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Happy April! April Showers bring May flowers, but here in the Nevada desert, there is no rain at this time of year. Flowers are blooming and the days are getting longer and longer! Winter has been record warmth this year here in Vegas, but will that carry over to the hurricane seaosn?

Intro

In 2013, an unusually powerful +NPO block was noted across the Gulf of Alaska. This spark, which not only triggered a very cold winter across the US that year, warmed the water since high pressure means warmer sea surface temperature. This is at least partially responsible for a +PDO flip that was noted in early 2014, and sparked the EPAC in 2014.

2014 recap

As you guys probably know and remember very well, the 2014 Pacific hurricane season was a banner and magical year for the basin. It started off strong with Hurricanes Amanda and Cristina and never looked back. Exceeding all expectations, activity was non-stop until November, and ended up with 22 named storms, a record-tying 16 hurricanes, and 9 major hurricanes (5 knots short of a record-tying 10, stupid Vance could never clear out an eye).

El Nino

Signs of an El Nino can be traced back to late 2013, when record sea surface temperatures developed off the coast of the Philippines due to the lack of el Nino events over the previous several years. Then, in November, the greatest tropical cyclone of all time, Typhoon Haiyan, struck the Philippines. This sparked a westerly wind burst, and the warm pool migrated westward. Despite some setbacks, an El Nino developed by fall 2014, also aided by an unusually warm sub-surface pool that rivaled the one prior to the 1997 super El Nino event. It peaked in December, before weakening in early 2015. However, this El Nino has been fairly stable since then, and has even deepened slightly.

Will we get a super El Nino?

As of March 2015, a new warm subsurface pool has developed below the surface along the equatorial Central Pacific, arguably stronger than the one noted prior to the 2014 season. Cyclone Pam, the greatest tropical cyclone to ever exist in March, sparked a massive westerly wind burst. The reason why a westerly wind burst is so important is because during the aforementioned westerly wind burst, the trade wind pattern is reversed from it's traditional easterlies, to westerlies. These winds transport the very warm waters near Asia west, and since the sea surface temperatures are warmer in the West Pacific than the Central Pacific (hence why more TC's form in the WPAC than the CPAC), the WPAC-born waters, when located in the CPAC, are warmer than normal.

Around the same time as Pam formed, an unusually powerful MJO pulse migrated across the Pacific. Since record keeping of the MJO began in 1974, the March 2015 MJO episode along the Pacific was the highest on record, surpassing. This also helps spawn WWB's, and has already had major effects. Nino region 1+2 has warmed dramatically, from -1.5C to 1.2C in a a matter of weeks. Furthermore, this could help reduced shear in the EPAC in a long run.

Regarding the future, models all agree on the El Nino continuing through 2015, although many models have a warm bias when it comes to ENSO. The March 2015 model plume average was +1.2C, a moderate El Nino. Currently daily estimates have the strength of this El Nino at +0.75C. Given the warm-subsurface pool and the decrease of ocean temperatures across the WPAC, which prevented a super El Nino last year, it would not surprise me if we got a strong or even super El Nino, though the latter is a bit far fetched.

PDO

Now, onto the Eastern Pacific forecast. We appear to be re-entering the active era. PDO first became positive in early 2014 for the first time in years. Since then, the PDO signal has onyl gotten stronger, and by June, it was near-record levels. After weakening slightly that fall, the PDO came back with a vengeance in early 2015, and has been at record levels for the past few months, with totals near +2.50. This is a strong indication that the +PDO era has returned, which was dominant from 1976-1998. During that time span, the Eastern Pacific was at its most active levels ever seen in history, and until 2014, included the 5 most active EPAC seasons in history. Until 2014, the post-1998 time frame was consisted of -PDO mostly, although around 2005, a secondary blip of +PDO was noted. As such, from the late 1990s until 2013, the EPAC seasons were largely inactive. Therefore, given that it is unlikely that the +PDO time frame is a blip, I'd say there is a good chance the active era has returned. Given the fact that records prior to 1988 in the EPAC are sketchy due to the EPHC's low bias, as well as the fact that PDO now is stronger than it was for the most part of the 1976-1998 era, this could mean the the EPAC could be even more active than it was during it's 1980's heyday. The PDO is one of the main reasons for the bullish forecast issued below.

Sea surface temperatures

You thought 2014 was warm? Well, 2015 is looking better. 2014 had the second warmest ocean temperatures in EPAC history (satellite era), only trialling 2009, and the three month JAS of 2014 exceeded that of 2009. Pre-sat era, only 1959 was warmer than 2014. 2015 is off to an even better start, however. The months of January, February, and March of 2015 are the warmest on record, satellite era or not.

Here is the chart of the data:

  • 1948 24.659 24.544 25.082 25.912 26.298 26.299 26.574 26.920 26.518 25.763 25.462 25.286
  • 1949 24.769 24.963 24.920 25.577 26.162 26.090 26.512 26.767 26.383 26.062 25.477 24.975
  • 1950 24.580 24.483 25.075 25.548 25.812 25.787 26.201 26.527 26.505 26.108 25.453 24.979
  • 1951 24.694 24.692 24.958 25.407 25.800 26.054 26.589 26.960 26.810 26.753 26.199 25.567
  • 1952 25.115 25.084 25.405 25.863 26.357 26.356 26.537 26.848 26.715 26.447 25.987 25.325
  • 1953 24.935 25.032 25.347 25.971 26.291 26.426 26.811 27.052 26.839 26.416 26.014 25.238
  • 1954 24.964 24.826 25.210 25.723 26.127 26.119 26.371 26.610 26.538 26.262 25.594 25.086
  • 1955 24.696 24.615 25.012 25.416 25.903 26.026 26.280 26.384 26.272 25.552 25.065 24.632
  • 1956 24.328 24.596 24.925 25.391 25.722 25.783 25.946 26.450 26.332 26.061 25.555 25.193
  • 1957 25.003 25.167 25.477 26.071 26.629 26.874 27.309 27.601 27.437 27.052 26.732 26.174
  • 1958 25.766 25.749 26.041 26.493 26.819 27.045 27.249 27.373 27.305 27.004 26.502 25.910
  • 1959 25.709 25.749 25.899 26.386 26.832 26.833 27.136 27.309 27.229 26.822 26.070 25.383
  • 1960 24.879 24.689 25.290 25.984 26.236 26.355 26.810 26.988 26.783 26.402 25.781 25.311
  • 1961 24.889 24.893 25.241 25.747 26.208 26.329 26.538 26.644 26.413 26.243 25.693 25.034
  • 1962 24.626 24.811 25.113 25.493 25.903 25.985 26.453 26.792 26.607 26.268 25.713 25.126
  • 1963 24.849 24.975 25.501 26.272 26.513 26.665 26.900 27.185 27.210 27.095 26.531 25.783
  • 1964 25.191 25.127 25.226 25.692 26.053 26.091 26.415 26.392 26.202 25.952 25.454 24.678
  • 1965 24.390 24.491 25.005 25.741 26.156 26.092 26.409 26.850 26.933 26.801 26.630 25.934
  • 1966 25.312 25.149 25.587 26.176 26.499 26.575 26.882 26.937 26.767 26.444 25.943 25.283
  • 1967 24.874 24.805 25.349 25.815 26.408 26.436 26.648 26.912 26.779 26.456 25.994 25.279
  • 1968 24.807 24.755 25.114 25.801 26.276 26.500 26.743 26.954 26.877 26.668 26.260 25.734
  • 1969 25.523 25.531 25.558 26.162 26.580 26.696 26.869 26.985 26.974 26.700 26.116 25.553
  • 1970 25.147 25.071 25.429 25.999 26.053 26.083 26.076 26.246 26.164 26.025 25.495 24.818
  • 1971 24.284 24.086 24.484 25.029 25.448 25.492 25.874 26.091 26.039 25.730 25.028 24.445
  • 1972 24.297 24.401 24.950 25.740 26.223 26.302 26.776 27.126 27.058 26.966 26.524 26.018
  • 1973 25.391 25.251 25.514 25.709 25.982 25.989 26.281 26.353 26.174 25.918 25.529 24.676
  • 1974 24.440 24.408 24.851 25.437 25.730 25.830 26.151 26.408 26.261 25.984 25.402 24.821
  • 1975 24.316 24.394 24.718 25.248 25.499 25.481 25.746 26.022 25.850 25.561 25.064 24.335
  • 1976 23.837 24.214 24.922 25.308 25.669 26.033 26.422 26.689 26.783 26.798 26.321 25.657
  • 1977 25.195 25.095 25.312 25.605 26.174 26.256 26.684 26.963 26.975 26.628 25.957 25.577
  • 1978 25.385 25.243 25.627 26.172 26.507 26.466 26.618 26.805 26.645 26.532 26.092 25.477
  • 1979 25.145 25.009 25.417 25.997 26.273 26.497 26.640 26.917 26.878 26.885 26.341 25.930
  • 1980 25.715 25.637 26.000 26.125 26.552 26.512 26.650 26.733 26.703 26.295 25.884 25.236
  • 1981 24.784 24.812 25.202 25.722 26.109 26.304 26.459 26.689 26.841 26.679 26.261 25.909
  • 1982 25.348 25.294 25.724 26.549 26.862 26.776 26.768 27.176 27.278 26.892 26.574 26.036
  • 1983 25.624 25.415 25.560 25.913 26.455 26.658 26.889 26.911 26.713 26.592 26.307 25.788
  • 1984 25.149 25.184 25.552 25.765 26.167 26.200 26.408 26.583 26.585 26.314 25.784 25.092
  • 1985 24.594 24.543 25.064 25.601 26.135 26.293 26.541 26.790 26.851 26.678 26.209 25.513
  • 1986 25.100 25.241 25.471 26.179 26.573 26.461 26.805 27.147 27.201 26.789 26.531 25.969
  • 1987 25.240 25.374 25.482 25.800 26.490 26.610 26.859 27.053 27.544 27.175 26.759 26.106
  • 1988 25.507 25.311 25.665 26.200 26.658 26.198 26.394 26.404 26.460 26.190 25.873 24.988
  • 1989 24.397 24.220 24.648 25.684 26.239 26.401 26.712 26.753 26.590 26.311 26.296 25.467
  • 1990 24.966 25.037 25.602 26.451 26.847 26.849 26.987 27.247 27.145 26.948 26.406 25.802
  • 1991 25.542 25.387 25.855 26.283 26.669 26.698 27.014 27.106 27.160 26.716 26.210 25.528
  • 1992 25.012 24.979 25.561 26.130 26.904 27.085 26.933 27.142 27.079 26.853 26.544 25.808
  • 1993 25.572 25.691 25.943 26.424 26.893 26.921 26.916 27.052 26.827 26.904 26.645 26.243
  • 1994 25.866 25.764 26.135 26.610 26.780 26.805 27.147 27.138 27.264 26.996 26.612 25.765
  • 1995 25.498 25.592 26.005 26.236 26.524 26.623 26.827 26.867 26.835 26.546 26.238 25.715
  • 1996 24.755 24.927 25.339 25.824 26.310 26.492 26.637 26.974 26.976 26.699 26.140 25.329
  • 1997 24.908 24.830 25.245 25.837 26.587 27.091 27.302 27.784 27.820 27.458 27.069 26.339
  • 1998 25.726 25.491 25.652 25.882 26.608 26.691 26.837 27.181 26.974 26.545 25.968 25.156
  • 1999 24.558 24.551 24.875 25.489 25.888 26.022 26.188 26.391 26.272 25.800 25.494 24.751
  • 2000 24.310 24.511 24.884 25.573 26.097 26.150 26.457 26.777 26.713 26.452 25.931 25.351
  • 2001 24.932 24.777 24.971 25.494 26.037 26.218 26.633 27.139 27.028 26.651 26.320 25.582
  • 2002 24.923 24.733 25.281 25.992 26.381 26.339 26.722 27.040 26.972 26.893 26.294 25.857
  • 2003 25.304 25.531 25.776 26.065 26.542 26.543 26.718 27.193 27.293 26.903 26.573 25.675
  • 2004 25.228 25.073 25.507 26.034 26.456 26.638 26.791 27.207 27.137 27.071 26.466 25.640
  • 2005 25.405 25.341 25.577 26.052 26.516 26.652 26.672 26.975 27.026 26.472 25.970 25.448
  • 2006 24.968 24.855 25.290 26.062 26.323 26.278 26.780 27.194 27.228 27.143 26.435 25.655
  • 2007 25.038 24.999 25.327 25.908 26.168 26.362 26.690 26.761 26.836 26.364 25.706 25.132
  • 2008 24.345 24.407 24.875 25.414 26.007 26.079 26.303 26.854 26.788 26.538 26.071 25.434
  • 2009 25.015 25.015 25.377 26.030 26.469 26.920 27.193 27.579 27.738 27.551 26.658 26.226
  • 2010 25.513 25.362 25.431 26.052 26.350 26.273 26.364 26.561 26.496 26.076 25.564 24.695
  • 2011 24.287 24.247 24.776 25.496 26.005 25.871 26.070 26.477 26.589 26.199 25.680 24.972
  • 2012 24.622 24.666 24.843 25.594 26.027 26.073 26.444 26.755 27.042 26.886 26.349 25.905
  • 2013 25.048 25.061 25.176 25.965 26.614 26.470 26.818 27.129 27.001 26.831 26.241 25.627
  • 2014 25.053 25.310 25.888 26.335 26.770 27.010 27.402 27.600 27.286 27.314 26.773 26.160
  • 2015 25.756 25.828 26.105

These totals are much warmer than even 1992.

On another note, the SST configuration could put Baja California Sur and Hawaii at high risk for strikes, though a cool pool northwest of the islands, and only slightly above normal (cooler than last year) ocean temperatures exist. However, SST's near Hawaii started to warm up considerably at this time last year, so we'll see. Even if the sST's near Hawaii do not warm up, a pool of above average ocean temperatures east of Hawaii could callow systems to maintain their strength.

Other factors

In addition to the warm ocean temperatures, wind shear has been below average and vertical instability was above average. Vertical instability favors stronger storms, and wind shear also favors more storms and stronger ones in general. Both are positive factors for 2015. However, if Nino 1+2 region cools down a bit, wind shear could be much stronger, and thus, prevent storm formation. Conversely, if things stay were they are, 2015 could rival 1992 in activity.

Negative factors

The QBO is not as - as it was last year. -QBO favors more systems but of slightly less quality? Now the odds of a re-2013? Small. First of all, the very high vertical instability should help in that department. Secondly, it is tough to imagine a 1 or 2 major year in a multi-year El Nino event.

Another negative factor could be a possible late start to the season due to El Nino and the warm Nino region 1+2. The reason for this is the factor that cooler rather than warmer waters off the South American coast favors a more northerly ITCZ due to the fact cool waters means drier air, which means higher pressures in that part of the world, which forces the ITCZ upward. Howe3ver, I'd still favor an early start based on recent trends, as over the past 15 years, we have average a little over a storm per May. The reason for this is that the -IOD has been persistent since e1999, and favors a more northern ITCZ. This is also aided by a cool Gulf of Guinea and an Atlantic Nina, which favors higher pressure, which once again lifts the ITCZ up. The position of the ITCZ is very important in determining the start of the EPAC season. When the TICZ lands at around 10N, the EPAC season usually starts. Though sometimes if the ITCZ gets too north as in 2013, that could be bad as well, since the storms are forming close to cool waters. This was an big time issue in 2013.

Overall

Overall, I forecast the following numbers for 2015:

  • 23 named storms
  • 10 hurricanes
  • 5 major hurricanes
  • ACE:152 (Above average, but not hyperactive)


Confidence in this prediction is high, but if wind shear can remain low, it would not surprise me if 2015 was much active than indicated above. Given the above forecast, it is likely that the activity level observed in 2015 will be comparable, if not busier, to the 2014, as well as the glory days of the 80s and 90s.

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