Remnants Of Nadine Discussion Number 16
NWS National Hurricane Center Miami FL AL152018
1100 PM AST Fri Oct 12 2018
ASCAT data indicate that Nadine no longer has a closed circulation
nor a well-defined center. This is also confirmed by low cloud
motions from GOES-16. Thus Nadine has degenerated into an open
wave, and this is the last advisory on this system. The initial wind
speed is reduced to 30 kt to match the value from the scatterometer.
Strong shear should cause the remnants to slowly weaken as the
system moves quickly westward beneath the Atlantic subtropical
ridge.
Future information on the remnants of Nadine can be found in High
Seas Forecasts issued by the National Weather Service, under AWIPS
header NFDHSFAT1, WMO header FZNT01 KWBC, and available on the Web
at https://ocean.weather.gov/shtml/NFDHSFAT1.shtml.
Tropical Storm Nadine Discussion Number 2
NWS National Hurricane Center Miami FL AL152018
1100 AM AST Tue Oct 09 2018
The cloud pattern of the cyclone features a curved band that wraps
around the eastern and southern parts of the circulation. Dvorak
estimates from TAFB and SAB are both T2.5/35 kt, and that is used
for the initial intensity, making the system a tropical storm. The
environment appears conducive for some additional strengthening
during the next 24 hours or so, with SSTs above 28C and generally
light to moderate westerly shear. After that time, the shear
increases to 25-30 kt and SSTs along the forecast track fall below
27C by 72 hours. These factors should result in weakening, and all
of the global models show the cyclone dissipating in 4 to 5 days.
The NHC forecast follows these trends and is close to the various
consensus aids through the forecast period.
Based on geostationary imagery and a 0815Z SSMIS pass, the initial
motion estimate is a somewhat uncertain 285/08, with Nadine
currently situated south of a narrow mid-level ridge. The ridge will
weaken as a mid/upper-level trough that Leslie is embedded in digs
southward along 40W longitude. This pattern will cause Nadine to
turn more northwestward by 24 hours. By 96 hours, a weakening Nadine
should bend back to the west as a shallow system. The new NHC track
forecast is a bit to the right of the previous one due to the new
initial position, and lies near HCCA through 48 hours and closer to
the TVCA multi-model consensus after that time.
Tropical Depression Fifteen Special Discussion Number 1
NWS National Hurricane Center Miami FL AL152018
600 AM AST Tue Oct 09 2018
Geostationary satellite and recent microwave data indicate that the
low pressure system over the eastern Atlantic Ocean has developed
sufficently organized deep convection and a well-defined center of
circulation to be considered a tropical depression, the fifteenth
one of the 2018 Atlantic hurricane season. The initial intensity is
set at 30 kt, in agreement with Dvorak 2.0/30 kt classifications
from both TAFB and SAB. The depression is expected to strengthen a
little during the next 36 to 48 hours while it remains in favorable
oceanic and atmospheric conditions. Thereafter, a significant
increase in west-southwesterly shear, drier air, and slightly cooler
SSTs should cause weakening. The global models all show the
depression opening up into a trough by day 5, and the official
forecast predicts dissipation accordingly.
The initial motion is uncertain since the system just formed a
well-defined center, but my best guess is 285/10 kt. The
depression is expected to turn northwestward tonight and continue in
that general direction on Wednesday and Thursday as it moves
toward a broad trough over the central Atlantic, the same one that
Leslie is embedded in. After that time, when the system weakens and
becomes shallow, a turn back to the left is forecast. The models
are in fair agreement, and the NHC track forecast lies near the
middle of the guidance envelope.
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