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Tropical Storm Pamela Discussion Number 6...Corrected
NWS National Hurricane Center Miami FL EP162021
900 AM MDT Mon Oct 11 2021
Corrected to update Key Messages
Pamela's convective pattern has undergone a pronounced bursting
phase since the previous advisory, including significant lightning
activity in the inner-core region near the center, with formation
of a Central Dense Overcast (CDO) now evident. However, the
lightning ceased about 5 h ago and the CDO has recently become a
little disheveled looking along with pronounced warming of the
cloud tops compared to the much colder cloud tops colder than -85C
just a few hours ago. The advisory intensity has been increased to
55 kt based on an average of satellite intensity estimates of
T4.0/65 from TAFB, T3.0/45 kt from SAB, and T3.5/55 kt from
UW-CIMSS ADT.
Pamela has slowed down significantly since the previous advisory,
and the motion estimate is now northwestward or 320/07 kt. A
northwestward motion should continue today as Pamela approaches an
east-to-west-oriented subtropical ridge axis situated along 19-20N
latitude. By late tonight, the storm is forecast to turn slowly
northward, followed by a motion toward the northeast at a faster
forward speed by Tuesday night. As Pamela gets caught up in the
moderate southwesterly flow between the subtropical ridge to its
south and an approaching mid-latitude trough to the northwest, the
cyclone should continue to accelerate northeastward on Wednesday
until Pamela makes landfall along the southwest coast of Mexico. The
new NHC forecast track is a tad to the right of and slightly faster
than the previous advisory track, and close to the middle of the
tightly packed simple- and corrected-consensus track model envelope.
The recent disruption in Pamela's convective pattern has likely
been due the cyclone having entrained a slug of dry air. However,
this convective hiatus will likely be short-lived due to the robust
inner-core wind field noted in earlier ASCAT wind data, which should
allow for Pamela to mix out any dry air. Moderate northerly shear is
forecast to subside over the next 24 hours, giving way to the
development of an upper-level anticyclone over the storm, along
with an impressive outflow pattern developing in the northern
semicircle. The combination of a tight inner-core wind field, low
vertical shear, very warm sea-surface temperatures, and a moist
mid-level environment should allow for Pamela to rapid intensify
for the next 36 hours -- possibly even right up until Pamela
reaches the coast of Mexico. The latest official intensity
forecast is very similar to the previous advisory, and is an average
of the consensus intensity models IVCN and NOAA-HCCA, an remains
at the high end of the intensity guidance. Pamela is expected to
become a dangerous major hurricane prior to landfall. After inland
occurs, rapid weakening is expected as the storm moves over the
rugged terrain of west-central Mexico. However, higher elevations
could still receive tropical-storm force winds after Pamela moves
well inland.
An Air Force Reserve Hurricane Hunter aircraft is scheduled to
investigate Pamela Tuesday late morning and early afternoon.
Key Messages:
1. Pamela is forecast to be a major hurricane when it reaches the
coast of west-central mainland Mexico on Wednesday, and
life-threatening storm surge and dangerous hurricane-force winds are
possible within the Hurricane Watch area. Residents in this area
should monitor the progress of Pamela and follow any advice given by
local officials.
2. Pamela is expected to pass near or south of the southern tip of
the Baja California peninsula as a hurricane Tuesday night and early
Wednesday, and tropical-storm conditions are possible within the
Tropical storm Watch area.
3. Heavy rains associated with Pamela are expected to move into the
Mexican States of Sinaloa and western Durgano along with southern
portions of Baja California Sur Tuesday and Wednesday. This will
pose a threat of significant and life-threatening flash flooding and
mudslides.
FORECAST POSITIONS AND MAX WINDS
INIT 11/1500Z 16.8N 108.1W 55 KT 65 MPH
12H 12/0000Z 17.8N 108.9W 70 KT 80 MPH
24H 12/1200Z 19.3N 109.3W 85 KT 100 MPH
36H 13/0000Z 21.1N 108.8W 100 KT 115 MPH
48H 13/1200Z 23.3N 107.1W 105 KT 120 MPH
60H 14/0000Z 25.7N 104.9W 35 KT 40 MPH...INLAND
72H 14/1200Z 29.1N 100.8W 25 KT 30 MPH...POST-TROP/INLAND
96H 15/1200Z...DISSIPATED
$$
Forecaster Stewart
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