2021 EPAC Season

[Yellow Evan]

 https://twitter.com/philklotzbach/status/1445847301331685377

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 PM PDT Wed Oct 6 2021

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

1. An area of low pressure is forecast to form off the coast of Central
America and southern Mexico in a day or two. Environmental
conditions are expected to be conducive for development thereafter,
and a tropical depression could form over the weekend or early next
week while the system moves westward to west-northwestward.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...60 percent.

Forecaster Cangialosi

[Yellow Evan]

12z ECMWF still moves this ultra slowly because ridge is stronger and has this getting blocked because it can only feel the weakness so much. Shear also apparently increases.



12z ECMWF has this getting picked up by a positively titled trough and heading NW.



Despite this, the EPS continues to shift towards recurvature, although they agree on significant weakening once it happens.

[Yellow Evan]

18z GFS has landfall near the Jalisco/Colima border.

[Ubuntwo]

Tropical wave in the Western Caribbean, which I believe is the trigger for the modeled EPAC system. Same wave the GFS spun up in the Atlantic for several runs.

Wave axis already extending into the Pacific.

[Yellow Evan]

https://psl.noaa.gov/data/timeseries/mo ... mmsst.data

2021 -1.090 -2.640 -3.690 -1.220 -2.110 -2.600 -1.380 -0.340 0.550 -99.000 -99.000 -99.000

September PMM has come out and is positive for the first time since late 2020. Probably a good sign for next year.

[Yellow Evan]

https://psl.noaa.gov/cgi-bin/data/timeseries/timeseries.pl?ntype=1&var=SST&level=2000&lat1=10&lat2=25&lon1=230&lon2=265&iseas=0&mon1=0&mon2=10&iarea=0&typeout=1&Submit=Create+Timeseries

2000 22.482 22.741 23.053 23.854 24.559 24.701 25.531 26.116 25.998 25.389 24.406 23.429
2001 22.855 22.918 22.768 23.582 24.451 24.789 25.696 26.400 26.168 25.524 24.890 23.805
2002 22.828 22.472 23.256 24.209 24.758 24.898 25.458 26.066 25.940 25.767 24.556 23.707
2003 23.113 23.449 23.510 24.128 25.054 25.070 25.457 26.356 26.368 25.755 25.208 23.583
2004 22.922 22.618 23.432 23.974 24.917 25.236 25.788 26.442 26.249 26.034 24.864 23.549
2005 23.363 23.266 23.406 24.121 24.765 25.362 25.413 25.989 26.183 25.463 24.553 23.583
2006 22.965 22.868 23.325 24.335 24.661 24.937 25.881 26.372 26.324 26.061 24.915 23.613
2007 22.799 22.774 23.338 23.937 24.533 25.115 25.712 26.047 26.138 25.417 24.499 23.487
2008 22.423 22.435 22.756 23.663 24.496 24.820 25.105 26.032 25.784 25.493 24.687 23.696
2009 23.173 23.256 23.566 24.160 24.759 25.558 26.102 26.735 26.758 26.406 24.951 24.001
2010 23.125 22.875 23.101 23.958 24.666 24.938 25.163 25.690 25.606 24.951 23.976 22.707
2011 22.118 22.064 22.848 23.761 24.471 24.667 24.993 25.656 25.930 25.294 24.273 23.083
2012 22.622 22.687 23.008 23.792 24.602 24.710 25.182 25.781 26.117 25.972 24.981 24.202
2013 22.968 23.083 23.136 24.002 24.960 25.198 25.775 26.308 26.096 25.695 24.727 23.730
2014 22.960 23.397 23.989 24.531 25.226 25.828 26.403 26.953 26.477 26.362 25.208 24.403
2015 23.775 23.811 24.167 25.251 25.677 25.988 26.726 27.321 27.385 27.247 26.263 24.934
2016 23.804 23.654 24.204 24.767 25.385 25.761 26.339 26.773 26.648 26.366 25.780 24.365
2017 23.677 23.522 24.058 24.522 25.060 25.245 26.008 26.641 26.422 26.074 25.657 24.603
2018 23.660 23.841 24.104 24.779 25.373 25.581 26.242 26.740 26.790 26.073 25.073 24.103
2019 23.587 23.760 24.137 24.574 25.167 25.452 25.886 26.813 26.682 26.033 25.209 24.412
2020 23.530 23.292 23.990 24.462 25.173 25.527 26.050 26.501 26.350 26.291 25.437 23.864
2021 22.930 22.842 23.173 24.042 24.674 25.153 -999.999 -999.999 -999.999 -999.999 -999.999 -999.999
-999.999

June SST's coldest since 2013 once again.

2021 22.930 22.842 23.173 24.042 24.674 25.153 25.570 26.172 26.192 -999.999 -999.999 -999.999
-999.999

Trend has continued, September coldest since 2013.

[ElectricStorm]

0z GFS much weaker with the 0/60. Peaks at 971mb compared to the 940s-950s on previous runs. That would still be destructive for Mexico but could be some good news if that continues into future runs.

[Yellow Evan]

000
ABPZ20 KNHC 070502
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 PM PDT Wed Oct 6 2021

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

A tropical wave is producing a large area of disorganized showers
and thunderstorms over the southwestern Caribbean Sea and portions
of Central America. This system is expected to move westward and
emerge over the eastern Pacific Ocean in a day or so. Environmental
conditions are forecast to be conducive for gradual development,
and a tropical depression is likely to form over the weekend or
early next week while the system moves westward to
west-northwestward.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...high...70 percent.

$$
Forecaster Cangialosi

[Yellow Evan]

0z GFS much weaker with the 0/60. Peaks at 971mb compared to the 940s-950s on previous runs. That would still be destructive for Mexico but could be some good news if that continues into future runs.

This is a good example of meteorology not modelology.

GFS in the past was developing this too fast due to overdoing the vorticity as the wave interacts with Central and South America. A correction was due. The upper level pattern is as favorable as before.

[Teban54]

0z GFS much weaker with the 0/60. Peaks at 971mb compared to the 940s-950s on previous runs. That would still be destructive for Mexico but could be some good news if that continues into future runs.

0z Euro also weaker, peak at 987 mb (previous run had 977), but actually makes landfall this time

[Yellow Evan]

0z ECMWF continues to cave to the GFS setup wise, as trough is now strong enough to recurve it despite the stronger ridge. Now shows an actual landfall for the first time, although it has marked weakening before landfall, likely due to interaction with the STJ. Conditions look excellent in both major models prior to that.

[aspen]

So much for the “trending weaker” posts earlier in the day. 12z GFS has 944mb just before landfall in 156hrs.

Pamela is currently the only non-slop system on any model within the next 8-10 days. Everything in the WPac is too broad, the Atlantic won’t be favored for another week, and while there is a possibility of some NIO action, it hasn’t been as close or consistent as Pamela.

[Iceresistance]

So much for the “trending weaker” posts earlier in the day. 12z GFS has 944mb just before landfall in 156hrs.

Pamela is currently the only non-slop system on any model within the next 8-10 days. Everything in the WPac is too broad, the Atlantic won’t be favored for another week, and while there is a possibility of some NIO action, it hasn’t been as close or consistent as Pamela.

Could Pamela be like Patricia since it gets powerful before landfall & weakens rapidly at landfall?

[Shell Mound]

So much for the “trending weaker” posts earlier in the day. 12z GFS has 944mb just before landfall in 156hrs.

Pamela is currently the only non-slop system on any model within the next 8-10 days. Everything in the WPac is too broad, the Atlantic won’t be favored for another week, and while there is a possibility of some NIO action, it hasn’t been as close or consistent as Pamela.

Could Pamela be like Patricia since it gets powerful before landfall & weakens rapidly at landfall?

While I wouldn’t expect a repeat of Patricia, the upper-air environment could certainly favour a compact, powerful hurricane—perhaps even a Cat-5. If so, then future “Pamela” would join 2002’s Kenna, 2009’s Rick, 2015’s Patricia, 2018’s Willa as the most recent such instances in the EPAC during the month of October. This would be very unusual for -ENSO, so it should be monitored; the other cases that I mentioned occurred during +ENSO. In terms of intensity, at this point I think that something akin to Willa’s is the prospective “ceiling.” Bear in mind that Patricia made landfall with winds of 130 kt and is the strongest TC to strike Mexico’s Pacific coastline on record. (The 1959 Mexico hurricane was originally designated as a Cat-5 at landfall but was downgraded to a 120-kt Cat-4.) “Pamela” almost sounds like the Atlantic’s “Paloma,” and it could certainly attain a similar intensity: on the order of 125–140 kt.

[Yellow Evan]

12z GFS slams this into Nayarit, is stronger due to more time over water.

[Yellow Evan]

000
ABPZ20 KNHC 071730
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 AM PDT Thu Oct 7 2021

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

A tropical wave continues to produce disorganized cloudiness and
thunderstorms over portions of Central America and the adjacent
eastern Pacific waters. This system is expected to move westward
and emerge over the eastern Pacific Ocean later today or tonight.
Environmental conditions are forecast to be conducive for
development over the next several days, and a tropical depression
is likely to form over the weekend or early next week while the
system moves westward to west-northwestward.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 5 days...high...70 percent.

$$
Forecaster Brown

[Yellow Evan]

Initialization looks screwed up on the 12z ECMWF - seems to have a center forming way to the west of the GFS and even past ECMWF runs.

[aspen]

So far the ceiling looks pretty high for Pamela. The GFS has consistently shown a favorable 200mb-level environment and RI on nearly all of its runs, and SSTs of 30-30.5C are capable of supporting a sub-900mb storm. However, this is a -ENSO year, and the GFS has hyped up plenty of EPac systems this year that fell way short of expectations.

Pamela will only become anything significant if:
—It organizes at the pace the GFS has shown it to
—The UL environment is indeed favorable like the GFS says it’ll be
—No pesky mid-level shear pops up
—The precursor disturbance isn’t too broad that it slows development and/or results in a large core that’s hard to tighten up
—The presence of a -ENSO somehow doesn’t impact it

If Pamela somehow overcomes or avoids all of those hurdles, watch out Mexico.

[ElectricStorm]

GFS peaks it at 970mb. Which means the next run will be back in the 940s

Back and forth back and forth