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Tropical Depression One-E Forecast Discussion Number 3
2019-06-26 10:34:19| National Hurricane Center (East Pacific)
Issued at 300 AM MDT Wed Jun 26 2019 000 WTPZ41 KNHC 260834 TCDEP1 Tropical Depression One-E Discussion Number 3 NWS National Hurricane Center Miami FL EP012019 300 AM MDT Wed Jun 26 2019 The overall convective pattern of the cyclone has changed little since the previous advisory. However, passive microwave images indicate that the low-level center has become less distinct and that the inner-core convection has become ragged. In addition, the coldest cloud tops have migrated from north through east to now south of the center during the past 12 hours, another indication that the inner-core of the depression is undergoing some structural changes. Although no ASCAT wind data are available over the cyclone's core, a 0417Z ASCAT-C pass did catch the western portion of the circulation and only showed northerly winds of 5-10 kt within 30 nmi of the center, which suggests that the surface wind field might not be as well developed as the circulation aloft is. The initial position and the 275/13-kt motion are based on a blend of microwave and conventional fixes, and also continuity with the previous motion vector. The latest track model guidance is in decent agreement on a westward to west-northwestward motion accompanied by a gradual decrease in forward speed over the next few days as a strong deep-layer subtropical ridge holds steady to the north of the cyclone. The new NHC track forecast is similar to but south of the previous advisory track, mainly due to the more southerly initial position. As mentioned in the previous forecast package, the 00Z ECMWF model continues to show a more southward dip in the track during the next 24 h. That is a viable alternate track scenario if the center redevelops farther south closer to the coldest overshooting cloud tops later this morning. There is a narrow window of opportunity for the system to strengthen into a tropical storm during the next 24 h or so while the cyclone remains over warm water and in low vertical wind shear conditions. By 36-48 hours, the cyclone is expected to move over sub-26C SSTs and into a more stable environment that is not conducive for generating vigorous convection despite the favorable low-shear conditions forecast at that time. The combination of cooler waters, drier mid-level air, and increasing southwesterly wind shear shear are expected to induce steady weakening in 48-96 hours, with dissipation forecast by 120 h. The official intensity forecast is similar to the previous advisory, and follows the IVCN and ICON intensity consensus models. FORECAST POSITIONS AND MAX WINDS INIT 26/0900Z 15.5N 108.3W 30 KT 35 MPH 12H 26/1800Z 15.6N 110.3W 35 KT 40 MPH 24H 27/0600Z 15.8N 112.7W 35 KT 40 MPH 36H 27/1800Z 16.4N 114.9W 35 KT 40 MPH 48H 28/0600Z 17.0N 116.9W 30 KT 35 MPH 72H 29/0600Z 18.1N 120.4W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 30/0600Z 18.8N 123.8W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 01/0600Z...DISSIPATED $$ Forecaster Stewart
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