EPAC: HERNAN - Post-Tropical

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#61 Postby weathernerdguy » Sun Jul 27, 2014 2:39 pm

It looks like R.I is a lot more possible.
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#62 Postby northjaxpro » Sun Jul 27, 2014 2:58 pm

Observing IR and visible imagery, it appears to me almost as if a pinhole eye is trying to emerge. I'd be shocked if NHC doesn't upgrade this to a hurricane on the next update. Also, Hernan will peak out in intensity within the next 12-18 hours as shear will impact the core of the cyclone. You can already clearly see the shear impacting the western periphery of the cyclone on imagery.
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#63 Postby Yellow Evan » Sun Jul 27, 2014 3:31 pm

northjaxpro wrote:Observing IR and visible imagery, it appears to me almost as if a pinhole eye is trying to emerge. I'd be shocked if NHC doesn't upgrade this to a hurricane on the next update. Also, Hernan will peak out in intensity within the next 12-18 hours as shear will impact the core of the cyclone. You can already clearly see the shear impacting the western periphery of the cyclone on imagery.


According to the ATCF, it already is one.
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Re: EPAC: HERNAN - Hurricane

#64 Postby cycloneye » Sun Jul 27, 2014 3:33 pm


HURRICANE HERNAN DISCUSSION NUMBER 7
NWS NATIONAL HURRICANE CENTER MIAMI FL EP082014
200 PM PDT SUN JUL 27 2014

A faint eye was briefly apparent on visible satellite images, and
Dvorak classifications from TAFB as well as objective Dvorak
intensity estimates from UW-CIMSS support an intensity of 65 kt.
Therefore, Hernan is being upgraded to the third hurricane of the
2014 eastern North Pacific season. The system has a quite
impressive and symmetrical upper-level outflow pattern at this time.
Sea surface temperatures will be decreasing along the path of the
tropical cyclone, and vertical shear is expected to gradually
increase. Therefore, a weakening trend should commence on Monday.
The official intensity forecast closely follows the latest model
consensus, ICON.

The initial motion remains northwestward, or 305/13. There is no
significant change to the track forecast or the reasoning behind
it. For the next few days, Hernan will continue to be steered by
the flow on the southwest side of a ridge associated with a
mid-tropospheric high centered over the southwestern United States.
This ridge is forecast to build westward somewhat, which should
cause the track of Hernan to gradually shift toward the
west-northwest. By the latter part of the forecast period, the
weakening and increasingly shallow cyclone is likely to turn
westward following the lower-tropospheric steering flow. The
official track forecast is very close to the track model consensus,
TVCN, and is basically an update of the previous NHC forecast.

Based on a recent ASCAT overpass, only slight adjustments to the
wind radii were required.

FORECAST POSITIONS AND MAX WINDS

INIT 27/2100Z 18.6N 112.2W 65 KT 75 MPH
12H 28/0600Z 19.7N 113.9W 65 KT 75 MPH
24H 28/1800Z 21.2N 116.3W 60 KT 70 MPH
36H 29/0600Z 22.6N 118.7W 50 KT 60 MPH
48H 29/1800Z 23.4N 120.6W 45 KT 50 MPH
72H 30/1800Z 24.2N 124.0W 30 KT 35 MPH
96H 31/1800Z 24.5N 127.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 01/1800Z 24.5N 129.5W 20 KT 25 MPH...POST-TROP/REMNT LOW

$$
Forecaster Pasch
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#65 Postby northjaxpro » Sun Jul 27, 2014 3:40 pm

Yep, right on cue cycloneye and Yellow Evan. No doubt Hernan attained the upgrade when I checked in earlier on this thread. NHC also confirmed eye did pop out as a few of us suspected as well.
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#66 Postby Yellow Evan » Sun Jul 27, 2014 3:50 pm

Nice to see a hurricane again.
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#67 Postby hurricanes1234 » Sun Jul 27, 2014 3:52 pm

Hernan is a hurricane! :)
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Re: EPAC: HERNAN - Hurricane

#68 Postby supercane4867 » Sun Jul 27, 2014 5:15 pm

Appears to be a marginal hurricane at most

Image
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Re: EPAC: HERNAN - Hurricane

#69 Postby Yellow Evan » Sun Jul 27, 2014 6:44 pm

supercane4867 wrote:Appears to be a marginal hurricane at most

Image


Looks like it peaked.
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#70 Postby Yellow Evan » Sun Jul 27, 2014 8:28 pm

EP, 08, 2014072800, , BEST, 0, 189N, 1125W, 65, 992, HU, 64, NEQ, 10, 10, 0, 10, 1010, 150, 10, 0, 0, E, 0, , 0, 0, HERNAN, D,
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#71 Postby TropicalAnalystwx13 » Sun Jul 27, 2014 8:32 pm

I estimate that Hernan peaked at 70 knots around 19z when the pinhole eye was visible. Since that time, the eye has disappeared and the overall satellite presentation looks more ragged. A blend of T4.0/65kt from SAB, T3.8/61kt from UW-CIMSS ADT, and a bullish T4.5/77kt from TAFB supports keeping this a hurricane..for now.
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#72 Postby Yellow Evan » Sun Jul 27, 2014 9:31 pm

TropicalAnalystwx13 wrote:I estimate that Hernan peaked at 70 knots around 19z when the pinhole eye was visible. Since that time, the eye has disappeared and the overall satellite presentation looks more ragged. A blend of T4.0/65kt from SAB, T3.8/61kt from UW-CIMSS ADT, and a bullish T4.5/77kt from TAFB supports keeping this a hurricane..for now.


Agreed it is around 70 knts at peak. I doubt it'll be a hurricane much longer though, as it is probs 65 knts now.
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Re: EPAC: HERNAN - Hurricane

#73 Postby cycloneye » Sun Jul 27, 2014 9:41 pm

HURRICANE HERNAN DISCUSSION NUMBER 8
NWS NATIONAL HURRICANE CENTER MIAMI FL EP082014
800 PM PDT SUN JUL 27 2014

Hernan's cloud pattern has already begun to deteriorate a bit since
it reached hurricane strength this afternoon. The last few visible
images showed arc clouds emanating away from the western semicircle,
which could be an indication that drier air is getting into the
circulation. Satellite intensity estimates are somewhat
conflicting, with the subjective numbers from TAFB and SAB
increasing from 6 hours ago while the objective T-numbers from the
ADT have decreased. Therefore, the intensity is being held at 65 kt
for this advisory. Given the recent satellite trends, however,
Hernan may not last as a hurricane for much longer. The cyclone
only has about 12-18 hours left before it crosses the 26C isotherm
and plows over much colder water, leading to a quicker weakening
trend after 24 hours. The main difference with the previous
forecast is at 48 hours and beyond, with Hernan now expected to
become a remnant low by day 3 and dissipate by day 5.

Hernan continues to move northwestward with an initial motion of
310/13 kt. This motion is being caused by a strong mid-level ridge
located over Mexico and the southern United States and should
continue for the next 36 hours. After that time, the cyclone is
forecast to turn west-northwestward and slow down considerably as
it is left in an environment of weak low-level steering. The
updated NHC forecast is nudged a bit north of the previous forecast
beyond 48 hours toward the model consensus TVCE.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0300Z 19.3N 113.1W 65 KT 75 MPH
12H 28/1200Z 20.3N 114.9W 60 KT 70 MPH
24H 29/0000Z 21.8N 117.3W 55 KT 65 MPH
36H 29/1200Z 23.1N 119.5W 50 KT 60 MPH
48H 30/0000Z 23.9N 121.1W 40 KT 45 MPH
72H 31/0000Z 24.5N 123.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 01/0000Z 24.5N 125.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 02/0000Z...DISSIPATED

$$
Forecaster Berg
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Re: EPAC: HERNAN - Tropical Storm

#74 Postby cycloneye » Mon Jul 28, 2014 5:44 am

TROPICAL STORM HERNAN DISCUSSION NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL EP082014
200 AM PDT MON JUL 28 2014

Hernan is now on a weakening trend. The coverage of deep convection
has decreased markedly over the past several hours, and the cloud
pattern has a more elongated appearance than it did earlier.
Microwave images also show a pronounced vertical tilt of the vortex
due to about 15 kt of westerly shear. Dvorak and ADT intensity
estimates have decreased from all agencies, and using a blend of the
CI- and T-numbers yields an initial intensity of 60 kt. A
combination of moderate shear, a dry stable air mass, and decreasing
sea surface temperatures should cause Hernan to continue weakening
during the next few days. The system is expected to become a
remnant low in about 2 days when it is forecast to be over waters
cooler than 23 C.

The storm has turned slightly to the left, and the latest initial
motion estimate is 300/13 kt. This general motion should continue
for the next 24 hours while Hernan remains steered by a strong
mid-level high over the southwestern United States. After that
time, a gradual turn to the west with a decrease in forward speed
is predicted when the shallow system becomes more influenced by the
lighter low-level flow. The official track forecast is just a
little to the left of the previous one, and near the multi-model
consensus TVCE.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0900Z 19.9N 114.5W 60 KT 70 MPH
12H 28/1800Z 20.9N 116.4W 50 KT 60 MPH
24H 29/0600Z 22.3N 118.8W 45 KT 50 MPH
36H 29/1800Z 23.4N 120.6W 35 KT 40 MPH
48H 30/0600Z 24.1N 122.2W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 31/0600Z 24.5N 124.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 01/0600Z 24.5N 126.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 02/0600Z...DISSIPATED

$$
Forecaster Cangialosi
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Re: EPAC: HERNAN - Tropical Storm

#75 Postby cycloneye » Mon Jul 28, 2014 9:41 am

TROPICAL STORM HERNAN DISCUSSION NUMBER 10
NWS NATIONAL HURRICANE CENTER MIAMI FL EP082014
800 AM PDT MON JUL 28 2014

Persistent 15-20 kt of westerly shear is certainly deteriorating the
cyclone's organization this morning. Conventional satellite imagery
shows a rather shapeless cloud pattern with warming cloud tops. A
fortuitous 0934 UTC AMSU-A microwave pass indicated an eastward
vertical tilt with the low-level center located near the western
edge of the deep convection. A compromise of satellite intensity
estimates from TAFB and SAB along with a 0933 UTC UW-CIMSS SATCON
(which includes ADT, and AMSU intensity estimates) of 54 kt supports
an initial intensity of 55 kt for this advisory. The large-scale
models and the statistical/dynamical intensity guidance all show a
moderate shear environment through the forecast period.
Furthermore, an increasingly stable air mass and decreasing sea
surface temperatures should ultimately weaken Hernan into a shallow
post-tropical cyclone in 48 hours.

Hernan continues to move northwestward, with an initial motion
estimate of 295/14 kt. Global model guidance indicates that a
mid-level ridge to the northeast of the cyclone should steer Hernan
in this general motion through the 36 hour period. Afterward, a
turn toward the west and a reduction in forward speed is forecast as
the remnant low moves within the lower tropospheric flow of the
subtropical ridge. The NHC forecast is again adjusted slightly to
the left of the previous track beyond 36 hours, and lies between the
consensus model and the ECMWF.

FORECAST POSITIONS AND MAX WINDS

INIT 28/1500Z 20.5N 115.9W 55 KT 65 MPH
12H 29/0000Z 21.6N 117.8W 50 KT 60 MPH
24H 29/1200Z 22.9N 120.3W 40 KT 45 MPH
36H 30/0000Z 23.8N 122.2W 30 KT 35 MPH
48H 30/1200Z 24.0N 123.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 31/1200Z 24.0N 125.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 01/1200Z 24.0N 127.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 02/1200Z...DISSIPATED

$$
Forecaster Roberts
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#76 Postby TheStormExpert » Mon Jul 28, 2014 11:11 am

The East Pacific has been really struggling to produce anything of significance and quality for the past month or so. Why is that?
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Re:

#77 Postby Yellow Evan » Mon Jul 28, 2014 11:27 am

TheStormExpert wrote:The East Pacific has been really struggling to produce anything of significance and quality for the past month or so. Why is that?


At least this was a hurricane.

Shear has increased slightly, and the storm have been forming more east typical of El Ninos closer to the cool waters.
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Re: Re:

#78 Postby TheStormExpert » Mon Jul 28, 2014 12:09 pm

Yellow Evan wrote:
TheStormExpert wrote:The East Pacific has been really struggling to produce anything of significance and quality for the past month or so. Why is that?


At least this was a hurricane.

Shear has increased slightly, and the storm have been forming more east typical of El Ninos closer to the cool waters.

Is it possible this trying to become a Modoki El Niño and the Centeal Pacific sees the most activity, cause that's what it seems like lately?
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Re: EPAC: HERNAN - Tropical Storm

#79 Postby cycloneye » Mon Jul 28, 2014 3:37 pm

TROPICAL STORM HERNAN DISCUSSION NUMBER 11
NWS NATIONAL HURRICANE CENTER MIAMI FL EP082014
200 PM PDT MON JUL 28 2014

The cloud pattern of Hernan continues to degrade in appearance,
and what little deep convection remains is confined mainly to the
south of the center. The current wind speed estimate has been
reduced to 45 kt based on a blend of intensity estimates from SAB
and TAFB along with objective Dvorak numbers from UW-CIMSS. The
storm is now moving over waters cooler than 26 deg C, and sea
surface temperatures should continue to decrease beneath the
cyclone. These hostile oceanic conditions, combined with moderately
strong south-southwesterly shear, are likely to bring about
continued weakening. The official intensity forecast shows Hernan
degenerating into a remnant low in 36 hours, but the latest
intensity model guidance suggests that the system could weaken even
faster than indicated here.

Hernan continues on its west-northwestward trek, and the initial
motion is estimated to be 300/15 kt. A mid-level ridge over the
southwestern United States and northwestern Mexico should impart a
continued west-northwestward motion for the next couple of days.
Thereafter, the dying cyclone is expected to turn westward since
the steering should become dominated by the low-level tradewind
flow. The official track forecast is quite similar to the previous
NHC track and is very close to the latest dynamical model consensus
forecast, TVCE.

FORECAST POSITIONS AND MAX WINDS

INIT 28/2100Z 21.3N 117.3W 45 KT 50 MPH
12H 29/0600Z 22.4N 119.3W 40 KT 45 MPH
24H 29/1800Z 23.6N 121.5W 30 KT 35 MPH
36H 30/0600Z 24.2N 123.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 30/1800Z 24.5N 124.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 31/1800Z 24.5N 126.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 01/1800Z...DISSIPATED

$$
Forecaster Pasch
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Re: EPAC: HERNAN - Tropical Storm

#80 Postby cycloneye » Mon Jul 28, 2014 9:45 pm

TROPICAL STORM HERNAN DISCUSSION NUMBER 12
NWS NATIONAL HURRICANE CENTER MIAMI FL EP082014
800 PM PDT MON JUL 28 2014

Deep convection to the southeast of Hernan's center dissipated a few
hours ago, but a new burst of activity has recently developed to the
north of the center. Still, subjective and objective Dvorak
satellite estimates continue to decrease, and the initial intensity
is set at 40 kt based on a blend of these data. Due to decreasing
sea surface temperatures, increasing atmospheric stability, and
strengthening vertical shear, this new round of convective activity
is likely to be short lived. Based on the latest intensity
guidance, the updated NHC forecast now shows Hernan weakening to a
tropical depression in about 12 hours and becoming a remnant low by
36 hours. Dissipation is indicated by day 4, but some of the global
models indicate that it could occur sooner.

The initial motion remains 300/15 kt. Hernan is forecast to
continue moving west-northwestward during the next 48 hours, but it
should also slow down as it comes under the influence of weaker
low-level flow. A slow westward motion is expected just before the
remnant low dissipates. The model consensus TVCE has been trending
a little bit farther north, and the updated NHC track forecast is
nudged in that direction primarily at 48 and 72 hours.


FORECAST POSITIONS AND MAX WINDS

INIT 29/0300Z 22.1N 118.6W 40 KT 45 MPH
12H 29/1200Z 23.1N 120.5W 30 KT 35 MPH
24H 30/0000Z 24.0N 122.3W 25 KT 30 MPH
36H 30/1200Z 24.6N 123.7W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 31/0000Z 25.0N 124.8W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 01/0000Z 25.0N 127.0W 15 KT 15 MPH...POST-TROP/REMNT LOW
96H 02/0000Z...DISSIPATED

$$
Forecaster Berg
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