EPAC: OTIS - Aftermath - Discussion

[cycloneye]

EP, 91, 2023101818, , BEST, 0, 79N, 943W, 20, 1009, DB, 34, NEQ, 0, 0, 0, 0, 1010, 120, 80, 0, 0, E, 0, , 0, 0, INVEST, S, 0, , 0, 0, 0, 0, genesis-num, 029, SPAWNINVEST, ep722023 to ep912023

https://ftp.nhc.noaa.gov/atcf/btk/bep912023.dat

[ElectricStorm]

1. South of Southern Mexico:
A broad area of low pressure located several hundred miles south of
the Gulf of Tehuantepec is producing some disorganized showers and
thunderstorms. Gradual development of this system is expected, and a
tropical depression is likely to form over the weekend while the
system meanders or drifts northwestward over the far eastern portion
of the basin.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 7 days...high...70 percent.

[cycloneye]

South of Southern Mexico (EP91):
A weak area of low pressure located several hundred miles south of
the Gulf of Tehuantepec is producing a few disorganized showers and
thunderstorms. Any development of this system during the next couple
of days is expected to be slow to occur. However, environmental
conditions are expected to become more favorable for development
thereafter, and a tropical depression is likely to form over the
weekend or early next week. The disturbance is forecast to meander
for the next several days and then drift northward or northwestward
starting on Sunday or Monday.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 7 days...high...80 percent.

[Kingarabian]

Models developing this but could be another Max scenario where it runs out of time.

[cycloneye]

South of Southern Mexico (EP91):
A broad area of low pressure located several hundred miles south of
the Gulf of Tehuantepec continues to produce a large area of
disorganized showers and thunderstorms. Gradual development of this
system is expected, and a tropical depression is likely to form
during the next few days while the system meanders or drifts
generally northward over the far eastern portion of the basin.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 7 days...high...80 percent.

[cycloneye]

South of Southern Mexico (EP91):
A broad area of low pressure located several hundred miles south of
the Gulf of Tehuantepec continues to produce a large area of
disorganized showers and thunderstorms. Gradual development of this
system is expected, and a tropical depression is likely to form
during the next few days while the system meanders or drifts
generally northward over the far eastern portion of the basin.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 7 days...high...80 percent.

[ElectricStorm]

Hurricane models are finally running for this now. Both HAFS models don't develop it, and HMON has a weak TS. HWRF a major outlier showing a hurricane close to landfall

[aspen]

Hurricane models are finally running for this now. Both HAFS models don't develop it, and HMON has a weak TS. HWRF a major outlier showing a hurricane close to landfall

I’ve noticed that sometimes the early HAFS runs have difficulty latching on to development for an invest. This was the case with Tammy as well. The HAFS-B seems to be the most bearish with genesis, but often the most bullish with intensity after the system forms.

[cycloneye]

South of Southern Mexico (EP91):
Visible satellite imagery shows the circulation associated with a
broad area of low pressure located several hundred miles south of
the Gulf of Tehuantepec has become better defined. The system is
currently producing limited shower and thunderstorm activity well to
the west of its center due to strong upper-level winds, but
environmental conditions are expected to become more conducive for
development over the next couple of days. A tropical depression is
likely to form later this weekend or early next week. The system is
forecast to meander during the next couple of days and then drift
generally northward late this weekend and into early next week.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 7 days...high...80 percent.

[Subtrop]

EP, 18, 2023102212, , BEST, 0, 98N, 967W, 30, 1006, TD, 34, NEQ, 0, 0, 0, 0, 1010, 150, 90, 0, 0, E, 0, , 0, 0, EIGHTEEN, S, 0, , 0, 0, 0, 0, genesis-num, 029, TRANSITIONED, epC12023 to ep182023,

[Sciencerocks]

Tropical Depression Eighteen-E Discussion Number 1
NWS National Hurricane Center Miami FL EP182023
1000 AM CDT Sun Oct 22 2023

The area of low pressure (91E) that NHC has been monitoring has now
become a tropical depression well offshore of southern Mexico.
Satellite images show that deep convection has been increasing and
consolidating near the center, and ASCAT data from several hours ago
indicated that the system had developed a well-defined center.
Dvorak estimates from TAFB and SAB have increased to 2.5/35 kt, but
the initial intensity is set a little lower at 30 kt since the ASCAT
pass suggested that the Dvorak estimates have been running a little
high.

The depression is drifting northward at 2 kt. A continued slow
northward motion is expected during the next couple of days as the
system moves in the light steering flow between a ridge to its
northeast and a trough to its northwest. Beyond a few days, the
weakening system will likely turn westward in the low-level flow.
However, by the end of the forecast period, there is quite a bit of
spread in the track guidance making the long-term forecast somewhat
uncertain. The NHC track forecast is near the various consensus
aids.

Some slight strengthening is possible during the next couple of days
while the depression remains in generally conducive environmental
conditions. However, beyond that time, an increase in vertical wind
shear should cause slow weakening, and most of the models show the
system decoupling or dissipating by the end of the forecast period.
The NHC intensity forecast lies near the middle of the guidance
envelope.

FORECAST POSITIONS AND MAX WINDS

INIT 22/1500Z 9.9N 96.7W 30 KT 35 MPH
12H 23/0000Z 10.2N 96.8W 35 KT 40 MPH
24H 23/1200Z 10.8N 96.8W 35 KT 40 MPH
36H 24/0000Z 11.8N 96.7W 40 KT 45 MPH
48H 24/1200Z 12.8N 96.9W 40 KT 45 MPH
60H 25/0000Z 13.4N 97.4W 40 KT 45 MPH
72H 25/1200Z 13.7N 97.7W 40 KT 45 MPH
96H 26/1200Z 13.9N 98.1W 35 KT 40 MPH
120H 27/1200Z 13.9N 98.6W 30 KT 35 MPH

$$
Forecaster Cangialosi/Bucci

[Sciencerocks]

[xtyphooncyclonex]

This one's a male? Yet another tropical storm.

Otis wants to keep the pattern of major female - TS male alive.

[cycloneye]

Hello Otis.

EP, 18, 2023102218, , BEST, 0, 102N, 969W, 35, 1004, TS, 34, NEQ, 60, 60, 0, 0, 1010, 150, 60, 0, 0, E, 0, , 0, 0, OTIS

[Sciencerocks]

[cycloneye]

BULLETIN
Tropical Storm Otis Advisory Number 2
NWS National Hurricane Center Miami FL EP182023
400 PM CDT Sun Oct 22 2023

...DEPRESSION STRENGTHENS INTO TROPICAL STORM OTIS...


SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...10.3N 96.9W
ABOUT 500 MI...800 KM SSE OF ACAPULCO MEXICO
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...NNW OR 330 DEGREES AT 5 MPH...7 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.

Interests in southern and southwestern Mexico should monitor the
progress of the Otis.


Tropical Storm Otis Discussion Number 2
NWS National Hurricane Center Miami FL EP182023
400 PM CDT Sun Oct 22 2023

The tropical depression south of Mexico has strengthened into
Tropical Storm Otis. Satellite imagery shows that the center is just
east of an increasing area of deep convection that has continued to
consolidate. With this slight improvement in structure, the initial
intensity has been raised to 35 kt, which is below the 3.0/45 kt
Dvorak classifications from TAFB and SAB.

Otis is moving northward at 4 kt. A continued slow northward motion
is expected during the next couple of days as the system moves in a
light steering flow between a ridge to its northeast and a trough to
its northwest. By midweek, the system is expected to weaken as it
shifts northwestward in the low-level flow. However, by the end of
the forecast period, there is quite a bit of spread in the track
guidance making the long-term forecast somewhat uncertain. The NHC
track forecast is near the various consensus aids and a little to
the north of the previous one at days 4 and 5.

Some slight strengthening is possible during the next couple of days
while the storm remains in generally conducive environmental
conditions. However, beyond that time, an increase in vertical wind
shear should cause slow weakening, and most of the models show the
system decoupling or dissipating by the end of the forecast period.
The NHC intensity forecast lies near the middle of the guidance
envelope.


FORECAST POSITIONS AND MAX WINDS

INIT 22/2100Z 10.3N 96.9W 35 KT 40 MPH
12H 23/0600Z 10.7N 97.0W 40 KT 45 MPH
24H 23/1800Z 11.6N 96.9W 40 KT 45 MPH
36H 24/0600Z 12.7N 96.9W 40 KT 45 MPH
48H 24/1800Z 13.5N 97.2W 40 KT 45 MPH
60H 25/0600Z 13.9N 97.6W 40 KT 45 MPH
72H 25/1800Z 14.2N 97.8W 40 KT 45 MPH
96H 26/1800Z 14.5N 98.0W 35 KT 40 MPH
120H 27/1800Z 14.9N 98.2W 30 KT 35 MPH

$$
Forecaster Cangialosi/Bucci

[Sciencerocks]

[cycloneye]

Tropical Storm Otis Discussion Number 4
NWS National Hurricane Center Miami FL EP182023
400 AM CDT Mon Oct 23 2023

Deep convection has continued to pulse over the northwestern portion
of Otis overnight. The center was noted near the southeastern edge
of the deep convection in shortwave infrared satellite imagery
earlier in the night. Since that time, the center has become a
little more embedded within the cold cloud tops. As a result, the
initial intensity has been increased to 40 kt for this advisory.
This intensity is a blend of the most recent Dvorak T- and CI-
numbers from TAFB and SAB, and close to the latest SATCON and
D-PRINT objective estimates from UW/CIMSS.

Otis has been moving northward or 360/4 kt. The storm is expected
to move northward to north-northwestward between a ridge over the
northwestern Caribbean Sea and a trough over northwestern Mexico.
The ECMWF, UKMET, and Canadian models all take Otis near the coast
of southern Mexico by midweek, with the ECMWF being the fastest.
That model shows the storm making landfall in southern Mexico in
just over 48 hours. Meanwhile, the GFS continues to depict a weaker
system that stays embedded within the Intertropical Convergence Zone
and meanders well south of Mexico for several days. Since the
majority of the guidance has a track closer or inland over Mexico,
the NHC forecast continues to lean toward that scenario and takes
Otis inland in a few days, but this could occur much sooner. The
NHC track is a blend of the ECMWF, UKMET, Canadian, HMON, and the
HFIP corrected consensus aid.

The storm is over very warm waters and within an environment of
light to moderate shear. These conditions should allow for gradual
strengthening while the system remains over water. Some increase
in shear and the possibility of land interaction could cause the
intensity to level off in a couple of days. The NHC intensity
forecast is again near the higher end of the guidance, close to the
statistical guidance and the HCCA model.

Based on this latest forecast, the government of Mexico has issued a
Tropical Storm Watch for a portion of the coast of southern Mexico.

Key Messages:

1. Heavy rains from Otis will begin to impact areas of southwest
Mexico early this week. This rainfall will produce flash and urban
flooding, along with mudslides in areas of higher terrain.

2. Tropical storm conditions are possible by Tuesday night or early
Wednesday along portions of the southern coast of Mexico where a
Tropical Storm Watch is now in effect.


FORECAST POSITIONS AND MAX WINDS

INIT 23/0900Z 11.4N 97.1W 40 KT 45 MPH
12H 23/1800Z 12.1N 97.3W 45 KT 50 MPH
24H 24/0600Z 13.0N 97.5W 45 KT 50 MPH
36H 24/1800Z 14.0N 97.9W 50 KT 60 MPH
48H 25/0600Z 15.0N 98.4W 50 KT 60 MPH
60H 25/1800Z 15.6N 98.8W 50 KT 60 MPH
72H 26/0600Z 16.4N 99.4W 50 KT 60 MPH
96H 27/0600Z 17.9N 100.7W 30 KT 35 MPH...INLAND
120H 28/0600Z...DISSIPATED

$$
Forecaster Brown

[cycloneye]

Tropical Storm Otis Discussion Number 5
NWS National Hurricane Center Miami FL EP182023
1000 AM CDT Mon Oct 23 2023

Otis has been relatively steady in strength this morning. Satellite
images indicate that deep convection has been pulsing during the
past several hours. The low-level center remains on the east side
of the thunderstorm activity due to easterly wind shear. The
satellite intensity estimates have not changed much, therefore, the
initial intensity is held at 40 kt.

Otis is moving slowly north-northwestward at 5 kt in the flow
between a mid- to upper-level trough to its northwest and a ridge to
its east. There continues to be significant disagreement among the
models with the ECMWF showing Otis moving inland in about 48 hours
while the GFS, HWRF, and HAFS models keep the system offshore during
the next several days. A closer inspection of the guidance suggests
that the differences in these solutions are related to the vertical
depth and convective organization of Otis in the short term, which
affects its forward speed. Since it appears that the ECMWF model
has the best handle on the short term convective trends, the NHC
track forecast continues to favor that solution overall. This
prediction is a little to the left of the previous one, mostly based
on the initial position/motion.

Although Otis is expected to remain in a moderate wind shear
environment, abundant moisture and warm SSTs should support gradual
strengthening as long as Otis remains offshore. The NHC intensity
forecast is a little higher than the previous one, following the
IVCN and HCCA consensus aids. Rapid weakening is expected after
Otis moves inland due to the rugged terrain in southern and
southwestern Mexico.

Key Messages:

1. Heavy rains from Otis will begin to impact areas of southwest
Mexico early this week. This rainfall will produce flash and urban
flooding, along with mudslides in areas of higher terrain.

2. Tropical storm conditions are possible by Tuesday night along
portions of the southern coast of Mexico, where a Tropical Storm
Watch is in effect.


FORECAST POSITIONS AND MAX WINDS

INIT 23/1500Z 12.0N 97.5W 40 KT 45 MPH
12H 24/0000Z 12.6N 97.7W 45 KT 50 MPH
24H 24/1200Z 13.6N 98.0W 45 KT 50 MPH
36H 25/0000Z 14.6N 98.5W 50 KT 60 MPH
48H 25/1200Z 15.4N 99.0W 55 KT 65 MPH
60H 26/0000Z 16.2N 99.5W 55 KT 65 MPH
72H 26/1200Z 17.5N 100.5W 35 KT 40 MPH...INLAND
96H 27/1200Z...DISSIPATED

$$
Forecaster Cangialosi/Delgado

[Sciencerocks]