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08/16/2018, 5:13 am EDT

North America Season 1-3 Outlook

North America Season 1-3 Outlook: Potential climate scenarios favor a warmer-than-normal climate Executive Summary: The Climate Impact Company season 1-3 ahead forecast is updated. The outlook indicates a stronger-than-normal cold season polar vortex ahead most likely producing a mild climate (across U.S.) south of the cold air exposure. El Nino is forecast with below average confidence, also a mild regime contributor. Outlooks: Indicated is a simple analog forecast considering +AO regimes, OCN and the 3 ENSO possibilities indicated. The outlooks are annotated for high impact weather/climate. Forecasts are compared to previously indicated outlook. SEP/OCT/NOV 2018: Meteorological autumn 2018 for North America is warmer-than-normal with caveats. The far northern latitudes, the polar region and across northern Canada are likely trending colder than indicated. However, the warm forecast indicated for central continent is made with above normal forecast confidence. The Southeast and eventually the West Coast cool to near normal. The precipitation forecast is made with below average forecast confidence. A wetter scenario occurs if El Nino develops. The Southwest U.S. is likely wetter than indicated. Otherwise the East-Central to Northeast autumn outlook is drier-than-normal. Fig. 1-2: The Climate Impact Company SEP/OCT/NOV 2018 temperature and precipitation anomaly forecast for North America is indicated.  DEC/JAN/FEB 2018-19: Meteorological winter 2018-19 is overwhelmed by mild influences including OCN and a potential El Nino episode. The expected +AO regime implies the northern latitudes will be much colder than indicated. Cold (arctic) air masses may be prevalent in the northern latitudes and if released south can cause U.S. arctic outbreaks. However, in the absence of that scenario a very warm pattern is likely. The forecast is adjusted warmer from previous. The precipitation outlook is made with less confidence. The wet pattern in the Southeast U.S. is confidently forecast however the drier pattern indicated in the Southwest U.S. including California is made in anticipation of a weak El Nino (or neutral ENSO) and susceptible to reversing wet again. At the moment, much needed rainfall in California during winter 2018-19 is in-doubt. The northern U.S. is likely to observe below normal snow cover although Canada may be snowier than normal and if so colder than indicated. Fig. 5-8: The Climate Impact Company DEC/JAN/FEB 2018-19 temperature and precipitation anomaly forecast for North America is indicated. The previous forecast is below. MAR/APR/MAY 2019: Meteorological spring 2019 is forecast quite wet across Texas and the Great Plains. The East is marginally mild and drier than normal. The western U.S. outlook is temperate and possibly wetter-than-normal in northern California. Fig. 9-10: The preliminary Climate Impact Company MAR/APR/MAY 2019 temperature and precipitation anomaly forecast for North America is indicated.
06/29/2018, 10:04 am EDT

North America Season 1-3 Ahead Outlook

An El Nino Modoki-based Climate Outlook through winter 2018-19 Executive Summary: The Climate Impact Company season 1-3 ahead forecast is revised due to the likelihood of an emerging El Nino Modoki. The favored climate pattern is cool pattern change for later summer in the Great Plains, wet weather evolving in both autumn and winter across the southern states and a sneaky cold regime in the East for winter 2018-19. Climate discussion:  A somewhat recent discovery of an infrequent version of an El Nino episode known as El Nino Modoki is becoming a more likely scenario for the next 1-3 to as many as 9 months ahead according to the Japan Agency for Marine-Earth Science and Technology (Fig. 1) and various global SSTA forecast models governing the most likely climate patterns around the globe. Fig. 1: El Nino-Modoki Index forecast by the Japan Agency for Marine-Earth Science and Technology indicates a weak Modoki ahead for 2018-19. To estimate a historical precedent of El Nino Modoki regimes on global climate analog years are chosen. El Nino Modoki occurred in 2002-03, 2004-05 and 2009-10 (Fig. 2). There are other El Nino Modoki episodes prior to the 3 listed however they occurred when another important mode of climate variability, the Atlantic multi-decadal oscillation (AMO) was in the cool phase (Fig. 3). Fig. 2: Analog years comparing cool Nino12 SSTA and warm Nino34 characteristic of El Nino Modoki and the last 3 months of 2018. Fig. 3: Analog years are chosen from the past 20 years when the Atlantic multi-decadal oscillation has been in the warm phase. Outlooks: A simple El Nino Modoki analog forecast of temperature and precipitation anomalies is indicated for JUL/AUG, SEP/OCT/NOV and DEC/JAN/FEB 2018-19. The outlooks are a confident first estimate of what to expect in each sector of the globe as to general climate conditions inspired by this unique El Nino scenario. Regional influences such as soil moisture during the warm season and snow cover during the cold season plus regional SSTA regimes outside of the tropics can modify the El Nino Modoki climate. July/August 2018: An interesting forecast very much away from the warmer-than-normal persistence of spring and early summer. However, if El Nino Modoki unfolds as expected a U.S. pattern change is likely for the second half of summer possibly most focused on August considering current operational forecasts extending well into July. The pattern change is much cooler in the Central U.S. The anomalous warmth dominant during early summer 2018 shifts to the West Coast mid-to-late summer. The southern Plains to the Delta is wetter than normal while the Mid-Atlantic is also wet. The Gulf of Mexico is drier than normal as evolving El Nino-inspired upper shear thwarts tropical cyclone development. The central/east-central tropical Pacific Ocean is very wet with frequent tropical events. Fig. 4-5: An El Nino Modoki climate pattern featuring temperature and precipitation anomalies for North America for JUL/AUG 2018. SEP/OCT/NOV 2018: Typical of an El Nino climate the Modoki version of warm ENSO causes a wet regime across the southern U.S., wettest as mid-to-late autumn arrives. Much of the U.S. is temperate while Canada into the northern U.S. is warmer than normal. Fig. 6-7: An El Nino Modoki climate pattern featuring temperature and precipitation anomalies for North America for SEP/OCT/NOV 2018. DEC/JAN/FEB 2018-19: El Nino Modoki during North America winter causes a colder-than-normal climate in the East/Southeast U.S. The southern and eastern tier of the U.S. is wetter than normal. The pattern opens the door for extreme cold risk given a persistent blocking pattern over Greenland (i.e. negative North Atlantic oscillation). Southern U.S. drought should fade this winter season. Historically, El Nino means a mild pattern in the high demand energy East U.S. but this winter a cold risk is favored. Fig. 8-9: An El Nino Modoki climate pattern featuring temperature and precipitation anomalies for North America for DEC/JAN/FEB 2018-19.