Climate

Seasonal Climate Outlook

Background

The Qatar Meteorological Department is introducing monthly and seasonal (3-month) climate outlooks for Qatar and adjoining regions, beginning April 2014. Monthly and seasonal climate forecasts are generated world wide with an underlying assumption that sea surface temperatures in global oceans, snow-cover, soil-moisture of the land surface and other such slowly varying boundary conditions determine the ensuing global and regional climate anomalies. Leading climate centers around the world use fully coupled ocean-atmosphere general circulation models for generating seasonal climate forecasts wherein both sea surface temperatures and associated atmospheric circulation co-evolve. Climate forecasts are generally in the form of anomalies from a long-term climatology as simulated in the models. Individual climate centers produce monthly/seasonal forecasts based on a large suite of simulations (generally initiated every month and extending 6 months in to the future) with different initial conditions using their global climate model and then develop an ensemble forecast product employing advanced statistical techniques.  Show Details...

World Meteorological Organization (WMO) supports and coordinates seasonal forecasts through lead centers (LC) of long-range forecasts (LRF). Korea Meteorological Administration, Seoul, maintains one such lead center. This WMO Lead Center (WMOLC) uses all available forecasts from different climate centers around the world and generates multi-model ensemble (MME) monthly and seasonal climate forecasts for the globe. Several meteorological variables are predicted which include surface temperature (2m), precipitation etc. Apart from WMOLC, other climate centers like International Research Institute for Climate and Society (IRI, New York, USA), National Centers for Environmental Prediction (NCEP/NOAA, USA), APEC Climate Center (APCC, Korea), UK Meteorological Office (UKMO, UK), ECMWF (UK), Bureau of Meteorology (BoM, Australia) etc. also produce monthly/seasonal forecasts.

In preparation of this Climate Outlook for Qatar the monthly/seasonal products generated by the WMOLC have been used. This approach takes in to account a majority of the model forecasts from the Global Producing Centers (GPCs) and combines them using ensemble mean forecast system. However, we also take in to consideration of other forecast products while generating the outlook for the regional temperature and precipitation anomalies for the coming month and season.

The skill of WMOLC ensemble mean forecast products varies from month to month and from one meteorological variable to the other. Generally the skills of temperature forecasts are larger compared to the precipitation forecasts. This disparity in skills between temperature and precipitation forecasts is not unique to this region and is the case globally. The correlation skills estimated based on retrospective (hindcast) forecasts during the past 30 years of MME prediction system are in the range of 0.4-0.6 during different months in the year and for the surface temperatures over this region. These are considered reasonably high compared to the skills observed in other parts of the world.

The current Climate Outlook for Qatar is mainly for monthly/seasonal mean temperature forecast. The reason for the initial focus on temperatures is both due to higher skill and its prime relevance to climate sensitive activities in the national context. With further review of predictive skill and demand of user sectors, the scope of the seasonal climate outlooks can be expanded to cover more features of relevance to this region such as the probability of high wind events, exceedance of certain temperature thresholds etc.

Two types of forecast products are generated by climate centers. One is the probabilistic forecast where the seasonal climate anomalies are predicted to be in one of the three categories (below normal, normal and above normal) and the probability of predicted values falling in these categories is estimated. The other is the deterministic forecast where the magnitude of anomalies is estimated for the ensuing month and the season using different statistical techniques. This outlook uses the forecasts estimated based on simple ensemble mean after correcting the biases in each of the participating models.

Climate Outlook for May-June-July 2017

Global

The State of the Climate Summary Information is a synopsis of the collection of national and global summaries released each month. As per recently released 'Global Summary Information - March 2017' by the US National Oceanic and Atmospheric Administration (NOAA), the globally averaged temperature over land and ocean surfaces for March 2017 was 1.05°C above the 20th century average of 12.72°C. This is the second highest temperature for March in the 138-year period of record, trailing behind the record set in 2016 by 0.18°C. Both Arctic and Antarctic snow ice extents for March continue to be the lowest since records began in 1979 (http://www.ncdc.noaa.gov/sotc).

The latest forecasts available from the World Meteorological Organization Lead Center for Long-Range Forecast (WMOLC LRF) for the coming season (May-June-July) indicate a moderate probability for higher than normal temperatures over most of the continental land masses and relatively higher probability in the equatorial Pacific Ocean and western Indian Oceans (Fig.1). Probability for below normal precipitation is predicted over Australia, parts of northeast Brazil. Probability for slightly above normal precipitation is predicted for the central to eastern equatorial Pacific. The changes in the forecast probabilities of temperature and rainfall over the central and eastern equatorial Pacific Ocean are very similar to the previous month and reflect the evolving changes in the ENSO state.

ENSO

El Nino Southern Oscillation (ENSO) is an Ocean-Atmospheric Phenomenon in the Pacific Ocean that impacts the climate in different parts of the globe. The warm ENSO condition is known as El Nino and the cold ENSO condition is known as La Nina. As per the IRI, by mid-April 2017, the tropical Pacific remained in an ENSO-neutral state, with above-average SSTs present in the eastern Pacific Ocean, and near-average SSTs across the central and east-central part of the basin. The collection of ENSO prediction models indicates increasing chances of El Nino into the summer and fall of 2017 (>60%) (http://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/).

The latest ENSO update from CPC/NCEP also indicates the presence of ENSO-neutral conditions. These ENSO-neutral conditions are favored to continue through at least the Northern Hemisphere spring 2017, with increasing chances for El Nino development by late summer and fall. (http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf).

WMO ENSO Update released on 28 April 2017, reflects the ENSO outlooks provided by the IRI and CPC-NOAA (http://www.wmo.int/pages/prog/wcp/wcasp/enso_update_latest.html).

Regional

Probabilistic MME forecasts (based on 10 global models) from WMOLC shows that temperatures during May 2017 are likely to be slightly above normal with probabilities in the range of 40-60% across the GCC region. However, forecasts indicate slightly enhanced probability for seasonal (May-June-July) temperatures to be above normal in most parts of GCC with relatively higher probabilities over southern parts (Fig.2). Probabilistic MME seasonal (MJJ) forecasts of temperatures from IRI are indicating near normal temperatures over most parts of GCC with slightly above normal probability for above normal temperatures over southeastern parts (http://iri.columbia.edu/our-expertise/climate/forecasts/seasonal-climate-forecasts/).

The deterministic MME forecasts (based on 12 models from WMOLC) indicate above normal temperatures in the range of +0.25°C to 0.5°C over most of the GCC region with anomalies exceeding +0.5°C in some southern parts of GCC in May 2017. Temperature forecasts for the entire season (MJJ) are showing similar temperature anomalies over most of the GCC with slightly higher anomalies in the south eastern part. The temperature anomalies for the State of Qatar are expected to be in the range of +0.25°C to 0.5°C for May 2017 and also during MJJ season (Fig. 3) as well. Forecasts from other climate centers are generally in agreement with WMOLC outlook for Qatar and the GCC.

Model forecasts from WMOLC indicate near normal precipitation during May and the season (MJJ) as well over Qatar and GCC.

Climate for State of Qatar in April 2017

The monthly mean, minimum and maximum temperatures recorded in Doha in the month of April are (30.0°C, 25.8°C, 35.5°C) respectively. These deviate by (+3.4, +3.9, +2.7°C) from their respective long-term Climatological values.

Fig 1. Probabilistic MME forecast from WMO LC LRF: 2m Temperature and precipitation


Fig 2. Probabilistic MME forecast from WMO LC LRF : 2m Temperature

Fig 3. Deterministic MME forecast from WMO LC LRF : 2m Temperature