858 
WTPZ44 KNHC 161456
TCDEP4

Tropical Storm Lane Discussion Number   7
NWS National Hurricane Center Miami FL       EP142018
800 AM PDT Thu Aug 16 2018

Lane appears to be intensifying this morning, with a more symmetric
presentation on satellite imagery and pulsing deep convection near
the center.  A recent SSMI/S microwave pass indicates that an inner
core is trying to form, although it isn't well defined yet. The
current intensity estimates continue to display a large spread,
ranging from the overnight scatterometer data at low-end tropical-
storm strength, from hurricane strength in the TAFB Dvorak estimate.
The initial wind speed is set to 50 kt with the increased
organization, and this remains a low confidence estimate.

While so far Lane has only been slowly intensifying, the large-scale
environment appears favorable for more significant intensification
to occur soon, especially with current signs of a primitive inner
core. Thus the wind speed forecast will maintain the quick
strengthening from the previous forecast, and there remains a
significant chance that rapid intensification will occur during the
next few days.  The biggest change from yesterday is that more of
the global models are indicating that westerly shear could affect
Lane in the central Pacific, so more weakening is shown at day 5.
Otherwise, the new NHC intensity forecast is very close to the
previous one and is on the higher side of the guidance.

The initial motion estimate is 275/11.  The subtropical ridge to
the north of Lane should continue to be the dominant steering
mechanism, forcing the tropical cyclone to move westward or
west-northwestward for the next several days.  While the model
spread is low in the short range, it notably increases by days 4/5.
The GFS-based guidance is showing Lane move slower than the rest of
the guidance, which allows the eastern periphery of the ridge to
erode due to an inverted mid-level trough, and consequently a more
poleward motion of the cyclone.  The ECMWF and UKMET show Lane
moving faster and basically missing any influence of that trough,
causing the storm to move faster to the west.  There are no
strong signals pointing me to either solution, so the official
forecast follows the trend of the consensus, which ends up slightly
west of the previous forecast.


FORECAST POSITIONS AND MAX WINDS

INIT  16/1500Z 10.6N 127.6W   50 KT  60 MPH
 12H  17/0000Z 10.8N 129.4W   60 KT  70 MPH
 24H  17/1200Z 11.2N 132.1W   75 KT  85 MPH
 36H  18/0000Z 11.7N 134.9W   85 KT 100 MPH
 48H  18/1200Z 12.2N 137.6W   95 KT 110 MPH
 72H  19/1200Z 13.5N 142.7W  105 KT 120 MPH
 96H  20/1200Z 14.7N 147.3W  105 KT 120 MPH
120H  21/1200Z 15.3N 151.5W   95 KT 110 MPH

$$
Forecaster Blake