000
WTPZ42 KNHC 202031
TCDEP2

TROPICAL STORM LOWELL DISCUSSION NUMBER  12
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP122014
200 PM PDT WED AUG 20 2014

Lowell continues to feature a large circulation center with a
convective band that wraps most of the way around the circulation.
The latest TAFB and SAB Dvorak estimates are T3.5/55 kt, and that is
the initial intensity for this advisory. A little additional
intensification is possible in the next 12 to 24 hours before the
cyclone begins to move over cooler waters, and the NHC forecast
reflects this possibility. After that time, a gradual spin down is
forecast as the cyclone encounters increasingly hostile
thermodynamic conditions. The NHC intensity forecast is close to the
latest IVCN consensus and shows Lowell becoming a remnant low by 4
days.

The initial motion estimate is 315/4, as Lowell is moving slowly
northwestward into a break in the subtropical ridge caused by
a mid/upper-level low over southern California. The track forecast
reasoning remains unchanged, with the cyclone expected to gain some
forward speed after 12 hours while the trough lifts out and some
ridging rebuilds to the east. As Lowell weakens, the cyclone will
turn west-northwestward as it comes under the influence of a low-
level ridge over the north Pacific. Overall, the track model
guidance remains in good agreement on this scenario. The new NHC
track is generally an update of the previous forecast and is close
to a consensus of the GFS and ECMWF models.

FORECAST POSITIONS AND MAX WINDS

INIT  20/2100Z 19.4N 121.5W   55 KT  65 MPH
 12H  21/0600Z 19.8N 121.9W   60 KT  70 MPH
 24H  21/1800Z 20.6N 122.6W   60 KT  70 MPH
 36H  22/0600Z 21.6N 123.6W   55 KT  65 MPH
 48H  22/1800Z 22.8N 124.9W   50 KT  60 MPH
 72H  23/1800Z 24.9N 127.8W   35 KT  40 MPH
 96H  24/1800Z 26.5N 130.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  25/1800Z 27.5N 133.5W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Brennan