EPAC: IVO - Post-Tropical - Discussion

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EPAC: IVO - Post-Tropical - Discussion

#1 Postby cycloneye » Tue Aug 05, 2025 7:40 am

EP, 91, 2025080512, , BEST, 0, 91N, 904W, 25, 1010, DB, 34, NEQ, 0, 0, 0, 0, 1013, 200, 120, 0, 0, E, 0, , 0, 0, INVEST, S, 0, , 0, 0, 0, 0, genesis-num, 017, SPAWNINVEST, ep782025 to ep91202


https://ftp.nhc.noaa.gov/atcf/btk/bep912025.dat


South of Southern Mexico:
An area of low pressure located a couple hundred miles offshore of
the coast of Central America is producing a large area of
disorganized showers and thunderstorms. Environmental conditions
appear conducive for development of this system, and a tropical
depression is likely to form during the next couple of days while
it moves west-northwestward around 15 mph.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 7 days...high...90 percent.
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Re: EPAC: INVEST 91E - Discussion

#2 Postby cycloneye » Wed Aug 06, 2025 7:20 am

South of Southern Mexico (EP91):
Shower and thunderstorm activity associated with an area of low
pressure located a couple of hundred miles south-southwest of the
Gulf of Tehuantepec has increased during the past few hours.
Continued development is expected and a tropical depression or
tropical storm will likely form during the next day or so. The
system is forecast to move generally west-northwestward around 15
mph, parallel to but offshore of the coast of Mexico. For additional
information, including gale warnings, please see High Seas Forecasts
issued by the National Weather Service.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 7 days...high...90 percent.
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Re: EPAC: INVEST 91E - Discussion

#3 Postby cycloneye » Wed Aug 06, 2025 12:46 pm

Probably a TD or TS this afternoon.

South of Southern Mexico (EP91):
Microwave satellite imagery and derived surface wind data indicate
that the disturbance located a few hundred miles southwest of the
Gulf of Tehuantepec has become better organized this morning. If
current trends continue, advisories will likely be initiated for
either a tropical depression or tropical storm this afternoon. The
system is forecast to continue moving generally west-northwestward
at 15 to 20 mph, parallel to, but offshore of the coast of Mexico.
Regardless of the system's formation or exact track, heavy rainfall
is possible along the southern coast of Mexico today and tomorrow.
For additional information, including storm warnings, please see
High Seas Forecasts issued by the National Weather Service.
* Formation chance through 48 hours...high...near 100 percent.
* Formation chance through 7 days...high...near 100 percent.
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Re: EPAC: INVEST 91E - Discussion

#4 Postby StormWeather » Wed Aug 06, 2025 1:28 pm

18Z updated and has put this at 35 kts. This is likely going straight to Tropical Storm Ivo at 5.
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Re: EPAC: IVO - Tropical Storm - Discussion

#5 Postby StormWeather » Wed Aug 06, 2025 3:55 pm

Hello Ivo

130
WTPZ44 KNHC 062054
TCDEP4

Tropical Storm Ivo Discussion Number 1
NWS National Hurricane Center Miami FL EP092025
300 PM CST Wed Aug 06 2025

One-minute GOES-E visible imagery, microwave imagery and
scatterometer data from this morning indicate that the disturbance
south of Mexico has become much better organized. The system has
developed banding features, and the most recent TAFB Dvorak analysis
shows a Final-T of 2.0. The ASCAT data showed peak winds between
30-35 kt, so advisories have been initiated on Tropical Storm Ivo,
with an initial intensity of 35 kt.

Ivo has a relatively small circulation, but it's embedded within a
fairly large area of deep convection. SHIPS diagnostics indicate
that wind shear could be a limiting factor for Ivo's intensity
during the next couple of days, but the tropical storm is in an
otherwise conducive environment for strengthening. The NHC forecast
follows the multi-model consensus and shows Ivo reaching hurricane
strength within the next couple of days, but there is about 30 kt of
spread in the intensity guidance, both above and below the official
forecast.

Ivo is moving fairly quickly toward the west-northwest near 19 kt. A
deep-layer ridge centered over the southwestern U.S. should steer
Ivo parallel to the coast of Mexico for the next couple of days.
The ridge is forecast to weaken by the weekend, causing Ivo to move
at a slower forward speed, but by then Ivo will reach cooler SSTs
and a more stable environment. That should cause the cyclone to
quickly weaken and turn westward, steered primarily by low-level
flow. The NHC track forecast is near the center of the guidance
envelope, very close to HCCA throughout the 5-day period.

The tropical-storm-force winds associated with Ivo are expected to
remain offshore of the coast of Mexico, however heavy rain and
rough surf are likely along portions of the southwest coast of
Mexico during the next day or two.

FORECAST POSITIONS AND MAX WINDS

INIT 06/2100Z 14.2N 99.1W 35 KT 40 MPH
12H 07/0600Z 15.4N 101.9W 40 KT 45 MPH
24H 07/1800Z 17.2N 105.5W 50 KT 60 MPH
36H 08/0600Z 18.9N 108.5W 60 KT 70 MPH
48H 08/1800Z 20.0N 111.0W 70 KT 80 MPH
60H 09/0600Z 20.7N 113.3W 70 KT 80 MPH
72H 09/1800Z 21.0N 115.0W 60 KT 70 MPH
96H 10/1800Z 21.5N 117.6W 40 KT 45 MPH
120H 11/1800Z 22.5N 120.5W 30 KT 35 MPH...POST-TROP/REMNT LOW

$$
Forecaster D. Zelinsky
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Re: EPAC: IVO - Tropical Storm - Discussion

#6 Postby AnnularCane » Wed Aug 06, 2025 4:08 pm

I need to pay more attention. I had no idea anything other than Henriette even existed in the EPAC. :lol:
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Re: EPAC: IVO - Tropical Storm - Discussion

#7 Postby Yellow Evan » Wed Aug 06, 2025 7:22 pm

If this were moving slower this would be a solid major candidate but alias.
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Re: EPAC: IVO - Tropical Storm - Discussion

#8 Postby cycloneye » Wed Aug 06, 2025 9:16 pm

Some bands may move thru parts of the Mexican coast, but the core of the storm will move fairly away.

Image

Image
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Re: EPAC: IVO - Tropical Storm - Discussion

#9 Postby cycloneye » Wed Aug 06, 2025 9:42 pm

Tropical Storm Ivo Discussion Number 2
NWS National Hurricane Center Miami FL EP092025
900 PM CST Wed Aug 06 2025

Ivo's cloud pattern is gradually becoming better organized but the
convective banding features are not yet well defined. Very cold
cloud tops to -70 deg C or colder are evident, primarily over the
northern portion of the circulation. The upper-level outflow
pattern is fairly well defined over the system, but outflow is
restricted over the northeastern quadrant. The current intensity
estimate is kept at 35 kt for now, in agreement with a subjective
Dvorak classification from TAFB and most objective estimates from
UW-CIMSS.

Blending center fixes from SAB and TAFB give a swift
west-northwestward motion of around 295/19 kt, as in the
previous advisory. There is a strong 500 mb high situated to the
north of Ivo, which is predicted to remain in place for the next
couple of days. This should keep the tropical cyclone on a
west-northwestward track, parallel to, but offshore of, the coast
of southwestern Mexico. Beyond 24-36 hours, Ivo should turn a bit
to the left with decreasing forward speed while moving away from
Mexico. The official track forecast is very similar to the
previous one and close to the dynamical model consensus.

For the next couple of days, Ivo should be in an environment of
moderate vertical shear, fairly warm waters and high low- to
mid-level humidity. Therefore strengthening is likely and the
system is predicted to become a hurricane by late this week. Later
in the forecast period, the system should be traversing cooler
waters which is likely to reduce the cyclone to a remnant low in 5
days. The official intensity forecast is at the high end of the
model guidance.

The tropical-storm-force winds associated with Ivo are expected to
remain offshore of the coast of Mexico, however heavy rain and
rough surf are likely along portions of the southwest coast of
Mexico during the next day or two.


FORECAST POSITIONS AND MAX WINDS

INIT 07/0300Z 15.0N 100.9W 35 KT 40 MPH
12H 07/1200Z 16.3N 103.6W 45 KT 50 MPH
24H 08/0000Z 18.2N 107.0W 55 KT 65 MPH
36H 08/1200Z 19.7N 109.8W 65 KT 75 MPH
48H 09/0000Z 20.4N 112.1W 70 KT 80 MPH
60H 09/1200Z 20.8N 114.0W 65 KT 75 MPH
72H 10/0000Z 21.0N 115.4W 55 KT 65 MPH
96H 11/0000Z 21.4N 118.0W 40 KT 45 MPH
120H 12/0000Z 22.0N 121.0W 30 KT 35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Pasch
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Re: EPAC: IVO - Tropical Storm - Discussion

#10 Postby cycloneye » Thu Aug 07, 2025 4:32 am

Tropical Storm Ivo Discussion Number 3
NWS National Hurricane Center Miami FL EP092025
300 AM CST Thu Aug 07 2025

Ivo's satellite presentation is that of a storm that is steadily
intensifying. Deep convection has been continuously forming while
the central deep overcast has been expanding through the evening.
However, overnight scatterometer data from 0412 UTC revealed a
dubious, at best, low-level circulation. The data suggests that
even though the mid-level rotation appears robust, the low-level
flow has yet to reflect such organization, likely due to Ivo's rapid
forward motion. The intensity is held at 35 kt based on the latest
satellite-derived wind data.

The motion is estimated to be 295/20 kt. Ivo is racing along the
southern side of a strong mid-level ridge centered over the
southwestern United States. This motion is expected to continue
for the next day or so which should keep the tropical cyclone
moving parallel to, but offshore of, the coast of southwestern
Mexico. Around 36 h, Ivo is expected to turn more westward and slow
down. The latest NHC track forecast is slightly faster than the
previous forecast and lies between the various consensus aids.

Ivo is still forecast to steadily strengthen over then next day or
so. Moderate vertical wind shear, warm sea surface temperatures,
and a moist environment should provide the necessary conditions for
the cyclone to reach hurricane status within the next couple of
days. Ivo is expected to cross over cooler waters by 72 h, which
should induce a gradual weakening trend. Global models predict
increasing shear will separate the cyclone from deep convection and
Ivo is now forecast to become post-tropical by 96 h. The official
intensity forecast remains at the high end of the model guidance.

The tropical-storm-force winds associated with Ivo are expected to
remain offshore of the coast of Mexico, however heavy rain and
rough surf are likely along portions of the southwest coast of
Mexico during the next day or so. Outer bands of Ivo are expected
to produce locally heavy rainfall in portions of the Mexican states
of Guerrero, Michoacan de Ocampo and Colima through Friday. Flash
flooding is possible.


FORECAST POSITIONS AND MAX WINDS

INIT 07/0900Z 15.9N 103.0W 35 KT 40 MPH
12H 07/1800Z 17.3N 105.8W 45 KT 50 MPH
24H 08/0600Z 18.9N 108.9W 55 KT 65 MPH
36H 08/1800Z 20.0N 111.5W 65 KT 75 MPH
48H 09/0600Z 20.6N 113.5W 65 KT 75 MPH
60H 09/1800Z 20.7N 115.0W 60 KT 70 MPH
72H 10/0600Z 20.9N 116.5W 50 KT 60 MPH
96H 11/0600Z 21.3N 119.5W 35 KT 40 MPH...POST-TROPICAL
120H 12/0600Z 21.7N 122.4W 30 KT 35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Bucci
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Re: EPAC: IVO - Tropical Storm - Discussion

#11 Postby cycloneye » Thu Aug 07, 2025 10:55 am

Tropical Storm Ivo Discussion Number 4
NWS National Hurricane Center Miami FL EP092025
900 AM CST Thu Aug 07 2025

Finding the exact center of Ivo is tricky this morning, but my best
guess is that its track has deviated rightward since the prior
advisory. A pair of helpful microwave passes, an AMSR2 pass at 0850
UTC and a SSMIS pass at 1050 UTC, showed well-defined curved banding
on the 37-GHz to 91-GHz channels respectively. More recently, a
visible satellite animation of 1-min GOES-19 imagery shows bursting
convection near the estimated center. Subjective Dvorak estimates by
TAFB and SAB were T3.0/45 kt and T2.5/35 kt respectively, with the
objective intensity estimates ranging from 34 to 51 kt. Thus, the
initial intensity has been bumped up to 40 kt this morning.

Ivo appears to be maintaining a brisk west-northwestward motion,
estimated at 300/21 kt. This rapid forward motion is thanks in part
to a strong and large mid-level ridge stretching across northern
Mexico and southwestern United States. This ridge is forecast to
move along with Ivo though it does gradually dampen out in
magnitude. The net result of this pattern should keep Ivo on a
general west-northwestward heading, with the cyclone turning more
westward and slowing down towards the latter half of the forecast.
The track guidance this cycle is a little farther north, largely a
reflection of the farther north initial position. The latest NHC
track forecast is also farther north roughly blending the simple and
corrected consensus aids (TVCE and HCCA), but still remains offshore
of Mexico, making its point of closest approach in the next 12-18
hours.

The small core of Ivo likely could make it susceptible to rapid
changes in intensity, either up or down. Because vertical wind
shear is relatively low (10-15 kt), and sea surface temperatures
remain above 27 C for the next 36 hours, the NHC intensity forecast
continues to show significant intensification, making Ivo a
hurricane. Thereafter, the storm will reach a sharp sea-surface
temperature gradient, and should begin a gradual weakening trend.
Towards the end of the forecast Ivo will likely lose its remaining
deep convection over the sub 24 C waters west of Baja California,
marking its transition to a post-tropical remnant low by 96 h. The
NHC intensity forecast remains a bit on the high end of the overall
model suite.

Given the small radius of tropical-storm-force winds associated with
Ivo, these winds are expected to remain offshore as it makes its
closest approach to Mexico later today. However, heavy rain and
rough surf are likely to occur along portions of the southwest coast
of Mexico during the next day or so. Outer bands of Ivo are
expected to produce locally heavy rainfall in portions of the
Mexican states of Guerrero, Michoacan de Ocampo and Colima through
Friday where Flash flooding is possible.


FORECAST POSITIONS AND MAX WINDS

INIT 07/1500Z 17.8N 104.4W 40 KT 45 MPH
12H 08/0000Z 19.5N 106.8W 50 KT 60 MPH
24H 08/1200Z 20.8N 109.6W 60 KT 70 MPH
36H 09/0000Z 21.5N 111.7W 65 KT 75 MPH
48H 09/1200Z 21.7N 113.5W 60 KT 70 MPH
60H 10/0000Z 21.8N 114.8W 45 KT 50 MPH
72H 10/1200Z 22.0N 116.3W 35 KT 40 MPH
96H 11/1200Z 22.5N 119.6W 30 KT 35 MPH...POST-TROP/REMNT LOW
120H 12/1200Z...DISSIPATED

$$
Forecaster Papin
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Re: EPAC: IVO - Tropical Storm - Discussion

#12 Postby cycloneye » Thu Aug 07, 2025 4:02 pm

Tropical Storm Ivo Discussion Number 5
NWS National Hurricane Center Miami FL EP092025
300 PM CST Thu Aug 07 2025

Ivo remains a very small tropical cyclone, though an intensifying
one. Deep central convection continues to burst near the center,
though the vertical structure of the tropical storm does appear more
ragged with evidence that the mid-level vortex is tilted to the
southwest of the low-level center. A helpful Metop-B scatterometer
pass at 1643 UTC captured the tiny circulation with a max wind
retrieval of 44 kt. Assuming this instrument undersampled the peak
winds of the small cyclone, the initial intensity is being raised to
50 kt for this advisory, also close to the latest objective ADT
estimate.

The tropical storm continues to move quite quickly to the northwest,
with the motion estimated at 305/18 kt. The track forecast reasoning
is similar to earlier, where a strong and extensive mid-level ridge
parked over northern Mexico should keep Ivo moving quickly
west-northwestward to northwestward for the next 24 hours or so. On
this forecast track, Ivo will soon begin pulling away from the
southwestern coast of Mexico. By this weekend, the ridge begins to
weaken some and the guidance also suggests Ivo will start to become
more vertically shallow. A combination of these influences should
result in a westward turn in the track and a slowdown in the forward
motion. The track guidance for this cycle is quite similar to the
prior one, and the NHC track forecast is largely an update from
the previous one, blending the consensus aids HCCA and TVCE.

The intensity forecast presents a conundrum this afternoon. Ivo has
a small inner core wind field, is over warm 29-30 C ocean waters,
and vertical wind shear as diagnosed by SHIPS guidance is low, only
5-10 kt. Ordinarily these variables would suggest that Ivo could
undergo a period of rapid intensification (RI), and EC-SHIPS-RI
guidance now has a 71 percent chance of a 30-kt increase over the
next 24 h. However, other RI indices are lower, with DTOPS at only
12 percent for the same threshold. There is also evidence that Ivo's
structure is not ideal, with current visible satellite imagery
suggesting its circulation is tilted southwest with height. This
vertical tilt also matches the structure seen in the most recent
HAFS-A/B model grids. This may explain why the regional-hurricane
models are less aggressive with Ivo's intensification than SHIPS,
and only HAFS-B briefly makes Ivo a hurricane. Thus the NHC
intensity forecast is not as aggressive as the latest SHIPS
guidance, only taking Ivo to a 70 kt hurricane in 24 hours.
Thereafter, the storm will cross a sharp sea-surface temperature
gradient, which should lead to weakening after 24 hours. Like the
previous forecast, Ivo will likely lose its organized deep
convection west of Baja California in about 72 hours, where the
latest forecast shows it becoming a post-tropical remnant low. The
NHC intensity forecast is a little above the reliable HCCA aid, but
is lower than both SHIPS and LGEM aids.

Given the small radius of tropical-storm-force winds associated with
Ivo, these winds are expected to remain offshore as it begins to
move away from Mexico by tonight. However, heavy rain and rough surf
are likely to occur along portions of the southwest coast of Mexico
during the next day or so. Outer bands of Ivo are expected to
produce locally heavy rainfall in portions of the Mexican states of
Guerrero, Michoacan de Ocampo and Colima through Friday where flash
flooding is possible.


FORECAST POSITIONS AND MAX WINDS

INIT 07/2100Z 18.8N 105.8W 50 KT 60 MPH
12H 08/0600Z 20.1N 108.2W 60 KT 70 MPH
24H 08/1800Z 21.1N 110.9W 70 KT 80 MPH
36H 09/0600Z 21.5N 112.8W 65 KT 75 MPH
48H 09/1800Z 21.6N 114.1W 55 KT 65 MPH
60H 10/0600Z 21.7N 115.8W 40 KT 45 MPH
72H 10/1800Z 21.9N 117.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 11/1800Z 22.5N 121.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 12/1800Z...DISSIPATED

$$
Forecaster Papin
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Re: EPAC: IVO - Tropical Storm - Discussion

#13 Postby cycloneye » Thu Aug 07, 2025 9:53 pm

Tropical Storm Ivo Discussion Number 6
NWS National Hurricane Center Miami FL EP092025
800 PM MST Thu Aug 07 2025

While Ivo has a compact core with a concentrated area of convection,
the overall cloud pattern appears disorganized and lacks banding
features. The initial intensity remains 50 kt, near the high end of
the latest satellite intensity estimates and in agreement with the
earlier ASCAT data. Some of the associated thunderstorms are
brushing the coast of southwestern Mexico, likely bringing areas of
heavy rain and gusty winds. Ivo's tropical-storm-force winds remain
offshore near the tiny core, and are estimated to only extend about
40 n mi from the center.

The storm continues to move quickly to the northwest at 19 kt on the
south side of a strong mid-level ridge situated over the
southwestern U.S. This ridge is expected to weaken and shift
slightly westward during the next few days. As a result, Ivo is
forecast to turn to the west-northwest and then the west with a
notable decrease in forward speed. This motion should take Ivo away
from mainland Mexico and well south of the Baja California
peninsula. The NHC track forecast is similar to the previous one and
near the middle of the guidance envelope.

The large-scale conditions appear quite favorable for strengthening
during the next day or so with warm SSTs, low vertical wind shear,
and high mid-level relative humidities. However, it is possible that
Ivo might not take advantage of those conditions given its current
ragged structure. There is considerable divergence in the intensity
models with the dynamical-statistical aids showing significant
strengthening while the global and HAFS guidance show little to no
intensification. The NHC intensity forecast follows the previous
one and leans closer to the high end of the guidance in the short
term, but this is of low confidence. Regardless of what occurs in
the next 24 hours, weakening should begin over the weekend when Ivo
is forecast to move over progressively cooler waters and into an
air mass of drier air and stronger shear.


FORECAST POSITIONS AND MAX WINDS

INIT 08/0300Z 19.7N 107.3W 50 KT 60 MPH
12H 08/1200Z 20.7N 109.5W 60 KT 70 MPH
24H 09/0000Z 21.4N 111.6W 70 KT 80 MPH
36H 09/1200Z 21.7N 113.1W 60 KT 70 MPH
48H 10/0000Z 21.9N 114.8W 50 KT 60 MPH
60H 10/1200Z 22.1N 116.6W 40 KT 45 MPH
72H 11/0000Z 22.3N 118.6W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 12/0000Z 22.4N 122.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 13/0000Z...DISSIPATED

$$
Forecaster Cangialosi
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Re: EPAC: IVO - Tropical Storm - Discussion

#14 Postby zeehag » Thu Aug 07, 2025 11:34 pm

ivo is off cabo corrientes and here in mazatlan we are in a beautiful tormenta related to the storm. very wet and much lightning as ivo intensifies off corrientes. our sinaloa coast is being soaked well
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Re: EPAC: IVO - Tropical Storm - Discussion

#15 Postby StormWeather » Fri Aug 08, 2025 9:46 am

No longer forecast to become a hurricane, but NHC mentions the small possibility of doing so remains

ZCZC MIATCDEP4 ALL
TTAA00 KNHC DDHHMM CCA

Tropical Storm Ivo Discussion Number 7...Corrected
NWS National Hurricane Center Miami FL EP092025
200 AM MST Fri Aug 08 2025

Corrected T-number in the first paragraph

Ivo seems to be responding to the conducive environmental
conditions. Convection has been building within the core of the
storm and geostationary satellite imagery has depicted a growing
CDO overnight. The small storm has managed to elude recent
scatterometer and microwave overpasses and no new information has
been collected with respect to the low-level structure. The initial
intensity is held at 50 kt for this cycle based on persistence,
which is slightly above the latest TAFB Dvorak estimate of T3.0/45
kt.

Ivo is moving quickly along the southern periphery of a mid-level
ridge at 295/18 kt. The ridge is expected to continue turning the
storm toward the west during the next couple of days with a
significant decrease in forward motion. Ivo is forecast to stay
well south of the Baja California peninsula. The latest official
track forecast lies slightly to the south of the previous prediction
beyond the 24 h forecast time.

Atmospheric and oceanic conditions are conducive for strengthening
during the next day or so. The NHC intensity forecast still brings
Ivo up to hurricane strength within a day, however this peak lies
above all the latest model guidance. It should be noted that this
portion of the forecast has higher-than-average uncertainty due to
the high spread in the model guidance. Beyond 24 hours, the model
and official forecasts come into better agreement when Ivo moves
over cooling sea surface temperatures and into a dry and stable
environment with moderate vertical wind shear. The system is still
expected to become a remnant low within a few day and open into a
trough by the end of the forecast period.


FORECAST POSITIONS AND MAX WINDS

INIT 08/0900Z 20.4N 109.0W 50 KT 60 MPH
12H 08/1800Z 21.2N 111.0W 60 KT 70 MPH
24H 09/0600Z 21.6N 112.8W 65 KT 75 MPH
36H 09/1800Z 21.7N 114.4W 55 KT 65 MPH
48H 10/0600Z 21.8N 116.1W 45 KT 50 MPH
60H 10/1800Z 22.1N 117.9W 35 KT 40 MPH
72H 11/0600Z 22.2N 119.8W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 12/0600Z 22.2N 123.7W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 13/0600Z...DISSIPATED

$$
Forecaster Bucci




000
WTPZ44 KNHC 081436
TCDEP4

Tropical Storm Ivo Discussion Number 8
NWS National Hurricane Center Miami FL EP092025
800 AM MST Fri Aug 08 2025

Ivo's satellite presentation hasn't changed much since the last
advisory. The center appears to be embedded beneath the northern
side of the Central Dense Overcast, with one small convective band
forming on the northwestern side of the circulation. The Dvorak
estimate from TAFB increased to T3.5/55 kt, however the SAB
estimate and all objective guidance is much lower. Therefore, the
current intensity is held at 50 kt.

Ivo is slowing down and now has a west-northwestward initial motion
at 295/14 kt. Strong mid-level ridging to the north is expected to
be the main driver for the entirety of the forecast, keeping Ivo on
a westward or west-northwestward trajectory but at a slower forward
speed. No significant changes were made to the official track
forecast.

The more complicated part of the forecast is the intensity. Ivo is
expected to remain over waters warmer than 26 degrees Celsius and in
a moist environment with divergence aloft for the next 24 hours or
so. Because of that, the NHC intensity forecast continues to show
some strengthening through tonight. The forecast no longer
explicitly shows Ivo becoming a hurricane, but that is still a small
possibility, especially if Ivo is currently stronger than is being
estimated. Beginning in about 36 hours, colder ocean temperatures,
a more stable environment, and less divergence aloft should cause
the storm to weaken. Some of the models differ significantly on
exactly how quick that weakening will be. For example, the GFS
maintains tropical-storm-force winds for at least the next 3 days,
while the ECWMF degenerates Ivo into a remnant low in about 24
hours. As a compromise, the NHC forecast shows Ivo becoming
post-tropical by 60 hours, with dissipation by day 5, if not sooner.


FORECAST POSITIONS AND MAX WINDS

INIT 08/1500Z 20.7N 110.1W 50 KT 60 MPH
12H 09/0000Z 21.1N 111.7W 55 KT 65 MPH
24H 09/1200Z 21.3N 113.4W 60 KT 70 MPH
36H 10/0000Z 21.3N 114.9W 55 KT 65 MPH
48H 10/1200Z 21.5N 116.6W 45 KT 50 MPH
60H 11/0000Z 21.9N 118.3W 35 KT 40 MPH...POST-TROPICAL
72H 11/1200Z 22.0N 120.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 12/1200Z 22.0N 124.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 13/1200Z...DISSIPATED

$$
Forecaster Berg
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Re: EPAC: IVO - Tropical Storm - Discussion

#16 Postby cycloneye » Fri Aug 08, 2025 9:29 pm

Tropical Storm Ivo Discussion Number 9
NWS National Hurricane Center Miami FL EP092025
200 PM MST Fri Aug 08 2025

Ivo's structure has become more organized during the past few
hours, with inner core banding becoming more pronounced. Recent
WSF-M and GMI microwave data were helpful in confirming the
improved structure, and also showed that Ivo's center was located a
little farther south than previously estimated. Despite the
improved structure, there is a wide range in intensity estimates.
Subjective Dvorak estimates from TAFB and SAB range from 55-65 kt,
while objective numbers from UW-CIMSS are stuck at 40-45 kt. To
add to the quandary, ASCAT data only showed maximum winds of 35 kt,
but it is highly likely that Ivo is too small for the instrument to
effectively sample its maximum winds. For now, Ivo's maximum winds
are set to 55 kt.

The storm has turned westward and continues to slow down with an
initial motion of 275/11 kt. A westward to west-northwestward
trajectory is forecast to continue for the next several days as
strong mid-level ridging remains entrenched to the north. The NHC
track forecast has been shifted south of the previous prediction to
account for the adjustment of the initial position, but otherwise
it is very close to the various multi-model consensus aids.

Some additional strengthening is anticipated during the next 12-24
hours while Ivo remains in an unstable environment with upper-level
divergence, and over waters warmer than 26 degrees Celsius.
While not explicitly shown in the forecast, Ivo could still
become a hurricane between the nominal forecast times. All of
the aforementioned environmental factors turn detrimental in about
36 hours, at which point more significant weakening is expected to
begin. Ivo could lose its deep convection and become post-tropical
in about 60 hours. Dissipation is now shown by day 4 in line with
the ECWMF, UKMET, and Canadian model solutions, with the GFS being
an outlier and continuing the remnant low westward for another day
or so after that.


FORECAST POSITIONS AND MAX WINDS

INIT 08/2100Z 20.4N 111.2W 55 KT 65 MPH
12H 09/0600Z 20.5N 112.5W 60 KT 70 MPH
24H 09/1800Z 20.7N 114.0W 60 KT 70 MPH
36H 10/0600Z 21.0N 115.7W 55 KT 65 MPH
48H 10/1800Z 21.5N 117.5W 45 KT 50 MPH
60H 11/0600Z 21.8N 119.4W 35 KT 40 MPH...POST-TROPICAL
72H 11/1800Z 21.9N 121.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 12/1800Z...DISSIPATED

$$
Forecaster Berg
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Re: EPAC: IVO - Tropical Storm - Discussion

#17 Postby cycloneye » Fri Aug 08, 2025 9:35 pm

Tropical Storm Ivo Discussion Number 10
NWS National Hurricane Center Miami FL EP092025
800 PM MST Fri Aug 08 2025

After gaining some strength earlier today, Ivo's intensity appears
to have leveled off again. The compact storm is still producing a
concentrated area of deep convection, but the cloud tops have been
warming over the past several hours. In addition, dry air appears to
be eroding some of the outer bands. The initial intensity is held at
55 kt, which is in line with the latest satellite intensity
estimates.

Ivo could strengthen a little later tonight or early Saturday, but a
weakening trend should begin shortly thereafter as the storm moves
over progressively cooler waters and into a drier air mass. The
NHC intensity forecast is a little lower than the previous one, and
now shows Ivo becoming a post-tropical cyclone in a couple of days
when it is anticipated to be over cool 23 to 24 C waters.

The storm is moving westward at about 10 kt. The track forecast
appears straightforward as Ivo should being steered westward to
west-northwestward on the south side of a low- to mid-level ridge
during the next few days. This motion should take the system away
from the Baja California peninsula and over the open eastern
Pacific. The NHC track forecast follows the various consensus
models, and is a touch to the north of the previous track.


FORECAST POSITIONS AND MAX WINDS

INIT 09/0300Z 20.5N 112.1W 55 KT 65 MPH
12H 09/1200Z 20.7N 113.2W 55 KT 65 MPH
24H 10/0000Z 21.0N 114.7W 50 KT 60 MPH
36H 10/1200Z 21.5N 116.5W 45 KT 50 MPH
48H 11/0000Z 21.9N 118.6W 40 KT 45 MPH...POST-TROPICAL
60H 11/1200Z 22.1N 120.7W 35 KT 40 MPH...POST-TROPICAL
72H 12/0000Z 22.1N 123.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 13/0000Z...DISSIPATED

$$
Forecaster Cangialosi
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Re: EPAC: IVO - Tropical Storm - Discussion

#18 Postby cycloneye » Sat Aug 09, 2025 5:00 am

Tropical Storm Ivo Discussion Number 11
NWS National Hurricane Center Miami FL EP092025
200 AM MST Sat Aug 09 2025

Ivo is having intermittent bursts of deep convection since the last
advisory. An ASCAT pass from 0412 UTC showed the center of the
small circulation near the northeastern edge of the CDO. Subjective
and objective satellite intensity estimates have generally decreased
in recent hours and the initial intensity is lowered to 50 kt for
this cycle.

The storm is moving westward at 8 kt. A general westward to
west-northwestward motion is anticipated through the forecast period
while Ivo is steered along the southern side of a ridge positioned
to its north. The track guidance has shifted poleward this cycle,
and the latest official forecast lies on the southern side of the
envelope between the ECMWF to its south and the simple consensus aid
TVCE to its north.

Ivo is currently crossing a cooling gradient of sea surface
temperatures and moving towards a dry and stable airmass. The storm
is expected to gradually weaken through the weekend, until it
becomes a post-tropical cyclone sometime Sunday night or Monday
morning. The NHC intensity forecast has been adjusted lower based
on the decrease in initial intensity and is in the middle of the
guidance envelope.


FORECAST POSITIONS AND MAX WINDS

INIT 09/0900Z 20.6N 112.4W 50 KT 60 MPH
12H 09/1800Z 20.9N 113.4W 45 KT 50 MPH
24H 10/0600Z 21.3N 115.1W 45 KT 50 MPH
36H 10/1800Z 21.7N 117.1W 40 KT 45 MPH
48H 11/0600Z 22.0N 119.3W 35 KT 40 MPH...POST-TROPICAL
60H 11/1800Z 22.1N 121.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 12/0600Z 22.2N 123.7W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 13/0600Z...DISSIPATED

$$
Forecaster Bucci
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Re: EPAC: IVO - Tropical Storm - Discussion

#19 Postby cycloneye » Sat Aug 09, 2025 9:55 am

Tropical Storm Ivo Discussion Number 12
NWS National Hurricane Center Miami FL EP092025
800 AM MST Sat Aug 09 2025

Ivo is being affected by moderate northeasterly shear, with its
low-level center near the northern edge of the deep convection.
Dvorak CI numbers from TAFB and SAB are 3.5/55 kt and 3.0/45 kt,
respectively, while objective numbers from UW-CIMSS range from
35-55 kt. Ivo's intensity is held at 50 kt, leaning toward the
blend of CI numbers. The cyclone is expected to reach sub-26
degree Celsius waters in 12-24 hours, while at the same time the
environment becomes more stable and more convergent aloft. As a
result, steady weakening is anticipated, and Ivo is forecast to
become post-tropical in about 36 hours when the environment becomes
too hostile to support organized deep convection. The remnant low
will last for a few more days after that, likely opening up into a
trough by late Tuesday/early Wednesday.

Ivo's position was adjusted a bit north based on recent data, which
ended up shifting the entire forecast track in that direction as
well. Still, the track models are tightly clustered and in good
agreement that Ivo will move generally west-northwestward and then
westward, steered by low- to mid-level ridging to the north. The
NHC track forecast is relatively close to the HCCA and TVCE
consensus aids.


FORECAST POSITIONS AND MAX WINDS

INIT 09/1500Z 21.0N 112.7W 50 KT 60 MPH
12H 10/0000Z 21.4N 113.8W 45 KT 50 MPH
24H 10/1200Z 21.9N 115.7W 40 KT 45 MPH
36H 11/0000Z 22.4N 117.6W 35 KT 40 MPH...POST-TROPICAL
48H 11/1200Z 22.6N 119.7W 30 KT 35 MPH...POST-TROP/REMNT LOW
60H 12/0000Z 22.7N 121.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 12/1200Z 22.6N 124.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 13/1200Z...DISSIPATED

$$
Forecaster Berg
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Re: EPAC: IVO - Tropical Storm - Discussion

#20 Postby cycloneye » Sat Aug 09, 2025 3:53 pm

Tropical Storm Ivo Discussion Number 13
NWS National Hurricane Center Miami FL EP092025
200 PM MST Sat Aug 09 2025

Moderate northeasterly shear is displacing most of Ivo's convection
south of the center, and the convective mass itself has begun to
shrink. The initial intensity is lowered to 45 kt based on a T3.0
classification from TAFB, and this is also supported by a recent
ASCAT pass which showed a maximum of 38 kt (but is likely limited
by the instrument's resolution). Continued moderate shear,
gradually cooling sea surface temperatures, and a stable air mass
ahead of Ivo are forecast to continue the weakening trend. GFS-
and ECMWF-based simulated satellite imagery show all deep convection
dissipating by 36 hours, which is when Ivo is shown degenerating
into a remnant low in the official forecast. Dissipation is now
expected by day 3, which is when the remnant low loses its
integrity in the global model fields.

Ivo has been moving westward, or 280/6 kt. Low- to mid-level
ridging is expected to keep Ivo on a westward or west-northwestward
track through dissipation. There is low spread among the track
models, and only minor adjustments were made to the new NHC
forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 09/2100Z 21.0N 113.5W 45 KT 50 MPH
12H 10/0600Z 21.4N 114.7W 40 KT 45 MPH
24H 10/1800Z 22.0N 116.5W 35 KT 40 MPH
36H 11/0600Z 22.5N 118.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 11/1800Z 22.8N 120.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
60H 12/0600Z 22.9N 123.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 12/1800Z...DISSIPATED

$$
Forecaster Berg
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