ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM Tropical Depression Twenty-Two-E Discussion Number 3 NWS National Hurricane Center Miami FL EP222018 1000 PM CDT Sun Oct 14 2018 For the first time in the depression's (and its predecessor low's) existence, deep convection has persisted for more than a few hours. The convective canopy has been slowly expanding, although it is still a little restricted on the eastern side due some easterly shear. Based on microwave data, the structure of the cyclone has been slow to improve in organization, and consensus T2.0s from TAFB and SAB support maintaining a 30-kt initial intensity. The depression is located near the western edge of a mid-level ridge, with a deep-layer trough located not too far to the north across northwestern Mexico and the western United States. Its position places the depression within weak steering currents, and the system is likely to drift west-northwestward or even meander at speeds of less than 5 kt for much of the forecast period. The track guidance has shifted a little more to the northwest on this cycle, and the NHC forecast has therefore been adjusted north of the previous official forecast, although not as far as the TVCN multi-model consensus nor the HCCA aid. Despite this adjustment, the cyclone is expected to remain small, which should keep tropical-storm-force winds offshore of the coast of Mexico. The forecast reasoning for the future intensity has changed substantially. For the first 3 days, vertical shear is expected to gradually decrease, and the cyclone's small size will make it prone to significant strengthening during that period. In fact, based on the Rapid Intensification Indices, the chance of a 30-kt increase in 24 hours is 3 times more than average, and the chance of a 65-kt increase in 72 hours is almost 9 times more than average. Therefore, the NHC intensity forecast is above most of the guidance through day 3, with the possibility of the depression becoming a hurricane during that time. After day 3, the models are trending toward the cyclone entering a region of higher shear associated with the western U.S. trough, which would likely lead to a weakening trend. Most of the intensity models suggest that the cyclone's intensity will peak around 3 days, and therefore the NHC intensity forecast now indicates weakening on days 4 and 5 (although it is still well above most of the models). This is a low-confidence intensity forecast, and additional adjustments are likely in future advisories. The small size of the circulation and its projected motion away from Mexico does not require tropical storm warnings or watches at this time. However, only a slight deviation to the right of the forecast track would bring stronger winds closer to the coast, which would require the issuance of a tropical storm warning. Regardless of the winds, heavy rainfall will be the primary threat along the coast of southwestern Mexico due to the system's slow motion, and flash flooding will be possible in mountainous areas. FORECAST POSITIONS AND MAX WINDS INIT 15/0300Z 17.5N 104.3W 30 KT 35 MPH 12H 15/1200Z 17.7N 104.7W 35 KT 40 MPH 24H 16/0000Z 17.7N 104.7W 40 KT 45 MPH 36H 16/1200Z 17.8N 105.0W 45 KT 50 MPH 48H 17/0000Z 17.9N 105.3W 50 KT 60 MPH 72H 18/0000Z 18.4N 106.8W 65 KT 75 MPH 96H 19/0000Z 19.3N 108.4W 60 KT 70 MPH 120H 20/0000Z 19.6N 108.9W 55 KT 65 MPH $$ Forecaster Berg NNNN
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