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Tropical Depression Daniel Forecast Discussion Number 8

2018-06-25 22:32:21| National Hurricane Center (East Pacific)

Issued at 200 PM PDT Mon Jun 25 2018 000 WTPZ45 KNHC 252032 TCDEP5 Tropical Depression Daniel Discussion Number 8 NWS National Hurricane Center Miami FL EP052018 200 PM PDT Mon Jun 25 2018 Convection associated with Daniel continues to diminish as the cyclone moves over cooler water, and most satellite intensity estimates have dropped below tropical-storm strength. Thus, Daniel is downgraded to a tropical depression. The system should continue to weaken over sea surface temperatures near 23C, and it is forecast to degenerate into a remnant low by 24 h and to dissipate completely between 48-72 h. The initial motion is now 305/7. Daniel should turn more westward during the next 24 h as low-level easterly flow on the south side of the subtropical ridge becomes the main steering mechanism, and this motion should continue through dissipation. The new track forecast is similar to the previous forecast and it is a little north of the center of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 25/2100Z 19.4N 118.1W 30 KT 35 MPH 12H 26/0600Z 19.8N 119.4W 25 KT 30 MPH 24H 26/1800Z 20.0N 121.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 27/0600Z 20.1N 123.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 48H 27/1800Z 20.0N 125.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 28/1800Z...DISSIPATED $$ Forecaster Beven

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Tropical Storm Daniel Forecast Discussion Number 7

2018-06-25 16:33:16| National Hurricane Center (East Pacific)

Issued at 800 AM PDT Mon Jun 25 2018 000 WTPZ45 KNHC 251433 TCDEP5 Tropical Storm Daniel Discussion Number 7 NWS National Hurricane Center Miami FL EP052018 800 AM PDT Mon Jun 25 2018 Convection associated with Daniel is gradually diminishing as the cyclone moves over cooler water, with the remaining convection just to the west or southwest of the center. The initial intensity is reduced to 35 kt based on various subjective and objective satellite intensity estimates. Daniel should continue to weaken over sea surface temperatures of 23-24C, with the system expected to drop below tropical storm strength in the next 12 h and to degenerate to a remnant low by 36 h. The cyclone is starting its expected left turn with the initial motion now 315/8. A combination of a mid- to upper-level low to the west-southwest and a low- to mid-level ridge to the north should cause Daniel to turn west-northwestward to westward during the next 36 h, with the westward motion continuing until the cyclone dissipates. The new track forecast is similar to the previous forecast and is close to the center of the guidance envelope through 48 h. FORECAST POSITIONS AND MAX WINDS INIT 25/1500Z 19.0N 117.8W 35 KT 40 MPH 12H 26/0000Z 19.6N 118.9W 30 KT 35 MPH 24H 26/1200Z 20.1N 120.6W 25 KT 30 MPH 36H 27/0000Z 20.2N 122.4W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 27/1200Z 20.3N 124.4W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 28/1200Z 20.0N 128.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 29/1200Z...DISSIPATED $$ Forecaster Beven

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Tropical Storm Daniel Forecast Discussion Number 6

2018-06-25 10:39:39| National Hurricane Center (East Pacific)

Issued at 200 AM PDT Mon Jun 25 2018 000 WTPZ45 KNHC 250839 TCDEP5 Tropical Storm Daniel Discussion Number 6 NWS National Hurricane Center Miami FL EP052018 200 AM PDT Mon Jun 25 2018 Cloud tops have been steadily warming since the previous advisory and the overall amount of convection has also been shrinking. However, a small mass of convection has persisted near and over the low-level center, and a 0443Z ASCAT partial pass indicated that the wind field in the western semicircle hadn't changed since the previous overpasses just 12 h prior. Therefore, it is assumed that winds near 40 kt still exists in the unsampled eastern semicircle. The last UW-CIMSS SATCON estimate at 0225Z was 43 kt. Based on the apparent lack of any significant low-level structural change noted in the latest ASCAT data, along with the SATCON estimate, the intensity is being maintained at 40 kt for this advisory. The initial motion estimate is 330/09 kt. Daniel is expected to gradually make a turn toward the northwest within the next 12 h as the small cyclone moves around the eastern periphery of a mid- to upper-level low located about 450 nmi to the west-southwest. As Daniel moves over progressively cooler waters, the weakening cyclone will become vertically more shallow and be steered westward by the low-level easterly tradewind flow on days 2-4. The latest model guidance remains good agreement with this developing track scenario. As a result, the new NHC track forecast is similar to the previous advisory track and is close to the consensus models TVCN and HCCA. The small cyclone is currently located over sea-surface temperatures (SST) of about 25C, with colder water lying ahead of the system. Although the vertical wind shear is forecast to be low, steady weakening and gradual erosion of the central convection is expected throughout the forecast period due to the colder SSTs and a lack of instability, especially after 12-18 hours. Daniel is forecast to weaken to a depression by 24 h, and degenerate into a remnant low pressure system shortly thereafter. However, given the current small and relatively weak circulation, faster weakening could occur than what is currently indicated. The latter scenario is supported by the ECMWF and UKMET models, which show dissipation by 72 hours. FORECAST POSITIONS AND MAX WINDS INIT 25/0900Z 18.8N 116.9W 40 KT 45 MPH 12H 25/1800Z 19.5N 117.8W 35 KT 40 MPH 24H 26/0600Z 20.2N 119.3W 30 KT 35 MPH 36H 26/1800Z 20.4N 121.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 27/0600Z 20.5N 122.8W 25 KT 30 MPH...POST-TROP/EXTRATROP 72H 28/0600Z 20.3N 126.7W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 29/0600Z...DISSIPATED $$ Forecaster Stewart

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Tropical Storm Daniel Forecast Discussion Number 5

2018-06-25 04:35:38| National Hurricane Center (East Pacific)

Issued at 800 PM PDT Sun Jun 24 2018 000 WTPZ45 KNHC 250235 TCDEP5 Tropical Storm Daniel Discussion Number 5 NWS National Hurricane Center Miami FL EP052018 800 PM PDT Sun Jun 24 2018 Daniel's convective structure is slowly degrading. Recent IR imagery indicates that active deep convection is primarily occuring in a single burst, southwest of the tropical storm's center. The initial intensity has been held at 40 kt based on an earlier ASCAT overpass around 1700 UTC, but given the overall degradation of the structure of the cyclone since that time, it is possible this is generous. The tropical storm is quickly approaching the 26 deg C isotherm, so it is likely that Daniel has already reached its peak intensity. All of the guidance is in good agreement that the cyclone will gradually spin down over the next couple of days, likely losing all deep convection within the next 48 h. Essentially no change has been made to the NHC intensity forecast, which now calls for Daniel to dissipate by 96 hours. Several recent microwave overpasses suggest that the center of the tropical storm is slightly northeast of the previous estimate. As a result, the official track forecast has been nudged in that direction for the first 24 hours, but is very similar to the previous advisory beyond that time. There is otherwise no change in the reasoning behind the track forecast, and Daniel is still expected to begin a turn toward the northwest by tomorrow as it moves along the eastern edge of a weak mid-level low. Once Daniel becomes a remnant low, it will be steered westward in the low-level tradewind flow. The new official track forecast remains near the middle of the track guidance envelope, close to the consensus models TVCN and HCCA. FORECAST POSITIONS AND MAX WINDS INIT 25/0300Z 17.9N 116.4W 40 KT 45 MPH 12H 25/1200Z 18.9N 117.4W 35 KT 40 MPH 24H 26/0000Z 19.7N 118.8W 30 KT 35 MPH 36H 26/1200Z 20.1N 120.3W 30 KT 35 MPH 48H 27/0000Z 20.2N 122.0W 25 KT 30 MPH...POST-TROP/EXTRATROP 72H 28/0000Z 20.1N 126.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 29/0000Z...DISSIPATED $$ Forecaster Zelinsky

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Tropical Storm Daniel Forecast Discussion Number 4

2018-06-24 22:36:36| National Hurricane Center (East Pacific)

Issued at 200 PM PDT Sun Jun 24 2018 000 WTPZ45 KNHC 242036 TCDEP5 Tropical Storm Daniel Discussion Number 4 NWS National Hurricane Center Miami FL EP052018 200 PM PDT Sun Jun 24 2018 Daniel continues to generate a curved band of convection near the center, although the cloud tops have warmed notably during the past several hours. A recent ASCAT overpass showed maximum winds of 40 kt in the southeastern quadrant, so the initial intensity has been increased to that value. The initial and forecast wind radii have also been revised based on the scatterometer data. The initial motion is now 340/10. There is again no change in the track forecast philosophy, as the various dynamical models remain in good agreement that Daniel will move northward around the east side of a mid-/upper-level low for the next 12-18 hours, then encounter the broad Pacific subtropical ridge to its north. This should result in a northwestward turn on Monday and a generally westward motion on Tuesday and beyond. The only appreciable change in the guidance since the last advisory is that the cyclone is forecast to move a little faster. Thus, the official forecast is mostly an update of the previous track with a slightly faster forward speed. Daniel should cross the 26C isotherm in 12 h or less, and the forecast track takes the system over progressively cooler water. Thus, the new intensity forecast calls for a slow weakening after 12 h, with the cyclone forecast to weaken to a depression by 36 h, degenerate to a remnant low by 72 h, and dissipate completely between 96-120 h. All of these events could occur earlier than currently forecast. FORECAST POSITIONS AND MAX WINDS INIT 24/2100Z 16.9N 116.4W 40 KT 45 MPH 12H 25/0600Z 18.1N 117.1W 40 KT 45 MPH 24H 25/1800Z 19.2N 118.3W 35 KT 40 MPH 36H 26/0600Z 19.8N 119.6W 30 KT 35 MPH 48H 26/1800Z 20.2N 121.2W 25 KT 30 MPH 72H 27/1800Z 20.5N 124.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 28/1800Z 20.0N 128.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 29/1800Z...DISSIPATED $$ Forecaster Beven

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