EPAC: RACHEL - Post-Tropical

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Re: EPAC: RACHEL - Tropical Storm

#121 Postby cycloneye » Mon Sep 29, 2014 9:48 am

BULLETIN
TROPICAL STORM RACHEL ADVISORY NUMBER 21
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182014
800 AM PDT MON SEP 29 2014

...RACHEL QUICKLY WEAKENING WHILE IT INCHES SLOWLY NORTHWARD...


SUMMARY OF 800 AM PDT...1500 UTC...INFORMATION
----------------------------------------------
LOCATION...22.8N 117.5W
ABOUT 485 MI...780 KM W OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...N OR 360 DEGREES AT 2 MPH...4 KM/H
MINIMUM CENTRAL PRESSURE...993 MB...29.33 INCHES


TROPICAL STORM RACHEL DISCUSSION NUMBER 21
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182014
800 AM PDT MON SEP 29 2014

Rachel's cloud pattern has become considerably less organized.
Deep convection associated with the cyclone has significantly
decreased in coverage and intensity during the past several hours.
First-light visible images also indicate that the center has become
exposed on the south side of the nearest convection, the remnants
of what was a central dense overcast 6 to 12 hours earlier. This
change in structure has resulted from strong upper-level south-
southwesterly winds, which is confirmed by UW-CIMSS analyses and
SHIPS model output diagnosing 20-25 kt of shear. Satellite
classifications are decreasing, and were T3.0/45 kt and 3.5/55 kt at
1200 UTC from SAB and TAFB, respectively. A blend of these yields
an intensity of 50 kt, which is in line with data from an overnight
ASCAT pass.

Even though Rachel will be over marginally warm waters during the
next several days, strong south-southwesterly vertical wind shear
associated with a trough moving through the western United States
should cause the cyclone to decouple within 24 hours. The shear, in
combination with increasingly less conducive thermodynamic factors,
should cause steady or even rapid weakening. Rachel is likely to
become a remnant low in about 24 hours, and dissipation is indicated
after 72 hours in agreement with the latest global model guidance.

Rachel's forward motion has decreased further, and the initial
motion estimate is 360/01. While still a vertically coupled vortex,
the cyclone could inch northward or become stationary in a col area
during the next 24 hours. Rachel should transition into a shallower
cyclone after that time and be carried southwestward and westward
with some increase in forward speed by the low-level trade wind
flow. The new NHC track forecast is largely an update of the
previous one but is adjusted slightly southward in light of the
cyclone's reduction in forward speed.


FORECAST POSITIONS AND MAX WINDS

INIT 29/1500Z 22.8N 117.5W 50 KT 60 MPH
12H 30/0000Z 23.0N 117.5W 40 KT 45 MPH
24H 30/1200Z 23.1N 117.6W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 01/0000Z 22.9N 117.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 01/1200Z 22.7N 118.1W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 02/1200Z 22.0N 119.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 03/1200Z...DISSIPATED

$$
Forecaster Kimberlain/Lewitsky
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Re: EPAC: RACHEL - Tropical Storm

#122 Postby cycloneye » Mon Sep 29, 2014 3:34 pm

BULLETIN
TROPICAL STORM RACHEL ADVISORY NUMBER 22
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182014
200 PM PDT MON SEP 29 2014

...RACHEL CONTINUES TO SLOWLY WEAKEN...


SUMMARY OF 200 PM PDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...23.0N 117.5W
ABOUT 485 MI...780 KM W OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...N OR 360 DEGREES AT 2 MPH...4 KM/H
MINIMUM CENTRAL PRESSURE...998 MB...29.47 INCHES



TROPICAL STORM RACHEL DISCUSSION NUMBER 22
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182014
200 PM PDT MON SEP 29 2014

Rachel continues to slowly weaken. Visible satellite imagery shows
its exposed low-level center located on the south side of a small
patch of deep convection, with the remnant mid-level circulation
displaced well to the northeast. The cyclone's current ragged
structure is partly a result of persistent south-southwesterly shear
of around 25 kt as diagnosed by UW-CIMSS analyses. A 1715 UTC AMSU
microwave pass also suggested that dry and stable air has been
wrapping around the circulation of the storm. The initial intensity
estimate is lowered to 45 kt based on peak winds of 43 kt from a
1714 UTC ASCAT-B pass.

With strong southwesterly shear expected to continue and
thermodynamic conditions likely to become even more unfavorable,
further steady weakening is expected. These hostile environmental
factors should cause Rachel to weaken to a remnant low in about 24
hours and dissipate in 2-3 days, as shown in global model guidance.
The new NHC intensity forecast represents an update of the previous
one and is in good agreement with the multi-model consensus.

Rachel has been drifting steadily northward, and the initial motion
estimate is 360/02. In the next 12 hours or so, a slow northward
motion is likely to continue, so long as the cyclone maintains
enough vertical integrity. After that time, Rachel should
transition into a shallower vortex and be carried generally
west-southwestward with a modest increase in forward speed. The NHC
track forecast is adjusted a bit to the right and is somewhat south
and west of the ECMWF, GFS, and multi-model consensus model, TVCE.

FORECAST POSITIONS AND MAX WINDS

INIT 29/2100Z 23.0N 117.5W 45 KT 50 MPH
12H 30/0600Z 23.2N 117.6W 35 KT 40 MPH
24H 30/1800Z 23.1N 118.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 01/0600Z 23.0N 118.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 01/1800Z 22.8N 118.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 02/1800Z 22.6N 120.0W 15 KT 15 MPH...POST-TROP/REMNT LOW
96H 03/1800Z...DISSIPATED

$$
Forecaster Kimberlain/Lewitsky
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Re: EPAC: RACHEL - Tropical Storm

#123 Postby cycloneye » Mon Sep 29, 2014 9:36 pm

BULLETIN
TROPICAL STORM RACHEL ADVISORY NUMBER 23
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182014
800 PM PDT MON SEP 29 2014

...RACHEL WEAKENS SOME MORE WHILE IT DRIFTS NORTHWARD...


SUMMARY OF 800 PM PDT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...23.3N 117.5W
ABOUT 485 MI...780 KM W OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...N OR 360 DEGREES AT 2 MPH...4 KM/H
MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES



TROPICAL STORM RACHEL DISCUSSION NUMBER 23
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182014
800 PM PDT MON SEP 29 2014

A burst of deep convection with cloud tops of -70C to -75C
developed during the late afternoon in the same region where
earlier ASCAT overpasses indicated several surface wind vectors of
40-43 kt. As a result, the intensity at 0000 UTC synoptic time was
maintained at 45 kt. However, over the past couple of hours, cloud
tops have warmed and decreased in areal coverage significantly, so
the advisory intensity has been lowered to 40 kt.

The initial motion estimate is 360/02 kt. Steering currents are
collapsing as Rachel moves into a large break in the subtropical
ridge created by a mid-latitude trough to the north of the cyclone.
As a result, Rachel is expected to become nearly stationary fairly
soon and meander in the same general area for the next 24 hours or
so. After that, the ridge to the north of what should be a
significantly weakened tropical cyclone is expected to build back
in as the mid-latitude trough lifts out, driving Rachel or its
remnants slowly toward the west or west-southwest until dissipation
occurs in 72-96 hours. The new NHC forecast track is similar to the
previous advisory track and the consensus model TVCE.

Rachel is not long for this world due to the combination of strong
southwesterly vertical wind shear, sea-surface temperatures less
than 26C, and a cooler and drier airmass working its way into the
inner core region of the cyclone. As a result, the storm is expected
to weaken to a remnant low pressure system within 24 hours and
dissipate by 96 hours. The official intensity forecast closely
follows a blend of the Decay-SHIPS model and the consensus
intensity model IVCN.

FORECAST POSITIONS AND MAX WINDS

INIT 30/0300Z 23.3N 117.5W 40 KT 45 MPH
12H 30/1200Z 23.3N 117.8W 35 KT 40 MPH
24H 01/0000Z 23.3N 118.1W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 01/1200Z 23.2N 118.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 02/0000Z 23.1N 118.7W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 03/0000Z 23.0N 120.3W 15 KT 15 MPH...POST-TROP/REMNT LOW
96H 04/0000Z...DISSIPATED

$$
Forecaster Stewart
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Re: EPAC: RACHEL - Tropical Storm

#124 Postby cycloneye » Tue Sep 30, 2014 5:09 am

TROPICAL STORM RACHEL DISCUSSION NUMBER 24
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182014
200 AM PDT TUE SEP 30 2014

Rachel has lost all of its deep convection, although it is possible
that some sporadic bursts of showers and thunderstorms could return
to the circulation today. A couple of recent ASCAT passes missed
the radius of maximum winds, but using a blend of the latest Dvorak
estimates from TAFB and SAB, the current intensity is set, perhaps
generously, at 35 kt. Southwesterly shear over Rachel is forecast
to become even stronger, more than 30 kt, within a day or so and
continued weakening is expected. The system should degenerate into
a remnant low in 12-24 hours. The official intensity forecast is
close to the model consensus, although just a little higher,
suggesting that the cyclone could weaken even faster than indicated
here.

There has been little movement over the past several hours, which
was anticipated by the track model guidance. Rachel is in an
environment of weak steering currents, and is expected to remain so
through today. A weak low-level ridge developing to the northwest
and north is expected to cause the post-tropical cyclone to move
very slowly west-southwestward in 1-2 days, followed by a turn
toward the west. The official track forecast is close to the model
consensus.

FORECAST POSITIONS AND MAX WINDS

INIT 30/0900Z 23.3N 117.5W 35 KT 40 MPH
12H 30/1800Z 23.2N 117.8W 30 KT 35 MPH
24H 01/0600Z 23.1N 118.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 01/1800Z 23.0N 118.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 02/0600Z 22.8N 118.7W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 03/0600Z 22.8N 120.3W 15 KT 15 MPH...POST-TROP/REMNT LOW
96H 04/0600Z...DISSIPATED

$$
Forecaster Pasch
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Re: EPAC: RACHEL - Tropical Depression

#125 Postby cycloneye » Tue Sep 30, 2014 8:08 am

Down to TD.

18E RACHEL 140930 1200 23.3N 117.5W EPAC 30 1005
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Re: EPAC: RACHEL - Tropical Depression

#126 Postby cycloneye » Tue Sep 30, 2014 12:59 pm

TROPICAL DEPRESSION RACHEL DISCUSSION NUMBER 25
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182014
800 AM PDT TUE SEP 30 2014

Satellite imagery indicates that deep convection associated with
Rachel dissipated almost 12 hours ago, with the cyclone now
consisting of a tight swirl of low- to middle-level clouds. Dvorak
intensity estimates continue to decrease, and the initial intensity
is lowered to 30 kt in agreement with the latest satellite
classifications. A continuation of southwesterly shear of around 30
kt and very unfavorable thermodynamic factors suggest that deep
convection is unlikely to redevelop, and Rachel should weaken
into a remnant low later today. Global model guidance shows the
remnant low degenerating into an open trough in about 2 days and
dissipating shortly thereafter. The official intensity forecast is
close to the previous forecast and the multi-model consensus.

Rachel has been nearly stationary for the last 6-12 hours, trapped
in an environment of weak steering. The shallow cyclone should
drift west-southwestward and westward during the next couple of days
around the eastern side of a weak low-level ridge until dissipation.
The track forecast is essentially an update of the previous one,
nearly between the ECMWF and GFS model solutions.


FORECAST POSITIONS AND MAX WINDS

INIT 30/1500Z 23.1N 117.5W 30 KT 35 MPH
12H 01/0000Z 23.0N 117.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 01/1200Z 22.9N 118.1W 20 KT 25 MPH...POST-TROP/REMNT LOW
36H 02/0000Z 22.7N 118.5W 15 KT 15 MPH...POST-TROP/REMNT LOW
48H 02/1200Z 22.5N 119.0W 15 KT 15 MPH...POST-TROP/REMNT LOW
72H 03/1200Z...DISSIPATED

$$
Forecaster Kimberlain/Ramos
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Re: EPAC: RACHEL - Post-Tropical

#127 Postby cycloneye » Tue Sep 30, 2014 3:57 pm

BULLETIN
POST-TROPICAL CYCLONE RACHEL ADVISORY NUMBER 26
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182014
200 PM PDT TUE SEP 30 2014

...RACHEL BECOMES A REMNANT LOW...
...THIS IS THE LAST ADVISORY...


SUMMARY OF 200 PM PDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...22.9N 117.5W
ABOUT 485 MI...780 KM W OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...30 MPH...45 KM/H
PRESENT MOVEMENT...S OR 180 DEGREES AT 2 MPH...4 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES


POST-TROPICAL CYCLONE RACHEL DISCUSSION NUMBER 26
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182014
200 PM PDT TUE SEP 30 2014

Rachel artfully draws to a close. Deep convection associated with
Rachel dissipated about 15 hours ago and it is unlikely to redevelop
due to unfavorable thermodynamic factors and strong shear. Based on
these conditions, the cyclone is being declared a post-tropical
remnant low at this time. Dvorak intensity estimates have decreased
further and the initial intensity has been lowered to 25 kt. Global
model guidance shows the remnant low degenerating into an open
trough by Friday. The official intensity forecast is close to the
previous forecast and the GFS model.

During the last couple of hours, the now-shallow vortex associated
with Rachel has taken on a southward drift. A slow southwestward
motion is expected during the next two days as it continues to move
around the eastern periphery of a low-level ridge. The track
forecast is essentially an update of the previous one, nearly
between the ECMWF and GFS model solutions.

This is the last advisory on Rachel by the National Hurricane
Center. For additional information on the remnant low please see
High Seas Forecasts issued by the National Weather Service...under
AWIPS header NFDHSFEPI and WMO header FZPN01 KWBC.

FORECAST POSITIONS AND MAX WINDS

INIT 30/2100Z 22.9N 117.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
12H 01/0600Z 22.8N 117.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 01/1800Z 22.6N 118.4W 20 KT 25 MPH...POST-TROP/REMNT LOW
36H 02/0600Z 22.4N 119.0W 15 KT 15 MPH...POST-TROP/REMNT LOW
48H 02/1800Z 22.2N 119.9W 15 KT 15 MPH...POST-TROP/REMNT LOW
72H 03/1800Z...DISSIPATED

$$
Forecaster Cangialosi/Ramos
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