 24H 27/0600Z 18.2N 108.7W 75 KT 85 MPH 36H 27/1800Z 18.8N 110.4W 60 KT 70 MPH 48H 28/0600Z 19.2N 112.1W 50 KT 60 MPH 72H 29/0600Z 19.9N 115.1W 35 KT 40 MPH...POST-TROPICAL 96H 30/0600Z 20.0N 118.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 01/0600Z...DISSIPATED $$ Forecaster Blake

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Tropical Storm Dora Forecast Discussion Number 5

2017-06-26 04:46:41| National Hurricane Center (East Pacific)

Issued at 1000 PM CDT Sun Jun 25 2017 000 WTPZ44 KNHC 260246 TCDEP4 Tropical Storm Dora Discussion Number 5 NWS National Hurricane Center Miami FL EP042017 1000 PM CDT Sun Jun 25 2017 Dora's cloud pattern has continued to quickly improve this evening. Several well-defined spiral bands wrap around the center and the CDO has become more symmetric and expanded since the previous advisory. Recent microwave imagery suggest that an eye feature has formed within the CDO. Subjective Dvorak intensity estimates from TAFB and objective estimates from UW/CIMSS supported an intensity of 55 kt at 0000 UTC, but with the continued improved structure, the initial intensity has been set to 60 kt for this advisory. Dora is forecast to move over warm water and remain within a low shear environment during the next 12 to 24 hours. These conditions should allow for additional intensification and Dora is likely to become a hurricane by early Monday. The tropical cyclone is forecast to reach cooler waters in about a day, which should begin the weakening process. A faster rate of spin down is expected by late Tuesday as Dora moves over even colder waters and into a more stable environment. The NHC intensity forecast is a little above the ICON consensus through 36 hours, and is in best agreement with the LGEM guidance later in the period. Dora is moving west-northwestward or 300/12 kt. A strong mid-level ridge to the north of Dora is expected to steer the tropical cyclone west-northwestward over the next couple of days. After that time, a weaker and more shallow Dora should turn westward. The updated NHC track forecast is similar to the previous advisory and lies a little south of the TVCN model consensus out of respect for the typically reliable ECMWF which is along the southern edge of the guidance envelope. Although Dora is forecast to remain offshore, the outer bands of the tropical cyclone could bring locally heavy rainfall to portions of coastal southwestern Mexico through Monday. FORECAST POSITIONS AND MAX WINDS INIT 26/0300Z 16.4N 104.3W 60 KT 70 MPH 12H 26/1200Z 17.2N 105.9W 70 KT 80 MPH 24H 27/0000Z 18.2N 107.9W 75 KT 85 MPH 36H 27/1200Z 19.0N 109.8W 65 KT 75 MPH 48H 28/0000Z 19.4N 111.7W 55 KT 65 MPH 72H 29/0000Z 19.8N 115.0W 40 KT 45 MPH 96H 30/0000Z 20.0N 118.2W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 01/0000Z 19.0N 121.5W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Brown

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