2020 EPAC Season

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Mon May 25 2020

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

1. A broad area of low pressure is expected to form later this week a
few hundred miles south of the coasts of southern Mexico, Guatemala,
and El Salvador. Conditions appear favorable for some development
of this system while it moves little or drifts northward through
the end of the week.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...40 percent.

Forecaster Stewart

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 AM PDT Mon May 25 2020

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

1. A broad area of low pressure is expected to form later this week a
few hundred miles south of the coasts of southern Mexico, Guatemala,
and El Salvador. Conditions appear favorable for some development
of this system while it moves little or drifts northward through
the end of the week.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...50 percent.

Forecaster Stewart

[cycloneye]

 https://twitter.com/AndyHazelton/status/1265043043406811138

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 PM PDT Mon May 25 2020

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

1. A broad area of low pressure is expected to form in a few days
south of the coasts of southern Mexico, Guatemala, and El Salvador.
Environmental conditions appear conducive for gradual development
of this system, and a tropical depression could form late this week
or this weekend while it moves little or drifts northward.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...60 percent.

Forecaster Cangialosi

[Kingarabian]

12z Euro would be a best case scenario for CA. The TC it forms, gets bounced SW away from CA and then likely heads out to sea. Shows a less robust CAG. GFS solution shows a TC from the CAG and going into CA. It keeps the CAG active and stagnant which will probably mean a great risk of flooding.

[NDG]

Ridging building across the central US will play a big roll, if the Euro is correct in building a strong ridge across the south central US & lower MS river valley a track westward south of C.A. and MX will happen but if ridging is focused further north across the Great Lakes like the GEFS has it would live room for it to move north towards C.A. and possibly towards the western Caribbean/southern GOM.

[Yellow Evan]

Been out of the loop for a couple days...

000
ABPZ20 KNHC 261116
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Tue May 26 2020

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

A broad area of low pressure is expected to form in a few days
south of the coasts of southern Mexico, Guatemala, and El Salvador.
Environmental conditions appear conducive for gradual development
of this system, and a tropical depression could form late this week
or over the weekend while it moves little or drifts northward.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...60 percent.

$$
Forecaster Zelinsky

[cycloneye]

Up to 70%

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 AM PDT Tue May 26 2020

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

A broad area of low pressure is expected to form in a few days
south of the coasts of southern Mexico, Guatemala, and El Salvador.
Environmental conditions appear conducive for gradual development
of this system, and a tropical depression is likely to form late
this week or over the weekend while it moves little or drifts
northward.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...high...70 percent.

$$
Forecaster Stewart

[Kingarabian]

There should be another yellow circle near 120w. Weak development expected but there's very good agreement between the Euro and the GFS.

[GCANE]

I hope I am following the rules here by creating this thread.

More models are now jumping on a spinup around Bay of Tehuantepec with a move into the BOC and possible strenghtening in the GOM.

Crossover would be over relatively flat terrain making this plausible.

NHC currently has a 70% chance for development within 5 days.

Stay tuned.

[GCANE]

Great looking anti-cyclone over this area in the EPAC

[GCANE]

Sparks are flying.
Multiple high-helicity towers firing off.

[GCANE]

[SoupBone]

Seems like more people would be talking about this.

[toad strangler]

Seems like more people would be talking about this.

Not many have faith in the possibility.

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 AM PDT Wed May 27 2020

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

1. A large area of disorganized showers and thunderstorms located a
few hundred miles south of the coasts of southern Mexico,
Guatemala, and El Salvador are associated with a trough of low
pressure. Environmental conditions appear conducive for gradual
development of this system, and a tropical depression is likely to
form late this week or over the weekend while it drifts generally
northward.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 5 days...high...80 percent.

Forecaster Latto

[northjaxpro]

I am monitoring this with keen interest. It is not very often a possibility of a basin crossover system could occur. I think it has a decent shot of doing this within the next week. The season already has offered 2 cyclones before June 1.

I am watching this!

[TheStormExpert]

I really wouldn’t put too much stock into the GFS beyond 5 days as it seems to be all over the place with when and where tropical cyclone formation occurs with the CAG. Consensus though seems to be high though that something for sure will at least come from this whether it’s on the Atlantic or East Pacific side or both is yet to be known.

[TheAustinMan]

There's a lot of moving parts to this one, to say the least. 2020 certainly won't be making it a clear-cut forecast, and we'll still probably be as confused as ever even when the Central American Gyre does form (or maybe it simply doesn't). The action begins in the Eastern Pacific where SSTs are toasting at 30C and upper-level winds should be on the lighter side. It's an active scene out there this afternoon with thunderstorms galore, aided perhaps by a tropical wave that's currently analyzed over the western Caribbean and Honduras (the same one may have supported Bertha's genesis).

The EPAC disturbance is quite broad right now, so it'll take some time to develop. The model guidance has a broad low becoming better established on Friday south of El Salvador.

After that... well, calling it a "mess" might be putting it lightly. CAGs are broad; sometimes they turn into TCs themselves (see the 06z GFS), sometimes they might spawn mesolows that may individually become TCs (see the 12z GFS), sometimes the gyre splits into several components that could potentially evolve into TCs (see the 12z GEM), and sometimes they fail to really get anything started (see the 00z ECMWF). Oftentimes the bundles of vorticity that rotate around the gyre intermittently interfere with each other, creating an aggravating soup of maybe-TCs and TC-wannabes and conditions ripe for hair-pulling from forecasters, all the while producing flooding rainfall over Central America.

A crossover storm? One storm in the EPAC and one in the ATL? One or more storms in the EPAC and none in the ATL? No storms at all? All options are still on the table with a decent shot at verifying.

I talked about some of this in an earlier post, and the descriptions there are applicable here. Given how much depends on where/when/if this CAG sets up, I'd suggest continuing to use the ensemble guidance (EPS, GEFS, GEPS, etc.) as a starting point even as the event moves into the shorter range where deterministic guidance is often used.

I'll be taking this one step at a time. The first step is monitoring how possible-Amanda evolves in the eastern Pacific—how much it strengthens and where it tracks. Perhaps it might saunter westward, taking the vorticity from Central America along with it and dragging it to sea, or perhaps it might swing into Central America and add a whole bunch of vorticity into the Atlantic side of the isthmus. As for now, the NHC has this tagged as having an 80% of developing within 5 days. That will only be the start of this whole atmospheric jumble.

[CyclonicFury]

Significant shift north with the 12z ECMWF, it now tries to put a weak low in the extreme southwestern BoC.