Global SSTA Forecast (JUL/AUG/SEP 2019) Check

Discussion: In the ever-changing ENSO regime of the past 12+ months do we now need to be addressing potential El Nino Modoki? According to the NCEP CFS V2 forecast for JUL/AUG/SEP 2019 the weak El Nino of June 2019 becomes split between robust warming near and just east of the Dateline while off the northwest coast of South America is cool. The analog years for JUL/AUG/SEP El Nino Modoki since 1980 are: 1986, 1991, 1994, 2002, 2004 and 2009. What are some of the more dramatic climate events around the globe using the analogs for JUL/AUG/SEP? Drier than normal in the Corn Belt! Wouldn’t that be a relief! But wet weather dominates the remainder of the U.S. east of the Continental Divide. A cool summer in the Great Plains. France, Poland and Southwest Russia are dry. North-central China and Western Indonesia are very dry.

Normally, warm phase of the Pacific decadal oscillation (warm SSTA Northeast Pacific) accompanies El Nino. +PDO appears to be developing now and should strengthen the next few months which supports the lingering El Nino forecast. The primary implication is formation of an upper ridge across northwest and possibly most of western North America. So…it should go very dry on the U.S. West Coast.

Meanwhile waters are warm and stay warm off the Southeast/Mid-Atlantic States of the U.S. which supports a warm subtropical ridge biasing these U.S. regions warm for summertime. However, an unusually cool SSTA regime east of New England IS NOT well—forecast. New England looks cool for summertime. The boundary between cool New England and warm Mid-Atlantic is likely to drive a wet summer in that region.

The North Atlantic tropics are normally warm. Once systems depart the tropics and enter the Gulf or waters off the Southeast U.S. Coast watch out! The warm SSTA should force rapid intensification. The Gulf States and Southeast U.S. need to be on-guard for tropical cyclones that over-achieve in intensity as they approach the coast late this summer.

There are a few unusual regional forecasts. Cool SSTA is forecast along the north coasts of northern hemisphere land masses just south of the polar ice cap. Cool SSTA forecast across the Norwegian Sea is very unusual. Implied is cool air aloft (weather-making upper trough) from east of New England, across the North Atlantic and into west/northwest Europe. This regime pushes the drought risk for Europe to Eastern Europe and Southwest Russia as previously mentioned.

The 11^th episode of the positive phase of the Indian Ocean Dipole (+IOD) since 1960 is developing. +IOD has a drying influence on Australian climate during their winter and spring.

An interesting forecast is the marginal cool SSTA just off the Antarctica coast now into mostly very warm anomalies over the next 1-3 months. A warmer and dramatic change. Why that change would occur is unknown but this forecast is a great way to judge skill of the NCEP CFS V2 model once JUL/AUG/SEP has passed.

What should risk management professionals in industry take from this assessment?

1. Know that El Nino/La Nina is not the only driver of global climate.
2. We have a new twist on the ENSO forecast…possible El Nino Modoki.
3. Implications for JUL/AUG/SEP is drier in the U.S. Corn Belt (but wet everywhere else in the U.S. east of the Divide) and the Great Plains are cool.
4. Dry-to-drought conditions are possible in Southwest Russia stretching west into France.
5. Emerging dryness in western North America (propels fire season).
6. Reginal SSTA forecasts are as important if not more so than ENSO to generating climate projections.