EPAC: POLO - Post-Tropical

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cycloneye
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Re: EPAC: POLO - Tropical Storm

#21 Postby cycloneye » Wed Nov 18, 2020 9:36 pm

Tropical Storm Polo Discussion Number 6
NWS National Hurricane Center Miami FL EP212020
700 PM PST Wed Nov 18 2020

Satellite imagery shows that the convection associated with Polo
has diminished this evening, with the remaining convection now to
the east of the exposed low-level center. The initial intensity
is held at a possibly generous 35 kt as a blend of subjective and
objective satellite intensity estimates. Polo is moving into an
environment of moderate westerly shear, a dryer air mass, and
decreasing sea surface temperatures, and the system should
gradually weaken during the next 48 h. The new intensity forecast
has minor adjustments from the previous forecast, and it calls for
Polo to degenerate to a remnant low by 36 h and dissipate by 60 h.

The initial motion is 285/11. A low-level ridge to the north of
the cyclone should steer the system generally westward until it
dissipates. and the new track forecast is an update of the previous
forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 19/0300Z 16.9N 118.3W 40 KT 45 MPH
12H 19/1200Z 17.2N 119.9W 35 KT 40 MPH
24H 20/0000Z 17.3N 122.0W 30 KT 35 MPH
36H 20/1200Z 17.3N 124.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 21/0000Z 17.3N 126.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
60H 21/1200Z...DISSIPATED

$$
Forecaster Beven
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Re: EPAC: POLO - Tropical Depression

#22 Postby cycloneye » Thu Nov 19, 2020 9:36 am

Tropical Depression Polo Discussion Number 8
NWS National Hurricane Center Miami FL EP212020
700 AM PST Thu Nov 19 2020

Occasional bursts of deep convection have been developing to the
east and northeast of Polo's center since yesterday evening, but
none have lasted for more than about an hour or two. ASCAT-C data
received after the scatterometer pass noted in the previous advisory
did not explicitly show tropical-storm-force winds, suggesting that
Polo continues to weaken, and the most recent Dvorak CI numbers from
TAFB and SAB are 2.0. For these reasons, Polo is now assumed to be
a 30-kt tropical depression. Polo has not maintained enough
organized convection to be considered a tropical cyclone for the
last 12 to 15 hours, and if sustained convection does not redevelop
soon, the system will likely be declared a remnant low later this
afternoon. The remnant low is expected to continue weakening due to
westerly shear, only marginally warm waters, and dry air, and it is
expected to dissipate by 48 hours, if not sooner.

Polo is being steered westward (275/10 kt) to the south of a low- to
mid-level ridge. Once Polo becomes a remnant low, the shallow
circulation should take on a south-of-due-west motion in about 24
hours, continuing that trajectory until it dissipates. This
pattern is shown by nearly all the reliable track models, and the
NHC forecast lies down the middle of the guidance envelope.


FORECAST POSITIONS AND MAX WINDS

INIT 19/1500Z 17.1N 120.3W 30 KT 35 MPH
12H 20/0000Z 17.1N 121.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 20/1200Z 17.0N 123.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 21/0000Z 16.7N 126.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 21/1200Z...DISSIPATED

$$
Forecaster Berg
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Re: EPAC: POLO - Tropical Depression

#23 Postby underthwx » Thu Nov 19, 2020 11:42 am

cycloneye wrote:
Tropical Depression Polo Discussion Number 8
NWS National Hurricane Center Miami FL EP212020
700 AM PST Thu Nov 19 2020

Occasional bursts of deep convection have been developing to the
east and northeast of Polo's center since yesterday evening, but
none have lasted for more than about an hour or two. ASCAT-C data
received after the scatterometer pass noted in the previous advisory
did not explicitly show tropical-storm-force winds, suggesting that
Polo continues to weaken, and the most recent Dvorak CI numbers from
TAFB and SAB are 2.0. For these reasons, Polo is now assumed to be
a 30-kt tropical depression. Polo has not maintained enough
organized convection to be considered a tropical cyclone for the
last 12 to 15 hours, and if sustained convection does not redevelop
soon, the system will likely be declared a remnant low later this
afternoon. The remnant low is expected to continue weakening due to
westerly shear, only marginally warm waters, and dry air, and it is
expected to dissipate by 48 hours, if not sooner.

Polo is being steered westward (275/10 kt) to the south of a low- to
mid-level ridge. Once Polo becomes a remnant low, the shallow
circulation should take on a south-of-due-west motion in about 24
hours, continuing that trajectory until it dissipates. This
pattern is shown by nearly all the reliable track models, and the
NHC forecast lies down the middle of the guidance envelope.


FORECAST POSITIONS AND MAX WINDS

INIT 19/1500Z 17.1N 120.3W 30 KT 35 MPH
12H 20/0000Z 17.1N 121.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 20/1200Z 17.0N 123.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 21/0000Z 16.7N 126.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 21/1200Z...DISSIPATED

$$
Forecaster Berg

Looks like Polo is headed for the bone yard...
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Re: EPAC: POLO - Post-Tropical

#24 Postby cycloneye » Thu Nov 19, 2020 3:40 pm

Post-Tropical Cyclone Polo Discussion Number 9
NWS National Hurricane Center Miami FL EP212020
100 PM PST Thu Nov 19 2020

A few convective cells continue to pulse over 100 n mi northeast of
Polo's center, but overall the cyclone has not produced persistent,
organized deep convection since yesterday evening. Therefore, Polo
is being designated as a remnant low. A recent ASCAT pass sampled
the eastern part of Polo's circulation and showed winds around 25
kt, so it is assumed that 30-kt winds are still occurring closer to
the center. Moderate westerly shear, marginally warm waters, and a
dry environment should cause Polo's winds to gradually decrease,
and the circulation is expected to open up into a trough by 36
hours, per the latest global model guidance.

Polo is moving just south of due west (265/10 kt), steered by a
low- to mid-level ridge to its north. This general motion is
expected to continue until the low dissipates, and the NHC track
forecast is down the middle of the tightly packed guidance envelope.

For additional information on the remnant low please see High Seas
Forecasts issued by the National Weather Service, under AWIPS
header NFDHSFEPI, WMO header FZPN02 KWBC, and on the web at
ocean.weather.gov/shtml/NFDHSFEPI.php


FORECAST POSITIONS AND MAX WINDS

INIT 19/2100Z 16.9N 121.3W 30 KT 35 MPH...POST-TROP/REMNT LOW
12H 20/0600Z 16.9N 122.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 20/1800Z 16.8N 125.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 21/0600Z...DISSIPATED

$$
Forecaster Berg
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