2021 EPAC Season

[Kingarabian]

12z Euro also weaker. We'll see if there's any EPS pullback.

[BYG Jacob]

Looks like this will be the last hurrah for the EPAC.

[Kingarabian]

Still very good EPS support for both systems. Guess the operational models are being erratic.

[Kingarabian]

18z GFS now has three separate systems off this robust MT.

[Kingarabian]

This 18z GFS run went pretty nuclear:




5-6 named systems in 16 days lol

[Kingarabian]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 PM PDT Sat Jul 10 2021

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

1. An area of low pressure is expected to develop south or southeast of
the Gulf of Tehuantepec in the next few days. Environmental
conditions are expected to support gradual development of this
system. A tropical depression could form during the middle portion
of next week while this system moves generally westward or
west-northwestward at 10 to 15 mph.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...60 percent.

2. Another area of low pressure is expected to form several hundred
miles southwest of the southern coast of Mexico by early next
week. Some slow development of this system is possible while
it moves westward or west-northwestward at 10 to 15 mph.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...20 percent.

Forecaster Papin/Blake

[Yellow Evan]

18z GFS randomly now favors the westward 0/20 system. No reason to not believe it's an outlier.

[Kingarabian]

00z UKMET doesn't develop the western system this run, only the eastern system.

00z CMC basically the same as the UKMET.

00z GFS isn't as crazy as the 18z run but still has 3-4 systems eventually developing.



00z Euro favoring the western system in the medium range more, but eventually develops the eastern system:

[Kingarabian]

The 0/20 system should be higher IMO.

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 PM PDT Sat Jul 10 2021

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

1. An area of low pressure is forecast to develop southeast or south
of the Gulf of Tehuantepec in the next few days and move generally
westward or west-northwestward at 10 to 15 mph, well offshore the
southern coast of Mexico. Environmental conditions are expected to
support gradual development of this system, and a tropical
depression could form during the middle portion of next week.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...high...70 percent.

2. Another area of low pressure is expected to form several hundred
miles southwest of the southern coast of Mexico by early next
week. Some slow development of this system is possible while
it moves westward or west-northwestward at 10 to 15 mph.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...20 percent.

Forecaster Stewart

[AlphaToOmega]

ZCZC MIATWOEP ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Sun Jul 11 2021

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

1. An area of low pressure is forecast to develop southeast or south
of the Gulf of Tehuantepec in the next few days and move generally
westward or west-northwestward at 10 to 15 mph, well offshore the
southern coast of Mexico. Environmental conditions are expected to
support gradual development of this system, and a tropical
depression is likely to form around mid-to-late week.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...high...70 percent.

2. Another area of low pressure is expected to form several hundred
miles southwest of the southern coast of Mexico within the next
few days. Gradual development of this system is possible while it
moves westward or west-northwestward at 10 to 15 mph.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...40 percent.

Forecaster Brown

[Yellow Evan]

6z GFS back to favoring the eastern 0/70 system though it likes both.

[Yellow Evan]

12z GFs through 84 hours. Develops the westward system by day 3.

[aspen]

Even though the NHC did bump up the western AOI’s odds to 0/40, it should probably be even higher because just about all of the models have this develop before the 0/70 system. However, it looks like the 0/40 AOI is too far west to become anything beyond a TS due to not having enough 28+C SSTs to work with. The 0/70 AOI might be the next opportunity for the EPac to produce a major thanks to its track taking it within the pool of 28-29C SSTs, although its 5-day odds shouldn’t be so high due to it most likely not coalescing until the end of the week.

[Yellow Evan]

12z GFS now makes the eastward system to 955 mbar.

[Yellow Evan]

12z CMC only has the eastward 0/70 system now.

[AlphaToOmega]

ZCZC MIATWOEP ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 AM PDT Sun Jul 11 2021

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

1. Disorganized showers and thunderstorms located several hundred miles
south of Acapulco, Mexico, are associated with a tropical wave.
Environmental conditions are forecast to be conducive for gradual
development, and a tropical depression could form well offshore the
southwest coast of Mexico around midweek as the disturbance moves
generally westward at 10 to 15 mph.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...50 percent.

2. An area of low pressure is forecast to develop southeast or south
of the Gulf of Tehuantepec around midweek and move generally
westward or west-northwestward at 10 to 15 mph, well offshore the
southern coast of Mexico. Environmental conditions are expected to
support the development of this system, and a tropical depression is
likely to form by late week.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...high...70 percent.

[Yellow Evan]

12z ECMWF still quite bearish.

[Kingarabian]

Pretty out there as this would at least be 14 days away and not likely due to this years setup: Most recent ECMWF runs show that the 0/70 system remains weak for an extended period, moving west (possibly WSW) until it reaches the 12N-14N/126W-129W area where it begins to develop.


Most recently, this is a spot where Hilda 2015, Hector 2018, Lane 2018, and Douglas 2020 were able to intensify while slowly lifting WNW then NW as they round the ridge. These systems all had recon so they were a Hawaii concern at one point. Of course this year's ENSO state is not on the level of 2015 and 2018 but there is some +ENSO conditions, similar to July 2020, as well as a similar SST configuration to 2020. This could be something for Hawaii to pay attention to in about 2 weeks.

[Nuno]

Pretty out there as this would at least be 14 days away and not likely due to this years setup: Most recent ECMWF runs show that the 0/70 system remains weak for an extended period, moving west (possibly WSW) until it reaches the 12N-14N/126W-129W area where it begins to develop.
https://i.imgur.com/0zWVpfe.gif

Most recently, this is a spot where Hilda 2015, Hector 2018, Lane 2018, and Douglas 2020 were able to intensify while slowly lifting WNW then NW as they round the ridge. These systems all had recon so they were a Hawaii concern at one point. Of course this year's ENSO state is not on the level of 2015 and 2018 but there is some +ENSO conditions, similar to July 2020, as well as a similar SST configuration to 2020. This could be something for Hawaii to pay attention to in about 2 weeks.

What impacts did you feel from Douglas if any?

[Kingarabian]

Pretty out there as this would at least be 14 days away and not likely due to this years setup: Most recent ECMWF runs show that the 0/70 system remains weak for an extended period, moving west (possibly WSW) until it reaches the 12N-14N/126W-129W area where it begins to develop.
https://i.imgur.com/0zWVpfe.gif

Most recently, this is a spot where Hilda 2015, Hector 2018, Lane 2018, and Douglas 2020 were able to intensify while slowly lifting WNW then NW as they round the ridge. These systems all had recon so they were a Hawaii concern at one point. Of course this year's ENSO state is not on the level of 2015 and 2018 but there is some +ENSO conditions, similar to July 2020, as well as a similar SST configuration to 2020. This could be something for Hawaii to pay attention to in about 2 weeks.

What impacts did you feel from Douglas if any?

Despite it being the closest system ever to ever pass Oahu, nothing really serious. Its strongest winds were in the NE quad, and fortunately the upper level SW' winds kept all those winds and rains well off shore.