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Aug
29
2017

Tropical Cyclone Activity Report – Pacific Ocean / Indian Ocean / Arabian Sea

Tropical Cyclone 17W (Sanvu) is located about 197 NM east-southeast of Chichi Jima, Japan

Potential Tropical Cyclone 14E  is located about 380 miles south-southeast of the southern tip of Baja California

PDC Disaster Alert, displaying PDC Active Hazards, Tropical Cyclone segments, positions, wind radii, for TC 17W (Sanvu)

Tropical Storm 17W (Sanvu) will strengthen…reaching typhoon status

Here’s a satellite image of this system…along with what the computer models are showing

Here’s a looping satellite image of this storm

The Joint Typhoon Warning Center reports that satellite images show an elongated system with a large main feeder band extending 20 degrees to the southwest. This band is wrapping into a partially exposed low level circulation center…with convection sheared to the northeast.

Environmental analysis reveals TS 17W is being offset by strong poleward and equatorward outflow channels…along with warm sea surface temperatures along the systems track.

TS 17W is forecast to move northwest, and after 24 hours the system will slow considerably. By 48 hours, TS Sanvu will curve to the northeast and accelerate. Marginally favorable environmental conditions will persist along the strong track, allowing the system attain a peak intensity of 75 knots.

After 72 hours, TS Sanvu will track northeastward and gradually accelerate, after 96 hours the system will begin extra-tropical transition. The environment will become increasingly unfavorable, as wind shear increases, causing TS 17W to gradually weaken.

Maximum sustained winds as of the JTWC Warning #6 were 50 knots with gusts of 65 knots

PDC Disaster Alert, displaying PDC Active Hazards, 3-hour Precipitation Accumulation, and a tropical disturbance with a high chance of developing (circled in red above)

Meanwhile, in the northeastern Pacific, a tropical disturbance, referred to as Invest 94E…is now Potential Tropical Cyclone 14E

Here’s a satellite image…and what the computer models are showing

According to the NHC:

Satellite images indicate that the disturbance just off the
southwest coast of Mexico is gradually becoming better organized.
The system is developing some banding features, especially over the
western semicircle.  However, the circulation remains broad and
there is no indication of a well-defined center at this time.  The
initial wind speed is held at 25 kt, in agreement with a Dvorak
classification from TAFB.  The environmental conditions are
conducive for the disturbance to strengthen, and it will likely
become a tropical storm on Wednesday.  Additional strengthening
seems likely through about 72 hours, and it is possible that the
disturbance could reach hurricane strength.  After that time,
however, decreasing SSTs and drier air should end the strengthening
trend and cause weakening.  The NHC intensity forecast lies near the
high end of the guidance, and it is very similar to the previous
forecast.

The initial motion of the system is difficult to determine since
there is no clear center, but satellite fixes suggest that the
disturbance is moving northwestward at 9 kt.  A slower northwestward
to north-northwestward motion is expected during the next 2 to 3
days, followed by a turn to the left beyond that time when the
system moves on the south side of a mid-level ridge over the
western United States.  The models have shifted to the east this
cycle, and the new NHC track forecast has been adjusted in that
direction.  This forecast takes the center of the system close to
Baja California Sur in the 48- to 72-h time frame.  Based on the new
forecast, the government of Mexico has expanded the Hurricane Watch
northward on the west coast of Baja California Sur.

It is important to note that very heavy rain is possible outside of
the watch/warning area in southwestern Mexico.  These rains could
cause life-threatening flooding and mudslides.  In addition,
wind gusts to tropical-storm-force are possible along the coast of
Michoacan, Colima and Jalisco states through early Wednesday due to
the system's large circulation.

The National Hurricane Center now has the option to issue
advisories, watches, and warnings for disturbances that are not yet
a tropical cyclone, but which pose the threat of bringing tropical
storm or hurricane conditions to land areas within 48 hours.  Under
previous policy this was not possible.  These systems are known as
Potential Tropical Cyclones in advisory products and are numbered
from the same list as depressions.

Because of the threat to Baja California Sur, advisories are being
issued on Potential Tropical Cyclone Fourteen-E.  Advisory packages
will continue until the threat of tropical-storm-force winds for
land areas sufficiently diminishes, although if the system becomes a
tropical cyclone, the normal rules for discontinuing advisories
would apply.  Users should be aware that forecast uncertainty for
disturbances is generally larger than for tropical cyclones,
especially beyond 48-72 hours.

HAZARDS AFFECTING LAND:

WIND:  Tropical storm conditions are expected to first reach the
coast within the warning area by late Wednesday, making outside
preparations difficult or dangerous.  Hurricane conditions are also
possible within the watch area on Thursday.  Tropical-storm-force
wind gusts are possible in rainbands along the coast of Michoacan,
Colima and Jalisco tonight and Wednesday.

RAINFALL:  The system is expected to produce total rain
accumulations of 5 to 10 inches in the Mexican states of Michoacan,
Colima, Jalisco and Nayarit, with isolated maximum totals of 20
inches possible along the immediate coast.  This rain could cause
life-threatening flash floods and mudslides.

SURF:  Swells generated by the disturbance are affecting portions of
the coast of southwestern Mexico.  These swells will likely reach
the southern portions of the Baja California Sur on Wednesday, and
could cause life-threatening surf and rip current conditions.

* Formation chance through 48 hours…high…100 percent
* Formation chance through 5 days…high…100 percent

Eastern North Pacific

Potential Tropical cyclone 14E 

NHC textual forecast advisory
NHC graphical track map
NOAA satellite image

Satellite image of this area

Central North Pacific

There are no current tropical cyclones

Western North Pacific

Tropical cyclone 17W (Sanvu)

JTWC textual forecast warning
JTWC graphical track map
NOAA satellite image

South Pacific

There are no current tropical cyclones

Satellite image of this area

North Indian Ocean

There are no current tropical cyclones

Satellite image of this area

South Indian Ocean

There are no current tropical cyclones

Satellite image of this area

North Arabian Sea

There are no current tropical cyclones

Satellite image of this area

 

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