EPAC: COSME - Remnants

[cycloneye]

Tropical Storm Cosme Discussion Number 2
NWS National Hurricane Center Miami FL EP032019
200 PM PDT Sat Jul 06 2019

Cosme continues to have a lopsided appearance in satellite images,
with all of its associated deep convection east of the center.
While there have been some cells near the core of the cyclone, they
have not lasted long due to plentiful dry air in the mid-levels.
The initial wind speed is kept at 45 kt in agreement with recent
ASCAT data, again well above any Dvorak estimates.

While shear is clearly decreasing near the center, it will take
some time for the large cyclone to mix out the aforementioned
dry near and west of the core. In addition, Cosme has only about 36
hours over marginal SSTs before reaching cool waters. These factors
indicate little significant strengthening this weekend, and a
gradual weakening early next week due to cooler waters and higher
shear. The HWRF shows some strengthening right before Cosme
crosses into the cool waters, but the rest of the models holds
Cosme's intensity flat or decreasing during the next few days. The
official intensity forecast is similar to the previous one, which
goes with the weaker solution provided by the bulk of the models.

The center has been difficult to track, but ASCAT and visible
satellite suggest it is moving a bit slower and poleward than
before, or 295/12. The storm is expected to be steered to the west-
northwest during the next day or so due to a subtropical ridge over
Mexico. However all of the models show a break in the ridge forming
between 120-130W, which should induce a motion more to the
northwest by Monday. Guidance has shifted a bit to the north on
this cycle, and the ECMWF solution remains a bit of an outlier to
the southwest. The new NHC forecast is adjusted slightly to the
northeast of the previous one, but is southwest of the model
consensus.


FORECAST POSITIONS AND MAX WINDS

INIT 06/2100Z 16.2N 116.3W 45 KT 50 MPH
12H 07/0600Z 16.9N 117.8W 45 KT 50 MPH
24H 07/1800Z 17.8N 119.2W 45 KT 50 MPH
36H 08/0600Z 18.8N 120.3W 40 KT 45 MPH
48H 08/1800Z 19.8N 121.1W 35 KT 40 MPH
72H 09/1800Z 21.0N 122.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 10/1800Z 21.5N 125.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 11/1800Z...DISSIPATED

$$
Forecaster Blake

[Kingarabian]

12z HWRF tries to make this a hurricane last minute:

[cycloneye]

Tropical Storm Cosme Discussion Number 3
NWS National Hurricane Center Miami FL EP032019
800 PM PDT Sat Jul 06 2019

There has been little overall change in the tropical storm's
organization since the previous advisory. Deep convection continues
to burst over the northeastern portion of Cosme's circulation,
however it remains well removed from the center. The initial wind
speed has been maintained at 45 kt, which is based on earlier ASCAT
data and is still above the most recent Dvorak intensity estimates.

It appears that Cosme is unlikely to strengthen any more. Dry air
to the northwest of the cyclone and the sprawling structure of the
system should hinder intensification while the system moves over
26-27 degree Celsius water during the next 12-18 hours. After that
time, Cosme will reach cooler SSTs and gradual weakening should
begin, and the cyclone is forecast to become post-tropical within a
couple of days, if not sooner. The updated NHC intensity forecast
is in good agreement with the latest statistical guidance and the
various consensus aids.

Visible satellite imagery has revealed several cloud swirls rotating
within the storm's circulation, which has made tracking the center
of the system a little more difficult than usual. Using a mean
center of the various swirls yields an initial motion estimate of
300/10 kt. Cosme should continue to be steered west-northwestward
during the next 12-24 hours by a mid-level ridge extending westward
from northwestern Mexico. By Monday, the western portion of the
ridge is expected to weaken which should induce a slower
northwestward motion. Later in the period, the remnant low should
turn back toward the west-northwest or northwest within the
low-level trade wind flow. The guidance envelope did not change
much this cycle and the new NHC track forecast is essentially an
update of the previous advisory.

FORECAST POSITIONS AND MAX WINDS

INIT 07/0300Z 16.7N 117.1W 45 KT 50 MPH
12H 07/1200Z 17.4N 118.4W 45 KT 50 MPH
24H 08/0000Z 18.3N 119.7W 40 KT 45 MPH
36H 08/1200Z 19.3N 120.7W 35 KT 40 MPH
48H 09/0000Z 20.0N 121.4W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 10/0000Z 21.1N 123.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 11/0000Z 21.5N 125.8W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 12/0000Z...DISSIPATED

$$
Forecaster Brown

[cycloneye]

Tropical Storm Cosme Discussion Number 4...Corrected
NWS National Hurricane Center Miami FL EP032019
200 AM PDT Sun Jul 07 2019

Corrected to show dissipated at 10/0600Z

Dry air appears to be taking its toll on Cosme. Deep convection
mostly dissipated earlier tonight and water vapor imagery shows very
dry air impinging on the northwestern side of the cyclone, and
wrapping into the southern semicircle of the circulation. There has
been some new convection developing about 100 n mi northeast of the
center over the past few hours, which is likely associated
with the approaching diurnal convective maximum time period. A
recent scatterometer pass that partially captured Cosme's wind field
indicated weakening had occurred over the western portion of the
cyclone over the past several hours which suggests that an overall
weakening trend has begun. Therefore the initial intensity has been
lowered to 35 kt and this is in agreement with the latest TAFB and
ADT satellite intensity estimates.

Cosme will continue to battle dry air while moving over marginally
favorable SSTs today. There is a chance for the regenerating
convection to expand toward the cyclone's center over the next
several hours, thus prolonging the time Cosme will remain a tropical
storm. However, later today the cyclone will begin to cross the 26 C
isotherm and also will enter an even drier environment. This should
cause Cosme to weaken to a tropical depression. Thereafter, the dry
air and cooler SSTs will cause Cosme to become devoid of deep
convection and the cyclone should degenerate into a remnant low
either by tonight, or on Monday. The latest official intensity
forecast shows a weakening trend that is a little faster than
previously forecast, and is in agreement with the latest intensity
guidance as well as model simulated satellite imagery.

Cosme continues on a generally west-northwest track, and has slowed
slightly to around 9 kt. The cyclone will be steered toward a
weakness in the subtropical ridge developing to its northwest over
the next couple of days while gradually decreasing in forward
speed. The latest track guidance is close to the previous forecast
and near the consensus aids.

FORECAST POSITIONS AND MAX WINDS

INIT 07/0900Z 16.9N 118.0W 35 KT 40 MPH
12H 07/1800Z 17.6N 119.1W 30 KT 35 MPH
24H 08/0600Z 18.4N 120.3W 25 KT 30 MPH
36H 08/1800Z 19.1N 121.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 09/0600Z 19.7N 121.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 10/0600Z...DISSIPATED

$$
Forecaster Latto/Pasch

[cycloneye]

Tropical Storm Cosme Discussion Number 5
NWS National Hurricane Center Miami FL EP032019
800 AM PDT Sun Jul 07 2019

After a brief convective hiatus overnight, a small burst of
thunderstorms has redeveloped near and to the northeast of the
low-level center this morning, making positioning of the tropical
cyclone a little difficult. However, convection has been on the wane
during the past couple of hours despite relatively low vertical
wind shear conditions. The initial intensity has been maintained at
35 kt due to the increase in central convection.

The initial position and motion estimate of 305/08 kt are based
primarily on passive microwave satellite data. Cosme is forecast to
maintain a northwestward to west-northwestward motion over the next
few days due to the influence of a deep-layer ridge located to the
north of the cyclone. A 72-hr post-tropical position was added due
to the global models now hanging on to a closed surface low a
little bit longer. Otherwise, the new NHC forecast track is similar
to but north of the previous advisory track, mainly due to the more
northward initial position, and lies close to a blend of the HCCA
and the simple consensus models.

Cosme is moving over over marginal 26-deg-C SSTs, and the water
beneath the cyclone is forecast to cool to near 25C in about 24
hours. The unfavorable oceanic conditions, combined with the
entrainment of drier and more stable low- and mid-level air,
should result in complete loss of deep convection near the center by
Monday. As a result, Cosme is forecast to become a depression
later today, degenerate into post-tropical remnant low on Monday,
and dissipate in the 72-96 hour time period. The new official
intensity forecast is similar to the previous advisory, and closely
follows the HCCA and IVCN intensity consensus models.

FORECAST POSITIONS AND MAX WINDS

INIT 07/1500Z 17.7N 118.4W 35 KT 40 MPH
12H 08/0000Z 18.4N 119.5W 30 KT 35 MPH
24H 08/1200Z 19.1N 120.4W 30 KT 35 MPH
36H 09/0000Z 19.7N 121.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 09/1200Z 20.2N 122.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 10/1200Z 21.2N 124.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 11/1200Z...DISSIPATED

$$
Forecaster Stewart

[cycloneye]

Tropical Storm Cosme Discussion Number 6
NWS National Hurricane Center Miami FL EP032019
200 PM PDT Sun Jul 07 2019

Deep convection has been pulsing since the previous advisory, with a
small burst of thunderstorms having recently developed in the
northwestern quadrant. Satellite data indicate that the low-level
center is less than 45 nmi from the -30 deg C cloud tops and cirrus
has been blowing off toward the southeast across the center,
indications that convective feedback is still maintaining Cosme as a
tropical cyclone. The initial intensity remains 35 kt for this
advisory based on a few 30-33 kt vectors that were present in an
1813Z ASCAT-B partial scatterometer pass over the northwestern
quadrant of Cosme's surface wind field.

The initial motion estimate is 315/09 kt. Cosme is expected to move
northwestward tonight and then turn toward the west-northwest by
Monday afternoon, maintaining that motion throughout the remainder
of the forecast period as the shallow circulation comes under the
influence of the low-level easterly trade wind flow. The new NHC
track forecast is a little north of the previous advisory track and
is similar to a blend of the HCCA, TVCE, and TVDG consensus models.

Cosme has just passed over the 26-deg-C SST isotherm and water
temperatures ahead of the cyclone are forecast to cool to near 24C
in about 24 hours. The combination of cooler waters, entrainment of
dry stable air, and increasing northwesterly wind shear is expected
to bring about the demise of Cosme in 12-24 hours. The cyclone is
expected to weaken to a tropical depression later tonight,
becoming a post-tropical system on Monday, and dissipating by 96
hours, if not sooner. The new official intensity forecast is similar
to the previous advisory, and closely follows the HCCA, FSSE, and
IVCN intensity consensus models.

FORECAST POSITIONS AND MAX WINDS

INIT 07/2100Z 18.6N 119.0W 35 KT 40 MPH
12H 08/0600Z 19.2N 119.9W 30 KT 35 MPH
24H 08/1800Z 19.9N 120.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 09/0600Z 20.4N 121.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 09/1800Z 20.9N 122.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 10/1800Z 21.7N 124.8W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 11/1800Z...DISSIPATED

$$
Forecaster Stewart

[cycloneye]

Tropical Depression Cosme Discussion Number 7
NWS National Hurricane Center Miami FL EP032019
800 PM PDT Sun Jul 07 2019

All of the central convection associated with Cosme dissipated about
5 hours ago, around 2200 UTC, and the cyclone is on its way to
becoming a remnant low. Since the core convection has now
dissipated, it is assumed that the cyclone's winds have decreased
since the last ASCAT pass, which showed an area of 30-35 kt winds.
The initial intensity is lowered to 30 kt, making Cosme a tropical
depression. This intensity estimate is also in fair agreement with
the latest Dvorak classifications from TAFB and automated Dvorak
values from CIMSS at the University of Wisconsin.

Cosme is currently over cool 24 degree C waters, and it is headed
for even cooler waters during the next couple of days. These
unfavorable oceanic conditions combined with a dry and stable air
mass and an increase in westerly shear should cause the system to
degenerate to a remnant low overnight or early Monday and dissipate
in two or three days.

The tropical depression is moving northwestward at 9 kt. Cosme is
expected to slow down and gradually turn toward the left, within the
low-level flow, until the system dissipates. The NHC track forecast
lies near the middle of the guidance envelope and is just a tad
north of the previous advisory track.

FORECAST POSITIONS AND MAX WINDS

INIT 08/0300Z 19.1N 119.5W 30 KT 35 MPH
12H 08/1200Z 19.8N 120.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 09/0000Z 20.3N 121.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 09/1200Z 20.8N 121.9W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 10/0000Z 21.3N 122.8W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 11/0000Z...DISSIPATED

$$
Forecaster Cangialosi

[HurricaneRyan]

This storm may as well be named Cosmo. Cause it's giving me Cosmo vibes with these sheared dunce clouds

[AnnularCane]

This storm may as well be named Cosmo. Cause it's giving me Cosmo vibes with these sheared dunce clouds

Cosmo Kramer?

[cycloneye]

Tropical Depression Cosme Discussion Number 8
NWS National Hurricane Center Miami FL EP032019
200 AM PDT Mon Jul 08 2019

Cosme continues to gradually weaken over 23 to 24 degree C waters
and in a dry and stable atmospheric environment with about 10 to
15 kt of westerly shear. The depression now consists of scattered
mid- to high- level debris clouds over a low-level swirl, with a
small area of convection located nearly 200 n mi northeast the
system's center. A scatterometer pass at 0450 UTC showed peak winds
of 25 kt associated with Cosme's circulation. This intensity agrees
with the satellite intensity estimates from TAFB and ADT and will be
the depression's initial intensity for this advisory.

The unfavorable environmental conditions for Cosme will not improve
as the depression continues to move over cooler waters today. This
should prevent any significant amounts of deep convection from
developing near the system's center, and Cosme is expected to become
a remnant low at some point later on today.

The initial motion of Cosme is northwest at 8 kt. This general
motion will continue through today with a slowing in forward speed.
Thereafter, the remnant low will drift northwestward to
west-northwestward in the low-level flow until it dissipates.

FORECAST POSITIONS AND MAX WINDS

INIT 08/0900Z 19.8N 120.1W 25 KT 30 MPH
12H 08/1800Z 20.4N 120.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 09/0600Z 21.0N 121.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 09/1800Z 21.5N 122.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 10/0600Z...DISSIPATED

$$
Forecaster Latto/Pasch

[cycloneye]

Tropical Depression Cosme Discussion Number 8
NWS National Hurricane Center Miami FL EP032019
200 AM PDT Mon Jul 08 2019

Cosme continues to gradually weaken over 23 to 24 degree C waters
and in a dry and stable atmospheric environment with about 10 to
15 kt of westerly shear. The depression now consists of scattered
mid- to high- level debris clouds over a low-level swirl, with a
small area of convection located nearly 200 n mi northeast the
system's center. A scatterometer pass at 0450 UTC showed peak winds
of 25 kt associated with Cosme's circulation. This intensity agrees
with the satellite intensity estimates from TAFB and ADT and will be
the depression's initial intensity for this advisory.

The unfavorable environmental conditions for Cosme will not improve
as the depression continues to move over cooler waters today. This
should prevent any significant amounts of deep convection from
developing near the system's center, and Cosme is expected to become
a remnant low at some point later on today.

The initial motion of Cosme is northwest at 8 kt. This general
motion will continue through today with a slowing in forward speed.
Thereafter, the remnant low will drift northwestward to
west-northwestward in the low-level flow until it dissipates.

FORECAST POSITIONS AND MAX WINDS

INIT 08/0900Z 19.8N 120.1W 25 KT 30 MPH
12H 08/1800Z 20.4N 120.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 09/0600Z 21.0N 121.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 09/1800Z 21.5N 122.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 10/0600Z...DISSIPATED

$$
Forecaster Latto/Pasch

[galaxy401]

Cosme's dead guys.

Post-Tropical Cyclone Cosme Discussion Number 9
NWS National Hurricane Center Miami FL EP032019
800 AM PDT Mon Jul 08 2019

The combination of cold sea surface temperatures, dry and stable
air, and modest westerly shear has taken a toll on Cosme. The
cyclone has been devoid of any central deep convection for more
than 12 hours, and has degenerated into a large swirl of mostly
cold-air stratocumulus clouds. As a result, the system no longer
meets the criteria of a tropical cyclone, and this is the last
advisory. The winds are estimated to be near 25 kt with higher
gusts based on an overnight ASCAT-C scatterometer pass. Additional
weakening is forecast, and the remnant low is expected to dissipate
in a couple of days while it moves slowly northwestward over cooler
waters.

For additional information on Post-Tropical Cyclone Cosme, 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 08/1500Z 20.5N 120.7W 25 KT 30 MPH...POST-TROP/REMNT LOW
12H 09/0000Z 21.0N 121.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
24H 09/1200Z 21.6N 122.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
36H 10/0000Z 22.1N 122.7W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 10/1200Z...DISSIPATED

$$
Forecaster Stewart