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Tropical Depression TEN-E Forecast Discussion Number 2
2015-08-06 10:33:23| National Hurricane Center (East Pacific)
Issued at 200 AM PDT THU AUG 06 2015 000 WTPZ45 KNHC 060833 TCDEP5 TROPICAL DEPRESSION TEN-E DISCUSSION NUMBER 2 NWS NATIONAL HURRICANE CENTER MIAMI FL EP102015 200 AM PDT THU AUG 06 2015 Dry mid- to upper-level air from the south has wrapped into the circulation and now surrounds the inner core, having completely cut off and weakened the convective band in the northern semicircle. However, a small concentration of deep convection has persisted near and to the west of the well-defined low-level center as noted in recent passive microwave satellite imagery. Dvorak satellite intensity estimates are a consensus T2.0/30 kt from TAFB and SAB, and a partial ASCAT-B overpass around 0552 UTC indicated 27-kt surface winds in the convection just west of the center. Therefore, the initial intensity remains at 30 kt for this advisory. The motion continues to be 270/10 kt. The depression is forecast to maintain a general westward motion for the next 48 hours or so, followed by a turn toward the west-northwest by 72 hours as the cyclone reaches the southwestern periphery of the deep-layer subtropical ridge located to its north. Most of the 0000 UTC global models, especially the GFS and ECMWF, have backed off somewhat on developing a large break in the ridge to the northeast of the Hawaiian Islands by days 4 and 5. This has resulted in a significant westward and southward shift of the guidance envelope. The official forecast track follows suit and has been shifted to the left of the previous advisory track after 72 hours, but not nearly as far left as the GFS-ECMWF model consensus. I would prefer to see a couple of more model runs before making such a large shift in the forecast track, in case this is a diurnal fluctuation for only one cycle. The cyclone is expected to remain over warm waters of at least 28C for the next 72 hours, and in a low-shear environment of 5-10 kt for the next 96 hours. These favorable factors would normally result in significant strengthening. Although proximity to the aforementioned dry air will likely inhibit and disrupt the normal intensification process, the cyclone is still forecast to achieve hurricane status by day 4. Westerly vertical wind shear of at least 20 kt is expected to impinge on the system by day 5, resulting in steady weakening. The NHC intensity forecast is similar to the intensity consensus model IVCN. FORECAST POSITIONS AND MAX WINDS INIT 06/0900Z 12.5N 130.8W 30 KT 35 MPH 12H 06/1800Z 12.6N 132.3W 35 KT 40 MPH 24H 07/0600Z 12.6N 134.3W 40 KT 45 MPH 36H 07/1800Z 12.9N 136.4W 45 KT 50 MPH 48H 08/0600Z 13.5N 138.4W 50 KT 60 MPH 72H 09/0600Z 14.7N 142.4W 60 KT 70 MPH 96H 10/0600Z 16.5N 145.6W 65 KT 75 MPH 120H 11/0600Z 18.3N 147.4W 55 KT 65 MPH $$ Forecaster Stewart
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