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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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