Tropical Storm Georgette Discussion Number 2
NWS National Hurricane Center Miami FL EP082022
200 PM PDT Wed Jul 27 2022
The satellite presentation of the tropical cyclone this afternoon
remains well organized, albeit very compact. The well curved band
seen earlier this morning on microwave has evolved into a small
central dense overcast with cloud top temperatures of -70 to -75 C,
and the center estimated to be embedded within this cirrus canopy.
Dvorak satellite estimates from the various agencies were T2.5/35-kt
from TAFB, T2.0/30-kt from SAB, and T2.4/34-kt from UW-CIMSS ADT.
Unfortunately today's ASCAT swaths missed the small wind field of
the cyclone, but given the healthy structure seen on satellite
imagery and the higher subjective and objective estimates, the
initial intensity is set at 35-kt, upgrading Tropical Depression
Eight-E to Tropical Storm Georgette.
Georgette has been moving just north of due west today with the
motion estimated at 275/8 kt. For the first 24 hours, the storm's
motion is expected to gradually bend westward and then
west-southwestward as its influenced by a weak mid-level ridge
oriented southwest-to-northeast ahead of the cyclone. Afterwards,
the track forecast becomes increasingly uncertain and complex. As
mentioned previously, larger tropical storm Frank will be
approaching Georgette from the east, and its outer wind field will
likely have some influence on Georgette's motion. Subtle differences
in structure and distance between Frank and Georgette could have
large implications on how far westward Georgette gets in the 3-4 day
forecast period. This is illustrated by the most recent ECMWF
ensemble tracks, which show an across-track spread of more than 500
n mi in just 72 hours, which is roughly 5 times the average forecast
track error at that forecast period. To add to the uncertainty, the
GFS and UKMET models do not appear to capture the tiny vortex of
Georgette well in their most recent cycle, and quickly absorb it in
Frank's larger circulation. Favoring a solution that keeps Georgette
a separate entity, the latest track forecast leans more heavily on a
blend between the ECMWF, its ensemble mean, and Canadian, which
mostly keep Georgette as a coherent feature through the forecast
period. This track is further north of the previous track early on,
and also takes Georgette further west over the next 3 days.
Afterwards, The larger monsoonal flow that is expected to wrap up
into Frank's larger circulation will likely also capture Georgette,
and a sharp turn to the north and north-northeast is now predicted
at the end of the forecast period. This current track forecast
remains low confidence and larger-than normal adjustments may be
necessary if Frank ends up getting closer and exerting more
influence on Georgette's track than currently indicated here.
The intensity forecast also remains challenging, both due to the
small size of Georgette, and the looming potential for its
interaction with Frank located further east. Easterly vertical wind
shear of 10-15 knots is expected to continue for the next couple of
days as the storm traverses over 28-29 C sea surface temperatures in
a relatively dry mid-level environment. The small structure of
Georgette also hints at the the potential for rapid intensity
changes, both up or down. Assuming occasional dry-air entrainment
could occur, only gradual intensification is shown over the next 36
hours, peaking Georgette as a 50 kt tropical storm. After that time,
the outflow from Frank to its east may result in a more hostile
environment, and most of the intensity guidance levels off at that
time. At the end of the forecast, Georgette is expected to move over
cooler SSTs and even higher shear, which could begin a weakening
trend. The latest intensity forecast is a bit higher than the
previous cycle, but is in fairly good agreement with the latest HCCA
and IVCN consensus aids. This intensity forecast is also low
confidence.
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