2021 EPAC Season

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 PM PDT Sat Sep 4 2021

For the eastern North Pacific...east of 140 degrees west longitude:

1. An area of low pressure is forecast to develop in a day or two off
the southwestern coast of Mexico. Environmental conditions are
expected to be conducive for gradual development thereafter, and the
system is likely to become a tropical depression around the middle
of next week while it moves west-northwestward or northwestward
just offshore the southwestern coast of Mexico.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...high...70 percent.

2. Another area of low pressure is forecast to form in a couple of days
well to the southwest of the southern tip of the Baja California
peninsula. Some slow development is possible while the system
remains nearly stationary out over the open eastern Pacific Ocean.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...20 percent.

Forecaster Stewart

[Yellow Evan]

I guess the base state is favorable enough where a weak CCKW could at least spawn something. I’m more bullish on this than I was yesterday.

[Yellow Evan]

000
ABPZ20 KNHC 050511
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 PM PDT Sat Sep 4 2021

For the eastern North Pacific...east of 140 degrees west longitude:

An area of low pressure is expected to form by Monday a few hundred
miles offshore the southwestern coast of Mexico. Environmental
conditions are forecast to be conducive for gradual development of
this system, and a tropical depression is likely to form by midweek
while it moves west-northwestward or northwestward at 5 to 10 mph
just offshore the southwestern coast of Mexico.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...high...70 percent.

Another area of low pressure is forecast to form early this week
well to the southwest of the southern tip of the Baja California
peninsula. Some slow development is possible thereafter while the
system meanders over the open eastern Pacific Ocean.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...30 percent.

$$
Forecaster Reinhart

[Kingarabian]

Yeah we'll probably see two named systems over the next 10 days. However they both look weak on the Euro.

[Yellow Evan]

468
ABPZ20 KNHC 051747
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 AM PDT Sun Sep 5 2021

For the eastern North Pacific...east of 140 degrees west longitude:

A broad area of low pressure is producing disorganized showers and
thunderstorms within a few hundred miles of the coast of
southwestern Mexico. Environmental conditions are conducive for
gradual development of this system, and a tropical depression is
likely to form by midweek while it moves west-northwestward or
northwestward at 5 to 10 mph just offshore of the coast of Mexico.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 5 days...high...80 percent.

Another area of low pressure is forecast to form in a few days
well to the southwest of the southern tip of the Baja California
peninsula. Some slow development is possible thereafter while the
system meanders over the open eastern Pacific Ocean.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...30 percent.

$$
Forecaster Latto

[Zonacane]

18z GFS trying again with Arizona:
https://i.imgur.com/aa9oqfu.gif

MOAR. RAIN

[Yellow Evan]

12z GFS bringing a tropical storm into Guerrero while 12z ECMWF brings a hurricane into Nayarit next week.

[Yellow Evan]

1. An area of low pressure is expected to form over the weekend a
couple of hundred miles south of the southern coast of Mexico.
Conditions appear favorable for some development of this system
early next week while it moves west-northwestward near or just
offshore of the coast of southern and southwestern Mexico.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...20 percent.

[Yellow Evan]

0z ECMWF into Sinaloa.

[Yellow Evan]

 https://twitter.com/dmorris9661/status/1435546097074720770




Posting this because it shows the 45 day EPS control. General anticipation of quiet September and active October from past runs, though the first uptick is likely coming around September 22.

[Yellow Evan]

18z GFS into Guerrero.

[Kingarabian]

EPS is 50/50 on seeing another named system over the next 5 days.

If that does occur, would take us to 16 NS. It's looking likely we'll see 20 NS by the time the season is over.

[Yellow Evan]

EPS is 50/50 on seeing another named system over the next 5 days.

If that does occur, would take us to 16 NS. It's looking likely we'll see 20 NS by the time the season is over.

GFS is still insistent on a Guerrero landfall tropical storm on Monday. 12z op ECMWF backed off, although it hasn’t been preforming well lately. With a small CCKW incoming, it’ll probably happen.

Next real window is going to be after September 20 despite the La Niña base state becoming established. Mexico needs to really watch out given the pattern this season and well the fact that October is historically the most dangerous month in terms of land impacts. Although this isn’t anywhere near as likely compared to an El Niño, a strong CCKW/MJO could help fuel a major hurricane that could recurve.

[Yellow Evan]

Disorganized showers and thunderstorms near the Pacific coast of
Central America and the adjacent waters are associated with the
southern portion of a tropical wave. A broad area of low pressure
is expected to form along this wave south of the southern coast of
Mexico during the next day or two, and the low could then develop
further into a tropical depression late this weekend or early next
week while it moves west-northwestward or northwestward near the
southern and southwestern coasts of Mexico.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 5 days...medium...60 percent.

[Extratropical94]

I haven‘t found a 2021 CPAC thread and I didn‘t want to create one just for this, so I‘ll just post it here:

The CPHC issued a Special Tropical Weather Outlook just to tell us that nothing is happening in the CPAC

Special Tropical Weather Outlook
NWS Central Pacific Hurricane Center Honolulu HI
735 PM HST Thu Sep 9 2021

For the central North Pacific...between 140W and 180W:

No tropical cyclones are expected during the next 5 days.

[Yellow Evan]

Disorganized showers and thunderstorms located within a couple of
hundred miles of the coasts of Guatemala and southern Mexico are
associated with the southern portion of an approaching tropical
wave. A broad area of low pressure is expected to form along this
wave to the south of the southern coast of Mexico during the next
day or so. Thereafter, environmental conditions could support some
development of this system, and a tropical depression could form
late this weekend or early next week while it moves generally
northwestward near the southern and southwestern coasts of Mexico.
Regardless of development, this system will likely produce heavy
rains across portions of Central America and southern Mexico during
the next few days.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 5 days...medium...60 percent.

[Kingarabian]

I haven‘t found a 2021 CPAC thread and I didn‘t want to create one just for this, so I‘ll just post it here:

The CPHC issued a Special Tropical Weather Outlook just to tell us that nothing is happening in the CPAC

Special Tropical Weather Outlook
NWS Central Pacific Hurricane Center Honolulu HI
735 PM HST Thu Sep 9 2021

For the central North Pacific...between 140W and 180W:

No tropical cyclones are expected during the next 5 days.

Lmao

[Yellow Evan]

GFS and ECMWF no longer close off a center for the Guerrero system.

[Kingarabian]

GFS and ECMWF no longer close off a center for the Guerrero system.

Not enough time with that steering.

[Yellow Evan]

A broad area of low pressure appears to be forming a couple of
hundred miles south-southwest of the Gulf of Tehuantepec. This
system is producing a large area of disorganized showers and
thunderstorms extending from the coast of Mexico to several hundred
miles offshore. Gradual development of this system is possible if
it remains over water, and a tropical depression could form during
the next couple of days while moving west-northwestward very near
the southern and southwestern coasts of Mexico. Regardless of
development, this system will likely produce heavy rains across
portions of Central America and southern Mexico during the next few
days.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 5 days...medium...60 percent.