Climate

Climate Outlook for February-March-April 2017

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.

Outlook

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- December 2016' by the US National Oceanic and Atmospheric Administration (NOAA), the globally averaged temperature over land and ocean surfaces for 2016 was 0.94°C above the 20th century average. This was the highest among all years since record keeping began in 1880 surpassing the previous record set last year by 0.04°C. During December, the average temperature across global land and ocean surfaces was 0.79°C above the 20th century average. This was the third highest for December in the 1880–2016 record. Only the Decembers of 2014 and 2015 were warmer. The record warmth in 2016 was broadly spread around the world (http://www.ncdc.noaa.gov/sotc).

The World Meteorological Organization Lead Center for Long-Range Forecast (WMOLC LRF) indicates that the latest forecasts for the coming season (February-March-April) are nearly similar to those that were predicted last month for January-February-March season. Therefore, the positive temperature anomalies predicted last month over southern parts of Asia will continue to prevail for the season February-March-April 2017 (Fig.1). Forecasts also indicate high probability of above normal temperature in the north Indian Ocean mainly over Arabian Sea and Bay of Bengal and adjacent land areas. They also show higher probabilities of warmer than normal temperatures over western Pacific Ocean. Enhanced probability of above normal temperature is predicted over equatorial Atlantic, Mediterranean and northern parts of eastern Africa. Near normal temperature is highly probable over the central equatorial Pacific. Near normal precipitation is predicted for the maritime continent. Enhanced probability for below normal precipitation is predicted for the central equatorial Pacific east of the dateline and parts of equatorial Indian Ocean. Enhanced probability for near normal precipitation in the eastern equatorial eastern Pacific is related to the near neutral ENSO or very weak La Ni?a conditions that are persisting in the Pacific.

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 IRI, during mid January, 2017 the tropical Pacific SST anomaly was near -0.5C which is the threshold for weak La Nina. They also state that many of the atmospheric variables across the tropical Pacific remain consistent with weak La Nina conditions with some of them becoming much weaker. ENSO prediction models indicate SST anomailes that are near the threshold of La Nina now are in the process of dissipating to neutral levels by February (http://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/). The latest ENSO update from CPC/NCEP also hints at a transition to ENSO-neutral to occur by February 2017, and such condition continuing through the first half of 2017. (http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf).

Regional

Probabilistic MME forecasts (based on 10 global models) from WMOLC shows that temperatures during February, 2017 are likely to be slightly above normal across the GCC region with moderate probabilities (50-70%). However, forecasts indicate that relatively lower probability for seasonal (February-March-April) temperatures to be above normal (40-50% probability) in most parts of GCC with relatively higher probabilities over southern parts (Fig.2). Probabilistic MME seasonal (FMA) forecasts of temperatures from IRI are generally in agreement with the WMOLC combined forecasts (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 +0.5°C to 1.0°C to occur across the GCC region in February 2017. Temperature forecasts for the entire season (FMA) are showing slightly lower anomalies over the region. The temperature anomalies for the State of Qatar are expected to be in the same range of +0.5°C to 1.0°C for February 2017 and in the range of +0.25 to +0.5°C during FMA season (Fig. 3). Forecasts from other climate centers are generally in agreement with WMOLC outlook for Qatar and the GCC.

Model forecasts from WMOLC indicate slightly above normal precipitation during February and the season (FMA) as well over the GCC region.

Climate for State of Qatar in January, 2017

The monthly mean, minimum and maximum temperatures recorded in Doha in the month January are (20.4°C, 17.1°C, 24.1°C ) respectively. These are deviate by (+2.9, +3.6, +2.1°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