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Tropical Storm Pamela Forecast Discussion Number 8
2021-10-12 04:38:03| National Hurricane Center (East Pacific)
Issued at 900 PM MDT Mon Oct 11 2021 000 WTPZ41 KNHC 120237 TCDEP1 Tropical Storm Pamela Discussion Number 8 NWS National Hurricane Center Miami FL EP162021 900 PM MDT Mon Oct 11 2021 Pamela continues to be affected by some modest northwesterly mid-level shear that has caused the low-level center to be located near the northwestern edge of the deep convection. This was evident in an earlier AMSR2 microwave image that arrived shortly after the release of the previous NHC advisory package. Recent objective and subjective Dvorak T-numbers still support an intensity of around 60 kt, and that value is maintained as the initial wind speed for this advisory. An Air Force Reserve reconnaissance aircraft is scheduled to fly into the storm late tomorrow morning and early afternoon to better provide a better assessment of Pamela's structure, intensity, and wind field. The guidance suggests that the shear that has been plaguing Pamela should relax during the next 12-24 hours, allowing for strengthening. Nearly all of the statistical and dynamical model intensity guidance calls for strengthening, but they have trended toward a lower peak intensity primarily due to the fact that Pamela so far has not strengthened as much as expected. The NHC intensity forecast again calls for Pamela to become a hurricane overnight or early Tuesday, and shows the system nearing major hurricane strength before it reaches the coast of mainland Mexico early Wednesday. Although the official forecast is at the high end of the intensity guidance, it is supported by the GFS model which has been consistent in significantly deepening Pamela during the cyclone's approach to Mexico on Tuesday and Tuesday night. After landfall, rapid weakening should occur as the system moves over the mountainous terrain of west-central Mexico, and Pamela is forecast to become a post-tropical remnant low or dissipate by Thursday. Pamela is moving north-northwestward or 335/7 kt. The track forecast philosophy again remains unchanged this advisory. The cyclone is forecast to turn northward tonight as it reaches the western portion of a deep-layer subtropical ridge. A faster northeastward motion is expected by late Tuesday as Pamela recurves ahead of a broad mid-latitude trough moving into northwestern Mexico. The track guidance is in very good agreement on the overall evolution of the steering pattern, but there are still some differences in how quickly Pamela accelerates northeastward on Tuesday. Therefore, the NHC forecast is once again close to the various multi-model consensus aids. Although the cyclone could dissipate over the mountainous terrain of Mexico, deep moisture associated with the system's remnants are likely to spread over north-central and northeastern Mexico on Wednesday, and then move into portions of the south-central United States late Wednesday or Thursday. Key Messages: 1. Pamela is forecast to be near major hurricane intensity when it reaches the southwestern coast of Mexico on Wednesday morning, and life- threatening storm surge and dangerous hurricane-force winds are expected within the Hurricane Warning area. Residents in this area should follow any advice given by local officials. 2. Pamela is expected to pass south of the southern tip of the Baja California peninsula as a hurricane on Tuesday and Tuesday night, and tropical-storm conditions are possible within the Tropical storm Watch area. 3. Heavy rains associated with Pamela are expected to move into the Mexican States of Sinaloa and western Durgano along with southern portions of Baja California Sur Tuesday and Wednesday. This will pose a threat of significant and life-threatening flash flooding and mudslides. 4. Heavy rains associated with the remnants of Pamela are expected across portions of central Texas and southeastern Oklahoma late Wednesday and Thursday. This may result in flash and urban flooding. FORECAST POSITIONS AND MAX WINDS INIT 12/0300Z 17.9N 108.9W 60 KT 70 MPH 12H 12/1200Z 19.2N 109.1W 70 KT 80 MPH 24H 13/0000Z 21.0N 108.5W 85 KT 100 MPH 36H 13/1200Z 23.1N 106.9W 95 KT 110 MPH 48H 14/0000Z 26.1N 103.3W 40 KT 45 MPH...INLAND 60H 14/1200Z 29.5N 99.5W 25 KT 30 MPH...POST-TROP/INLAND 72H 15/0000Z...DISSIPATED $$ Forecaster Brown
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