Climate Outlook
Climate Outlook for September-October-November
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 latest model forecasts available for September -November 2014 from World Meteorological Organization Lead Center for Long-Range Forecast (WMOLC LRF) indicate warming across the tropical pacific north of the equator. The forecasts for SON 2014 (Fig. 1) show an anomalously warm pattern persisting in the tropical/subtropical Pacific consistent with anomalous wet conditions. Warmer than normal conditions are expected in many regions in the Middle East, most parts in Asia, Europe and the Arctic. The Caribbean is expected to be warm and anomalously dry. On the other hand, the west coast of the contiguous U.S. and central South America are expected to experience anomalous wet conditions.

ENSO

During March-June 2014, sea surface temperatures have remained above average across the Pacific Ocean, especially in the eastern Pacific and near the Date Line. During July 2014, above-average sea surface temperatures (SST) continued in the far eastern equatorial Pacific. Most of the Ni?o indices decreased toward the end of the month with values of with values of +0.3°C in Ni?o-4, -0.1°C in Ni?o-3.4 (5N-5S, 170W-120W), +0.2°C in Ni?o-3 (5N-5S, 150W-90W), and +0.6°C in Ni?o-1+2 (0-10S, 90W-80W). Most of the ENSO prediction models indicate warming again in the coming months probably reaching El Ni?o like conditions in the next three months. As per Climate Prediction Center of NOAA and IRI, USA, the chance of El Ni?o has decreased to about 65% during the Northern Hemisphere fall and early winter.

Regional

Probabilistic MME forecasts (based on 10models) from WMOLC show high probability (more than 50%) for the mean temperatures for the month of September to be higher-than normal in the GCC countries. Forecasts also indicate that probability of temperatures to be above normal (> 50% probability) for the season (September-October-November) (Fig. 2). Probabilistic MME seasonal forecast (September-October-November) from IRI also shows that the temperature is expected to be above normal (> 50% probability) in the Middle East and GCC countries along with 50% - 60% probability of above normal temperatures in the state of Qatar.

The deterministic MME forecasts (based on 12 models from WMOLC) indicate warmer-than-normal temperature conditions in the GCC countries in September 2014 . The temperature anomalies for the State of Qatar are expected to be in the range of 0.25°C to 1°C for September 2014 and such warmer-than-normal conditions are likely to be slightly lower in October and November months (Fig. 3). Forecasts from other climate centers are generally in agreement with WMOLC outlook for Qatar and the GCC.

Most of the models from WMOLC indicate near normal precipitation during September-November 2014 for Qatar and adjoining regions.

Climate for State of Qatar in August 2014

The monthly mean, minimum and maximum temperatures recorded in Doha in the month of August are 36.0, 32.5 and 40.5°C respectively. These deviate by +0.9, +1.9 and -0.5°C from their respective long-term Climatological values.

Fig 1. Deterministic 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

EXPLORE

@2014 Qatar Meteorology Department