je.st
news
Tropical Depression Ten-E Forecast Discussion Number 1
2018-07-31 22:39:41| National Hurricane Center (East Pacific)
Issued at 200 PM PDT Tue Jul 31 2018 142 WTPZ45 KNHC 312039 TCDEP5 Tropical Depression Ten-E Discussion Number 1 NWS National Hurricane Center Miami FL EP102018 200 PM PDT Tue Jul 31 2018 The broad low pressure system and area of disturbed weather that the NHC has been tracking for the past several days has finally become well-defined enough and has acquired sufficient organized deep convection near the center to be classified as a tropical depression. The low-level center is estimated to be just inside the southeastern edge of the figure-6 cloud mass based on conventional and microwave satellite fix data. The initial intensity estimate of 30 kt is based on Dvorak satellite classifications of T2.0/30 kt from TAFB and T2.5/35 kt from SAB, along with uncontaminated 30-kt winds in a 1634 UTC Scatsat-1 scatterometer pass. The initial motion estimate is west-northwestward or 290/11 kt. A deep-layer ridge to the north of the depression should keep the tropical cyclone moving toward the west-northwest for the next 48 hours or so, followed by a turn toward the west thereafter due to the ridge building slightly southward on days 3-5. The NHC track forecast closely follows a blend of the consensus models TVCN and HCCA since this is the first forecast on this system. Although the comma-shaped cloud pattern is suggestive of a slightly stronger system, microwave imagery and the Scatsat-1 pass indicate that the circulation envelope is elongated northeast-to-southwest, and that westerly winds likely only extend about 30 n mi to the south of the center. Due to the cyclone's irregular shape, the peak winds are being held lower than the Dvorak T2.5 data-T numbers. Visible satellite imagery shows the tops of shallow convection in the eastern semicircle blowing off toward the west, which is indicative of modest mid-level shear undercutting the favorable high-level cirrus outflow layer. This mid-level flow is also likely producing some intrusions of dry air, a negative condition that should act to inhibit inner-core convective development in the short term. These aforementioned unfavorable environmental conditions, in conjunction with the irregular shape of the cyclone's circulation, should result in only slow strengthening for the next 48 hours or so, despite the very favorable deep-layer, low vertical wind shear environment. In the 48-72 h period, both the GFS and ECMWF models are forecasting the shear to increase to near 15 kt, which should act to maintain only slow development. By days 4 and 5, the shear is forecast to abate, and the cyclone is forecast to become a hurricane by 120 hours. The intensity forecast follows the trend of the HCCA and IVCN intensity consensus models, but is slightly higher due to the HMON model showing immediate weakening, which is pulling down the consensus intensity forecasts. FORECAST POSITIONS AND MAX WINDS INIT 31/2100Z 12.7N 116.7W 30 KT 35 MPH 12H 01/0600Z 13.1N 118.4W 35 KT 40 MPH 24H 01/1800Z 13.6N 120.3W 40 KT 45 MPH 36H 02/0600Z 13.8N 122.4W 45 KT 50 MPH 48H 02/1800Z 14.0N 124.6W 50 KT 60 MPH 72H 03/1800Z 13.8N 128.7W 55 KT 65 MPH 96H 04/1800Z 13.7N 132.6W 60 KT 70 MPH 120H 05/1800Z 13.6N 136.7W 65 KT 75 MPH $$ Forecaster Stewart
Tags: number
discussion
tropical
depression
Category:Transportation and Logistics
Latest from this category |
All news |
||||||||||||||||||
|
|||||||||||||||||||