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The sub-seasonal to seasonal prediction project (S2S) is a 5-year project, established in 2013 by the World Weather Research Program (WWRP) and the World Climate Research Program (WCRP). This paper briefly describes the S2S project in the context of extended range prediction of extreme events. We provide evidence that S2S forecasts have the potential to predict the onset, evolution and decay of some large-scale extreme events several weeks ahead. For instance, S2S models displayed skill to predict high probabilities of extreme 2-m temperature anomalies over Russia during the worst week of the 2010 Russian heat wave up to 3 weeks in advance. In other cases, like for tropical cyclone prediction, S2S models can produce useful information on the probability of the occurrence of tropical storms within sufficiently large areas through the prediction of large-scale predictors, such as the Madden–Julian Oscillation (MJO). In future, S2S forecasts of extreme events could be integrated into a “ready-set-go” framework between seasonal and medium range forecasts, by providing an early warning of an extreme event a few weeks in advance. Finally, S2S forecasts can also be used to investigate the causality of some extreme events and we show evidence that the cold March 2013 over western Europe and North Asia was linked to a MJO event propagating over the western Pacific.

The subseasonal predictability of surface temperature and precipitation is examined using two global ensemble prediction systems (ECMWF VarEPS and NCEP CFSv2), with an emphasis on the week 3–4 lead (i.e. 15–28 days ahead) fortnight-average anomaly correlation skill over the United States, in each calendar season. Although the ECMWF system exhibits slightly higher skill for both temperature and precipitation in general, these two systems show similar geographical variations in the week 3–4 skill in all seasons and encouraging skill in certain regions. The regions of skill are then interpreted in terms of large-scale teleconnection patterns. Over the southwest US in summer, the North American monsoon system leads to higher skill in precipitation and surface temperature, while high skill over northern California in spring is found to be associated with the seasonal variability of the Arctic Oscillation (AO). During winter, in particular, week 3–4 predictability is found to be higher during extreme phases of the El Niño–Southern Oscillation, Pacific-North American (PNA)/Tropical-Northern Hemisphere mode, and AO/North Atlantic Oscillation (NAO). Both forecast systems are found to predict these teleconnection indices quite skillfully, with the anomaly correlation of the wintertime NAO and PNA exceeding 0.5 for both models. In both models, the subseasonal contribution to the PNA skill is found to be larger than for the NAO, where the seasonal component is large.

The prediction skill of precipitation at submonthly time scales during the boreal summer season is investigated based on hindcasts from three global ensemble prediction systems (EPSs). The results, analyzed for lead times up to 4 weeks, indicate encouraging correlation skill over some regions, particularly over the Maritime Continent and the equatorial Pacific and Atlantic Oceans. The hindcasts from all three models correspond to high prediction skill over the first week compared to the following three weeks. The ECMWF forecast system tends to yield higher prediction skill than the other two systems, in terms of both correlation and mean squared skill score. However, all three systems are found to exhibit large conditional biases in the tropics, highlighted using the mean squared skill score. The sources of submonthly predictability are examined in the ECMWF hindcasts over the Maritime Continent in three typical years of contrasting ENSO phase, with a focus on the combined impact of the intraseasonal MJO and interannual ENSO. Rainfall variations over Borneo in the ENSO-neutral year are found to correspond well with the dominant MJO phase. The contribution of ENSO becomes substantial in the two ENSO years, but the MJO impact can become dominant when the MJO occurs in phases 2–3 during El Niño or in phases 5–6 during the La Niña year. These results support the concept that “windows of opportunity” of high forecast skill exist as a function of ENSO and the MJO in certain locations and seasons, which may lead to subseasonal-to-seasonal forecasts of substantial societal value in the future.

Large-scale atmospheric circulation regime structures are used to diagnose subseasonal forecasts of wintertime geopotential height fields over the North American sector, from the NCEP CFSv2 model. Four large-scale daily circulation regimes derived from reanalysis 500-hPa geopotential height data using K -means clustering are used as a low-dimensional basis for diagnosing the model’s forecasts up to 45 days ahead. On average, hindcast skill in regime space is found to be limited to 10–15 days ahead, in terms of anomaly correlation of 5-day averages of regime counts, over the 1999–2010 period. However, skill up to 30 days ahead is identified in individual winters, and intraseasonal episodes of high skill are identified using a forecast-evolution graphical tool. A striking vacillation between the West Coast and Pacific ridge patterns during December–January 2008/09 is shown to be predicted 20–25 days in advance, illustrating the possibility to identify “forecasts of opportunity” when subseasonal forecast skill is much higher than the average. The forecast-evolution tool also provides insight into the poor seasonal forecasts of California precipitation by operational centers during the 2015/16 El Niño winter. The Pacific trough regime is shown to be greatly overpredicted beyond 1–2 weeks in advance during the 2015/16 winter, with weather-scale features dominating the forecast evolution at shorter lead times. A similar though less extreme situation took place during the weaker El Niño of 2009/10, with the Pacific trough overforecast at S2S lead times.

Patient and public involvement (PPI) has gained increased attention in research circles. The consistency of PPI reporting has been addressed by the development of validated checklists such as GRIPP and GRIPP2. The primary aim of this study was to identify the incidence of PPI reporting in bariatric research. MEDLINE/PubMed, EMBASE, and CINAHL/Cochrane databases were searched for publications between 1st January 2018 to 31st December 2021 for “bariatric surgery” OR “weight loss surgery” OR “obesity surgery” AND “randomized controlled trials.” Ninety studies fulfilled exclusion criteria; two studies reported direct PPI involvement, one indirectly used PPI and one reported not using PPI methods. No other study made direct or indirect mention of PPI. Concluding, that GRIPP2 and PPI reporting in bariatric surgery trials is lacking.

Myeloperoxidase (MPO) is a highly abundant protein within the neutrophil that is associated with lipoprotein oxidation, and increased plasma MPO levels are correlated with poor prognosis after myocardial infarct. Thus, MPO inhibitors have been developed for the treatment of heart failure and acute coronary syndrome in humans. 2-(6-(5-Chloro-2-methoxyphenyl)-4-oxo-2-thioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamide PF-06282999 is a recently described selective small molecule mechanism-based inactivator of MPO. Here, utilizing PF-06282999, we investigated the role of MPO to regulate atherosclerotic lesion formation and composition in the Ldlr-/- mouse model of atherosclerosis. Though MPO inhibition did not affect lesion area in Ldlr-/- mice fed a Western diet, reduced necrotic core area was observed in aortic root sections after MPO inhibitor treatment. MPO inhibition did not alter macrophage content in and leukocyte homing to atherosclerotic plaques. To assess non-invasive monitoring of plaque inflammation, [18F]-Fluoro-deoxy-glucose (FDG) was administered to Ldlr-/- mice with established atherosclerosis that had been treated with clinically relevant doses of PF-06282999, and reduced FDG signal was observed in animals treated with a dose of PF-06282999 that corresponded with reduced necrotic core area. These data suggest that MPO inhibition does not alter atherosclerotic plaque area or leukocyte homing, but rather alters the inflammatory tone of atherosclerotic lesions; thus, MPO inhibition could have utility to promote atherosclerotic lesion stabilization and prevent atherosclerotic plaque rupture.

In 2022, a record-breaking monsoon caused flooding throughout Pakistan, particularly in the southern regions, resulting in deaths, property losses, and severe crop damage, affecting the food supply chain that could last for years. This study assesses the accuracy of sub-seasonal calibrated probabilistic rainfall forecasts for Pakistan. The evaluation focuses on forecasts initialized throughout the summer monsoon season (June–September) and utilizes the European Center for Medium Range Forecast (ECMWF) ensemble prediction system. Forecasts are calibrated using a canonical correlation analysis (CCA) and evaluated using cross-validated hindcasts from 2002 to 2021. The calibrated hindcasts exhibit positive ranked probability skill score and are reliable for weeks 1 (days 1–7), 2 (days 8–14), and 3 – 4 (days 15–28), lead times. In the extraordinary monsoon season of 2022, tercile-category probabilistic forecasts provided useful information up to 4 weeks ahead. Furthermore, the occurrences of intense monsoon rainfall in the highly affected southern region of Pakistan were forecasted reasonably well up to 2 weeks in advance. The ECMWF model's ability to predict sub-seasonal monsoon rainfall in Pakistan during 2022 is attributed to the model’s successful prediction of monsoonal intra-seasonal oscillations.

California experienced a historic run of nine consecutive landfalling atmospheric rivers (ARs) in three weeks’ time during winter 2022/23. Following three years of drought from 2020 to 2022, intense landfalling ARs across California in December 2022–January 2023 were responsible for bringing reservoirs back to historical averages and producing damaging floods and debris flows. In recent years, the Center for Western Weather and Water Extremes and collaborating institutions have developed and routinely provided to end users peer-reviewed experimental seasonal (1–6 month lead time) and subseasonal (2–6 week lead time) prediction tools for western U.S. ARs, circulation regimes, and precipitation. Here, we evaluate the performance of experimental seasonal precipitation forecasts for winter 2022/23, along with experimental subseasonal AR activity and circulation forecasts during the December 2022 regime shift from dry conditions to persistent troughing and record AR-driven wetness over the western United States. Experimental seasonal precipitation forecasts were too dry across Southern California (likely due to their overreliance on La Niña), and the observed above-normal precipitation across Northern and Central California was underpredicted. However, experimental subseasonal forecasts skillfully captured the regime shift from dry to wet conditions in late December 2022 at 2–3 week lead time. During this time, an active MJO shift from phases 4 and 5 to 6 and 7 occurred, which historically tilts the odds toward increased AR activity over California. New experimental seasonal and subseasonal synthesis forecast products, designed to aggregate information across institutions and methods, are introduced in the context of this historic winter to provide situational awareness guidance to western U.S. water managers.

The interannual variability of precipitation over the island of Borneo in association with El Niño–Southern Oscillation (ENSO) has been studied by using the Global Precipitation Climatology Centre (GPCC) gridded rain gauge precipitation, the NOAA Climate Prediction Center (CPC) Morphing Technique (CMORPH) satellite estimated precipitation, the Quick Scatterometer (QuikSCAT) satellite estimated sea winds, and the National Centers for Environmental Prediction (NCEP)–National Center for Atmospheric Research (NCAR) reanalysis data. Analysis of the GPCC precipitation shows a dipolar structure of wet southwest versus dry central and northeast in precipitation anomalies associated with El Niño over Borneo Island during the austral summer [December–February (DJF)]. By using the 0.25° and 3-hourly CMORPH precipitation, it is found that rainfall over Borneo is strongly affected by the diurnal cycle of land–sea breezes. The spatial distribution of rainfall over Borneo depends on the direction of monsoonal winds. Weather typing analysis indicates that the dipolar structure of rainfall anomalies associated with ENSO is caused by the variability in the frequency of occurrence of different weather types. Rainfall is enhanced in the coastal region where sea breezes head against off-shore synoptic-scale low-level winds (i.e., in the lee side or wake area of the island), which is referred to here as the “wake effect.” In DJF of El Niño years, the northwesterly austral summer monsoon in southern Borneo is weaker than normal over the Maritime Continent and easterly winds are more frequent than normal over Borneo, acting to enhance rainfall over the southwest coast of the island. This coastal rainfall generation mechanism in different weather types explains the dipole pattern of a wet southwest versus dry northeast in the rainfall anomalies over Borneo Island in the El Niño years.