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Hurricane FERNANDA Forecast Discussion Number 21

2017-07-17 04:33:02| National Hurricane Center (East Pacific)

Issued at 800 PM PDT Sun Jul 16 2017 000 WTPZ41 KNHC 170232 TCDEP1 Hurricane Fernanda Discussion Number 21 NWS National Hurricane Center Miami FL EP062017 800 PM PDT Sun Jul 16 2017 Fernanda's eye has become less distinct, although the overall cloud pattern remains quite symmetric and the central cloud tops have not warmed significantly so far. The current intensity is set to 105 kt which is a blend of subjective Dvorak intensity estimates from TAFB and SAB and ADT values from UW/CIMSS. Sea surface temperatures beneath the hurricane will should be slowly cooling over the next few days and, later in the forecast period, west-southwesterly shear is forecast to increase. Therefore gradual weakening is forecast during the next couple of days followed by a more rapid decline thereafter. The official intensity forecast is a little above the model consensus through 48 hours and very close to it in 3-5 days. The initial motion estimate, 290/10 kt, is not much different from earlier today. Fernanda is expected to approach the western periphery of a mid-tropospheric ridge extending westward from the United States. This should cause the tropical cyclone to slow down and turn a little to the right. In 4-5 days the global models show a ridge building to the north of Fernanda and this is likely to cause a turn toward the west around that time. The official track forecast is similar to the previous one and lies between the latest GFS and ECMWF solutions. FORECAST POSITIONS AND MAX WINDS INIT 17/0300Z 13.0N 129.2W 105 KT 120 MPH 12H 17/1200Z 13.7N 130.6W 100 KT 115 MPH 24H 18/0000Z 14.6N 132.1W 95 KT 110 MPH 36H 18/1200Z 15.5N 133.4W 90 KT 105 MPH 48H 19/0000Z 16.3N 134.6W 80 KT 90 MPH 72H 20/0000Z 17.3N 137.3W 60 KT 70 MPH 96H 21/0000Z 17.8N 140.7W 45 KT 50 MPH 120H 22/0000Z 18.3N 144.3W 35 KT 40 MPH $$ Forecaster Pasch

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Community Forum--Small Group Discussion Responses

2017-07-17 01:42:35| PortlandOnline

Responses of the 35 community members who participated in the June 27, 2017 community forum on the search for a new ONI director. Responses are grouped by question and small group. PDF Document, 119kbCategory: ONI Director's Selection Process

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Hurricane Fernanda Forecast Discussion Number 19

2017-07-16 16:44:58| National Hurricane Center (East Pacific)

Issued at 800 AM PDT Sun Jul 16 2017 000 WTPZ41 KNHC 161444 TCDEP1 Hurricane Fernanda Discussion Number 19 NWS National Hurricane Center Miami FL EP062017 800 AM PDT Sun Jul 16 2017 It appears that Fernanda completed an eyewall replacement overnight with an 1109 UTC SSMI microwave overpass showing evidence of a single eyewall with a diameter of about 15-20 n mi. This may have led to the restrengthening that was indicated in the previous advisory. Since that time, the eye has remained very distinct in infrared satellite pictures but the convective cloud tops have warmed a little this morning. Although Dvorak data T-numbers have decreased slightly, the initial intensity remains at 115 kt, in agreement with the Dvorak CI-numbers from TAFB and SAB. Fernanda is forecast to remain over warm water and within a low shear environment during the next 24 hours. During that time, additional eyewall replacement cycles could occur leading to some fluctuations in intensity. Since the timing of eyewall replacement cycles are difficult to predict, little change in intensity is indicated in the NHC forecast through Monday morning. After that time, Fernando is forecast to begin moving over cooler waters which should initiate gradual weakening. The rate of weakening is expected to increase later in the period when Fernanda moves over SSTs of 25-26C and westerly shear increases. The NHC intensity forecast is similar to the previous advisory and is close to the various consensus aids. The hurricane is moving west-northwestward at about 11 kt. The track forecast reasoning remains unchanged yet again. Fernanda is expected to remain on a west-northwestward heading during the next 3 days while it is steered by a deep layer ridge to the north of the hurricane. A westward turn is foreast later in the period, as the ridge builds westward when a trough northeast of the Hawaiian Islands lifts out. The track guidance remains in very good agreement and the updated NHC track is similar to the previous advisory. FORECAST POSITIONS AND MAX WINDS INIT 16/1500Z 12.4N 127.4W 115 KT 130 MPH 12H 17/0000Z 13.0N 129.0W 115 KT 130 MPH 24H 17/1200Z 13.8N 130.9W 110 KT 125 MPH 36H 18/0000Z 14.7N 132.6W 100 KT 115 MPH 48H 18/1200Z 15.5N 134.0W 90 KT 105 MPH 72H 19/1200Z 16.9N 136.5W 65 KT 75 MPH 96H 20/1200Z 17.5N 139.8W 45 KT 50 MPH 120H 21/1200Z 17.9N 143.3W 35 KT 40 MPH $$ Forecaster Brown

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Hurricane Fernanda Forecast Discussion Number 18

2017-07-16 10:46:27| National Hurricane Center (East Pacific)

Issued at 200 AM PDT Sun Jul 16 2017 000 WTPZ41 KNHC 160846 TCDEP1 Hurricane Fernanda Discussion Number 18 NWS National Hurricane Center Miami FL EP062017 200 AM PDT Sun Jul 16 2017 A 0235Z SSMI/S microwave overpass indicated that Fernanda was still undergoing an eyewall replacement cycle (ERC), with concentric eyewalls remaining at about 20 and 45 n mi diameters. Although the eye has once again cleared out and become warmer, the convective cloud tops surrounding the eye have not cooled much. However, the overall convective cloud pattern has improved and become more symmetric, and outer banding features have developed in the southeastern semicircle. Satellite intensity estimates are a consensus T6.0/115 kt from TAFB and SAB, and T6.2/122 kt from UW-CIMSS ADT. Therefore, the intensity has been increased slightly to 115 kt, making Fernanda once again a category 4 hurricane. The initial motion estimate is 285/10 kt. There is no significant change to the previous track forecast reasonings. Fernanda is forecast to be steered generally west-northwestward for the next 72 h by a large low-/mid-level ridge that spans the central and eastern Pacific Ocean, extending from north of the Hawaiian Islands eastward to the U.S. west coast. After that time, a broad upper-level trough currently located north of Hawaii is expected to weaken and lift out to the northeast, causing the ridge to build slightly southward and forcing Fernanda on a more westward track. The new NHC track forecast is similar to the previous advisory track, and lies close to the consensus model TVCN. Although Fernanda has about 24 hours or so remaining over warm-water and within a low vertical wind shear environment, there are already indications in SST data from Remote Sensing Systems that upwelling beneath the hurricane has begun. This cooler water, coupled with the ongoing ERC, makes the intensity forecast difficult in the near term. As a result, little change from the current intensity is forecast for the next 24 hours, although some intensity fluctuations could easily occur during that time. By 36 hours and beyond, steady weakening is forecast as Fernanda moves over sub-26C SSTs, and enters a hostile westerly wind shear regime by 96-120 hours. The official intensity forecast is similar to the previous one, and closely follows the consensus models ICON and IVCN. FORECAST POSITIONS AND MAX WINDS INIT 16/0900Z 12.1N 126.2W 115 KT 130 MPH 12H 16/1800Z 12.6N 127.9W 115 KT 130 MPH 24H 17/0600Z 13.4N 130.1W 115 KT 130 MPH 36H 17/1800Z 14.2N 132.0W 105 KT 120 MPH 48H 18/0600Z 15.1N 133.5W 95 KT 110 MPH 72H 19/0600Z 16.6N 136.2W 70 KT 80 MPH 96H 20/0600Z 17.3N 139.4W 50 KT 60 MPH 120H 21/0600Z 17.6N 142.7W 35 KT 40 MPH $$ Forecaster Stewart

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Hurricane Fernanda Forecast Discussion Number 17

2017-07-16 04:42:53| National Hurricane Center (East Pacific)

Issued at 800 PM PDT Sat Jul 15 2017 000 WTPZ41 KNHC 160242 TCDEP1 Hurricane Fernanda Discussion Number 17 NWS National Hurricane Center Miami FL EP062017 800 PM PDT Sat Jul 15 2017 Recent microwave imagery, including a just-received GPM overpass, indicate that Fernanda continues to have concentric eyewalls with diameters of roughly 10 and 45 n mi. The eye has become less distinct in conventional satellite imagery since the last advisory, and the central convection has become more ragged. Based on this, the initial intensity is lowered to 110 kt, which is a little below the average of the various satellite intensity estimates. While the inner core has become a little less organized since yesterday, the hurricane has developed a large and symmetric area of outer convective banding. Fernanda has about 24 h more in a warm-water, light-shear environment. The intensity forecast is based on the premise that the current eyewall replacement cycle will finish before the hurricane leaves the warmest water, and thus it calls for some re-intensification during that time. From 24-96 h, Fernanda should remain in a light shear environment, but will move over decreasing sea surface temperatures and into a drier air mass. After 96 h, the cyclone will also encounter significant westerly shear. The intensity forecast thus calls for steady to rapid weakening after 36 h. Overall, the new intensity forecast is a little higher than the model consensus for the first 36 h and near the consensus after that. Fernanda is now moving 285/12, steered by a mid- to upper-level ridge to the north and northeast. A west-northwestward motion is expected to continue for the next several days while the hurricane moves toward a weakness at the western periphery of the ridge. After 96 h, most of the guidance suggests that Fernanda should turn westward as it weakens and becomes steered by the low-level subtropical ridge. The new forecast track remains near the middle of the guidance envelope and in best agreement with the various consensus models. FORECAST POSITIONS AND MAX WINDS INIT 16/0300Z 11.7N 125.4W 110 KT 125 MPH 12H 16/1200Z 12.4N 127.3W 115 KT 130 MPH 24H 17/0000Z 13.2N 129.5W 120 KT 140 MPH 36H 17/1200Z 14.0N 131.6W 115 KT 130 MPH 48H 18/0000Z 14.7N 133.3W 100 KT 115 MPH 72H 19/0000Z 16.5N 136.0W 75 KT 85 MPH 96H 20/0000Z 17.5N 139.0W 55 KT 65 MPH 120H 21/0000Z 17.5N 142.5W 40 KT 45 MPH $$ Forecaster Beven

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