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Tropical Depression Eleven-E Forecast Discussion Number 1

2018-08-04 22:34:40| National Hurricane Center (East Pacific)

Issued at 400 PM CDT Sat Aug 04 2018 280 WTPZ41 KNHC 042034 TCDEP1 Tropical Depression Eleven-E Discussion Number 1 NWS National Hurricane Center Miami FL EP112018 400 PM CDT Sat Aug 04 2018 Satellite images indicate that the disturbance located over the far eastern Pacific has become significantly better organized throughout the day, with the formation of a well-defined low pressure center and deep convection organized in a distinct curved band. Based on these criteria, the system is being designated as a tropical depression, and the initial intensity is set at 25 kt in accordance with Dvorak estimates from TAFB and SAB. Because the system has congealed so quickly, the initial motion is uncertain but estimated to be 285/11 kt. The cyclone's future motion will ultimately be dictated by a large mid-tropospheric ridge to its north and its proximity to another disturbance located about 450 n mi to the west. A west-northwestward motion at a nearly constant speed is expected during the next 2-3 days due to the ridge. After that time, the cyclone could begin to slingshot around the northern side of the larger weather system to its west. Many of the track models are not handling the depression very well; the GFS barely depicts a surface low from the get-go, and the HWRF does not appear to be accounting sufficiently for the possibility of binary interaction. As a result, the NHC official track forecast matches the consensus of the ECMWF and UKMET, the only two models which appear to have a decent grasp on the situation. Although the depression will be moving over very warm waters of 29-30 degrees Celsius over the next 2-3 days, the upper-level wind environment may not be ideal due to possible outflow from the larger disturbance to the west. As a result, the official intensity forecast is not too aggressive and is essentially close to the ICON intensity consensus. Even though the ECMWF and UKMET were used for the track forecast, the two models disagree on the cyclone's ultimate demise. The ECMWF has the system absorbed by the other disturbance by day 4, while the UKMET keeps it distinct and holds it just beyond the forecast period. As a compromise, the official forecast shows dissipation or absorption by day 5, but the confidence in this forecast is low. Based on the forecast, tropical-storm-force winds are expected to remain offshore the coast of Mexico. However, only a slight deviation in the forecast track or an increase in size could bring those winds closer to the coast, and interests along the southern and southwestern coast of Mexico should monitor the progress of the depression. FORECAST POSITIONS AND MAX WINDS INIT 04/2100Z 12.4N 95.0W 25 KT 30 MPH 12H 05/0600Z 12.9N 96.4W 30 KT 35 MPH 24H 05/1800Z 13.6N 98.3W 35 KT 40 MPH 36H 06/0600Z 14.3N 100.2W 40 KT 45 MPH 48H 06/1800Z 15.3N 102.4W 45 KT 50 MPH 72H 07/1800Z 18.3N 107.8W 50 KT 60 MPH 96H 08/1800Z 20.0N 114.0W 45 KT 50 MPH 120H 09/1800Z...DISSIPATED $$ Forecaster Berg

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Hurricane Hector Forecast Discussion Number 16

2018-08-04 16:35:40| National Hurricane Center (East Pacific)

Issued at 800 AM PDT Sat Aug 04 2018 085 WTPZ45 KNHC 041435 TCDEP5 Hurricane Hector Discussion Number 16 NWS National Hurricane Center Miami FL EP102018 800 AM PDT Sat Aug 04 2018 There have been some subtle changes in Hector during the past several hours with satellite imagery indicating a slight disruption of the eyewall convective pattern. This appears to be due to a slowly evolving eyewall cycle, which can only be readily seen by high-resolution microwave data such as AMSR2, due to Hector's small size. Intensity estimates remain virtually the same, so the wind speed is held at 105 kt. Due the eyewall cycle, future intensity changes are harder to predict. Since Hector is forecast to remain in a favorable large-scale environment, albeit with marginal SSTs, little overall change in strength is indicated during the next couple of days. Hector's small size could also make it prone to short-term fluctuations in intensity, up or down, like the one observed yesterday. In about 3 days, Hector is forecast to move over somewhat cooler SSTs and into a drier environment, so gradual weakening is shown. Little change was made to the previous NHC wind speed prediction, near or just above the model consensus. Hector is locked into a westward motion of 270/10 kt. A large subtropical ridge to the north should steer the hurricane generally westward throughout the forecast period, with Hector gradually gaining some latitude on Sunday and beyond due to a weakness in the ridge. Overall the model guidance is in much better agreement than yesterday, and only cosmetic changes were made to previous track forecast. There is the potential for Hector to affect portions of the Hawaiian Islands by the middle of next week, but it is too soon to specify the magnitude of any impacts or where they could occur. This is a good time for everyone in the Hawaiian Islands to ensure they have their hurricane plan in place. For additional information on any potential local impacts from Hector in Hawaii, please refer to products issued by the NWS Weather Forecast Office in Honolulu at http://www.prh.noaa.gov/hnl. FORECAST POSITIONS AND MAX WINDS INIT 04/1500Z 14.2N 132.7W 105 KT 120 MPH 12H 05/0000Z 14.2N 134.2W 105 KT 120 MPH 24H 05/1200Z 14.4N 136.4W 110 KT 125 MPH 36H 06/0000Z 14.7N 138.8W 110 KT 125 MPH 48H 06/1200Z 15.1N 141.4W 105 KT 120 MPH 72H 07/1200Z 16.1N 147.2W 95 KT 110 MPH 96H 08/1200Z 16.6N 153.1W 90 KT 105 MPH 120H 09/1200Z 17.0N 158.5W 85 KT 100 MPH $$ Forecaster Blake

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Hurricane Hector Forecast Discussion Number 15

2018-08-04 10:45:06| National Hurricane Center (East Pacific)

Issued at 200 AM PDT Sat Aug 04 2018 700 WTPZ45 KNHC 040845 TCDEP5 Hurricane Hector Discussion Number 15 NWS National Hurricane Center Miami FL EP102018 200 AM PDT Sat Aug 04 2018 Hector has maintained an impressive satellite presentation so far this morning. The clear eye of the major hurricane is surrounded by a ring of cloud tops colder than -75 deg C and its outflow has become well established in all quadrants. Recent satellite intensity estimates from TAFB, SAB, and the UW-CIMSS ADT are in good agreement and support an initial intensity of 105 kt. The hurricane will remain in a favorable environment for the next 48 to 72 h, so the NHC forecast keeps Hector as a fairly steady-state major hurricane, close to the HWRF model. In reality, while recent SSMIS and AMSU microwave data do not suggest that another eyewall replacement cycle is imminent, it would not be surprising if one did occur sometime in the next couple of days, causing the cyclone to at least briefly weaken. Hector's small size could also make it particularly prone to short-term fluctuations in intensity, up or down, like the one observed yesterday. By day 4, Hector is forecast to move over somewhat cooler SSTs, and into a drier environment, so gradual weakening is anticipated. Confidence in this portion of the forecast is fairly low since there large spread in the intensity guidance. Hector has continued to move steadily westward, and the initial motion estimate is 270/10 kt. A large subtropical ridge to the north should steer the hurricane generally westward through the entire forecast period. There is still uncertainty as to how much latitude Hector will gain in the 2 to 4 day time frame due to a slight weakness in the ridge, however the spread of the track guidance has generally decreased since yesterday. The official track forecast has been nudged very slightly northward, in line with the latest consensus guidance, but overall is very similar to the previous advisory. There is the potential for Hector to affect portions of the Hawaiian Islands by the middle of next week, but it is too soon to specify the magnitude of any impacts or where they could occur. This is a good time for everyone in the Hawaiian Islands to ensure they have their hurricane plan in place. For additional information on any potential local impacts from Hector in Hawaii, please refer to products issued by the NWS Weather Forecast Office in Honolulu at http://www.prh.noaa.gov/hnl. FORECAST POSITIONS AND MAX WINDS INIT 04/0900Z 14.3N 131.7W 105 KT 120 MPH 12H 04/1800Z 14.3N 133.2W 110 KT 125 MPH 24H 05/0600Z 14.5N 135.3W 110 KT 125 MPH 36H 05/1800Z 14.7N 137.6W 110 KT 125 MPH 48H 06/0600Z 15.0N 140.1W 110 KT 125 MPH 72H 07/0600Z 16.0N 145.8W 100 KT 115 MPH 96H 08/0600Z 16.5N 151.5W 90 KT 105 MPH 120H 09/0600Z 17.0N 157.5W 80 KT 90 MPH $$ Forecaster Zelinsky

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Hurricane Hector Forecast Discussion Number 14

2018-08-04 04:35:03| National Hurricane Center (East Pacific)

Issued at 800 PM PDT Fri Aug 03 2018 283 WTPZ45 KNHC 040235 TCDEP5 Hurricane Hector Discussion Number 14 NWS National Hurricane Center Miami FL EP102018 800 PM PDT Fri Aug 03 2018 Hector has continued to quickly strengthen since the last advisory, with the eye becoming more distinct and the cloud tops in the eyewall cooling to near -80C. Satellite intensity estimates from TAFB and SAB were 102 kt near 00Z, and given the increasing organization since that time the initial intensity is increased to 105 kt. The initial motion is now 275/10. There is again little change to the track forecast philosophy, as a large subtropical ridge to the north of the hurricane should steer Hector generally westward during the forecast period. Due to a weakness in the ridge, the hurricane is forecast to gain some latitude from 36-96 h. While the guidance agrees with this scenario, there is a significant amount of spread between the GFS and NAVGEM on the north side of the guidance envelope and the UKMET and ECMWF on the south side. The consensus models are in the center of the envelope, and the new forecast is close to these in best agreement with the HCCA corrected consensus. The new forecast is little changed from the previous track. Recent satellite microwave data show that Hector is developing an outer eyewall, which suggests the hurricane should undergo an eyewall replacement cycle during the next day or so. This makes it a little unclear how long the current intensification will last. The intensity forecast will show a little more strengthening during the next 12 hr followed by little change in strength through 36 h. The HWRF, HMON, and COAMPS-TC models show a little more intensification at 48-60 h, and the official forecast follows suit. After that time, while Hector should remain in a light-shear, warm-water environment, entrainment of drier air should lead to a gradual weakening of the cyclone. Overall, the new intensity forecast lies near the upper edge of the intensity guidance. There is the potential for Hector to bring some impacts to portions of the Hawaiian Islands by the middle of next week, but it is too soon to specify the magnitude of the impacts or where they could occur. This is a good time for everyone in the Hawaiian Islands to ensure they have their hurricane plan in place. For additional information on any potential local impacts from Hector in Hawaii, please refer to products issued by the NWS Weather Forecast Office in Honolulu at http://www.prh.noaa.gov/hnl. FORECAST POSITIONS AND MAX WINDS INIT 04/0300Z 14.2N 130.9W 105 KT 120 MPH 12H 04/1200Z 14.3N 132.4W 110 KT 125 MPH 24H 05/0000Z 14.2N 134.5W 110 KT 125 MPH 36H 05/1200Z 14.2N 136.6W 110 KT 125 MPH 48H 06/0000Z 14.5N 139.1W 115 KT 130 MPH 72H 07/0000Z 15.5N 144.5W 105 KT 120 MPH 96H 08/0000Z 16.5N 150.5W 90 KT 105 MPH 120H 09/0000Z 16.5N 156.0W 80 KT 90 MPH $$ Forecaster Beven

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Hurricane Hector Forecast Discussion Number 13

2018-08-03 22:46:32| National Hurricane Center (East Pacific)

Issued at 200 PM PDT Fri Aug 03 2018 652 WTPZ45 KNHC 032046 TCDEP5 Hurricane Hector Discussion Number 13 NWS National Hurricane Center Miami FL EP102018 200 PM PDT Fri Aug 03 2018 Satellite images indicate that Hector is re-strengthening. The eye has cleared out again on visible imagery, with an increase in deep convection in the eyewall. Perhaps this shouldn't be a surprise because of Hector's small size, since these systems are known to fluctuate up and down rapidly. The initial intensity is set to 90 kt, between the 75 kt SATCON from CIMSS and a 102 kt estimate from SAB. The large-scale environment would seem to favor some intensification of Hector during the next couple of days, with SSTS of 27-27.5C, light shear, and moderate levels of mid-level moisture forecast. The new NHC forecast favors the dynamical models over the more statistical-based guidance and shows steady strengthening. This should be considered a low-confidence forecast due to the divergent guidance and the small size of Hector. At the end of the forecast, some weakening is shown due to increasing dryness in the mid-levels and a potential increase in shear. The initial motion remains 270/10 kt. There has been no change to the synoptic steering pattern. A large subtropical ridge should push the hurricane westward for the next couple of days. Due to a weakness in the ridge in 2 or 3 days, Hector is forecast to gain some latitude in the long range. Model guidance has been oscillating northward and southward with the forecast in the Central Pacific, with the latest guidance a little faster and farther south. The NHC forecast is shifted in that direction, but not as far south as the new model consensus. There is the potential for Hector to bring some impacts to portions of the Hawaiian Islands by the middle of next week, but it is too soon to specify the magnitude of the impacts or where they could occur. This is a good time for everyone in the Hawaiian Islands to ensure they have their hurricane plan in place. For additional information on any potential local impacts from Hector in Hawaii, please products issued by the NWS Weather Forecast Office in Honolulu. FORECAST POSITIONS AND MAX WINDS INIT 03/2100Z 14.1N 129.8W 90 KT 105 MPH 12H 04/0600Z 14.1N 131.3W 95 KT 110 MPH 24H 04/1800Z 14.1N 133.4W 100 KT 115 MPH 36H 05/0600Z 14.1N 135.5W 100 KT 115 MPH 48H 05/1800Z 14.2N 137.8W 105 KT 120 MPH 72H 06/1800Z 15.2N 142.9W 105 KT 120 MPH 96H 07/1800Z 16.2N 148.5W 90 KT 105 MPH 120H 08/1800Z 16.7N 154.5W 80 KT 90 MPH $$ Forecaster Blake

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