2019 EPAC season

[Shell Mound]

Threads for other basins having already started, surely the 2019 Eastern North Pacific season deserves its first look...

Currently, the indicators in the tropical Pacific indicate redevelopment of El Niño is probable later in 2019. The current evolution of ENSO, based on existing oceanic heat content (OHC) along the equator, is similar to that of 2014-15. In that case, a late-developing El Niño of modest intensity in the winter of 2014-15 preceded a nearly record-breaking "super" El Niño by the following winter of 2015-16. Given that the Pacific Meridional Mode (PMM) remains in a positive state, with above-average SSTs in the tropical Pacific to northward of the equator, the incoming, downwelling, convectively coupled Kelvin wave (CCKW) is likely to reinforce a strong westerly wind burst by late January or the initial weeks of February, which would further reinforce the existing +PMM and strengthen the warm pool at the subsurface along the equator.

Since the Atlantic Multi-decadal Oscillation (AMO) remains on the negative side, with a relatively cool Main Development Region (MDR) relative to the other global basins (with the tropical North Pacific being the warmest), the trend toward El Niño would couple with the Atlantic to reinforce positive convective feedback (upward motion) migrating eastward over the tropical Pacific, further strengthening westerly low-level wind anomalies. Furthermore, actual low-level winds, not anomalies, over the far western Pacific are quite strong, and are likely to grow even stronger as the CCKW moves into the basin. The ECMWF has been routinely underestimating the amplitude of the Madden-Julian Oscillation (MJO), even though the GFS has a bias in favour of amplification. This is another factor that favours a potentially strong second El Niño.

Given all these early signs, we are likely to see another extremely active EPAC season in 2019, likely comparable to 2018, 2015, and/or 2014. My early call would be for a top-five season in terms of overall numbers, including named storms, hurricanes, and major hurricanes, with long-tracking, basin-crossing threats to Hawaii and the CPAC likely to reemerge. 2018 set a remarkable record in terms of the ACE index, but 2019 could well match or even exceed it.

Happy New Year to S2K!

[NotSparta]

Threads for other basins having already started, surely the 2019 Eastern North Pacific season deserves its first look...

Currently, the indicators in the tropical Pacific indicate redevelopment of El Niño is probable later in 2019. The current evolution of ENSO, based on existing oceanic heat content (OHC) along the equator, is similar to that of 2014-15. In that case, a late-developing El Niño of modest intensity in the winter of 2014-15 preceded a nearly record-breaking "super" El Niño by the following winter of 2015-16. Given that the Pacific Meridional Mode (PMM) remains in a positive state, with above-average SSTs in the tropical Pacific to northward of the equator, the incoming, downwelling, convectively coupled Kelvin wave (CCKW) is likely to reinforce a strong westerly wind burst by late January or the initial weeks of February, which would further reinforce the existing +PMM and strengthen the warm pool at the subsurface along the equator.

Since the Atlantic Multi-decadal Oscillation (AMO) remains on the negative side, with a relatively cool Main Development Region (MDR) relative to the other global basins (with the tropical North Pacific being the warmest), the trend toward El Niño would couple with the Atlantic to reinforce positive convective feedback (upward motion) migrating eastward over the tropical Pacific, further strengthening westerly low-level wind anomalies. Furthermore, actual low-level winds, not anomalies, over the far western Pacific are quite strong, and are likely to grow even stronger as the CCKW moves into the basin. The ECMWF has been routinely underestimating the amplitude of the Madden-Julian Oscillation (MJO), even though the GFS has a bias in favour of amplification. This is another factor that favours a potentially strong second El Niño.

Given all these early signs, we are likely to see another extremely active EPAC season in 2019, likely comparable to 2018, 2015, and/or 2014. My early call would be for a top-five season in terms of overall numbers, including named storms, hurricanes, and major hurricanes, with long-tracking, basin-crossing threats to Hawaii and the CPAC likely to reemerge. 2018 set a remarkable record in terms of the ACE index, but 2019 could well match or even exceed it.

Happy New Year to S2K!

This may happen, but it relies on multiple assumptions. First, while the likelihood for El Niño is higher than climatology, it is not guaranteed, and a strong El Niño so soon after 2015-6 seems dubious. The PMM & PDO are much less +ve than 2014 at this point, which stacked the playing field in favor of a strong El Niño. So far, we are missing the strong, persistent -EPO (and +NAO, see paragraph after next) of 2014/5 & 2017/8 that fueled the record-setting +PMMs of the following MAMs.

There are indications of a WWB, but we need to know whether it continues and fuels a strong El Niño or just amplifies the current event.

This also assumes a -AMO configuration. The atmospheric conditions as of late are more that of a -NAO-dominated winter, which usually flips the AMO. While it can change, and could stay -ve, it's not wise to hang your hat on a -AMO quite yet esp given atmospheric conditions.

While I wouldn't rule it out, a lot would have to go right for another very hyperactive season there, not as easy as it was last yr or in 2014.

[Kingarabian]

The 2018 EPAC hurricane season was eye opening for me as it was the first time I truly felt threatened by a hurricane. It wasn't CPAC homebrews that threatened Hawaii, it was the beasts that the EPAC was spewing out. Thankfully the SW shear decapitated Lane in time and forced the system west and away from Oahu. But the fact of the matter is that in the past 5 years, hurricanes threatening Hawaii have become the norm.

If we have another El Nino this year, it'll likely increase the prospects of 2019 being a hyperactive season. But even if ENSO is warm neutral, there is also a great chance of seeing at least above average hurricane activity as we've seen in the past 4-5 years it doesn't take much to get the EPAC going.

Indicators for EPAC activity other than ENSO such as the PDO and PMM remain neutral or warm.

[Chris90]

It's obviously still very early, but I'm feeling like we're going to get another above average season in the EPAC this year. I don't think we're going to match last year in terms of ACE or storm count, but I still think it'll be above average. Early guess is that the sweet spot will migrate a little further east than last year too. In 2018 right around 125-135W was really favorable for storms, allowing storms to gather steam before crossing into the CPAC. This year I think it might be a little more focused somewhere between 100-120W.
It's going to be interesting to see how things evolve over the next few months.

[Ntxw]

The 2014-2018 period showed that it doesn't matter if there is El Nino or La Nina (though those events do play a role in enhancing or downplaying) the current stretch we are in is favorable for the EPAC. Kind of like what happened in the 80s and early 90s. Even if you low ball a season it would likely be near normal at the worst. Until something drastic reverses it like a Super La NIna flipping to a strong -PDO, then I don't see why you'd go any less.

[cycloneye]

Surprise,surprise. Look what we have: It would be a first in January on this basin if it develops.

Special Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1215 PM PST Thu Jan 3 2019

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

A large area of disturbed weather associated with a broad area of
low pressure has formed about 1300 miles southwest of the southern
tip of the Baja California peninsula. The low is forecast to move
slowly northward over the next few days and could acquire some
tropical or subtropical characteristics during that time.
Environmental conditions are expected to become unfavorable for
further development by early next week. Regardless of tropical or
subtropical cyclone development, the low will likely produce
gale-force winds over the weekend. Additional information on this
system can be found in High Seas Forecasts issued by the National
Weather Service. The next Special Tropical Weather Outlook on this
system will be issued by 11 AM PST Friday, or earlier, if necessary.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 5 days...medium...50 percent.

[Kingarabian]

Both the 12Z GFS and Euro spin it up into a TS.

 https://twitter.com/MJVentrice/status/1080924830898311170

[CrazyC83]

That would be historic, right? There's never been a January storm in the EPAC? (I know there have been several in the CPAC)

[Yellow Evan]

It's obviously still very early, but I'm feeling like we're going to get another above average season in the EPAC this year. I don't think we're going to match last year in terms of ACE or storm count, but I still think it'll be above average. Early guess is that the sweet spot will migrate a little further east than last year too. In 2018 right around 125-135W was really favorable for storms, allowing storms to gather steam before crossing into the CPAC. This year I think it might be a little more focused somewhere between 100-120W.
It's going to be interesting to see how things evolve over the next few months.

Considering the expected El Nino pattern, I wouldn't count on it. Usually in cold PDO or La Nina seasons, you see the activity migrate eastward. If anything, I'd expect the sweet spot to move westward.

[Yellow Evan]

I don't have too much to say regarding developmental chances to be honest; it's not like we have much precedent to go by, though I've seen GFS and ECMWF show phantoms in the off-season in the past (I remember one in January 2015).

[cycloneye]

Winona in 1989 formed on January in CPAC.

[syryquil]

The earliest pacific hurricane to form (West of 180) was Pali in Jan 7, though this is unheard of for the epac.

[Kingarabian]

I would be skeptical about this developing but there is an active MJO coming through and the Euro/GFS runs continue to bring in the time frame closer.

EPS has a nearly 100% chance of a TD developing out of this and a 70% chance for this to become a TS in the next 48 hours.

[WAcyclone]

The 00z EPS significantly reduces the chances of TS development compared to yesterdays 12z run:

[Yellow Evan]

I'm not sure how much I trust the EPS given it's unique situation in general.

[cycloneye]

Window is closing for any development.

Special Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1040 AM PST Fri Jan 4 2019

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

Shower activity associated with a broad low pressure system centered
about 1200 miles southwest of the southern tip of the Baja
California peninsula has become a little better organized since
yesterday. Some slight additional tropical or subtropical
development is possible overnight and early Saturday while the low
drifts slowly northward, but environmental conditions are expected
to become unfavorable for further development by Saturday afternoon.
Regardless of tropical or subtropical cyclone development, winds
near gale-force associated with the low are possible over the
weekend. Additional information on this system can be found in High
Seas Forecasts issued by the National Weather Service. The next
Special Tropical Weather Outlook on this system will be issued by 11
AM PST Saturday, or earlier, if necessary.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 5 days...low...30 percent.

&&

High Seas Forecasts are issued by the National Weather Service
under AWIPS header NFDHSFEPI, WMO header FZPN02 KWBC, and are
available on the web at
https://ocean.weather.gov/shtml/NFDHSFEPI.shtml.

$$
Forecaster Zelinsky

[TorSkk]

Development not anticipated anymore

Special Tropical Weather Outlook
NWS National Hurricane Center Miami FL
740 AM PST Sat Jan 5 2019

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

Shower activity associated with a broad low pressure system centered
about 1100 miles west-southwest of the southern tip of the Baja
California peninsula has become less organized since yesterday.
Environmental conditions have become unfavorable and tropical or
subtropical cyclone development is not anticipated. Additional
information on this system can be found in High Seas Forecasts
issued by the National Weather Service. This is the last Special
Tropical Weather Outlook that will be issued on this system.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...near 0 percent.

Routine issuance of the Tropical Weather Outlook will resume on May
15, 2019. During the off-season, Special Tropical Weather Outlooks
will be issued as conditions warrant.

&&

High Seas Forecasts are issued by the National Weather Service
under AWIPS header NFDHSFEPI, WMO header FZPN02 KWBC, and are
available on the web at
https://ocean.weather.gov/shtml/NFDHSFEPI.shtml.

$$
Forecaster Zelinsky

[DioBrando]

good game, was the best tropical system of the year

lmao

[Kingarabian]

I thought it could do it! Oh well. Theres a reason why it hasn't happened in the modern era (or ever?)

[Shell Mound]

If the upcoming WWB fully materialises and expedites the development of a (potentially very strong) El Niño, then I fully expect a hyperactive 2019 EPAC hurricane season to unfold, likely rivalling the most active seasons on record, in terms of overall activity and especially seasonal ACE indices. The +PMM, although considerably weaker than in recent years, is still present, and the PDO is slowly but surely shifting toward a positive state. The only factor that might hinder activity is a warmer-than-average MDR (possible +AMO) in the Atlantic. Even so, I would still anticipate a top-five season, with more long-tracking threats to Hawaii, although activity is likely to shift farther east vs. 2018.