ATL: JOYCE - Post-Tropical - Discussion

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Re: ATL: JOYCE - Tropical Storm - Discussion

#41 Postby EquusStorm » Fri Sep 14, 2018 7:18 pm

I had kinda written Joyce off yesterday but convection just keeps getting more impressive. Could be mid end TS before it starts to weaken.
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...but still, though, a lot more interesting than the 2013 season.

Not a meteorologist, in fact more of an idiot than anything. You should probably check with the NHC or a local NWS office for official information.

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Re: ATL: JOYCE - Tropical Storm - Discussion

#42 Postby galaxy401 » Fri Sep 14, 2018 9:13 pm

Joyce has really organized in the past few hours. Much less sheared with impressive banding.

https://www.tropicaltidbits.com/sat/sat ... t=vis-swir
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I don't get hurricanes here but I do get their remnants.

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Re: ATL: JOYCE - Tropical Storm - Discussion

#43 Postby Hammy » Fri Sep 14, 2018 9:42 pm

I wonder if Joyce could make hurricane intensity given the small size and the fact that it's found a small favorable area.
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Re: ATL: JOYCE - Advisories

#44 Postby cycloneye » Sat Sep 15, 2018 3:38 pm

Tropical Storm Joyce Discussion Number 13
NWS National Hurricane Center Miami FL AL102018
500 PM AST Sat Sep 15 2018

The circulation of Joyce is elongated this afternoon, with the
center partially exposed. It has been interesting to watch deep
convection firing in the northeastern quadrant, kicking off new
small swirls that rotate around the mean circulation. A blend of
the Dvorak estimates from TAFB/SAB supports keeping the wind speed
40 kt on this advisory.

There is no change to the intensity forecast reasoning. The
environment is predicted to be nearly steady-state around Joyce
through Sunday, with strong shear being offset by waters near 27C.
Thereafter, as the hostile shear continues, the mid-level air should
become drier near the center, and SSTs cool off below 26C. These
conditions should cause Joyce to slowly weaken early next week, and
dissipate in 3 days or so. This forecast is basically the same as
the previous one, but it isn't out of the realm of possibility the
cyclone could open up into a trough before that time.

Joyce continues to accelerate, now moving east-northeastward at
about 15 kt. The storm remains embedded within the same trough as
Tropical Storm Helene, and Joyce should move east-northeastward
during the next day or so. Beyond that time, as Joyce becomes a
shallow cyclone, it is forecast to turn southeastward due to
low-level flow around the eastern side of a building ridge over the
central Atlantic Ocean. The track forecast is simply an update to
the previous one, and continues to be on the southern side of the
guidance envelope.


FORECAST POSITIONS AND MAX WINDS

INIT 15/2100Z 33.1N 39.6W 40 KT 45 MPH
12H 16/0600Z 34.1N 37.2W 40 KT 45 MPH
24H 16/1800Z 34.8N 33.8W 40 KT 45 MPH
36H 17/0600Z 34.8N 30.5W 35 KT 40 MPH
48H 17/1800Z 34.0N 28.0W 30 KT 35 MPH
72H 18/1800Z 31.5N 26.5W 25 KT 30 MPH
96H 19/1800Z...DISSIPATED

$$
Forecaster Blake
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Re: ATL: JOYCE - Advisories

#45 Postby cycloneye » Sun Sep 16, 2018 9:42 am

Tropical Depression Joyce Discussion Number 16
NWS National Hurricane Center Miami FL AL102018
1100 AM AST Sun Sep 16 2018

Joyce is barely a tropical cyclone at the moment. The cloud
pattern consists of a low-level swirl with a small patch of deep
convection located about 80 n mi northeast of the center and another
patch of weakening convection well removed from the center in the
northeast quadrant. Visible satellite images and a partial ASCAT
pass indicate that the circulation of the cyclone has also become
increasingly elongated from northeast to southwest. Based on the
system's appearance and the satellite intensity estimates, the
initial wind speed is lowered to 30 kt, making Joyce a tropical
depression.

The depression is moving east-northeastward at 16 kt within the
mid-latitude westerlies, and this motion should continue through
tonight. After that time, the shallow cyclone is expected to slow
down and turn southeastward and then southwestward as it is moves
in the flow on the east side of a building low- to mid-level ridge.
The track models are in fairly good agreement, and little overall
change was made to the previous NHC forecast.

Joyce is currently in a quite hostile environment of 30-40 kt of
west-southwesterly shear. Even though SSTs are relatively warm,
the ongoing strong shear and nearby dry air should continue to cause
the cyclone to gradually weaken. Although the NHC forecast shows
Joyce hanging on as a tropical depression for a couple of more days,
it is very possible that the system could degenerate into a trough
or a remnant low at any time during that period.

FORECAST POSITIONS AND MAX WINDS

INIT 16/1500Z 34.7N 34.3W 30 KT 35 MPH
12H 17/0000Z 34.9N 31.4W 30 KT 35 MPH
24H 17/1200Z 34.5N 28.7W 30 KT 35 MPH
36H 18/0000Z 33.6N 27.0W 30 KT 35 MPH
48H 18/1200Z 32.6N 26.7W 25 KT 30 MPH
72H 19/1200Z 30.4N 29.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 20/1200Z...DISSIPATED

$$
Forecaster Cangialosi
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Re: ATL: JOYCE - Advisories

#46 Postby cycloneye » Sun Sep 16, 2018 3:42 pm

Tropical Depression Joyce Discussion Number 17
NWS National Hurricane Center Miami FL AL102018
500 PM AST Sun Sep 16 2018

Joyce continues to hang on as a tropical depression. The cloud
pattern consists of a swirl of low-level clouds with patches
of deep convection that become sheared off in the northeast
quadrant. The initial intensity is held at 30 kt, in agreement
with an ASCAT pass from several hours ago that showed maximum winds
in the 25-30 kt range. Even though Joyce is over relatively warm
water, the current hostile atmospheric environment of 30-40 kt of
west-southwesterly shear and nearby dry air should cause Joyce to
gradually weaken during the next few days. Although remnant low
status is not predicted to occur for 2-3 days, it is very possible
that Joyce could degenerate into a trough or a remnant low well
before then.

The depression has turned to the east, with the latest initial
motion estimate being 090/15. The weak and shallow system is
expected to move in the low- to mid-level flow during the next few
days. This should cause the cyclone to slow down and turn
southeastward on Monday, followed by a southward and then
southwestward motion on Tuesday and Wednesday as the system moves
around a building ridge over the northeastern Atlantic. The track
models are in fairly good agreement, and only small changes were
made to the previous NHC forecast.

FORECAST POSITIONS AND MAX WINDS

INIT 16/2100Z 34.4N 32.6W 30 KT 35 MPH
12H 17/0600Z 34.2N 30.2W 30 KT 35 MPH
24H 17/1800Z 33.6N 28.0W 30 KT 35 MPH
36H 18/0600Z 32.4N 27.0W 25 KT 30 MPH
48H 18/1800Z 31.2N 27.4W 25 KT 30 MPH
72H 19/1800Z 29.4N 30.1W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 20/1800Z...DISSIPATED

$$
Forecaster Cangialosi
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Re: ATL: JOYCE - Tropical Depression - Discussion

#47 Postby HurricaneRyan » Sun Sep 16, 2018 7:45 pm

Is Joyce still here or no?
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Re: ATL: JOYCE - Tropical Depression - Discussion

#48 Postby EquusStorm » Sun Sep 16, 2018 9:21 pm

Little Joyce would have been pretty well talked about if not for Florence and Isaac, but now it's technically the only storm with active NHC advisories, until they decide to write it up as post-tropical. Which... might not be long now, the exposed LLC is looking weaker and weaker and might open up soon. Can't sustain convection anywhere close to the surface low thanks to strong shear.
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...but still, though, a lot more interesting than the 2013 season.

Not a meteorologist, in fact more of an idiot than anything. You should probably check with the NHC or a local NWS office for official information.

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Re: ATL: JOYCE - Advisories

#49 Postby cycloneye » Sun Sep 16, 2018 9:51 pm

Tropical Depression Joyce Discussion Number 18
NWS National Hurricane Center Miami FL AL102018
1100 PM AST Sun Sep 16 2018

Joyce is managing to maintain tropical cyclone status despite very
strong westerly vertical wind shear. The system still displays cold
cloud tops, but only within the northeast quadrant and at least
100 nm from the center. The shear is being induced primarily by
50-kt 200 mb winds. Usually such strong vertical shear would
completely decapitate a tropical cyclone. However, systems in
higher latitudes and moving in the same direction as the shear
vector tend to be somewhat more resilient to the detrimental
effects of the shear. Nonetheless, it is anticipated that Joyce
will soon succumb to the combination of high shear, cool waters,
and dry mid-levels, and become a remnant low within 48 hours, if not
sooner. The official intensity forecast shows a gradual weakening,
nearly the same as the previous advisory and based upon a blend of
the LGEM statistical scheme and the HWRF/HMON dynamical models.

Joyce is moving toward the east at a quick 18-kt clip. The system
has not been picked up by the mid-latitude westerlies and is
expected to be advected around the lower tropospheric Bermuda-Azores
high. Joyce should slow its forward speed and turn toward the
southeast (on Monday), the south (on Tuesday), and finally the
southwest (on Wednesday) before dissipating in about four days. The
track forecast is based upon the tightly clustered TVCN multi-model
consensus and is slightly farther east because of the quicker
eastward initial motion than previously observed.

FORECAST POSITIONS AND MAX WINDS

INIT 17/0300Z 34.0N 30.3W 30 KT 35 MPH
12H 17/1200Z 33.7N 27.9W 30 KT 35 MPH
24H 18/0000Z 32.8N 26.5W 30 KT 35 MPH
36H 18/1200Z 31.7N 26.3W 25 KT 30 MPH
48H 19/0000Z 30.5N 27.1W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 20/0000Z 28.9N 29.8W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 21/0000Z...DISSIPATED

$$
Forecaster Landsea
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Re: ATL: JOYCE - Advisories

#50 Postby cycloneye » Mon Sep 17, 2018 9:45 am

Tropical Depression Joyce Discussion Number 20
NWS National Hurricane Center Miami FL AL102018
1100 AM AST Mon Sep 17 2018

Joyce is gradually losing organization, with drier air entraining
into the circulation. Visible satellite imagery this morning
shows a few cloud swirls pivoting around a mean center with
only a small amount of deep convection displaced about 90 miles
northeast of the mean center. ASCAT scatterometer data indicate
that winds of 25 to 30 kt remain on the southwestern side of the
cyclone. Based on these data, Joyce remains a 30-kt tropical
depression for this advisory. Dry air and strong vertical wind shear
are expected to continue to weaken Joyce over the next few days, and
the cyclone is expected to degenerate into a remnant low by 24
hours. The official intensity forecast is similar to the previous
advisory and remains close to the model consensus. The only notable
change is that Joyce is now expected to become a remnant low a
little faster than the previous advisory.

The initial motion is 105/07 kt. Joyce has slowed down this
morning as anticipated as it is now reaching the northeastern
periphery of a mid-level high pressure area. Over the next couple of
days, the cyclone is expected to turn southeastward, southward, and
then southwestward around the eastern periphery of the high. The
lastest track guidance is tightly clustered, with the NHC track
forecast lying in the middle of the guidance envelope, and close to
the previous official forecast track.

FORECAST POSITIONS AND MAX WINDS

INIT 17/1500Z 34.0N 28.4W 30 KT 35 MPH
12H 18/0000Z 33.5N 27.2W 30 KT 35 MPH
24H 18/1200Z 32.3N 26.6W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 19/0000Z 31.2N 27.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 19/1200Z 30.3N 28.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 20/1200Z 28.9N 31.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 21/1200Z...DISSIPATED

$$
Forecaster Cangialosi/Latto
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Re: ATL: JOYCE - Advisories

#51 Postby cycloneye » Mon Sep 17, 2018 9:55 pm

Tropical Depression Joyce Discussion Number 22
NWS National Hurricane Center Miami FL AL102018
1100 PM AST Mon Sep 17 2018

Joyce remains a very resilient tropical cyclone. After an earlier
burst of deep convection just east of the low-level center that has
since dissipated, a new convective burst has developed just north of
the center with a curved convective band trying to develop in the
eastern semicircle. All of this convective activity has been
occurring despite westerly 850-200-mb vertical wind shear of near
35 kt and in the presence of very dry mid-level air. The initial
intensity is being maintained a 30 kt based on earlier 28-kt ASCAT
wind data, and the fact that no significant change has occurred to
Joyce's low-level appearance in satellite imagery.

The initial motion estimate is now 155/06 kt. Joyce is forecast to
move around the eastern periphery of a deep-layer ridge located
across the eastern Atlantic to the southwest and west of the
cyclone. This large-scale steering feature is expected to gradually
turn Joyce toward the south overnight and on Tuesday, and then force
the cyclone toward the southwest on Wednesday and Thursday. The new
NHC track forecast is to the west of the previous advisory track,
and lies near the middle of the guidance envelope close to a blend
of the consensus models TVCA and HCCA.

Convective development during the past 12 hours has been in large
part due to the strong atmospheric instability created by very cold
200-mb temperatures near -57 deg C overlaying relatively warm ocean
temperatures of 25.5 deg C. A contributing factor to the most recent
convective development appears to be enhanced uplift caused by an
approaching shortwave trough noted in water vapor imagery between
30W-35W longitude. The latter feature is forecast by most of the
global models to cut off south of the Azores and become entangled
with Joyce's circulation over the next few days, resulting in a
sharp decrease in the vertical wind shear and an increase in
atmospheric instability/CAPE by 48 h and beyond, which would aid
convective development and re-strengthening. For now, however, the
new intensity forecast continues the weakening trend of the previous
advisories due to an abundance of very dry mid-level air being
entrained into the circulation, which is expected to shut down
convective development, causing Joyce to dissipate shortly after
72 h. However, confidence in this forecast scenario is not very
high, and some adjustments may be required to subsequent forecasts
once the 18/0000Z model guidance becomes available, especially since
the GFS- and ECMWF-based SHIPS and LGEM intensity guidance maintains
Joyce as a 30- to 35-kt tropical cyclone through the next 120 hours.

FORECAST POSITIONS AND MAX WINDS

INIT 18/0300Z 33.2N 27.3W 30 KT 35 MPH
12H 18/1200Z 32.4N 27.1W 30 KT 35 MPH
24H 19/0000Z 31.4N 27.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 19/1200Z 30.5N 28.7W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 20/0000Z 29.9N 29.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 21/0000Z 29.2N 33.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 22/0000Z...DISSIPATED

$$
Forecaster Stewart
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Re: ATL: JOYCE - Tropical Depression - Discussion

#52 Postby EquusStorm » Mon Sep 17, 2018 11:17 pm

Oh man, I know nobody else really cares much about Joyce because weak swirl in absolute nowhere, but lemme just copy the intensity bit over from the 11pm advisory:

A contributing factor to the most recent convective development appears to be enhanced uplift caused by an approaching shortwave trough noted in water vapor imagery between 30W-35W longitude. The latter feature is forecast by most of the global models to cut off south of the Azores and become entangled with Joyce's circulation over the next few days, resulting in a sharp decrease in the vertical wind shear and an increase in atmospheric instability/CAPE by 48 h and beyond, which would aid convective development and re-strengthening. For now, however, the new intensity forecast continues the weakening trend of the previous advisories due to an abundance of very dry mid-level air being entrained into the circulation, which is expected to shut down convective development, causing Joyce to dissipate shortly after 72 h. However, confidence in this forecast scenario is not very high, and some adjustments may be required to subsequent forecasts once the 18/0000Z model guidance becomes available, especially since the GFS- and ECMWF-based SHIPS and LGEM intensity guidance maintains Joyce as a 30- to 35-kt tropical cyclone through the next 120 hours.


Surprise! How about tracking a weak swirl with intermittent convection sitting in the middle of nowhere for another week
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...but still, though, a lot more interesting than the 2013 season.

Not a meteorologist, in fact more of an idiot than anything. You should probably check with the NHC or a local NWS office for official information.

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Re: ATL: JOYCE - Tropical Depression - Discussion

#53 Postby HurricaneRyan » Tue Sep 18, 2018 3:03 am

Can she even make ACE as a tropical depression?
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Re: ATL: JOYCE - Tropical Depression - Discussion

#54 Postby Hammy » Tue Sep 18, 2018 4:49 am

HurricaneRyan wrote:Can she even make ACE as a tropical depression?


I think the min ACE threshhold is 35kt
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Re: ATL: JOYCE - Advisories

#55 Postby cycloneye » Tue Sep 18, 2018 9:40 am

Tropical Depression Joyce Discussion Number 24
NWS National Hurricane Center Miami FL AL102018
Issued by the NWS Weather Prediction Center College Park MD
1100 AM AST Tue Sep 18 2018

Earlier in the morning, the low-level center of Joyce became
decoupled from a small area of deeper convection. However, another
convective burst has recently developed after 12Z closer to the
low-level center. The initial intensity of Joyce was held at 30 kt
based on a recent ASCAT pass, which showed an area of 25-30 kt winds
on the north side of the circulation. The number of wind retrievals
close to 30 kt was rather limited, so Joyce's winds should decrease
below 30 kt when it eventually loses deep convection. The
depression is in an environment with strong westerly vertical wind
shear (30-40 kt) and marginal sea surface temperatures (around 25C),
and thus the primary forecast question is when Joyce will succumb to
the relatively hostile environment, lose deep convection and become
a remnant low. The GFS and ECMWF models both show some deep
convection lingering into tomorrow before warming upper-level
temperatures and increasingly dry air aloft kill off any remaining
convection. Therefore, the 12-hour forecast point maintains tropical
depression status, and the 24-hour forecast point indicates a
post-tropical system.

The initial motion of Joyce is now more southerly (185 degrees at 7
kt), and it will begin to turn increasingly to the southwest and
west as the central Atlantic ridge builds to the north. The new
forecast track is essentially an update of the previous one, which
was close to the TVCA and HCCA consensus models. Minor adjustments
were made in the first 24 hours to account for a slightly faster
observed motion to the south in the past 6-12 hours.


FORECAST POSITIONS AND MAX WINDS

INIT 18/1500Z 31.6N 27.4W 30 KT 35 MPH
12H 19/0000Z 30.6N 27.7W 25 KT 30 MPH
24H 19/1200Z 29.9N 28.7W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 20/0000Z 29.4N 29.9W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 20/1200Z 29.0N 31.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 21/1200Z...DISSIPATED

$$
Forecaster Lamers/Blake
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Re: ATL: JOYCE - Advisories

#56 Postby cycloneye » Tue Sep 18, 2018 4:44 pm

Tropical Depression Joyce Discussion Number 25
NWS National Hurricane Center Miami FL AL102018
Issued by the NWS Weather Prediction Center College Park MD
500 PM AST Tue Sep 18 2018

Deep convection has generally been on the wane during the past day
or so near the center of Joyce, and it is getting very close to no
longer having organized deep convection. With the decrease in
overall organization, the initial wind speed is set to 25 kt. An
environment of strong westerly vertical wind shear (30-40 kt)
and marginal sea surface temperatures (around 25C) should cause
Joyce to become a remnant low by late tonight or early Wednesday.
This agrees well with the latest global model guidance, and the
timing of remnant low status has been moved up to 12 hours (or
less).

The initial motion of Joyce continues to turn and is now south-
southwestward (205 degrees at 6 kt). The depression is forecast
to turn increasingly to the southwest and west as the central
Atlantic ridge builds to the north. Model guidance, except the HWRF,
is tightly clustered, so the new forecast track is essentially an
update of the previous one, closest to the HCCA consensus model.


FORECAST POSITIONS AND MAX WINDS

INIT 18/2100Z 30.9N 27.8W 25 KT 30 MPH
12H 19/0600Z 30.2N 28.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
24H 19/1800Z 29.6N 29.4W 20 KT 25 MPH...POST-TROP/REMNT LOW
36H 20/0600Z 29.1N 30.9W 15 KT 15 MPH...POST-TROP/REMNT LOW
48H 20/1800Z...DISSIPATED

$$
Forecaster Campbell/Blake
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Re: ATL: JOYCE - Post-Tropical - Discussion

#57 Postby CyclonicFury » Tue Sep 18, 2018 9:41 pm

Now post-tropical
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Re: ATL: JOYCE - Advisories

#58 Postby cycloneye » Tue Sep 18, 2018 9:51 pm

Post-Tropical Cyclone Joyce Discussion Number 26
NWS National Hurricane Center Miami FL AL102018
1100 PM AST Tue Sep 18 2018

During the past couple of days, Joyce had been producing patches of
deep convection that would quickly shear off due to strong westerly
winds aloft. Each convective burst appeared weaker than the
previous one, and during the past 12-18 hours, the circulation has
been nearly devoid of deep convection. Therefore, Joyce no longer
meets the criteria of a tropical cyclone, and this is the last
advisory issued by the National Hurricane Center on this system. The
initial wind speed is held at 25 kt, in agreement with a recent
ASCAT pass around 2200Z that showed maximum winds in the 20-25 kt
range. The remnant low is expected to gradually weaken and
ultimately dissipate in a couple of days due to dry and stable air,
cool SSTs, and moderate to strong westerly shear.

Joyce is moving south-southwestward at 7 kt on the east side of a
low- to mid-level ridge. A turn to the southwest is expected on
Wednesday as the ridge builds to the northeast of the cyclone, and
that motion should continue until the remnant low dissipates. The
NHC track forecast lies near the middle of the guidance envelope.

FORECAST POSITIONS AND MAX WINDS

INIT 19/0300Z 30.4N 27.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
12H 19/1200Z 29.9N 28.7W 20 KT 25 MPH...POST-TROP/REMNT LOW
24H 20/0000Z 29.4N 29.9W 20 KT 25 MPH...POST-TROP/REMNT LOW
36H 20/1200Z 28.9N 31.5W 15 KT 15 MPH...POST-TROP/REMNT LOW
48H 21/0000Z...DISSIPATED

$$
Forecaster Cangialosi
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