EPAC: IVETTE - Post-Tropical

[Yellow Evan]

I wouldn't rule out a Flossie type intensity

Flossie 07 or 13?

[Alyono]

I wouldn't rule out a Flossie type intensity

Flossie 07 or 13?

07

[Kingarabian]

03/0000 UTC 13.6N 116.5W T2.5/2.5 10E -- East Pacific

[Yellow Evan]

EP, 10, 201608030000, 10, DVTS, CI, , 1330N, 11720W, , 3, 30, 2, 1009, 2, DVRK, , , , , , , , , , , , , , E, TAFB, CM, VI, 5, 2020 /////, , , GOES15, CSC, T,

Umm no.

[Yellow Evan]

EP, 10, 2016080300, , BEST, 0, 137N, 1170W, 30, 1006, TD, 34, NEQ, 0, 0, 0, 0, 1010, 150, 40, 0, 0, E, 0, , 0, 0, TEN, M,

[Yellow Evan]

It always irks me that the NHC goes 30 when ADT is at T2.3, SAB is T2.5, and TAFB is T2.0.

----- Current Analysis -----
Date : 03 AUG 2016 Time : 000000 UTC
Lat : 13:30:21 N Lon : 116:26:38 W


CI# /Pressure/ Vmax
2.3 /1011.9mb/ 33.0kt


Final T# Adj T# Raw T#
2.3 2.6 2.6

Center Temp : -52.7C Cloud Region Temp : -44.3C

Scene Type : CURVED BAND with 0.58 ARC in LT GRAY
Maximum CURVED BAND with 0.68 ARC in LT GRAY
at Lat: 12:41:59 N Lon: 116:26:24 W

[Kingarabian]

They selectively choose the agency with the lowest intensity. I don't know why.

[Alyono]

I have found the TAFB Dvoraks to be the least reliable. All over the place

That said, the ASCAT from 1739 UTC did not show any strong winds and a very poorly defined circulation

[cycloneye]

TROPICAL DEPRESSION TEN-E DISCUSSION NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL EP102016
800 PM PDT TUE AUG 02 2016

The deep convection associated with the tropical depression is
showing some limited banding features in combination with a
developing central dense overcast. Dvorak classification numbers
are gradually rising, though a blend of TAFB, SAB, and CIMSS-ADT
values still indicates an intensity of about 30 kt.

A 1941Z AMSR2 microwave image indicated that the center of the
system was slightly farther north than earlier indicated.
Extrapolating forward in time from that point suggests a center
that is near the northeastern edge of the deep convection, perhaps
reflecting the moderate northeasterly shear affecting the cyclone.
The initial motion is assessed at a fast 17 kt toward the
west-northwest, primarily due to the steering of an east-west
extended deep-layer ridge to its north. The tightly packed track
guidance suggests a turn toward the west at a slightly slower rate
of forward speed during the next few days. The NHC track forecast
is slightly north of the previous advisory for the next day due to
the more northerly initial motion, and then nearly the same out
through the end of the period. This is supported by the global
and HWRF model consensus.

The system should only gradually intensify during the next
day or so because of the moderate northeasterly shear and as the
system develops an inner core structure. A more steady
strengthening is anticipated out to about day three as the shear
relaxes and the system moves over 28C water and through a very
moist and unstable atmosphere. Around day four or five, the cyclone
may start gradually weakening as SSTs decrease and the shear
increases again. The NHC intensity forecast is based upon the IVCN
consensus and peaks just slightly higher than that from the
previous advisory.

FORECAST POSITIONS AND MAX WINDS

INIT 03/0300Z 13.9N 117.8W 30 KT 35 MPH
12H 03/1200Z 14.5N 120.1W 35 KT 40 MPH
24H 04/0000Z 15.1N 123.1W 45 KT 50 MPH
36H 04/1200Z 15.4N 126.1W 55 KT 65 MPH
48H 05/0000Z 15.7N 129.0W 65 KT 75 MPH
72H 06/0000Z 16.5N 133.7W 80 KT 90 MPH
96H 07/0000Z 17.5N 138.0W 80 KT 90 MPH
120H 08/0000Z 18.5N 142.0W 70 KT 80 MPH

$$
Forecaster Landsea

[Yellow Evan]

"though a blend of TAFB, SAB, and CIMSS-ADT values still indicates an intensity of about 30 kt."

that is not true ADT/SAB are T2.5 TAFB is T2.0.

[wxmann_91]

TS Ivette now. Already at the I storm and it's only August 3rd, and with the A storm only coming on July 2nd.

TROPICAL STORM IVETTE DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL EP102016
200 AM PDT WED AUG 03 2016

The cloud pattern of the tropical cyclone has gradually improved
since yesterday afternoon, with an increase in banding over the
western portion of the circulation. Microwave images show
that the center is located near the northeastern edge of the
convective band due to moderate northeasterly shear, but a new
burst of deep convection has very recently developed near the
estimate center location. Although earlier ASCAT data showed
maximum winds around 30 kt, the recent improvement in organization
and Dvorak T-numbers from TAFB and SAB support increasing the
initial intensity to 35 kt. Ivette becomes the ninth tropical storm
to form in the eastern Pacific basin since July 2nd.

Ivette is moving westward at an atypically fast speed of 17 kt.
A strong subtropical ridge to the north of the cyclone should keep
it moving westward to west-northwestward during the next several
days, with the forward speed gradually decreasing as it nears the
western portion of the ridge. By late in the period, Ivette should
turn west-northwestward and decelerate further as a break in the
ridge develops between 140W and 150W. The updated NHC track is
similar to the previous advisory, but has been nudged southward to
be closer to the multi-model consensus.

The northeasterly shear affecting the tropical cyclone is forecast
to decrease during the next 24 hours. This should allow
strengthening while Ivette moves over warm water and remains
in a moist environment. The NHC intensity forecast is above the
statistical guidance and is closer to the HWRF model, which brings
Ivette to hurricane strength in a couple of days. Increasing
southwesterly shear, slightly cooler SSTs, and drier mid-level air
should cause gradual weakening late in the period.


FORECAST POSITIONS AND MAX WINDS

INIT 03/0900Z 14.2N 119.2W 35 KT 40 MPH
12H 03/1800Z 14.6N 121.5W 40 KT 45 MPH
24H 04/0600Z 15.0N 124.5W 45 KT 50 MPH
36H 04/1800Z 15.2N 127.3W 55 KT 65 MPH
48H 05/0600Z 15.4N 130.0W 65 KT 75 MPH
72H 06/0600Z 16.0N 134.5W 80 KT 90 MPH
96H 07/0600Z 17.0N 138.5W 75 KT 85 MPH
120H 08/0600Z 18.0N 142.0W 65 KT 75 MPH

$$
Forecaster Brown

[cycloneye]

TROPICAL STORM IVETTE DISCUSSION NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL EP102016
800 AM PDT WED AUG 03 2016

Ivette's convective pattern is gradually improving, with a band
lying to the west of a central cluster of deep convection.
However, recent microwave data still shows the low-level center
displaced to the northeast of the deepest convection due to some
shear. Dvorak intensity estimates are T3.0/45 kt from SAB and
T2.5/35 kt from TAFB; the initial intensity is therefore raised to
40 kt.

Sea surface temperatures are expected to be 27-28C for the next
96 hours, while the vertical shear affecting the cyclone is
forecast to gradually diminish over the next couple of days. These
conditions would seem to support steady or even fast strengthening.
Surprisingly, the SHIPS, LGEM, GFDL, and HWRF models only intensify
Ivette to near the hurricane threshold. Given the seemingly
favorable environment, the NHC official forecast is above all of the
main intensity models, with the exception of COAMPS-TC, and it does
not deviate from the peak intensity indicated in the previous
advisory. Slightly lower SSTs and increasing shear are likely to
cause some weakening by days 4 and 5.

A strong subtropical ridge extending westward from northern Mexico
is causing Ivette to move quickly west-northwestward at 285/15 kt.
The ridge is expected to remain entrenched north of Ivette for the
next three days, putting the cyclone on a westward heading but with
a gradually decreasing forward speed. By days 4 and 5, Ivette
could gain a little more latitude due to a break in the ridge that
will develop northeast of the Hawaiian Islands. There is high
confidence in the future track of Ivette due to a tightly clustered
model envelope, and the NHC track forecast is mainly an update of
the previous forecast.

FORECAST POSITIONS AND MAX WINDS

INIT 03/1500Z 14.6N 120.4W 40 KT 45 MPH
12H 04/0000Z 15.0N 122.7W 45 KT 50 MPH
24H 04/1200Z 15.2N 125.6W 55 KT 65 MPH
36H 05/0000Z 15.4N 128.3W 65 KT 75 MPH
48H 05/1200Z 15.6N 130.8W 70 KT 80 MPH
72H 06/1200Z 16.5N 135.1W 80 KT 90 MPH
96H 07/1200Z 18.0N 138.5W 75 KT 85 MPH
120H 08/1200Z 19.0N 141.5W 65 KT 75 MPH

$$
Forecaster Berg

[cycloneye]

TROPICAL STORM IVETTE DISCUSSION NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL EP102016
200 PM PDT WED AUG 03 2016

Ivette continues to display a sheared convective pattern with the
low-level center located to the north-northeast of the deepest
convection. Recent ASCAT data shows that the maximum winds are
near 40 kt, which is also an average of the Dvorak estimates from
TAFB and SAB. The vertical shear affecting the cyclone is still
expected to diminish during the next 24 hours, and sea surface
temperatures will be between 27-28C for the next 3 to 4 days.
Therefore, strengthening is anticipated, with a peak intensity
likely occurring in about 3 days. Most of the intensity models
still don't show significant intensification even though the shear
gets quite low in a couple of days. For now, the NHC official
intensity forecast leans on persistence and continues to be near the
high end of the intensity guidance. Incidentally, the HWRF model
has come in a little stronger on this cycle and now shows Ivette
getting near the threshold of a category 2 hurricane.

The initial motion remains 295/15 kt. The subtropical ridge to the
north is expected to turn Ivette westward by tonight, with that
heading continuing through 48 hours. After that time, a break in
the ridge to the northeast of Hawaii is forecast to cause Ivette to
turn back to the west-northwest and slow down on days 3-5.
Confidence in the track forecast remains high through day 5 due to a
tightly packed guidance envelope, and the official NHC track
forecast is relatively close to the previous forecast and the TVCN
multi-model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT 03/2100Z 14.9N 122.0W 40 KT 45 MPH
12H 04/0600Z 15.2N 124.2W 45 KT 50 MPH
24H 04/1800Z 15.4N 127.1W 55 KT 65 MPH
36H 05/0600Z 15.5N 129.6W 65 KT 75 MPH
48H 05/1800Z 15.8N 131.8W 70 KT 80 MPH
72H 06/1800Z 17.0N 135.7W 80 KT 90 MPH
96H 07/1800Z 18.5N 139.5W 75 KT 85 MPH
120H 08/1800Z 19.5N 142.5W 60 KT 70 MPH

$$
Forecaster Berg

[cycloneye]

TROPICAL STORM IVETTE DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL EP102016
800 PM PDT WED AUG 03 2016

Moderate northeasterly vertical shear continues to afflict
Ivette, as the deep convection is asymmetric with most of the cold
cloud tops southwest of the center. A blend of the TAFB and SAB
subjective Dvorak, the CIMSS Advanced Dvorak, and AMSU estimates
gives an intensity of 40 kt, unchanged from the previous advisory.
A pair of ASCAT scatterometer passes around 18Z indicates that
Ivette remains small sized, but slightly larger in
tropical-storm-force wind radii than previously estimated.

The scatterometer passes and an AMSR2 image at 2023Z suggested that
Ivette's center was farther south than previously analyzed. This
was confirmed by the brief appearance of the low-level center in
geostationary visible imagery, as it peeked out from the edge of the
deep convection. Ivette is moving toward the west at 14 kt, along
the southern edge of a deep-layer subtropical ridge extending
westward from Mexico. The tropical cyclone should continue moving
toward the west or west-northwest at a slightly slower rate of
forward speed for the next few days. The NHC track forecast is
based upon the tightly clustered global and regional hurricane
models, and is slightly south of the previous advisory because of
the southward revision to the initial position.

The continuing steady state of Ivette would argue for little
change in the short term, but the global models insist that the
vertical shear should be diminishing now. The NHC intensity
forecast assumes that the shear will lower during the next two to
three days while the SSTs are quite warm and the atmosphere is
moist and unstable, leading to a steady intensification of Ivette.
Beyond day three, the vertical shear should ramp up again out of the
southwest as a large upper-level trough approaches Ivette while the
SSTs cool, causing Ivette to gradually weaken. The NHC intensity
forecast is based upon a blend of the SHIPS and HWRF models, and is
slightly below that from the previous advisory.

FORECAST POSITIONS AND MAX WINDS

INIT 04/0300Z 14.6N 123.4W 40 KT 45 MPH
12H 04/1200Z 14.7N 125.5W 45 KT 50 MPH
24H 05/0000Z 14.9N 128.2W 50 KT 60 MPH
36H 05/1200Z 15.1N 130.5W 60 KT 70 MPH
48H 06/0000Z 15.5N 132.5W 70 KT 80 MPH
72H 07/0000Z 16.7N 136.3W 75 KT 85 MPH
96H 08/0000Z 18.0N 140.0W 65 KT 75 MPH
120H 09/0000Z 19.0N 143.0W 50 KT 60 MPH

$$
Forecaster Landsea

NNNN

[cycloneye]

TROPICAL STORM IVETTE DISCUSSION NUMBER 7
NWS NATIONAL HURRICANE CENTER MIAMI FL EP102016
200 AM PDT THU AUG 04 2016

Shear and the entrainment of dry mid-level air appear to have
taken a toll on Ivette, as the thunderstorm activity has decreased
in coverage and organization during the past 12 hours or so. Recent
microwave and geostationary satellite pictures show very little
banding features and a significant displacement of the convection to
the south and southwest of the low-level center. Despite the
decrease in organization, overnight ASCAT data showed 35 to 40 kt
winds over the northern semicircle of the tropical cyclone.
Therefore, the initial wind speed remains 40 kt for this advisory.

A UW/CIMMS shear analysis and the SHIPS model suggest that the
shear may be beginning to decrease, however the current lack of
organization and nearby dry air is likely to prevent significant
intensification today. However, strengthening is still
anticipated by tonight or Friday when Ivette is forecast to
be over warm water and in a low shear environment. After day 3,
cooler waters and increasing southwesterly shear should begin the
weakening process. The new NHC intensity forecast is slightly
lower than the previous advisory, but remains above the statistical
guidance, and it is closer to the HWRF that still brings Ivette
to hurricane intensity in a couple of days.

Ivette continues to move just north of due west at about 13 kt. The
tropical storm should continue moving westward during the next 36
hours as it remains to the south of a strong subtropical ridge.
After that time, the western portion of the ridge is forecast to
weaken when a trough deepens to the north of the Hawaiian Islands.
This should cause Ivette to turn west-northwestward and slow down.
There is very good agreement among the track guidance this morning
and higher than normal confidence in the track forecast. The new
NHC track forecast is near the multi-model consensus and is
essentially an update of the previous advisory.


FORECAST POSITIONS AND MAX WINDS

INIT 04/0900Z 14.7N 124.7W 40 KT 45 MPH
12H 04/1800Z 14.8N 126.7W 40 KT 45 MPH
24H 05/0600Z 14.9N 129.2W 45 KT 50 MPH
36H 05/1800Z 15.2N 131.3W 55 KT 65 MPH
48H 06/0600Z 15.8N 133.2W 65 KT 75 MPH
72H 07/0600Z 16.9N 136.7W 70 KT 80 MPH
96H 08/0600Z 18.3N 140.0W 55 KT 65 MPH
120H 09/0600Z 19.3N 143.0W 40 KT 45 MPH

$$
Forecaster Brown

[cycloneye]

TROPICAL STORM IVETTE DISCUSSION NUMBER 8
NWS NATIONAL HURRICANE CENTER MIAMI FL EP102016
800 AM PDT THU AUG 04 2016

After Ivette produced very little convection near its low-level
center last evening, a large burst of thunderstorms developed around
0700 UTC, and the cirrus canopy has continued to expand since then.
However, there is no data to support that this convection has led to
any intensification yet, and the maximum winds remain 40 kt based on
Dvorak CI numbers of 3.0/45 kt and 2.5/35 kt from TAFB and SAB,
respectively.

Vertical shear appears to have decreased below 10 kt, which may be
fostering the recent increase in convection. With sea surface
temperatures remaining between 27-28C and shear expected to be low
during the next three days or so, intensification is still
anticipated. But because Ivette has failed to strengthen during the
past 24 hours, the peak winds shown by the intensity models continue
to decrease, and none of the guidance makes the cyclone a hurricane.
For now, the NHC official forecast continues to show Ivette reaching
hurricane intensity in 2-3 days, but this forecast may need to be
adjusted if Ivette does not start strengthening soon. A significant
increase in shear and marginal SSTs should lead to fairly quick
weakening on days 4 and 5.

Ivette is moving westward, or 280/13 kt. A strong subtropical high
located north of the cyclone is expected to steer Ivette westward
for the next 36 hours. After that time, a break in the ridge
northeast of Hawaii should cause the storm to slow down and move
west-northwestward through the end of the forecast period. Again
there have been no significant changes in the track guidance, and
the updated NHC track forecast remains very close to the TVCN
multi-model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT 04/1500Z 15.1N 126.2W 40 KT 45 MPH
12H 05/0000Z 15.2N 128.2W 45 KT 50 MPH
24H 05/1200Z 15.4N 130.4W 50 KT 60 MPH
36H 06/0000Z 15.7N 132.4W 55 KT 65 MPH
48H 06/1200Z 16.3N 134.1W 65 KT 75 MPH
72H 07/1200Z 17.5N 137.4W 65 KT 75 MPH
96H 08/1200Z 18.5N 140.5W 50 KT 60 MPH
120H 09/1200Z 19.5N 143.5W 35 KT 40 MPH

$$
Forecaster Berg

[hurricanes1234]

Let's see if it can start back strengthening now that shear has decreased.

What do y'all think?

[Yellow Evan]

Let's see if it can start back strengthening now that shear has decreased.

What do y'all think?

It should. Idk why the NHC has backed off so much, but if this doesn't start deepening soon, I doubt this gets much beyond minimal hurricane intensity.

[ScottNAtlanta]

Looking at it just now doesnt look sheared at all. In fact, its looking a lot better today

[Yellow Evan]

Code: Select all

 04/1800 UTC   14.8N    126.7W       T3.5/3.5         IVETTE -- East Pacific 

Not what I would have gone. guess they're using a shear pattern.