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Tropical Depression Fourteen-E Forecast Discussion Number 1
2021-08-25 22:50:41| National Hurricane Center (East Pacific)
Issued at 400 PM CDT Wed Aug 25 2021 000 WTPZ44 KNHC 252050 TCDEP4 Tropical Depression Fourteen-E Discussion Number 1 NWS National Hurricane Center Miami FL EP142021 400 PM CDT Wed Aug 25 2021 Scatterometer data from a few hours ago revealed that a small but sufficiently well-defined circulation has formed on the western end of a broader circulation which lies a few hundred miles south of the southern coast of Mexico. Although the system is still in its formative stages and banding features are not readily apparent, Dvorak estimates from TAFB and SAB have been a consensus T2.0/30 kt since this morning. The system is therefore now designated as a 30-kt tropical depression, although the scatterometer data suggested that its winds are already very near tropical storm force. The depression's surface center apparently formed a little south of the vorticity maximum we have been tracking over the past day or so. Therefore, the initial motion is very uncertain but is estimated to be westward, or 275/7 kt. The evolution of the steering pattern is fairly consistent among the models. A strong mid-tropospheric high over the U.S. Southern Plains is forecast to weaken over the next couple of days, causing the depression to turn from a westward motion now, to a west-northwest motion tonight, to a northwest and north-northwest motion by Friday and Saturday. On this track, most of the models bring the center of the system near but still offshore the southwestern coast of Mexico. The GFS has been a notable exception, bringing the system inland over southwestern Mexico in about 3 days. However, that model shows a complex interaction with multiple low-level centers that consolidate farther east, and most of the GEFS ensemble members remain offshore with the other deterministic models. As a result, this first NHC official forecast also shows a track remaining offshore and is a little to the left of the HCCA and TVCE consensus aids. Moderate easterly to northeasterly shear is likely to continue over the depression for the next day or so, which would temper any fast strengthening in the short term. Still, the system will be moving over warm waters of 28-29 degrees Celsius over the next few days, and lower shear in 2-3 days should allow it to strengthen to a hurricane by the weekend as it passes near the southwestern coast of Mexico and approaches the southern part of the Baja California peninsula. The intensity guidance is in fairly good agreement during the first 2 days, but there is much more spread after that time, likely related to the degree of land interaction. The NHC intensity forecast is near the consensus aids during the first 3 days and then a little bit above them on days 4 and 5, lying between the HWRF and HMON models at those forecast times. Key Messages: 1. The depression is forecast to strengthen to a tropical storm tonight and be near hurricane intensity by Saturday. While the core of the storm is currently expected to remain offshore of 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. 2. The system is expected to pass near the southern portion of Baja California Sur as a hurricane Sunday and Monday, bringing a risk of wind and rain impacts to that area early next week. Given the uncertainty in the forecast, it is too soon to determine the magnitude and location of these potential impacts, but interests in this area should monitor the progress of this system and updates to the forecast. FORECAST POSITIONS AND MAX WINDS INIT 25/2100Z 11.7N 99.4W 30 KT 35 MPH 12H 26/0600Z 12.0N 100.4W 35 KT 40 MPH 24H 26/1800Z 12.8N 102.1W 40 KT 45 MPH 36H 27/0600Z 13.6N 103.7W 45 KT 50 MPH 48H 27/1800Z 14.7N 105.0W 55 KT 65 MPH 60H 28/0600Z 16.2N 106.0W 60 KT 70 MPH 72H 28/1800Z 18.0N 106.9W 65 KT 75 MPH 96H 29/1800Z 21.1N 109.6W 75 KT 85 MPH 120H 30/1800Z 22.7N 112.1W 65 KT 75 MPH $$ Forecaster Berg
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