EPAC: TERRY - Remnants

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Re: EPAC: INVEST 93E

#21 Postby Nancy Smar » Thu Nov 04, 2021 9:08 am

CIRA/NESDIS Experimental AMSU-A TC Intensity/Size Estimation - NOAA19

Tropical Cyclone EP182021 EIGHTEEN
Current date/time: 2021 1104 1405 UTC
ATCF file date/time: 2021 1104 1200 UTC

AMSU swath date/time: 2021 1104 1200 UTC

INTENSITY/SIZE ESTIMATION FAILED
Storm too far from center of AMSU data swath
Observed Distance: 9986. km
Max allowable distance: 700. km
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Re: EPAC: INVEST 93E

#22 Postby cycloneye » Thu Nov 04, 2021 9:15 am

EP182021 - Tropical Depression EIGHTEEN

https://rammb-data.cira.colostate.edu/t ... r=ep182021
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#23 Postby cycloneye » Thu Nov 04, 2021 9:51 am

Tropical Depression Eighteen-E Discussion Number 1
NWS National Hurricane Center Miami FL EP182021
1000 AM CDT Thu Nov 04 2021

The area of low pressure we have been tracking since it formed
several days ago over the southwestern Caribbean Sea has moved
over the far eastern Pacific and gradually become better-defined
over the past couple of days. In addition, the convective
organization has steadily increased. An ASCAT-C overpass earlier
this morning showed that the surface low was slightly elongated.
However, the deep convection has persisted near, or just east of
that low for several hours since that time. First light visible
satellite imagery also indicates that the circulation is
well-defined. Therefore, advisories are being initiated for
Tropical Depression Eighteen-E. The ASCAT pass also showed peak
winds of 28 kt associated with the system, and a blend of the latest
Dvorak intensity estimates from TAFB and SAB suggest an initial
advisory intensity of 30 kt.

The initial motion of the depression is 280/7 kt. The cyclone is
located to the south of a broad mid-tropospheric ridge extending
across southern Mexico and much of the eastern Pacific basin. This
feature should steer the depression generally westward for most of
the forecast period, along with a gradual increase in forward speed.
By day 5, a turn to the west-northwest may occur, as the cyclone
becomes situated along the southwestern portion of the ridge. The
track model guidance is in good agreement on this scenario, and the
NHC track forecast is near the various multi-model consensus
solutions.

The environment surrounding and ahead of the depression appears
generally favorable for strengthening with ample atmospheric
moisture and SSTs of 27 to 28 degrees C. The only inhibiting factor
to strengthening may be the westerly shear vector, which although
should remain under 10 kt, when combined with the cyclone's
increasing westerly forward motion may cause convection to
periodically get stripped to its east of its center. Based on these
conditions, the model guidance indicates a slow and steady pace of
strengthening over the next several days, and NHC follows suit with
an intensity forecast near the IVCN and NOAA-HCCA consensus.


FORECAST POSITIONS AND MAX WINDS

INIT 04/1500Z 9.4N 90.0W 30 KT 35 MPH
12H 05/0000Z 9.6N 90.9W 30 KT 35 MPH
24H 05/1200Z 9.4N 92.0W 35 KT 40 MPH
36H 06/0000Z 9.2N 93.4W 35 KT 40 MPH
48H 06/1200Z 9.0N 95.2W 40 KT 45 MPH
60H 07/0000Z 9.0N 97.3W 40 KT 45 MPH
72H 07/1200Z 9.0N 99.6W 45 KT 50 MPH
96H 08/1200Z 9.7N 104.1W 50 KT 60 MPH
120H 09/1200Z 11.1N 108.5W 55 KT 65 MPH

$$
Forecaster Latto
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#24 Postby cycloneye » Thu Nov 04, 2021 1:11 pm

A. 18E (NONAME)

B. 04/1730Z

C. 9.5N

D. 90.2W

E. THREE/GOES-E

F. T3.0/3.0

G. IR/EIR/VIS

H. REMARKS...AN LLCC LESS THAN HALF A DEGREE FROM EDGE OF CONVECTION
YIELDS A DT OF 3.0 BASED ON SHEAR PATTERN. MET IS EQUAL TO 2.5 AND PT
IS 3.0 BASED ON DEVELOPMENT TREND IN THE LAST 24 HOURS. FT IS BASED ON
PT DU TO UNCERTAINTY IN THE EXACT CENTER LOCATION.

I. ADDL POSITIONS

NIL


...TUGGLE
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#25 Postby Yellow Evan » Thu Nov 04, 2021 3:18 pm

This might have a window to deepen later on but westerly shear is killing this atm.
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#26 Postby cycloneye » Thu Nov 04, 2021 3:48 pm

Tropical Depression Eighteen-E Discussion Number 2
NWS National Hurricane Center Miami FL EP182021
400 PM CDT Thu Nov 04 2021

The depression's overall appearance has not improved much today,
and the cyclone consists of a curved band that extends primarily to
the northeast of the estimated center, with the low-level center
near the edge of the deep convection. The initial intensity is
being held at 30 kt for this advisory, and is based on the latest
Dvorak intensity estimates from TAFB and the UW-CIMSS ADT.

The cyclone has wobbled a little to the west-northwest today and the
initial motion is 285/6 kt. A mid-tropospheric ridge located to the
north of the depression is forecast to strengthen and expand
westward over the next few days. This should force the cyclone on
more of a westward track, or even a little south of west, along with
an increase in forward speed. This westward motion should continue
for the remainder of the 5-day forecast period. The model track
guidance remains in good agreement, and has shifted slightly south.
The latest NHC track forecast was also nudged to the south, but lies
on the northern end of the clustered track consensus solutions.

The forecast intensity philosophy remains unchanged. The environment
surrounding and ahead of the depression appears generally favorable
for strengthening with ample atmospheric moisture and SSTs of 27 to
28 degrees C. However, 5 to 10 kt of westerly shear combined with
the cyclone's increasing westward motion may cause convection to
periodically get stripped to the east of its center. The latest NHC
intensity forecast is essentially unchanged from the previous one,
and remains near the IVCN and NOAA-HCCA consensus.


FORECAST POSITIONS AND MAX WINDS

INIT 04/2100Z 9.6N 90.5W 30 KT 35 MPH
12H 05/0600Z 9.7N 91.3W 30 KT 35 MPH
24H 05/1800Z 9.5N 92.5W 35 KT 40 MPH
36H 06/0600Z 9.2N 94.2W 35 KT 40 MPH
48H 06/1800Z 9.0N 96.3W 40 KT 45 MPH
60H 07/0600Z 8.9N 98.5W 40 KT 45 MPH
72H 07/1800Z 9.2N 100.8W 45 KT 50 MPH
96H 08/1800Z 10.1N 105.3W 50 KT 60 MPH
120H 09/1800Z 11.0N 110.0W 55 KT 65 MPH

$$
Forecaster Latto
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#27 Postby Yellow Evan » Thu Nov 04, 2021 3:51 pm

Great to see we have an agency ignoring ASCAT.
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#28 Postby aspen » Thu Nov 04, 2021 4:58 pm

Yellow Evan wrote:Great to see we have an agency ignoring ASCAT.

ASCAT supports a TS? Or does it not even show a closed LLC?
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#29 Postby Yellow Evan » Thu Nov 04, 2021 5:43 pm

aspen wrote:
Yellow Evan wrote:Great to see we have an agency ignoring ASCAT.

ASCAT supports a TS? Or does it not even show a closed LLC?


Former at least at the time of the ASCAT pass though it’s clearly degrading now.
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#30 Postby Yellow Evan » Thu Nov 04, 2021 7:33 pm

TXPZ22 KNES 050013
TCSENP

A. 18E (NONAME)

B. 04/2330Z

C. 9.8N

D. 90.7W

E. THREE/GOES-E

F. T1.5/2.5

G. IR/EIR/SWIR/VIS

H. REMARKS...VERY LITTLE ACTIVE DEEP CONVECTION REMAINS. SLIGHTLY MORE
THAN 2/10 BANDING WAS MEASURED WELL SOUTHWEST OF THE CENTER FOR A DT
OF 1.0. RAPID WEAKENING OVER THE LAST 24 HOURS RESULTS IN A MET OF LESS
THAN 1.0 AND THE PT AGREES. FT IS BASED ON CONSTRAINTS LIMITING CHANGES
IN T-NUMBER TO 1.0 OVER 6 HOURS.

I. ADDL POSITIONS

NIL


...TURK
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#31 Postby aspen » Thu Nov 04, 2021 8:24 pm

It looked pretty good for a few moments. Odds are this will still become TS Sandra in the next 24-36 hours, but a hurricane is unlikely this late in the calendar year during a La Niña. Anything above 80 kt is even less likely.
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#32 Postby cycloneye » Thu Nov 04, 2021 8:32 pm

Is looking horrible.

Image
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#33 Postby Yellow Evan » Thu Nov 04, 2021 9:39 pm

aspen wrote:It looked pretty good for a few moments. Odds are this will still become TS Sandra in the next 24-36 hours, but a hurricane is unlikely this late in the calendar year during a La Niña. Anything above 80 kt is even less likely.


Unless thunderstorm activity can re-develop, and the shear direction is not exactly favorable right now, this is unlikely to become a named storm and will probably open up into a trough in a day or so.
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#34 Postby cycloneye » Thu Nov 04, 2021 9:49 pm

Tropical Depression Eighteen-E Discussion Number 3
NWS National Hurricane Center Miami FL EP182021
1000 PM CDT Thu Nov 04 2021

TD18-E is a poorly organized system this evening. Most of the
deeper convection that was near the center earlier today has
collapsed, with only a few skeletal outer bands remaining south of
the low-level circulation. Last light visible satellite imagery
also indicated that the low-level center was not vertically
aligned, located to the west ahead of the mid-level center. While I
have yet to receive new scatterometer data which should be
arriving soon, the current satellite structure argues against
any development. Indeed, the latest TAFB and SAB Dvorak satellite
estimates have held steady or decreased from earlier today. The
current intensity will remain at 30 kt for this advisory, and even
this might be a bit generous.

After a motion to the west-northwest earlier, the depression appears
to have resumed a due westward motion, estimated at 270/6 kt. A
narrow mid-tropospheric ridge north of the cyclone has been steering
the system slowly westward, and this ridge is expected to strengthen
and merge with a larger mid-level ridge currently centered over the
Baja California peninsula. The end result of this pattern
reconfiguration on the depression should be a faster motion to the
west, or even west-southwest due to the orientation of the ridge
complex. By the end of the forecast period, the ridge is expected to
shift a bit more to the east, which will provide an opportunity for
the depression to gain some latitude by the end of the forecast
period. The model track guidance continues to be in good agreement,
though with a bit of along-track spread. The guidance overall has
made another shift to the south this cycle, and the latest NHC track
was also once again nudged further south, staying on the northern
side of the guidance envelope but not too far from the TVCE and HCCA
consensus solutions.

The intensity forecast is somewhat challenging. While the latest
SHIPS guidance indicates the depression will remain in low 200-850
hPa vertical wind shear, have ample mid-level moisture, and be over
27-28 C sea-surface temperatures, the majority of the intensity
guidance shows only modest strengthening over the next 2-3 days.
Model-derived soundings from the GFS and HWRF suggest that higher
mid-level shear could be undercutting this favorable upper-level
flow pattern over the time period. This undercutting shear may help
explain why the low and mid-level centers of the depression are
currently not aligned. In addition, surface-based backwards
trajectories suggest that the tropical cyclone is ingesting air
originating over the equator, which currently is dominated by an
environment of stable stratocumulus clouds. This may help explain
the anemic convective appearance of the system currently. An
additional forecast concern is the low-latitude track of the
cyclone, with the forecast showing the system losing additional
latitude over the next several days. All these factors make me
skeptical that there will be significant intensification over the
next 2-3 days and the intensity forecast has been lowered somewhat
from the previous one over this time period. The latest NHC
intensity forecast is a bit under the latest IVCN and NOAA-HCCA
consensus, but is higher than the current LGEM and ECMWF guidance,
which essentially show no intensification through the forecast
period.


FORECAST POSITIONS AND MAX WINDS

INIT 05/0300Z 9.7N 91.2W 30 KT 35 MPH
12H 05/1200Z 9.6N 92.0W 30 KT 35 MPH
24H 06/0000Z 9.2N 93.5W 30 KT 35 MPH
36H 06/1200Z 9.1N 95.4W 35 KT 40 MPH
48H 07/0000Z 8.9N 97.4W 35 KT 40 MPH
60H 07/1200Z 8.9N 99.5W 35 KT 40 MPH
72H 08/0000Z 9.3N 102.0W 40 KT 45 MPH
96H 09/0000Z 10.0N 106.7W 50 KT 60 MPH
120H 10/0000Z 10.6N 111.5W 55 KT 65 MPH

$$
Forecaster Papin
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#35 Postby Sciencerocks » Thu Nov 04, 2021 9:54 pm

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Re: EPAC: EIGHTEEN-E - Tropical Depression

#36 Postby cycloneye » Fri Nov 05, 2021 4:36 am

Tropical Depression Eighteen-E Discussion Number 4
NWS National Hurricane Center Miami FL EP182021
400 AM CDT Fri Nov 05 2021

The depression has not become much better organized since
yesterday. Some small clusters of deep convection have formed to
the northeast and east of the center, and there are some thin
convective banding features over the southern and western portions
of the circulation. Cirrus-level outflow from the system is rather
weak at this time. The advisory intensity estimate is held at 30 kt
which is in general agreement with the latest Dvorak analyses from
TAFB and SAB, along with earlier scatterometer observations. The
latter data, however, suggest that this may be a slightly generous
estimate.

Latest center fixes indicate a continued westward motion, or around
265/6 kt. A mid-level ridge associated with a large high pressure
system centered over western Mexico should provide the primary
steering mechanism for the cyclone during the forecast period. A
mainly westward motion at a somewhat faster forward speed is
expected, as the system encounters slightly stronger easterlies on
the south side of the ridge within the next couple of days. The
dynamical track guidance is in fairly good agreement, although the
GFS model is a bit of a northern outlier. The official forecast
track is similar to the previous one, and close to the model
consensus.

Since it is still not very well organized, the tropical cyclone
is not expected to strengthen much through today. Although the
environment is seemingly conducive for strengthening, the model
guidance is not very aggressive in showing intensification during
the next few days. This may be partially due to a lack of mid- to
upper-level instability ,as suggested by the decay-SHIPS output.
The official forecast, like the previous one, shows only slow
strengthening beginning tomorrow, following the intensity model
consensus.


FORECAST POSITIONS AND MAX WINDS

INIT 05/0900Z 9.7N 91.7W 30 KT 35 MPH
12H 05/1800Z 9.5N 92.6W 30 KT 35 MPH
24H 06/0600Z 9.2N 94.2W 30 KT 35 MPH
36H 06/1800Z 9.0N 96.1W 35 KT 40 MPH
48H 07/0600Z 8.9N 98.3W 35 KT 40 MPH
60H 07/1800Z 9.1N 100.7W 40 KT 45 MPH
72H 08/0600Z 9.5N 103.1W 45 KT 50 MPH
96H 09/0600Z 10.6N 108.0W 50 KT 60 MPH
120H 10/0600Z 11.5N 112.5W 55 KT 65 MPH

$$
Forecaster Pasch
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#37 Postby aspen » Fri Nov 05, 2021 7:30 am

HWRF still wants a November major out of this lol.
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#38 Postby cycloneye » Fri Nov 05, 2021 11:59 am

Tropical Depression Eighteen-E Discussion Number 5
NWS National Hurricane Center Miami FL EP182021
1000 AM CDT Fri Nov 05 2021

The convective structure with the depression this morning remains
disheveled, with only scattered convection pulsing around the
circulation without much organization. The latest subjective Dvorak
satellite estimates are T2.0/30 kt from TAFB and T1.5/25 kt from
SAB, while the most recent UW-CIMSS ADT estimate was T2.1/31 kt. A
blend of these data support maintaining the intensity at 30 kt this
advisory.

Early morning visible satellite imagery suggests that the system is
moving south of due west, with the latest motion estimate at 260/8
kt. As an amplified short-wave trough located over the Gulf of
Mexico propagates eastward, a mid-level ridge ridge centered near
the Baja California peninsula is expected to expand eastward over
Mexico. This feature should dominate the steering pattern over the
depression through the forecast period, leading to a general
westward motion but at a gradually accelerating forward speed.
Because the depression is quite shallow currently, low-level flow in
association with a developing gale-force gap wind event in the Gulf
of Tehuantepec may also assist the system in losing a bit more
latitude over the next 24-36 hours. After 48 hours, a weakness under
the ridge from an downstream disturbance may allow the depression to
gain back a bit of latitude. The track guidance remains in fairly
good agreement, though differences in speed are seen between the
slower GFS versus the faster ECMWF guidance, and another southward
shift has taken place. The official NHC track forecast is a bit
further south and a touch faster compared to the previous one,
following the consensus aids TVCE and HCCA.

The current poor organization of the convection argues against any
short-term intensity changes. While deep-layer (200-850 hPa)
vertical wind shear is expected to remain low, higher mid-level
shear may prevent better convective organization over the next 36-48
hours. While mid-level relative humidity is forecast to be
sufficently moist, visible satellite imagery suggests stable
stratocumulus inflow from the south, while the aforementioned gap
wind event to the north may also contribute to a less-than-optimal
thermodynamic environment. The official NHC intensity forecast now
shows no intensification over the next 36 hours with only gradual
intensification thereafter, favoring the more pessimistic guidance.
If the latest ECMWF and LGEM guidance are correct, the depression
may fail to intensify at all over the forecast period.


FORECAST POSITIONS AND MAX WINDS

INIT 05/1500Z 9.4N 92.4W 30 KT 35 MPH
12H 06/0000Z 9.2N 93.5W 30 KT 35 MPH
24H 06/1200Z 8.9N 95.4W 30 KT 35 MPH
36H 07/0000Z 8.7N 97.5W 30 KT 35 MPH
48H 07/1200Z 8.7N 99.7W 35 KT 40 MPH
60H 08/0000Z 9.2N 102.0W 40 KT 45 MPH
72H 08/1200Z 9.8N 104.4W 45 KT 50 MPH
96H 09/1200Z 10.9N 109.4W 50 KT 60 MPH
120H 10/1200Z 11.3N 114.2W 55 KT 65 MPH

$$
Forecaster Papin
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#39 Postby cycloneye » Fri Nov 05, 2021 3:50 pm

Tropical Depression Eighteen-E Discussion Number 6
NWS National Hurricane Center Miami FL EP182021
400 PM CDT Fri Nov 05 2021

For the last 6-9 hours, TD18-E has not produced enough organized
deep convection to be classifiable as a tropical cyclone. Indeed,
the current satellite structure primarily consists of a low-level
cloud swirl, with only a few disorganized puffs of colder cloud tops
that quickly decay after they form. In addition, an earlier ASCAT-B
pass valid at 1608 UTC suggested that the circulation was also
becoming increasingly fragile, with less than 10 kt winds on the
southwest side of the vortex and a peak wind retrieval of only 25
kt. Subjective satellite Dvorak estimates have been decreasing, with
the latest T numbers down to T1.5 from TAFB and T1.0 from SAB.
Assuming some undersampling could still be occuring from the earlier
ASCAT wind data, the intensity was held at 30 kt this advisory,
though this is likely generous.

The motion continues to be south of due west, with the latest
estimate now at 260/9 kt. There has not been much change to the
latest track reasoning. An expansive mid-level ridge is expected to
build eastward over Mexico over the next several days, helping to
maintain the tropical cyclone on a westward heading throughout the
forecast period. However, the cyclone is vertically shallow,
and the influence of the low-level gap wind flow emanating from the
Gulf of Tehuantepec could be causing the short-term south of due
west bend in the track. Yet again, the track guidance has come in
further south and a bit faster compared to the previous cycle, and
the latest NHC track forecast has been shifted in that direction,
though still not quite as far south and west as the HCCA and TVCE
consensus aids.

Without any organized convection occuring near the center of the
depression currently, its future status as a tropical cyclone could
be in jeopardy. Apparently stable air has infiltrated the
circulation and is limiting convective output despite sufficently
warm sea-surface temperatures and vertical wind shear that does not
seem too inhibiting. The GFS, ECMWF, and HWRF model simulated IR
brightness temperature forecasts suggest that better organized
convection should return near the low-level center during tonight's
diurnal maximum. Even so, the global model guidance continues to
trend downward in the intensity forecast, delaying intensification
further out into the future. Indeed the most recent GFS run
maintains status quo intensity over the next 48 hours, joining the
ECMWF, SHIPS and LGEM guidance. The only guidance that shows
significant intensification over the next several days is the HWRF
and this model has had a persistent high bias. The latest intensity
forecast has been lowered a bit more beyond 36 h. As alluded above,
if organized deep convection does not return soon, it's possible
this depression could degenerate into a remnant low as early as
tomorrow.


FORECAST POSITIONS AND MAX WINDS

INIT 05/2100Z 9.1N 93.5W 30 KT 35 MPH
12H 06/0600Z 8.9N 94.7W 30 KT 35 MPH
24H 06/1800Z 8.6N 96.7W 30 KT 35 MPH
36H 07/0600Z 8.4N 99.0W 30 KT 35 MPH
48H 07/1800Z 8.7N 101.3W 30 KT 35 MPH
60H 08/0600Z 9.2N 103.6W 35 KT 40 MPH
72H 08/1800Z 9.6N 106.3W 40 KT 45 MPH
96H 09/1800Z 10.6N 111.1W 45 KT 50 MPH
120H 10/1800Z 11.0N 116.0W 50 KT 60 MPH

$$
Forecaster Papin
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#40 Postby Category5Kaiju » Fri Nov 05, 2021 4:53 pm

Seems like the recurrent theme this late season in the EPAC is that instead of the Atlantic, tropical waves are entering the EPAC in copious numbers due to the southward ITCZ shift. The problem: given the La Nina, tropical waves that do form begin to really struggle with intensifying and keeping organized.
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