Hurricane Fernanda Discussion Number 11
NWS National Hurricane Center Miami FL EP062017
800 AM PDT Fri Jul 14 2017
The satellite presentation of Fernanda continues to improve. An
eye has been apparent in shortwave and longwave IR imagery for the
past several hours. An AMSR-2 overpass around 0843 UTC showed a
well defined eye structure, completely surrounded by deep
convection. Subjective Dvorak T-numbers at 1200 UTC increased to
5.0 from TAFB and 5.5 from SAB, and since that time the cloud top
structure has improved a little more. On that basis, the initial
intensity has been increased to 100 kt, making Fernanda the second
major hurricane of the 2017 eastern North Pacific hurricane season.
Fernanda remains in a very favorable environment for
intensification. The cyclone's intensity has increased by 40 kt in
the past 24 hours and there are no current indications that the
period of rapid intensification has ended. In fact, according to
the SHIPS diagnostics, the hurricane is now approaching an area of
higher ocean heat content. Surprisingly, most of the guidance shows
relatively little increase in intensity during the next 48 hours.
Considering that most of the guidance has thus far shown not nearly
the extent of intensification that has been observed, the NHC
forecast remains well above the guidance. The NHC forecast has
been adjusted substantially higher for the first 36 hours to
account for the higher initial intensity, but is closer to the
previous forecast after that. Beyond 48 hours, lower SSTs along the
forecast track and a drier environment should lead to a gradual
weakening.
The hurricane is continuing its steady westward track and the
initial motion estimate is 265/10 kt. There is no change to the
track forecast reasoning, and confidence in the track forecast
remains high due to a tight clustering of the model tracks.
Fernanda is still expected to move generally westward for the next
day or so, before turning toward the west-northwest due to a
weakening of the ridge to the north. No significant changes were
made to the NHC track forecast, which remains very close to the
various multi-model consensus aids.
FORECAST POSITIONS AND MAX WINDS
INIT 14/1500Z 10.9N 118.9W 100 KT 115 MPH
12H 15/0000Z 10.9N 120.3W 110 KT 125 MPH
24H 15/1200Z 11.3N 122.5W 120 KT 140 MPH
36H 16/0000Z 11.8N 124.9W 125 KT 145 MPH
48H 16/1200Z 12.5N 127.3W 125 KT 145 MPH
72H 17/1200Z 13.8N 131.8W 115 KT 130 MPH
96H 18/1200Z 15.0N 135.2W 95 KT 110 MPH
120H 19/1200Z 16.3N 138.6W 75 KT 85 MPH
$$
Forecaster Zelinsky
NWS National Hurricane Center Miami FL EP062017
800 AM PDT Fri Jul 14 2017
The satellite presentation of Fernanda continues to improve. An
eye has been apparent in shortwave and longwave IR imagery for the
past several hours. An AMSR-2 overpass around 0843 UTC showed a
well defined eye structure, completely surrounded by deep
convection. Subjective Dvorak T-numbers at 1200 UTC increased to
5.0 from TAFB and 5.5 from SAB, and since that time the cloud top
structure has improved a little more. On that basis, the initial
intensity has been increased to 100 kt, making Fernanda the second
major hurricane of the 2017 eastern North Pacific hurricane season.
Fernanda remains in a very favorable environment for
intensification. The cyclone's intensity has increased by 40 kt in
the past 24 hours and there are no current indications that the
period of rapid intensification has ended. In fact, according to
the SHIPS diagnostics, the hurricane is now approaching an area of
higher ocean heat content. Surprisingly, most of the guidance shows
relatively little increase in intensity during the next 48 hours.
Considering that most of the guidance has thus far shown not nearly
the extent of intensification that has been observed, the NHC
forecast remains well above the guidance. The NHC forecast has
been adjusted substantially higher for the first 36 hours to
account for the higher initial intensity, but is closer to the
previous forecast after that. Beyond 48 hours, lower SSTs along the
forecast track and a drier environment should lead to a gradual
weakening.
The hurricane is continuing its steady westward track and the
initial motion estimate is 265/10 kt. There is no change to the
track forecast reasoning, and confidence in the track forecast
remains high due to a tight clustering of the model tracks.
Fernanda is still expected to move generally westward for the next
day or so, before turning toward the west-northwest due to a
weakening of the ridge to the north. No significant changes were
made to the NHC track forecast, which remains very close to the
various multi-model consensus aids.
FORECAST POSITIONS AND MAX WINDS
INIT 14/1500Z 10.9N 118.9W 100 KT 115 MPH
12H 15/0000Z 10.9N 120.3W 110 KT 125 MPH
24H 15/1200Z 11.3N 122.5W 120 KT 140 MPH
36H 16/0000Z 11.8N 124.9W 125 KT 145 MPH
48H 16/1200Z 12.5N 127.3W 125 KT 145 MPH
72H 17/1200Z 13.8N 131.8W 115 KT 130 MPH
96H 18/1200Z 15.0N 135.2W 95 KT 110 MPH
120H 19/1200Z 16.3N 138.6W 75 KT 85 MPH
$$
Forecaster Zelinsky
Every 30 mins and :40 and :10 past the hour usually in the EPAC/ATL, and other times in different basins.
