Executive summary: The combination of an impressive warm ENSO and positive Indian Ocean dipole is forecast by the Australia Bureau of Meteorology for JUL/AUG/SEP 2023. If so, analogs emphasize a strong upper ridge across Europe returning the dry/hot regime observed last year biased slightly farther eastward. The El Nino/+IOD pattern favors an upper-level anomalous warmth and dry climate-inducing regime over the North-central U.S. to possibly the Northwest States during this time. Discussion: The latest Australia Bureau of Meteorology (ABOM) ENSO and Indian Ocean Dipole (IOD) forecasts feature sharp positive phase for mid-year. El Nino onset is in APR/MAY and strong El Nino emerges by JUL/AUG (Fig. 1). At the same time, an impressive +IOD also emerges (Fig. 2). Analog years (since 1980) producing El Nino/+IOD regimes are 1982, 1983, 1997, 2006, 2012, and 2015 (during JUL/AUG/SEP). The 500 MB anomaly pattern for the analog years combined during JUL/AUG/SEP produces a RED FLAG upper ridge/drought risk for Europe (Fig. 3). Using the modern-day analogs (2006, 2012, and 2015) the upper ridge is centered on Ukraine (Fig. 4). In North America, the analogs render a strong upper ridge over Central Canada to the North-central U.S. in-between upper troughs on both coasts (Fig. 5). This scenario could produce a North-central/Central U.S. drought concern. The modern-day analogs, the upper ridge exposure to the U.S. is across the Northwest while an upper trough occupies the eastern Ohio Valley (Fig. 6). Elsewhere, an upper trough is produced by the analogs for much of China suppressing drought risk. In the southern hemisphere, a strong upper ridge resides just south of Australia while upper troughs emerge either side of Argentina replacing the persistent ridge patterns in this location during much of the past decade. Fig. 1: Australia Bureau of Meteorology ENSO forecast. Fig. 2: Australia Bureau of Meteorology Indian Ocean dipole forecast. Fig. 3-4: El Nino and positive Indian Ocean dipole analog years since 1980 and the upper air pattern generated over Europe (left). Analog years since 2000 (right). Fig. 5-6: El Nino and positive Indian Ocean dipole analog years since 1980 and the upper air pattern generated over North America (left). Analog years since 2000 (right).

Fig: 1-2: The short-term 500 MB anomalies across the northern hemisphere and their pattern change in the middle latitudes in the 11-15-day period. Discussion: The northern hemisphere upper air pattern has generally been highly amplified through the northern hemisphere cold season featuring a persistent stormy upper trough over the U.S. West Coast and Northeast Asia, super ridge over the marine heat wave (NEP22A) north-northeast of Hawaii, and equally impressive warm climate producing upper ridge areas over eastern North America and Europe. Heading into early March, the northern hemisphere upper air pattern remains quite amplified (Fig. 1). However, a large pattern change is ahead! In the 11-15-day period, ECM ENS indicates a reversal in mid-latitude upper air character (Fig. 2) to zonal (stronger west-to-east flow, less amplified). One sensible attendant weather pattern change is a broad colder shift in the U.S. The cause of this pattern change is an eastward shift of the Madden Julian oscillation (MJO) across the equatorial Pacific (Fig. 3) with intensity (for March) not seen since 2015. Following that event, El Nino developed. A rapid demise in La Nina 2020-23 will occur with this MJO transition over the next 2 weeks! The eastward shift of a strengthening MJO across the equatorial Pacific strengthens the positive phase of global atmospheric angular momentum (GLAAM) which erodes the amplified upper pattern of winter 2022-23 in middle latitudes (Fig. 4). The Australia Bureau of Meteorology adjusts their ENSO forecast to strong El Nino by JUL/AUG and El Nino onset as early as APR/MAY (Fig. 5). Fig: 3-4: The strongest March MJO event since 2015 is ahead and will contribute to the strengthening of a positive phase global atmospheric angular momentum. Fig: 5: Australia Bureau of Meteorology ENSO forecast using Nino34 SSTA.  

Climate Impact Company Global Drought Outlook Crop Area Drought Risk Monitor for MAR/APR and MAY/JUN 2023 Drought WARNING: U.S. hard winter wheat, Russia eastern spring wheat, Northern Kazakhstan wheat, Argentina, Southern China soybeans and corn, Drought WATCH: U.S. and Canada spring wheat, Western Europe corn and wheat and Southern Russia corn and wheat. Northern Hemisphere Location/Crop Table 1 Current Soil Moisture MAR/APR 2023 Drought Risk MAY/JUN 2023 Drought Risk   U.S. Corn Western Corn Belt drought, Indiana is dry. Wetter than normal, mainly east, and south. Wetter than normal. U.S. Hard Winter Wheat Drought for most of the crop area. Eastern areas (March) and southern areas (April) are wet. Otherwise, dry. Drier than normal. U.S. Soybeans Near Normal West; East Wet. Wetter than normal, especially March. Marginally wet forecast; drier trend possible. U.S. Spring Wheat Moderate drought is dominant. Wetter than normal March, drier April. Marginally dry. Canada Spring Wheat Moderate drought is dominant. Wetter than normal for southern zones in March and eastern zones in April. Otherwise, dry. Drier than normal. Europe Corn Western Corn Belt is in moderate drought; East is wet. West zone stays dry, wet east, especially April.   Wetter than normal. Europe Wheat Western Wheat Belt is in moderate drought; East is wet. West zone stays dry, wet east especially April.   Wetter than normal. Ukraine Wheat Wet west; dry east. Mostly drier than normal. Dry May, wet June. Russia Corn Wet north; dry tendencies well south. Northern areas are wet, otherwise dry.   Drier than normal. Russia Winter Wheat Wet north; dry tendencies well south. Northern areas are wet, otherwise dry.   Drier than normal. Russia Spring Wheat Wet west/central; dry east. Favoring wetter than normal. Mostly wet in May; dry west/central region in June. Kazakhstan Wheat Northern areas in drought. Wetter than normal except dry southern areas. Dry except wet far north/northeast wheat areas. Table 1: Major crop areas for the northern hemisphere, their current soil moisture classification and drought risk for MAR/APR to MAY/JUN 2023. U.S. discussion: The Western U.S. Corn Belt is in D2 to D4 drought. The Eastern U.S. Corn Belt contains dry soils in Indiana. The short-term forecast is wet across the central and eastern Corn Belt which will ease soil moisture deficits. The U.S. Hard Red Winter Wheat zone is also in D2 to D4 drought. Only eastern Kansas is avoiding this condition. Moderate precipitation is in the 2-week forecast for this region, which should provide some slight benefit. U.S. and Canadian Spring Wheat are in moderate drought. Two-week forecasts offer moderate snow across these regions. MAR/APR Outlook: Dry risks are mainly the western Great Plains and northern Great Plains in April. Canadian spring wheat has marginal wet opportunities far south and east crop region. MAY/JUN Outlook: Central and eastern corn look wetter than normal. Western corn (and soybeans) has a dry risk. Also, drier than normal is the west/southwest Great Plains and spring wheat growing areas in both the U.S. and Canada. Widening drought concerns are appearing for the western Great Plains. Europe discussion: The Europe Corn and Wheat Belt is split between marginal to moderate dryness western areas, worst condition in France while central and eastern areas are wetter than normal. The 2-week outlook generally supports the current pattern: Drier than normal western areas and wet across south and east sections. MAR/APR Outlook: Western Europe drought strengthens while Southern Europe drought may ease. Eastern Europe is wet, especially in April. MAY/JUN Outlook: A marginally confident wetter than normal forecast for late spring. Ukraine discussion: Soil moisture is generally wetter than normal across western Ukraine and drier than normal in far eastern sections. The 2-week outlook is slightly drier than normal. MAR/APR Outlook: Mostly drier than normal. MAY/JUN Outlook: Forecast confidence is low. Drier than normal May climate and wetter June is expected. Avoiding drought heading into summer. Russia discussion: Both the corn and wheat growing areas are quite wet across northern sections drying to near normal central and south with a drier tendency far south. Spring wheat growing areas contain wetter than normal soils west and central region reversing into drought for the eastern 40% of the crop area. The 2-week outlook is wetter than normal across the entire spring wheat zone with patchy wet weather across corn and wheat areas. MAR/APR Outlook: Northern corn and wheat-growing areas are wet while farther south a drier tendency is likely. Spring wheat region is mostly wetter than normal especially in March. MAY/JUN Outlook: Drought is developing for southern portions of the corn and wheat-growing areas. Spring wheat has enough of a varied precipitation forecast to avoid significant drought heading into summer. Kazakhstan discussion: Northern Kazakhstan Wheat is in drought. The 2-week outlook is mostly dry across this region. MAR/APR Outlook: Wetter than normal although far southern areas are dry. MAY/JUN Outlook: Far north and east wheat-growing areas are likely wetter than normal while the remainder of the crop areas is drier than normal. Heading into summer a major drought is not indicated. South Asia and Southern Hemisphere Location/Crop Table 2 Current MAR/APR 2023 Drought Risk MAY/JUN 2023 Drought Risk   Thailand Sugarcane Mostly wetter than normal. Slightly drier than normal. Wetter than normal. China Soybeans/Corn North Wetter than normal soils. Drier than normal. Marginally wetter than normal. China Soybeans/Corn South Strong drought away from coast. Beneficial rainfall. Marginally drier than normal. China Wheat Drought far south; wet elsewhere. Drier than normal. Near normal rainfall. India Wheat Eastern wheat region is drying while west/northwest sections are wetter than normal. Trending wetter than normal April. Wetter than normal. Sumatra/Borneo Palm Oil Marginal dryness appearing in Borneo, Malaysia is wetter than normal. Wetter than normal March, drier than normal April. Turning drier than normal. Australia Wheat West Core of crop area is wet while surrounding fringe is dry. Mostly drier than normal. Mixed signals, favoring a dry pattern. Australia Wheat East Wet soils except much drier than normal soils far northern crop area. Mostly drier than normal. Mixed signals, favoring a dry pattern. Brazil Corn No. 1 Far southern areas are in drought. Central and north areas are near normal. Wet North; Dry South. Turning drier than normal. Brazil Corn No. 2 Marginally dry North, mostly wet southern areas. Mostly drier than normal. Wet near Paraguay. Turning drier than normal. Brazil Soybeans Marginally dry North, mostly wet southern areas. Mostly drier than normal. Wet near Paraguay. Turning drier than normal. Brazil Wheat Mostly wet. Mostly wetter than normal. Turning drier than normal. Argentina Corn/Soybean Major drought. Staying mostly dry. Turning wetter than normal. Table 2: Major crop areas for the southern hemisphere, their current soil moisture classification and drought risk for MAR/APR to MAY/HUN 2023. Thailand discussion: Marginally wet soils are across the entire sugarcane region. The 15-day outlook is dry. MAR/APR Outlook: Typically dry for the next 2 months. MAY/JUN Outlook: Low forecast confidence in a wetter than normal regime. China discussion: Southern China soybeans and corn are in an intense drought. Eastern portions are trending wetter. Northern China soybeans and corn have plentiful soil moisture. The wheat crop is mostly OK with wetter than normal soils although far southern wheat is in a drought. The 2-week forecasts are seasonably dry. MAR/APR Outlook: Northern crop areas are expected to shift drier. Southern crop areas where drought is present are likely to gain above normal rainfall but not enough to reverse drought. MAY/JUN Outlook: Southern crop areas are likely marginally dry with marginally wet conditions across northern crop areas. India discussion: Eastern wheat areas are observing a steady drier trend. West/northwest sections are marginally wetter than normal. The 2-week outlook is seasonably dry. MAR/APR Outlook: There are dry concerns across northeastern India. However, the climate outlooks trend wetter than normal, especially in April. MAY/JUN Outlook: Low forecast confidence in a wetter than normal regime. Sumatra/Borneo discussion: The tendency is drier across Borneo while wetter than normal soils persist across Sumatra. Sumatra is quite wet in the 2-week outlook while Borneo observes marginally dry conditions. MAR/APR Outlook: March is projected to be wetter than normal. However, a drier pattern change is likely in April. MAY/JUN Outlook: El Nino development strongly favors a dry climate. Australia discussion: In the East, soil moisture is ample except for northern wheat zones where dryness is developing. Western wheat core crop area is wetter than normal while surround areas are quite dry. The 2-week outlook is dry. MAR/APR Outlook: A drier than normal climate is ahead. MAY/JUN Outlook: A shift toward El Nino and a possible +IOD pattern supports a dry climate pattern. Brazil discussion: The far southern Corn Crop Number 1 is in drought while the remainder of this region varies and averages near normal. The southern Corn Crop Number 2 and the soybeans region is quite wet with a drier tendency for northern areas. The Brazil wheat-growing areas continue to observe wet episodes. The 2-week outlook is mostly wetter than normal. MAR/APR Outlook: Areas near and east of Paraguay are susceptible to heavy rains. Elsewhere, a drier than normal pattern. MAY/JUN Outlook: Turning drier than normal as ENSO transition toward El Nino is the catalyst. Argentina discussion: A strong drought is in-place across Argentina. The 2-week outlook is mostly drier than normal. MAR/APR Outlook: A drier than normal pattern is expected. MAY/JUN Outlook: The ENSO transition fuels a wetter than normal pattern although not sufficient to break drought.  

Marine heat wave brings historic rains and heat to New Zealand during summer 2022-23. Executive summary: The most recent example of devastating climate regimes and embedded weather events is across New Zealand as summer 2022-23 has produced historic warmth across South Islands while Northern New Zealand has endured the worst flooding episode on record. The catalyst to the heat and flooding rainfall is the persistence of anomalous warm waters which reached record levels in early 2023 surrounding New Zealand. These “warm blobs” also known as marine heat waves have become more frequent and intense in both hemispheres during the past 10 years. Introduction: Since 2017, exceptionally warm sea surface temperature anomalies (SSTA) associated with a marine heat wave (MHW) have centered near or just east of the Dateline in the South Pacific occasionally extending westward into New Zealand waters. The current MHW has produced record warm SST in New Zealand waters particularly off the west coast of South Island. MHW’s are not new. However, their frequency and intensity have increased dramatically during the past 10 years most prominently in the Northeast Pacific but also in parts of the North Atlantic, West Pacific, and both the South Indian and South Pacific Oceans. Climate Impact Company has noted that the influence on regional climate by these large areas of anomalous warm water are well-correlated to a warmer mid-atmosphere therefore above normal 500 MB heights which support a warmer/drier climate. Conversely, the warmer ocean surface also represents above normal low atmospheric moisture which if entrained into renegade upper-level low pressure troughs can lead to extreme rainfall events. Additionally, tropical cyclones moving across MHW’s can strengthen quickly and become unusually powerful. MHW’s produce a long-term climate pattern generally favoring anomalous warmth and dryness that can be interrupted by weather events producing the opposite extreme: Excessive rainfall. During early 2023, New Zealand has witnessed this opposite weather within a climate regime circumstance. Discussion: During the 2017-2022 MHW centered just east of New Zealand, the 500 MB anomaly pattern reveals a persistent titanic upper-level ridge in the same location (Fig. 1). Speculated is the location of the high-pressure area and attendant warm SSTA near and east of New Zealand to the general neutral to cold phase of ENSO during this period (Fig. 2). In 2023 so far, the MHW has featured areas of record strength (Fig. 3) propelling a strong upper-level ridge although farther south this year than the 2017-2022 (MHW) climatology (Fig. 4). Frequently, MHW-inspired upper-level ridge areas are compensated by adjacent upper troughs. Consequently, the New Zealand summer 2022-23 climate was exposed to historic heat across South Island (Fig. 5) and the “biggest (flooding) climate event in New Zealand history” observed in Auckland (Fig. 6). Fig. 1-2: The annual 500 MB anomaly analysis for 2017-2022 in the vicinity of Australia and New Zealand and tendency for neutral ENSO to mostly La Nina during that 6-year period. Fig. 3-4: The daily South Pacific SSTA analysis reveals the presence of the New Zealand MHW and the attendant summer 2022-23 upper air pattern. Fig. 5-6: The summer 2022-23 (so far) temperature and precipitation anomalies across New Zealand. Conclusion: Marine heat waves have persisted in the vicinity of New Zealand since 2017. Due to the anomalous warm ocean water, the middle atmosphere has warmed as indicated by high-pressure ridging during this time centered just to the east of New Zealand. The summer 2022-23 MWH surrounding New Zealand reached record strength southwest of South Island. The farther south warm SSTA pattern was well-correlated to a shift in the subtropical ridge from just east of New Zealand to just south of the island nation. The upper ridge position was responsible for an unusually warm summer across South Island. Meanwhile, to compensate for the titanic upper ridge, a similarly intense low-pressure areas formed just-off the East Coast of Australia. The upper trough frequently entrained tropical moisture to unload historic rainfall on Northern New Zealand during the summer 2022-23 season. Included was the “biggest climate event in New Zealand history” which was a devastating flood centered on Auckland. MHW are not new, but their frequency and intensity has increased in both hemispheres during the past 10 years. Regions exposed to MHW climate have increased risk of hostile climate regimes and weather events. For more information on the New Zealand MHW’s please visit the New Zealand/NIWA or MOANA Project web sites.