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07/19/2019, 10:00 am EDT

AG Research: Influence of Soil Moisture on Hot Weather

Not the hottest July week, but possibly the highest heat stress Discussion: The projected U.S. population weight cooling degree day value for the week ending July 18 (and July 25) is in the 93-94 range (Fig. 1). The hottest 3rd (or 4th) week of July since 2000 was the last week in July 2016 which produced a whopping 105 CDD. The 3rd week of July in 2006 observed 102 CDD and the last week in July 2011 registered 101 CDD. While 2019 barely makes the top 5 hottest this year is unique compared to all others since 2000. Much of the Central and East U.S. has record soil moisture (Fig. 2) adding high humidity to the hot weather pattern creating high heat index/heat stress on the public (and energy grid) and causing a gigantic area of excessive heat warnings today (Fig. 3). Fig. 1: Hottest 3rd (and 4th) weeks of July since 2000 using CDD values. Fig. 2: Unlike other hot late July weeks since 2000 in 2019 record wet soils are present causing high heat index/heat stress. Fig. 3: NOAA/NWS excessive heat warnings are widespread! Gas population weight CDD forecast: The outlook continues to stay hotter than normal into early August, a warmer change for early August (Fig. 4). Biasing the higher CDD for early August is a warmer trend in the PJM sector. Fig. 4: U.S. gas population weight CDD forecast using all major models.      
07/19/2019, 9:58 am EDT

AG Research: Influence of +IOD on Global Climate

Strong Indian Ocean Dipole Ahead, Dramatic Climate Influence Asia, Europe and possibly North America affected Discussion: Research published in the Journal of Climate (issued twice/month by the American Meteorological Society) has concluded that the Indian Ocean climate can at times be equal or slightly outweigh the influence of ENSO on global climate. The Bureau of Meteorology/Australia, a leading ENSO and IOD forecaster, recently issued an outlook calling for an exceptionally strong positive phase of the Indian Ocean Dipole to emerge AUG/SEP/OCT and likely longer through the end of the year (Fig. 1). The last +IOD analog years are 2006, 2012 and 2015. During those +IOD years during AUG/SEP/OCT the upper level pattern across Asia featured a cold trough over West-central Russia and a titanic upper ridge in Northeast Asia (Fig. 2). The pattern is caused by the excessive convection in the tropical Indian Ocean related to the very warm waters of the +IOD regime releasing latent heat northeastward into the prevailing mid-latitude westerlies amplifying the upper ridge in Northeast Asia. The atmosphere compensates (for that upper ridge) producing a cold trough in West-central Russia. A pattern featuring such strong influences on the climate pattern in Asia will bias the entire northern hemisphere regime. In Europe an upper ridge is likely mostly over Eastern Europe/Ukraine (Fig. 3). In the U.S. the confidence is lower to distance from the Indian Ocean convection but favored is an East U.S. trough and western ridge during AUG/SEP/OCT (Fig. 4). Fig. 1: Bureau of Meteorology/Australia forecasts a vigorous positive phase Indian Ocean Dipole. Fig. 2: The AUG/SEP/OCT upper air pattern during recent +IOD regimes across Asia. Fig. 3: The AUG/SEP/OCT upper air pattern during recent +IOD regimes across Europe. Fig. 4: The AUG/SEP/OCT upper air pattern during recent +IOD regimes across North America.  
01/29/2019, 3:01 pm EDT

What If The El Nino Fade Continues?

If ENSO Fades Toward La Nina…Great Plains/South America Precipitation Expectations the Next 4 Months. Discussion: The NINO SSTA regions have cooled significantly in January and are now mostly beneath El Nino thresholds (Fig. 1). During January the subsurface equatorial East Pacific has cooled markedly implying additional cooling at the surface is likely (Fig. 2). During the past 25 years there have been several weak El Nino events suddenly fading during mid-northern hemisphere winter (Fig. 3). Each analog continued to cool through following summer to neutral ENSO phase with 3 of 4 analogs maintaining that thermal descent into La Nina later that year. The consensus of dynamic and statistical models is less respectful of the observational cooling which is developing in January. Dynamic and statistical models carry El Nino into northern hemisphere summer with an uncertain wide spread in possibilities for later this year (Fig. 4). Because of the observational trend out of El Nino more quickly than expected and the historical precedent for additional backing away from El Nino to be replaced by a possible La Nina later this year a look at the FEB-MAY precipitation pattern across the Great Plains and Argentina/Brazil is provided. In the U.S. a wetter-than-normal regime is indicated across the Great Plains while the Missouri/Ohio Valley are drier than normal (Fig. 5). If an active MJO is present which is typical during a non-El Nino regime the indicated precipitation anomalies could be more extreme.  In South America the analog prediction indicates dryness in Paraguay plus Mato Gross Do Sul while Mato Grosso toward Bahia is wetter than normal (Fig. 6). Fig. 1: The Nino SSTA regions have cooled to neutral ENSO in January. Fig. 2: The story of a failed El Nino in the equatorial East Pacific is told by subsurface temperature anomalies which suddenly faded cool during January. Fig. 3: During the past 25 years 4 weak/short duration El Nino’s have also weakened suddenly during mid-northern hemisphere winter. A trend toward La Nina followed (except in 2003). Fig. 4: A collection of ENSO phase forecast models by the International Research Institute for Climate and Society. Fig. 5: The FEB-MAY 2019 analog precipitation potential for the Great Plains. Fig. 6: The FEB-MAY 2019 analog precipitation potential for Brazil and Argentina.
11/07/2018, 8:41 am EDT

AG Research: New Vs. Old Summer Rainfall South America

Warm Season South America Precipitation during El Nino: Wetter. Discussion: From a MARKET perspective, especially in agriculture, the influence of El Nino on precipitation has traditionally been recognized as observed by the titanic El Nino episodes of 1982-83 and 1997-98. El Nino 1982-83 and to a lesser extent 1997-98 occurred when global oceans were much cooler than they are now, the polar ice cap was more expansive and CO2 emissions were climbing but nowhere near values observed since 2000. Cycles identifying ocean thermal regimes as defined by El Nino southern oscillation (ENSO), Pacific decadal oscillation (PDO) and Atlantic multi-decadal oscillation (AMO) each changed phase in the late 1990’s along with the sharper increase in CO2 levels. Reasonable is the question of whether El Nino/La Nina historical climate regimes changed. A look at warm season rainfall across South America based on 3 El Nino episodes occurring since the 1997-98 El Nino (when the global oceans warmed, polar cap shrunk and ENSO/PDO/AMO long-term cycles changed) and 3 El Nino episodes just prior to that time including 1997-98 are reviewed. The clear trend with the more modern day El Nino climate is a somewhat wetter warm season regime across southwest and southeast Brazil to northeast Argentina. Dryness in central/northern Brazil tends to be stronger with post 1997-98 El Nino episodes. The wetter trend is likely related to a much warmer tropical North Atlantic in the post 1997-98 El Nino’s. In 2018 El Nino is developing with a warmer than normal tropical Atlantic. New (top) Versus Old (bottom) El Nino Precipitation OCT/NOV/DEC OCT/NOV/DEC discussion: Post 1997-98 El Nino’s are drier across Brazil and wetter in Southeast Brazil/Uruguay compared to earlier El Nino episodes. Thematically similar precipitation character but post 1997-98 El Nino’s are more extreme. New (top) Versus Old (bottom) El Nino Precipitation DEC/JAN/FEB DEC/JAN/FEB discussion: Meteorological summer is wetter Paraguay/Southeast Brazil/northeast Argentina during post 1997-98 El Nino’s compared to earlier El Nino episodes. Central and northern Brazil are drier with recent El Nino episodes. New (top) Versus Old (bottom) El Nino Precipitation JAN/FEB/MAR JAN/FEB/MAR discussion: During quarter 1 of the year the post 1997-98 El Nino events are wetter in Southeast Brazil to northeast Argentina.