ATL: KATE - Remnants - Discussion

[Iceresistance]

Well, Kate might be on it's way out . . .

...POORLY ORGANIZED KATE NOW A TROPICAL DEPRESSION...

11:00 AM AST Tue Aug 31
Location: 23.5°N 50.8°W
Moving: N at 5 mph
Min pressure: 1007 mb
Max sustained: 35 mph

[Teban54]

Calling it a TD is generous based on its current satellite appearance. Kate may not even have a LLC now.

[Sciencerocks]

[cycloneye]

Tropical Depression Kate Discussion Number 15
NWS National Hurricane Center Miami FL AL102021
500 PM AST Tue Aug 31 2021

Kate continues to produce small, sporadic bursts of convection near
and to the east of its partially exposed low-level center this
afternoon. The cyclone has moved north of the subtropical jet stream
that it has been centered under for the past couple of days, so the
mid- to upper-level vertical wind shear is beginning to diminish.
Unfortunately, all three ASCAT passes this morning missed Kate's
small circulation. The current intensity Dvorak estimates from TAFB
and SAB support maintaining the initial intensity at 30 kt for this
advisory.

The cyclone is moving a little faster to the north, or 360/6 kt. The
track forecast reasoning is largely unchanged. Kate is expected to
begin moving north-northwestward tonight as a mid-level ridge builds
to the east and northeast of the cyclone. This general motion should
continue through early Thursday, before an approaching mid- to
upper-level trough begins steering Kate more northward through
Friday. The official NHC track forecast is essentially an update of
the previous one and lies near the center of the guidance envelope,
remaining close to the multi-model consensus aids.

The intensity forecast is a bit more challenging, with mixed signals
noted from the various intensity models. On the one hand, satellite
imagery indicates the vertical wind shear is obviously diminishing
over Kate, and the cyclone is forecast to move over SSTs of around
28.5 deg C for the next couple of days. However, the cyclone remains
embedded within a dry mid-level environment that is clearly making
it difficult for Kate to produce organized convection. The official
NHC intensity forecast still shows no explicit intensity change and
remains closest to the HFIP corrected consensus approach (HCCA) and
IVDR aids. However, some short-term intensity fluctuations are
certainly possible, which is notable since Kate's intensity is
hovering around the tropical depression/storm threshold. By
Thursday, Kate will be moving into an even drier, more subsident
environment that will make it even more difficult to sustain deep
convection. Thus, the NHC forecast shows Kate becoming a remnant low
completely devoid of convection by Friday, with dissipation shortly
thereafter ahead of an approaching frontal system.


FORECAST POSITIONS AND MAX WINDS

INIT 31/2100Z 24.6N 50.9W 30 KT 35 MPH
12H 01/0600Z 25.5N 51.5W 30 KT 35 MPH
24H 01/1800Z 26.9N 52.6W 30 KT 35 MPH
36H 02/0600Z 28.6N 53.5W 30 KT 35 MPH
48H 02/1800Z 30.3N 54.2W 30 KT 35 MPH
60H 03/0600Z 32.0N 54.2W 30 KT 35 MPH
72H 03/1800Z 33.7N 53.8W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 04/1800Z...DISSIPATED

$$
Forecaster Reinhart

[aspen]

https://imagizer.imageshack.com/img924/7426/ad9WBh.gif

Aww it’s so tiny and pathetic.

[AnnularCane]

https://imagizer.imageshack.com/img924/7426/ad9WBh.gif

Aww it’s so tiny and pathetic.

I kinda like her.

[aspen]

Honestly the best Kate ever looked was when she was first designated as 98L.

[hurricanes1234]

Honestly the best Kate ever looked was when she was first designated as 98L.
https://i.imgur.com/ZfPZ75w.png

This is honestly the most hilarious thing I've ever seen. If you're the one who came up with this, I salute you.

[aspen]

Honestly the best Kate ever looked was when she was first designated as 98L.
https://i.imgur.com/ZfPZ75w.png

This is honestly the most hilarious thing I've ever seen. If you're the one who came up with this, I salute you.

Yeah I spent my time making a meme about a disappointment of a storm instead of doing something more productive like working on my Java program assignment.

Too bad that both Julian and Kate have failed to become hurricanes despite model guidance at one point heavily favoring that possibility. Maybe Kate can briefly regain TS status before becoming post-tropical, but that’s pretty much the best she can do now.

[wxman57]

This one should not have been updated. Used to be convection near a naked swirl had to persist for more than a couple of hours. Bones would show up here but he's too disgusted.

[cycloneye]

Tropical Depression Kate Discussion Number 16
NWS National Hurricane Center Miami FL AL102021
1100 PM AST Tue Aug 31 2021

Some bursts of convection have been forming within Kate's small
circulation during the past several hours, but none of it has any
real significant organization. In addition, the low clouds appear
to be losing definition, and a very-recent ASCAT-B pass showed that
the maximum winds are now only about 25 kt. It's going to be
difficult for Kate to make much of a comeback, if at all. Moderate
northerly shear, dry mid-level air, upper-level convergence, and an
increasingly anticyclonic low-level environment are likely to cause
the circulation to spin down further and make it hard for deep
convection to persist. Therefore, the NHC official forecast now
calls for additional weakening, with Kate likely becoming a remnant
low by 36 hours (if not sooner) and dissipating by 72 hours. This
scenario is closest to the GFS, HWRF, and HMON solutions.

Located on the southwestern periphery of a low-level area of high
pressure, Kate is moving toward the north-northwest (345/9 kt).
The depression is forecast to turn toward the northwest by morning,
but then recurve around the high toward the north and
north-northeast in a couple of days. The NHC track forecast remains
close to the consensus aids and is generally just an update from the
previous advisory.


FORECAST POSITIONS AND MAX WINDS

INIT 01/0300Z 25.4N 51.3W 25 KT 30 MPH
12H 01/1200Z 26.4N 52.1W 25 KT 30 MPH
24H 02/0000Z 27.9N 53.1W 25 KT 30 MPH
36H 02/1200Z 29.8N 53.8W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 03/0000Z 31.6N 54.1W 20 KT 25 MPH...POST-TROP/REMNT LOW
60H 03/1200Z 33.1N 53.7W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 04/0000Z...DISSIPATED

$$
Forecaster Berg

[Hammy]

Honestly the best Kate ever looked was when she was first designated as 98L.
https://i.imgur.com/ZfPZ75w.png

This is honestly the most hilarious thing I've ever seen. If you're the one who came up with this, I salute you.

Yeah I spent my time making a meme about a disappointment of a storm instead of doing something more productive like working on my Java program assignment.

Too bad that both Julian and Kate have failed to become hurricanes despite model guidance at one point heavily favoring that possibility. Maybe Kate can briefly regain TS status before becoming post-tropical, but that’s pretty much the best she can do now.

Given this is the third storm that the GFS has erroneously blown up into a major hurricane north of 30 (the others being Henri and Julian) I think we can toss the model entirely at that latitude and defer to the Euro or Canadian.

[cycloneye]

Tropical Depression Kate Discussion Number 17
NWS National Hurricane Center Miami FL AL102021
500 AM AST Wed Sep 01 2021

After the earlier convective hiatus, a concentrated area of
thunderstorm activity containing numerous lightning strikes has
developed over and to the east of the low-level center. In
addition, upper-level outflow has been expanding to the west, an
indication that the hostile shear conditions that have been
plaguing the cyclone the past few days has finally waned. ASCAT
data around 0000-0100Z showed peak winds near 25 kt; however, the
recent sharp increase in deep convection along with a consensus
Dvorak subjective intensity of T2.0/30 kt supports increasing the
intensity to 30 kt. The 30-kt advisory intensity is also supported
by UW-CIMSS objective intensity estimates of T2.1/31 kt from ADT
and 39 kt from SATCON.

The initial motion estimate is 340/08 kt. Kate is moving
north-northwestward between a small mid- to upper-level low to the
south of the cyclone and deep-layer ridge located to the north and
east of the system. A gradual turn toward the northwest is expected
later today, followed by a turn back toward the north on Thursday as
Kate rounds the western periphery of the ridge. By Friday,
recurvature toward the north-northeast and northeast into the
mid-latitude westerlies is forecast when the cyclone will be lifted
out by an eastward-moving deep-layer trough currently crossing the
western Atlantic. The new NHC track forecast is similar to but a
little to the left of the previous advisory track, and closely
follows the tightly packed consensus track forecast models TVCA and
NOAA-HCCA.

A 0505 UTC AMSR-2 microwave pass revealed that Kate's compact
circulation had tightened up considerably since the earlier 0100 UTC
ASCAT wind data, which shows a broad and elongated inner-core wind
field. Also, Kate is currently passing between two small upper-level
lows to the north and south of the cyclone, which is aiding the
upper-level divergence across the system, albeit somewhat
constrained due to the short distance of only about 300 nmi between
the two upper lows. Given the locally enhanced outflow and the
recent increase in deep convection, it s not out of the question
that Kate could restrengthen back into a low-end tropical storm
during the next 24 hours or so. However, the entrainment of dry
mid-level air with humidity values less than 50 percent should
prevent any significant or rapid restrengthening from occuring. by
48 hours, moderate northerly shear and even drier mid-level air
should cause convection weaken, resulting in a gradual spin down of
the circulation and eventual dissipation by 72 hours. The new NHC
intensity forecast is similar to but slightly lower than the
consensus intensity models IVCN and HCCA, and the Decay-SHIPS
statistical-dynamical intensity model.


FORECAST POSITIONS AND MAX WINDS

INIT 01/0900Z 25.7N 51.7W 30 KT 35 MPH
12H 01/1800Z 26.9N 52.5W 30 KT 35 MPH
24H 02/0600Z 28.5N 53.2W 30 KT 35 MPH
36H 02/1800Z 30.3N 53.7W 25 KT 30 MPH
48H 03/0600Z 31.9N 53.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
60H 03/1800Z 33.5N 53.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 04/0600Z...DISSIPATED

$$
Forecaster Stewart

[aspen]

I can’t find the LLC on visible imagery. I think this has already opened up.

[cycloneye]

Tropical Depression Kate Discussion Number 18
NWS National Hurricane Center Miami FL AL102021
1100 AM AST Wed Sep 01 2021

It has been difficult to pinpoint where the low-level circulation of
Kate is this morning. After last night's diurnal convective maximum,
the remaining convection has taken on a very disorganized structure,
with a mid-level vortex being left behind to the south, while
deeper, but more outflow driven convection is racing off to the
north, ahead of the estimated low-level center position. A recently
received 1211 UTC ASCAT-A pass indicated that Kate's low-level
circulation is still closed, but just barely. The scatterometer wind
data supports maintaining the current intensity at 30-kt, which also
agrees with the latest subjective and objective Dvorak estimates.

The estimated motion is continuing off to the north-northwest, at
340/9 kt. Kate appears to now be primarily steered by the low-level
flow around a subtropical ridge located to its east. A general
north-northwest motion is expected to continue today, followed by a
turn to the north and north-northeast around the periphery of this
ridge. The latest NHC track guidance has been adjusted a bit right
of the previous track, shifting towards the latest consensus
guidance (TVCN) that can still track the cyclone beyond 24 hours.

A 0958 UTC SSMIS microwave pass suggested that the better organized
structure observed last night has decayed, with the low- and
mid-level centers quite misaligned. Vertical wind shear diagnosed by
SHIPS is now between 15-20 kt out of the north. This shear is likely
contributing to the vortex tilt, while also helping to import very
dry mid-level air, preventing Kate's convective activity from
organizing. The bulk of the intensity guidance is in agreement that
gradual spin down of the low-level circulation will occur over the
next several days, with the deterministic ECMWF model suggesting
Kate could open up to a trough as soon as tomorrow. The latest NHC
intensity forecast makes Kate a remnant low in 36 hours, with
dissipation after 48 hours. However, given the current structure,
this could occur sooner than forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 01/1500Z 26.8N 52.3W 30 KT 35 MPH
12H 02/0000Z 27.9N 52.7W 25 KT 30 MPH
24H 02/1200Z 29.6N 53.1W 25 KT 30 MPH
36H 03/0000Z 31.1N 53.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 03/1200Z 32.4N 52.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
60H 04/0000Z...DISSIPATED

$$
Forecaster Papin

[ChrisH-UK]

This is Kate from GOES-16 using the Snow/Ice band. This band is really helpful in seeing the different layers to a cyclone. The Gray clouds are the higher level clouds and the white clouds are the lower level. So as you can see there is still a circulation at the lower level under the higher clouds, saying that it is a bit of a mess.

Source - https://col.st/EXGkV

[Sciencerocks]

[galaxy401]

Dead.

BULLETIN
Remnants Of Kate Advisory Number 19
NWS National Hurricane Center Miami FL AL102021
500 PM AST Wed Sep 01 2021

...KATE NO LONGER HAS A WELL-DEFINED CIRCULATION...
...THIS IS THE FINAL ADVISORY...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...28.5N 52.9W
ABOUT 960 MI...1545 KM NE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...30 MPH...45 KM/H
PRESENT MOVEMENT...NNW OR 340 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...1012 MB...29.89 INCHES

[cycloneye]

Remnants Of Kate Discussion Number 19
NWS National Hurricane Center Miami FL AL102021
500 PM AST Wed Sep 01 2021

Kate's structure this afternoon has deteriorated further. While
occasional bursts of deep convection are still occuring to the south
of a broad area of low-level cyclonic rotation, this activity lacks
much organization. Recent visible satellite imagery also suggests
that the low-level circulation is in the process of opening up into
a trough, with little if any northerly cloud motions being observed
to the west of the estimated center. In addition, I have been
fortunate to receive some in-situ data from the NASA-DC8 aircraft
that earlier preformed a research mission into Kate. Dropsonde data
launched near the center indicated that the surface pressure was
near 1012 mb, which is only a few millibars lower than the
environmental ambient pressure. The dropsondes launched west of the
center also failed to find any northerly surface winds. The
combination of these data suggest that Kate's center is losing
definition and no longer possesses a well-defined circulation.
Therefore, the system no longer meets the definition of a tropical
cyclone, and this will be the final advisory. Maximum sustained
winds have also been lowered to 25-kt based on the surface winds
from dropsonde data provided by the DC8 aircraft to the east of the
center.

The remnants of Kate have accelerated to the north-northwest today
with the estimated motion at 340/13 kt, likely as the low-level
vorticity maxima has become fully decoupled from the mid-level
vortex located well to the south and east. This motion should
continue until Kate completely fades away while embedded in
the synoptic environment near a low-level subtropical ridge.


FORECAST POSITIONS AND MAX WINDS

INIT 01/2100Z 28.5N 52.9W 25 KT 30 MPH
12H 02/0600Z...DISSIPATED

$$
Forecaster Papin