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Tropical Depression Fourteen-E Forecast Discussion Number 2
2021-08-26 04:43:50| National Hurricane Center (East Pacific)
Issued at 1000 PM CDT Wed Aug 25 2021 000 WTPZ44 KNHC 260243 TCDEP4 Tropical Depression Fourteen-E Discussion Number 2 NWS National Hurricane Center Miami FL EP142021 1000 PM CDT Wed Aug 25 2021 Recent satellite imagery and microwave data indicate that the depression has not become better organized this evening. It is producing a ragged area of convection over the northwestern portion of its circulation, which appears somewhat elongated along an east-west axis. The latest UW-CIMSS objective ADT estimate and subjective 00z Dvorak classifications from TAFB and SAB support an initial intensity of 30 kt for this advisory. The estimated initial motion of the poorly organized depression is an uncertain 280/6 kt. The cyclone is being steered generally westward along the southern extent of a mid-level ridge over the south-central United States. A deep-layer trough over the western U.S. is forecast to weaken the steering ridge during the next couple of days. Thus, the depression is forecast to gain some latitude and move west-northwestward overnight and Thursday, and then northwestward or north-northwestward on Friday and Saturday. Although the track guidance consensus and many GEFS and ECMWF ensemble members still keep the center of the cyclone offshore, there was a pronounced eastward shift in the guidance envelope this cycle. In fact, the GFS and several GEFS members show the system moving inland along the coast of southwestern Mexico in 2-3 days. The official NHC track forecast has been adjusted to the right of the previous one from 48 h onward and lies along the HFIP corrected consensus approach (HCCA) aid. This brings the center of the cyclone closer to the coast of southwestern Mexico, but remains offshore and to the left of much of the latest guidance. The extended forecast takes the system near the southern portion of Baja California Sur early next week, but overall there is above average uncertainty in the extended portion of the track forecast. Interests along the coast of southwestern Mexico and in Baja California Sur should closely monitor future updates to the forecast. The depression is located within a favorable thermodynamic environment for strengthening, but moderate to strong northeasterly vertical wind shear should limit its intensification rate in the short-term period. The shear is expected to weaken by Friday, and the system is forecast to become a hurricane this weekend over very warm SSTs. There remains a large amount of spread in the intensity guidance beyond 48 h, due to the potential for land interaction earlier in the forecast period. Since the latest NHC track forecast keeps the system offshore, the intensity forecast is much higher than the consensus aids during this period and trends toward the stronger statistical-dynamical guidance. Again, confidence is lower than normal in the day 3-5 forecast. Key Messages: 1. The depression is forecast to strengthen to a tropical storm on Thursday and be near hurricane intensity by Saturday. While the core of the storm is currently expected to pass near but offshore the southwestern coast of Mexico, strong winds and heavy rainfall, possibly resulting in flash floods and mudslides, could affect portions of that area over the next several days. Interests in this area should closely monitor the progress of this system and updates to the forecast. 2. The system is forecast to pass near the southern portion of Baja California Sur as a hurricane early next week, bringing a risk of wind and rain impacts to that area. Given the above average uncertainty in the forecast, it is too soon to determine the magnitude and location of these potential impacts. FORECAST POSITIONS AND MAX WINDS INIT 26/0300Z 11.9N 100.1W 30 KT 35 MPH 12H 26/1200Z 12.3N 101.2W 35 KT 40 MPH 24H 27/0000Z 13.1N 102.7W 40 KT 45 MPH 36H 27/1200Z 14.2N 103.9W 45 KT 50 MPH 48H 28/0000Z 15.6N 104.8W 55 KT 65 MPH 60H 28/1200Z 17.2N 105.6W 60 KT 70 MPH 72H 29/0000Z 18.8N 106.5W 65 KT 75 MPH 96H 30/0000Z 21.3N 108.7W 70 KT 80 MPH 120H 31/0000Z 23.0N 111.0W 60 KT 70 MPH $$ Forecaster Reinhart/Pasch
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