Tropical Storm Gilma Discussion Number 3
NWS National Hurricane Center Miami FL EP082018
200 AM PDT Fri Jul 27 2018
The cloud pattern associated with the cyclone has lost organization
during the past several hours, with the low-level center now located
at the northern edge of a smaller area of convection. Despite the
ragged appearance in satellite imagery, recent ASCAT-A data showed
an area of 35 kt winds to the northeast of the center. Based on
this, the cyclone has been upgraded to Tropical Storm Gilma.
The initial motion is 285/14. Gilma should be steered westward to
west-northwestward along the southwestern flank of a large mid-level
ridge extending westward from the southwestern United States. As
the cyclone decays to a shallow remnant low late in the period, a
more westward motion is expected. The new track forecast is
similar to, but a little faster than the previous forecast, and it
is a blend of the previous forecast and the multi-model consensus
aids.
Gilma is located just to the east of an upper-level trough, which
the large-scale models forecast to move or re-form westward just
ahead of the storm for the next couple of days. This evolution is
expected to keep the cyclone in an area of moderate vertical wind
shear, but with some upper-level divergence to maintain convection.
Based on this, the intensity forecast shows a little more
strengthening in agreement with the overall trend of the intensity
guidance. After 36-48 h, Gilma is likely to move into strong and
dry northwesterly upper-level flow west of the upper-level trough
axis, which should lead to weakening and eventual dissipation. The
new intensity forecast now shows dissipation by 120 h in agreement
with the dynamical models.
Tropical Depression Eight-E Discussion Number 1
NWS National Hurricane Center Miami FL EP082018
200 PM PDT Thu Jul 26 2018
A recent ASCAT pass indicated that a very small 30-kt circulation
has developed in association with the disturbance that the NHC has
been tracking southwest of Baja California Sur during the past
several days. On this basis, advisories are initiated on Tropical
Depression Eight. However, the satellite presentation is not very
well organized at this time, and Dvorak T-numbers are still low.
Given the current environment of low shear and warm ocean, gradual
strengthening is anticipated. However, global models indicate that
the shear will markedly increase beyond 48 hours, and this wind
pattern should result in weakening. The NHC forecast is a blend of
HCCA and the simple intensity consensus.
The depression is moving toward the west or west-northwest at 14 kt
around the periphery of the strong subtropical ridge. Since the
ridge is forecast to persist, no significant change in the steering
flow is anticipated. The cyclone should then continue on the same
track for the next several days, although by the end of the
forecast period, the cyclone is forecast to become a westward
moving remnant low. The NHC forecast is very close to the
multi-model consensus.
組圖打開中，請稍候......