Tropical Storm Felicia Discussion Number 24
NWS National Hurricane Center Miami FL EP062021
500 PM HST Mon Jul 19 2021
Felicia continues to rapidly weaken over sea-surface temperatures
(SST) of around 25 deg C and within a cooler and drier air mass.
After an earlier burst of strong convection, all that remains of it
is limited to the northeastern quadrant along with cloud tops now
having warmed to -55C to -60C. The latest satellite intensity
estimates from TAFB and SAB were 45 kt, and that is the intensity
assigned for this advisory. Additional weakening is forecast through
the remainder of the 72-h forecast period due to the cyclone
remaining over SSTs near 25C, westerly vertical wind shear
increasing to more than 30 kt by 24 hours, and continued entrainment
of drier and cooler low- to mid-level air. The new NHC intensity
forecast is similar to the previous advisory, and closely follows a
blend of the IVCN and HCCA intensity consensus models.
The initial motion estimate remains a little south of due west, or
265/13 kt. A low- to mid-level subtropical ridge to the north of
the cyclone is expected to steer Felicia west-southwestward to
westward over the next few days until the small cyclone dissipates
by 96 hours, if not sooner. Felicia will likely cross into the
Central Pacific basin by Tuesday night. The new official track
forecast is similar to the previous advisory track, and lies between
the tightly packed TVCE and NOAA-HCCA track forecast models.
Hurricane Felicia Discussion Number 20
NWS National Hurricane Center Miami FL EP062021
500 PM HST Sun Jul 18 2021
Felicia continues to decline over water temperatures near or just
below 26C. The eye is gradually becoming more difficult to locate in
satellite imagery, and the CDO, while already small to begin with,
has shrunk in size over the past several hours. A blend of the
latest Dvorak T- and CI-numbers from TAFB and SAB suggest that the
hurricane has weakened to 90 kt. However, given that environment is
not too hostile at the moment, is it reasonable to believe that the
vortex of this mature tropical cyclone will take time to spin down
despite the degradation in satellite images. Therefore, the initial
intensity is being lowered to a perhaps generous 95 kt for this
advisory.
The cooler waters alone should continue to take a toll on Felicia
over the next couple of days by gradually eroding the deep
convection. After 48 h, increasing northwesterly shear should help
to inject dry and stable air into what remains of the core of the
cyclone. By 96 h, if not sooner, Felicia is expected to have lost
all of its deep convection and decay into a remnant low. The latest
NHC intensity forecast has been lowered from the previous one
through the first few days of the forecast period due to the rapidly
decreasing wind speeds, and is near the ICON intensity consensus
model. Thereafter, the NHC intensity forecast is little changed from
the previous one.
Felicia continues its 10-kt west-northwestward trek to the south of
a subtropical ridge. There is no change to the track forecast
reasoning. Model guidance is in good agreement on the cyclone
turning westward by Monday then perhaps west-southwestward later in
the forecast period as the ridge expands and becomes oriented NE-SW.
The NHC track forecast is little changed from the previous one, and
lies in the middle of the consensus guidance. Based on this track,
Felicia should cross over into the central Pacific basin Tuesday
night.
Hurricane Felicia Discussion Number 17
NWS National Hurricane Center Miami FL EP062021
1100 PM HST Sat Jul 17 2021
Felicia has maintained its impressive structure tonight, with a
symmetric ring of very cold infrared cloud-top temperatures
surrounding a warm and well-defined eye. Recent microwave imagery
shows that Felicia still has a very compact inner core. The initial
intensity is maintained at 120 kt, as the hurricane's satellite
appearance has shown no signs of decay since the last advisory. This
intensity is consistent with subjective T6.0 Dvorak classifications
from TAFB and SAB.
Felicia should weaken during the next couple of days as the
hurricane moves over cooler sea-surface temperatures, although this
could be a gradual process while the vertical wind shear remains
low. By Tuesday, increasing northwesterly wind shear in a drier,
more stable environment is expected to accelerate the weakening of
Felicia through the middle and latter parts of the week. Although
the official NHC forecast shows remnant low status by day 5, it is
plausible that this could occur even sooner if the higher shear
values in the ECMWF SHIPS guidance materialize. The official NHC
intensity forecast lies above the guidance model consensus through
48 h, then aligns with the HFIP corrected consensus approach (HCCA)
aid through the rest of the forecast period.
Felicia is still moving west-northwestward at about 9 kt. The track
guidance has been quite consistent and remains in very good
agreement, which makes for a high confidence track forecast. The
cyclone is expected to turn more westward by Monday, then move
west-southwestward through midweek as Felicia becomes steered by an
expansive ridge across the central Pacific. The NHC track forecast
is essentially unchanged from the previous one and lies between the
reliable consensus aids TVCE and HCCA.
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