ZCZC MIATCDAT1 ALL
TTAA00 KNHC DDHHMM
TROPICAL DEPRESSION FIONA DISCUSSION NUMBER 23
NWS NATIONAL HURRICANE CENTER MIAMI FL AL062016
1100 AM AST MON AUG 22 2016
The satellite depiction of Fiona currently features an exposed
low-level circulation with a few small areas of convection
southeast of the center. Subjective satellite intensity estimates
from TAFB and SAB are 30 kt, while the various objective estimates
range from 25-45 kt. The initial intensity remains 30 kt based
mainly on the subjective estimates.
The dynamical models forecast that the current westerly vertical
shear will subside somewhat by 48 hours as Fiona moves under an
upper-level trough into an area of easterly upper-level winds to
the north of the trough. By 72 hours, the models forecast the
cyclone or its remnants to encounter a second trough, which should
produce another round of strong southwesterly shear. Based on the
premise that the cyclone will not be able to respond to the brief
period of more favorable conditions, the new intensity forecast
calls for Fiona to gradually decay and become a remnant low in about
36 hours. This would be followed by the system weakening to a trough
after 96 hours.
The initial motion is 285/16. The guidance remains in good
agreement on the forecast track through 72 hours, with Fiona moving
west-northwestward to northwestward toward a developing break in
the subtropical ridge. Beyond that time, the guidance diverges,
with the ECMWF turning the remnants of the system northeastward
while the GFS and UKMET show a westward turn. The new forecast
track will compromise between these extremes in showing a slow
north-northwestward motion. The new forecast track is shifted a
little to the west of the previous track and lies near the various
consensus models.
FORECAST POSITIONS AND MAX WINDS
INIT 22/1500Z 24.6N 59.7W 30 KT 35 MPH
12H 23/0000Z 25.3N 61.5W 30 KT 35 MPH
24H 23/1200Z 26.1N 63.5W 30 KT 35 MPH
36H 24/0000Z 27.0N 65.2W 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 24/1200Z 28.1N 66.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 25/1200Z 30.0N 68.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 26/1200Z 31.5N 68.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 27/1200Z...DISSIPATED
$$
Forecaster Beven
NNNN