Subseasonal variability of the stratus/stratocumulus cloud deck over the subtropical southeast Pacific is studied using satellite and buoy observations as well as the NCEP–NCAR reanalysis. It is found that subseasonal variability in the stratus cloud deck is closely related to variations in surface wind velocity, water vapor, sea level pressure, and 500-hPa geopotential height. An increase in c...

Abstract Subseasonal forecast skill is not homogeneous in time, and prior assessment of the likely would be valuable for end-users. We propose a method identifying periods high confidence using atmospheric circulation patterns, with an application to southern Australia precipitation. In particular, we use archetypal analysis derive six called archetypes, daily 500-hPa geopotential height ( Z 50...

The horizontal and vertical structure of unusually warm and dry spells (WDS) over the central parts of South America during the winter and post-winter months (JJAS) are studied. During WDS the mean temperature and humidity anomalies over central Brazil are about +4.1C and −13.2%, respectively. The mean duration of WDS is 11 days and their mean frequency is less than one per year during the mont...

This paper presents an analysis of the frequency and spatial distribution of droughts in Argentina during the 20th century. Special attention is given to the mean monthly atmospheric circulation associated with dry conditions in the Pampas during the second half of the century. A reduction in the number of dry cases is found throughout the century, especially during the warm season (October to ...

The spatial structure of bias errors in numerical model output is valuable to both model developers and operational forecasters, especially if the field containing the structure itself has statistical significance in the face of naturally occurring spatial correlation. A semi-parametric Monte Carlo method, along with a moving blocks bootstrap method is used to determine the field significance o...

A tropical transition (TT) is the process whereby a baroclinic, high-to-moderate vertical wind shear, extratropical or subtropical cyclone transformed into warm-core, low cyclone. Thirty TT events were identified over central and eastern North Atlantic basin during period 1979–2019. The here studied from synoptic storm-centered composite climatology an environmental classification perspective. ...

Abstract. In this study, we assess the skill of a stochastic weather generator (SWG) to forecast precipitation in several cities western Europe. The SWG is based on random sampling analogs geopotential height at 500 hPa (Z500). evaluated for two reanalyses (NCEP and ERA5). We simulate 100-member ensemble forecasts daily time increment. evaluate performance with scores compare it ECMWF forecasts...

This work analyses the link between Western Europe large-scale circulation and precipitation variability in Northern French Alps from 1950 to 2017. We consider simple descriptors characterizing daily 500 hPa geopotential height fields. They are maximum pressure difference (MPD)—representing range of heights over Europe, singularity—representing mean distance a shape its closest analogs, that is...

The predictability of Cyclone Sidr in the Bay of Bengal was explored in terms of track and intensity using the Advanced Research Hurricane Weather Research Forecast (AHW) model. This constitutes the first application of the AHW over an area that lies outside the region of the North Atlantic for which this model was developed and tested. Several experiments were conducted to understand the possi...