scholarly journals Cut-Off Lows and Extreme Precipitation in Eastern Spain: Current and Future Climate

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 835
Author(s):  
Rosana Nieto Ferreira
Keyword(s):  
Mediterranean Sea ◽  
Extreme Precipitation ◽  
Wrf Model ◽  
Future Climate ◽  
Synoptic Climatology ◽  
Weather Research And Forecasting ◽  
Climate Extreme ◽  
Low Levels ◽  
Event Simulations ◽  
Main Producer

This study presents a seasonal synoptic climatology of cut-off lows (COLs) that produced extreme precipitation in the Valencia region of Spain during 1998–2018 and uses simulations with the Weather Research and Forecasting (WRF) model to study how extreme COL precipitation may change in a future warmer climate. COLs were shown to be the main producer of extreme precipitation in the Valencia region, especially during the transition seasons. The strongest raining COL events occurred during September–November. Six-day composites of thermodynamic and dynamic fields and precipitation show that COLs that produce extreme precipitation in this region remain stationary over Spain for 2–3 days and tend to produce precipitation over the Valencia region for at least two consecutive days. In the low levels these COLs are characterized by low pressure over the Mediterranean sea and winds with an easterly, onshore component thus fueling precipitation. Comparison of current and future climate ensembles of WRF simulations of 14 September–November extreme precipitation producing COL events suggest that in a warmer climate extreme COL precipitation may increase by as much as 88% in northeastern Spain and 61% in the adjoining Mediterranean Sea. These projected increases in extreme COL precipitation in the northeast of Spain present additional challenges to a region where COL flooding already has significant socio-economic impacts. Additionally, about half of the future climate COL event simulations showed increases in precipitation in the Valencian region of eastern Spain. These results provide important nuance to projections of a decreasing trend of total precipitation in the Iberian Peninsula as the climate warms.

scholarly journals Study of NWP parameterizations on extreme precipitation events over Basque Country

2016 ◽  
Vol 13 ◽  
pp. 137-144 ◽  
Author(s):  
Iván R. Gelpi ◽  
Santiago Gaztelumendi ◽  
Sheila Carreño ◽  
Roberto Hernández ◽  
Joseba Egaña
Keyword(s):  
Extreme Precipitation ◽  
Numerical Models ◽  
Basque Country ◽  
Wrf Model ◽  
Cumulus Parameterization ◽  
Precipitation Forecast ◽  
Weather Research And Forecasting ◽  
Forecasting Model ◽  
Extreme Precipitation Events ◽  
Precipitation Events

Abstract. The Weather Research and Forecasting model (WRF), like other numerical models, can make use of several parameterization schemes. The purpose of this study is to determine how available cumulus parameterization (CP) and microphysics (MP) schemes in the WRF model simulate extreme precipitation events in the Basque Country. Possible combinations among two CP schemes (Kain–Fritsch and Betts–Miller–Janjic) and five MP (WSM3, Lin, WSM6, new Thompson and WDM6) schemes were tested. A set of simulations, corresponding to 21st century extreme precipitation events that have caused significant flood episodes have been compared with point observational data coming from the Basque Country Automatic Weather Station Mesonetwork. Configurations with Kain–Fritsch CP scheme produce better quantity of precipitation forecast (QPF) than BMJ scheme configurations. Depending on the severity level and the river basin analysed different MP schemes show the best behaviours, demonstrating that there is not a unique configuration that solve exactly all the studied events.

scholarly journals Analysis of Possible Physical Factors That Accelerate Downdrafts in Storm Clouds over Cuba

2021 ◽  
Vol 8 (1) ◽  
pp. 23
Author(s):  
Gleisis Alvarez-Socorro ◽  
Mario Carnesoltas-Calvo ◽  
Alis Varela-de la Rosa ◽  
José C. Fernández-Alvarez
Keyword(s):  
Relative Humidity ◽  
Potential Temperature ◽  
Wrf Model ◽  
Weather Research And Forecasting ◽  
Physical Factors ◽  
Equivalent Potential Temperature ◽  
Minimum Relative Humidity ◽  
Equivalent Potential ◽  
Low Levels ◽  
Do So

One of the manifestations of severe local storms is strong linear winds, which are known as a downburst and which are capable of causing great losses to the country’s economy and society. Knowing which factors in the atmosphere are necessary for the occurrence of this phenomenon is essential for its better understanding and prediction. The objective of this study was to analyze the possible physical factors that accelerate downdrafts in the storm clouds in Cuba. To do so, 10 study cases simulated with the weather research and forecasting (WRF) model at 3 km of the spatial resolution were used. The factors capable of discriminating between downbursts and thunderstorms without severity were obtained. These were the absorption of latent heat by evaporation and fusion, the equivalent potential temperature difference between the level of maximum relative humidity in the low levels and of minimum relative humidity in the middle levels, the speed of the downdraft, and the downdraft available convective potential energy (DCAPE). Unlike previous research, they discriminated against updraft buoyancy and energy advection, both at the middle levels of the troposphere.

Climatology of moisture sources fuelling extreme precipitation in the Western Mediterranean region

2021 ◽  
Author(s):  
Damián Insua Costa ◽  
Gonzalo Miguez-Macho ◽  
María Carmen Llasat
Keyword(s):  
Mediterranean Sea ◽  
Extreme Precipitation ◽  
Mediterranean Region ◽  
Wrf Model ◽  
Western Mediterranean ◽  
Moisture Sources ◽  
The Pacific ◽  
Torrential Rainfall ◽  
The Mediterranean ◽  
Open Question

<p>The Western Mediterranean region (WMR) is usually affected by heavy rainfall, which has been extensively studied in the past because of the enormous impact it causes. However, there is still an open question related to these potentially catastrophic episodes: does the water vapour that feeds precipitation actually come from the Mediterranean Sea? Several studies have pointed to a significant contribution from other moisture sources, but the debate remains open because only a few case studies with disparate findings have been analysed so far. Here we use the Weather Research and Forecasting (WRF) model with a coupled moisture tagging capability to simulate over one hundred cases of extreme precipitation in the WMR. In order to detect possible remote moisture sources, we use a domain that covers almost the entire northern hemisphere. Preliminary results show that, although the contribution from the Mediterranean Sea is crucial, the combined contribution from more distant sources in the tropical, subtropical and north Atlantic is higher on average. In some specific cases, a significant part of the humidity may come from sources as far away as the Pacific Ocean. Our findings suggest that when explaining WMR torrential rainfall episodes, the Mediterranean Sea should be generally understood as a precipitation enhancer rather than the main contributor to precipitation.</p>

scholarly journals Assimilating X- and S-Band Radar Data for a Heavy Precipitation Event in Italy

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1727
Author(s):  
Valerio Capecchi ◽  
Andrea Antonini ◽  
Riccardo Benedetti ◽  
Luca Fibbi ◽  
Samantha Melani ◽  
...  
Keyword(s):  
Extreme Event ◽  
Wrf Model ◽  
Heavy Precipitation ◽  
Radar Data ◽  
Flash Floods ◽  
Precipitation Event ◽  
Weather Research And Forecasting ◽  
Limited Area ◽  
Heavy Precipitation Event ◽  
The Town

During the night between 9 and 10 September 2017, multiple flash floods associated with a heavy-precipitation event affected the town of Livorno, located in Tuscany, Italy. Accumulated precipitation exceeding 200 mm in two hours was recorded. This rainfall intensity is associated with a return period of higher than 200 years. As a consequence, all the largest streams of the Livorno municipality flooded several areas of the town. We used the limited-area weather research and forecasting (WRF) model, in a convection-permitting setup, to reconstruct the extreme event leading to the flash floods. We evaluated possible forecasting improvements emerging from the assimilation of local ground stations and X- and S-band radar data into the WRF, using the configuration operational at the meteorological center of Tuscany region (LaMMA) at the time of the event. Simulations were verified against weather station observations, through an innovative method aimed at disentangling the positioning and intensity errors of precipitation forecasts. A more accurate description of the low-level flows and a better assessment of the atmospheric water vapor field showed how the assimilation of radar data can improve quantitative precipitation forecasts.

scholarly journals Relationship between the Track and Structural Evolution of Hurricane Sandy (2012) Using a Regional Ensemble

2018 ◽  
Vol 146 (12) ◽  
pp. 4279-4302 ◽  
Author(s):  
Alex M. Kowaleski ◽  
Jenni L. Evans
Keyword(s):  
Large Scale ◽  
Wrf Model ◽  
Structural Evolution ◽  
Hurricane Sandy ◽  
Weather Research And Forecasting ◽  
Extratropical Transition ◽  
Ensemble Forecasts ◽  
High Predictability ◽  
Regression Mixture ◽  
The Relationship

Abstract An ensemble of 72 Weather Research and Forecasting (WRF) Model simulations is evaluated to examine the relationship between the track of Hurricane Sandy (2012) and its structural evolution. Initial and boundary conditions are obtained from ECMWF and GEFS ensemble forecasts initialized at 0000 UTC 25 October. The 5-day WRF simulations are initialized at 0000 UTC 27 October, 48 h into the global model forecasts. Tracks and cyclone phase space (CPS) paths from the 72 simulations are partitioned into 6 clusters using regression mixture models; results from the 4 most populous track clusters are examined. The four analyzed clusters vary in mean landfall location from southern New Jersey to Maine. Extratropical transition timing is the clearest difference among clusters; more eastward clusters show later Sandy–midlatitude trough interaction, warm seclusion formation, and extratropical transition completion. However, the intercluster variability is much smaller when examined relative to the landfall time of each simulation. In each cluster, a short-lived warm seclusion forms and contracts through landfall while lower-tropospheric potential vorticity concentrates at small radii. Despite the large-scale similarity among the clusters, relevant intercluster differences in landfall-relative extratropical transition are observed. In the easternmost cluster the Sandy–trough interaction is least intense and the warm seclusion decays the most by landfall. In the second most eastward cluster Sandy retains the most intact warm seclusion at landfall because of a slightly later (relative to landfall) and weaker trough interaction compared to the two most westward clusters. Nevertheless, the remarkably similar large-scale evolution of Sandy among the four clusters indicates the high predictability of Sandy’s warm seclusion extratropical transition before landfall.

Predicting lightning activity in Greece with the Weather Research and Forecasting (WRF) model

2015 ◽  
Vol 156 ◽  
pp. 1-13 ◽  
Author(s):  
Theodore M. Giannaros ◽  
Vassiliki Kotroni ◽  
Konstantinos Lagouvardos
Keyword(s):  
Wrf Model ◽  
Lightning Activity ◽  
Weather Research And Forecasting ◽  
Weather Research

scholarly journals Evaluation of WRF Model Simulations of Tornadic and Nontornadic Outbreaks Occurring in the Spring and Fall

2010 ◽  
Vol 138 (11) ◽  
pp. 4098-4119 ◽  
Author(s):  
Chad M. Shafer ◽  
Andrew E. Mercer ◽  
Lance M. Leslie ◽  
Michael B. Richman ◽  
Charles A. Doswell
Keyword(s):  
Wrf Model ◽  
Severe Weather ◽  
Weather Research And Forecasting ◽  
Synoptic Scale ◽  
Sea Level Pressure ◽  
Significant Events ◽  
Skill Scores ◽  
Time Of Year ◽  
Tornado Outbreaks ◽  
Thermodynamic Instability

Abstract Recent studies, investigating the ability to use the Weather Research and Forecasting (WRF) model to distinguish tornado outbreaks from primarily nontornadic outbreaks when initialized with synoptic-scale data, have suggested that accurate discrimination of outbreak type is possible up to three days in advance of the outbreaks. However, these studies have focused on the most meteorologically significant events without regard to the season in which the outbreaks occurred. Because tornado outbreaks usually occur during the spring and fall seasons, whereas the primarily nontornadic outbreaks develop predominantly during the summer, the results of these studies may have been influenced by climatological conditions (e.g., reduced shear, in the mean, in the summer months), in addition to synoptic-scale processes. This study focuses on the impacts of choosing outbreaks of severe weather during the same time of year. Specifically, primarily nontornadic outbreaks that occurred during the summer have been replaced with outbreaks that do not occur in the summer. Subjective and objective analyses of the outbreak simulations indicate that the WRF’s capability of distinguishing outbreak type correctly is reduced when the seasonal constraints are included. However, accuracy scores exceeding 0.7 and skill scores exceeding 0.5 using 1-day simulation fields of individual meteorological parameters, show that precursor synoptic-scale processes play an important role in the occurrence or absence of tornadoes in severe weather outbreaks. Low-level storm-relative helicity parameters and synoptic parameters, such as geopotential heights and mean sea level pressure, appear to be most helpful in distinguishing outbreak type, whereas thermodynamic instability parameters are noticeably both less accurate and less skillful.

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