WTPZ43 KNHC 250833
TROPICAL STORM LESTER DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132016
300 AM MDT THU AUG 25 2016
The cyclone appears to be gradually gaining strength. Recent
microwave images show that the circulation of the system has become
better organized with the associated banding features more tightly
coiled than they were earlier. In addition, infrared satellite
pictures indicate that a central dense overcast feature has formed
with cloud tops colder than -70 deg C. The Dvorak classifications
from TAFB and SAB are both 2.5/35 kt, and ADT values from CIMSS at
the University of Wisconsin are a bit higher. Based on these data,
the initial wind speed is increased to 35 kt, making the cyclone
Tropical Storm Lester.
The tropical cyclone is expected to steadily strengthen during the
next 3 to 4 days while it remains over warm water, in a moist
environment, and in moderate wind shear conditions. By the end of
the forecast period, slight weakening should commence when Lester
moves over cooler water and into a more stable air mass. The
intensity guidance is a little higher this cycle, and the NHC
forecast is nudged upward to be in closer agreement with the
intensity model consensus.
The microwave passes have been helpful in locating the center,
and suggest that Lester is still moving west-northwestward at 10 kt.
A decrease in forward speed is expected to begin later today when
the cyclone moves closer to a break in the subtropical ridge. The
ridge is expected to rebuild to the north of the storm this weekend,
and that should cause Lester to move westward at a faster pace.
The NHC track forecast is largely an update of the previous one, and
it lies close to the consensus aids.
FORECAST POSITIONS AND MAX WINDS
INIT 25/0900Z 16.2N 111.6W 35 KT 40 MPH
12H 25/1800Z 16.7N 113.0W 45 KT 50 MPH
24H 26/0600Z 17.2N 114.4W 55 KT 65 MPH
36H 26/1800Z 17.5N 115.8W 60 KT 70 MPH
48H 27/0600Z 17.6N 117.3W 65 KT 75 MPH
72H 28/0600Z 17.7N 121.0W 75 KT 85 MPH
96H 29/0600Z 17.9N 125.8W 80 KT 90 MPH
120H 30/0600Z 18.0N 130.4W 75 KT 85 MPH