2020 EPAC Season

[Yellow Evan]

0z ECMWF caves to the GFS. Now at least showing northerly motion with regards to 0/60 while the GFS bring it into Baja.

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Mon Jun 22 2020

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

A broad area of low pressure located more than 1000 miles southwest
of the southern tip of the Baja California peninsula continues to
produce disorganized showers and thunderstorms. Environmental
conditions are expected to be conducive for gradual development,
and this system could become a tropical depression during the next
few days while it moves generally westward.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...medium...60 percent.


Another area of disturbed weather is forecast to form south of the
coast of Mexico in a couple of days. Development is expected to
occur after that time, and the system could become a tropical
depression by late this week as the disturbance moves
west-northwestward parallel to the coast of Mexico.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...60 percent.

$$
Forecaster Brown

[aspen]

Both the GFS and Euro have been calling for a TC to form around 130W on Tuesday/Wednesday, and this continues in both of their latest runs. The GFS also tries to spin up a weaker TC around 120W on Wednesday, and both models form another system closer to Mexico by 120-144 hrs out.

[aspen]

12z GFS develops the 40/60 and 50/60 disturbances in only 48 hours. The 0/60 disturbance follows around 84 hours out, and a fourth unmarked disturbance coalesces around 102 hours. All of them become moderate tropical storms.

[Yellow Evan]

12z GFS showing 5 systems in 12 days and no longer has an interaction between the two eastern systems (though both take parallel tracks).

[cycloneye]

There is a new one.

1. An area of low pressure located more than 1000 miles southwest
of the southern tip of the Baja California peninsula continues to
produce disorganized showers and thunderstorms. Environmental
conditions are expected to be conducive for gradual development,
and this system could become a tropical depression during the next
few days while it moves generally westward.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...medium...60 percent.

3. An area of disturbed weather is forecast to form south of the
coast of Mexico in a couple of days. Development is expected to
occur after that time, and the system could become a tropical
depression by late this week as the disturbance moves
west-northwestward parallel to the coast of Mexico.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...60 percent.

4. Another area of disturbed weather is forecast to form south of the
Gulf of Tehuantepec by late this week. Environmental conditions are
expected to be conducive for gradual development of this system
over the weekend as it moves west-northwestward parallel to the
coast of Mexico.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...20 percent.

[aspen]

There is a new one.

1. An area of low pressure located more than 1000 miles southwest
of the southern tip of the Baja California peninsula continues to
produce disorganized showers and thunderstorms. Environmental
conditions are expected to be conducive for gradual development,
and this system could become a tropical depression during the next
few days while it moves generally westward.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...medium...60 percent.

3. An area of disturbed weather is forecast to form south of the
coast of Mexico in a couple of days. Development is expected to
occur after that time, and the system could become a tropical
depression by late this week as the disturbance moves
west-northwestward parallel to the coast of Mexico.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...60 percent.

4. Another area of disturbed weather is forecast to form south of the
Gulf of Tehuantepec by late this week. Environmental conditions are
expected to be conducive for gradual development of this system
over the weekend as it moves west-northwestward parallel to the
coast of Mexico.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...20 percent.

https://i.imgur.com/c78lViD.png

That’s a mark for every single TC the GFS shows developing in its latest runs.

[Yellow Evan]

12z ECMWF through day 6 is quite bearish.

[Kingarabian]

[url]https://twitter.com/webberweather/status/1274442209547489280[url]
[url]https://twitter.com/pppapin/status/1274453606494683136[url]
[url]https://twitter.com/gtabwx/status/1274462324120846337[url]
[url]https://twitter.com/antmasiello/status/1274349016231432192[url]
[url]https://twitter.com/WorldClimateSvc/status/1274440739322290179[url]
Kingarabian, is this a possible sign that the standing waves this year will favour the EPAC, regardless of the MJO’s state, given the fact that -VP is farther W than in typical Niña and upward motion is concentrated over the Indian Ocean instead of the MC? This could indicate a lingering +PMM influence and thus hamper the growth of La Niña while inducing some enhanced VWS over the Caribbean/western MDR, owing in part to enhanced CPAC/EPAC convection relative to “typical” Niña-like background states.

Even if the EPAC goes through a period in where we see big bursts of activity, it doesn't mean it will shut the Atlantic down. Especially in weak La Nina/cool neutral seasons. In the most recent weak La Nina seasons (2016, 2017), the EPAC had big bursts of activity only for the Atlantic to still perform exceptionally well.


We'll simply have to wait and see. We've seen some years where we saw active Atlantic hurricane seasons that had similar 200mb VP configurations. The key is July where in those seasons, the sinking branch shifted further into the EPAC.

Now the model forecasts I must admit are a bit iffy. The Euro seems to finally be pushing the sinking branch into the EPAC during mid July, but only for a brief amount of time before breaking it down. The CFS is really having a hard time kicking off a traditional rising air branch near the MC and sinking branch over the EPAC. Just have to wait and see. The ocean continues to move toward La Nina so the odds still favor similar 2005/2017 setups.

[cycloneye]

An area of low pressure located more than 1500 miles southwest
of the southern tip of the Baja California peninsula has become a
little better organized during the past day. Environmental
conditions appear conducive for gradual development and this system
could become a tropical depression during the next few days while
it moves slowly westward.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 5 days...medium...60 percent.

An area of disturbed weather is forecast to form south of the coast
of Mexico in a day or two. Some development is expected after
that time, and the system could become a tropical depression by late
this week as the disturbance moves west-northwestward parallel to
the coast of Mexico.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...60 percent.

Another area of disturbed weather is forecast to form south of the
Gulf of Tehuantepec by late this week. Environmental conditions are
expected to be conducive for gradual development of this system
over the weekend as it moves west-northwestward parallel to the
coast of Mexico.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...20 percent.

[cycloneye]

3. Disorganized showers and thunderstorms located a few hundred miles
south-southwest of the Gulf of Tehuantepec are associated with a
tropical wave. Environmental conditions are expected to be
conducive for development, and the system is likely to become a
tropical depression in a few days while it moves west-northwestward
parallel to the coast of Mexico.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 5 days...high...80 percent.

4. Another area of disturbed weather is forecast to form south of the
Gulf of Tehuantepec by late this week. Environmental conditions are
expected to be conducive for gradual development of this system
over the weekend as it moves west-northwestward parallel to the
coast of Mexico.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...30 percent.

[aspen]

The GFS has become more aggressive with the 0/30 system because the track has changed. It was originally expected to move NW parallel to the Mexican Coast (think John ‘18), but now it’s calling for a turn to WNW that will keep it over warm SSTs for longer, so it now has a <975 mbar system around 180-200 hours out. It has also been decently aggressive with the 50/60 system, consistently forecasting a strong TS or minor hurricane in the 990-980 mbar range.

After 200 hours out, the GFS goes nuts with another Mexican system, and bombs it out to 937 mbar by 270 hours. Could be a ghost, or could be a signal of favorable conditions at the time.

[Extratropical94]

06Z GFS has a 930mb cane right behind the 0/30% system and another weak TS/TD after that. If all these were to develop into storms (including 92E), we'd have Genevieve by July 8th.

[aspen]

06Z GFS has a 930mb cane right behind the 0/30% system and another weak TS/TD after that. If all these were to develop into storms (including 92E), we'd have Genevieve by July 8th.

https://i.imgur.com/SJxMOsI.png

https://i.imgur.com/IETxEn8.png

Long-range Euro and CMC are also picking up on that fifth system forming, although it’s still very weak by the end of their 240 hour time window.

[aspen]

In the 12z GFS, Invests 93E and 92E both become strong TS/weak hurricanes, the 0/30 disturbance continues on its westward course, and the fifth signal crashes into Mexico and re-develops in the Gulf.

[cycloneye]

11 AM PDT:

Disorganized showers and thunderstorms located a few hundred miles
south-southwest of the Gulf of Tehuantepec are associated with a
tropical wave. Environmental conditions appear favorable for
development, and the system is likely to become a tropical
depression in a few days while it moves west-northwestward
parallel to the coast of Mexico.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...high...80 percent.

Another area of disturbed weather is forecast to form south of the
Gulf of Tehuantepec by late this week. Environmental conditions are
expected to be conducive for gradual development of this system
over the weekend as it moves west-northwestward parallel to the
coast of Mexico.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...30 percent.

[cycloneye]

Invest 94E is up

[aspen]

Nearly all of the major global models expect Invest 93E to be a developed TC by 48 hours, and it could be at least a moderate TS or possibly a minor hurricane.

Invest 92E probably won’t get any stronger than a weak TS, but the models that do show it have it developing within 48-72 hours.

Invest 94E also seems like it’ll be at least a moderate TS after it develops before day 3.

There’s a chance the 0/30 disturbance, expected to develop between 96-120 hours, could become a long-tracker that potentially reaches hurricane strength next week.

[aspen]

18z GFS has dropped 92E, but still develops 93E very soon and shows 94E and the 0/30 disturbance developing within the next 4-5 days.

[cycloneye]

Looks like the 0/30 will be the big one that may produce a good deal of ACE.