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Tropical Depression Two Forecast Discussion Number 1
2018-07-05 16:43:17| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Thu Jul 05 2018 000 WTNT42 KNHC 051443 TCDAT2 Tropical Depression Two Discussion Number 1 NWS National Hurricane Center Miami FL AL022018 1100 AM AST Thu Jul 05 2018 For the past day or so, we've been monitoring a small area of low pressure associated with a tropical wave over the tropical Atlantic Ocean. Despite a noticeable mid-level rotation in the convective clouds, it had not been conclusive whether or not the system had a closed circulation at the surface with a well-defined center. However, the system appears more distinct and independent from the Intertropical Convergence Zone as compared to yesterday, and scatterometer data appears conclusive enough to support a closed, yet tiny circulation. We are now confident enough that the system meets the criteria of a tropical cyclone, and have initiated advisories on Tropical Depression Two with maximum winds of 30 kt, which is supported by Dvorak classifications from TAFB and SAB. The depression will be located in a relatively low-shear environment for the next 3 days or so. However, the small cyclone is surrounded by abundant dry air, and the system will be moving over marginally warm waters during the next few days, which could both limit intensification. The NHC official forecast allows for some slight strengthening and most closely follows the HFIP Corrected Consensus guidance (HCCA), showing the depression becoming a tropical storm within the next 24 hours. Between 72 and 96 hours, the system is expected to begin encountering strong westerly shear and also accelerate, both of which should cause it to degenerate into an open wave east of the Lesser Antilles. Even though the center has been difficult to locate, the initial motion is estimated to be westward, or 270/14 kt. The depression is located to the south of a sprawling subtropical ridge, although a break in the ridge over the central Atlantic may cause the system to slow down a bit during the next 36 hours. After that time, the cyclone is likely to speed up again when it becomes situated to the south of a new mid-level high. The track guidance is in generally good agreement, and the NHC official forecast is close to the TVCX multi-model consensus and the HCCA guidance. Even though the cyclone is expected to dissipate east of the Lesser Antilles early next week, the remnant tropical wave will continue moving quickly westward, likely bringing locally heavy rains and gusty winds to portions of the Leeward Islands on Sunday and Monday. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 10.2N 41.4W 30 KT 35 MPH 12H 06/0000Z 10.7N 43.1W 30 KT 35 MPH 24H 06/1200Z 11.4N 45.2W 35 KT 40 MPH 36H 07/0000Z 12.1N 47.2W 35 KT 40 MPH 48H 07/1200Z 12.9N 49.6W 35 KT 40 MPH 72H 08/1200Z 14.7N 56.6W 35 KT 40 MPH 96H 09/1200Z...DISSIPATED $$ Forecaster Berg
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