500 AM HST Mon Jul 19 2021
Felicia continues to rapidly weaken as it heads toward the Central
Pacific. Satellite images show a shrinking area of deep convection
that is now generally confined to the northeast quadrant of the
circulation. The Dvorak classifications continue to fall, and a
blend of the latest estimates from TAFB, SAB, and CIMSS at the
University of Wisconsin support lowering the initial intensity to
70 kt, and even that seems generous.
The weakening and very compact storm is surrounded by dry mid-level
air. This stable environment, cool 25 C SSTs, and increasing wind
shear should cause the rapid weakening trend to continue. Felicia is
forecast to weaken to a tropical storm later today and a remnant
low in a few days when it expected to be in an environment of about
40 kt of northwesterly shear and very dry air, which will likely
cause all of the deep convection to dissipate. The NHC intensity
forecast is lower than the previous one, and in line with the
majority of the latest guidance.
Felicia is moving westward at about 10 kt. A slightly faster
westward to west-southwestward motion is expected during the next
several days as Felicia, or its remnants, move in the flow on the
south side of a low- to mid-level high to its north. The NHC track
forecast is just a tad south of the previous one and lies close to
the various consensus aids. Based on the current forecast, the
weakening system is expected to cross into the Central Pacific
basin by tomorrow night.
FORECAST POSITIONS AND MAX WINDS
INIT 19/1500Z 16.3N 132.3W 70 KT 80 MPH
12H 20/0000Z 16.2N 134.0W 50 KT 60 MPH
24H 20/1200Z 16.0N 136.5W 40 KT 45 MPH
36H 21/0000Z 15.5N 139.3W 35 KT 40 MPH
48H 21/1200Z 14.9N 142.2W 30 KT 35 MPH
60H 22/0000Z 14.5N 144.7W 30 KT 35 MPH
72H 22/1200Z 14.0N 147.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 23/1200Z 13.6N 153.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 24/1200Z...DISSIPATED
500 AM HST Mon Jul 19 2021
Guillermo's satellite presentation has continued to deteriorate
over the past several hours, although a new, small deep convective
burst has developed just to the southeast of the circulation
center. An earlier AMSR2 microwave overpass revealed a rather
elongated (west to east) and ill-defined circulation with
fragmented bands in the southeast quadrant. The initial intensity
is lowered to 35 kt and is based on a blend of the TAFB and SAB
Dvorak satellite intensity estimates.
Guillermo is moving over cooler (about 25C) water and into a
progressively more stable and drier surrounding environment.
The statistical-dynamical SHIPS models (GFS/ECMWF) indicate that
moderate west-northwesterly shear should also contribute to the
cyclone's degeneration to a remnant low on Wednesday night. The
intensity forecast now shows Guillermo becoming a remnant low
sooner than the previous advisory and conforms with a consensus of
the large-scale models and the SHIPS forecasts.
The initial motion is estimated to be westward, or 275/13 kt. A
subtropical ridge anchored to the north of the cyclone should
influence a generally westward motion through dissipation at day 5.
A few of the global models are now showing the lower levels
of the ridge building some to the east-northeast of the Hawaiian
Islands which could induce a west-southwestward motion, or slightly
left of due west, around mid-period. The NHC forecast is once
again adjusted a bit to the left of the previous one and is based on
the various consensus aids.
FORECAST POSITIONS AND MAX WINDS
INIT 19/1500Z 19.1N 117.8W 35 KT 40 MPH
12H 20/0000Z 19.0N 119.9W 35 KT 40 MPH
24H 20/1200Z 18.9N 123.0W 30 KT 35 MPH
36H 21/0000Z 18.6N 126.1W 30 KT 35 MPH
48H 21/1200Z 18.3N 128.9W 30 KT 35 MPH
60H 22/0000Z 18.1N 131.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 22/1200Z 17.9N 134.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 23/1200Z 17.9N 139.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 24/1200Z 17.9N 145.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
