Seasonal Weather Forecast Talk Show on Capricorn FM and North West FM

Transcription

1 Seasonal Weather Forecast Talk Show on Capricorn FM and North West FM How accurate was the Seasonal Forecast issued last month (October)? Accuracy is an important part of forecasting. Firstly, let me remind listeners about last month s seasonal rainfall forecast. The seasonal rainfall forecast shown in Figure 1 indicated high probabilities for below-normal rainfall conditions over Limpopo Province (LP) and continuing below-normal conditions in North West Province (NWP) during the period of October to December. The forecast was correct for most days in the month of October. This forecast highlighted one important aspect of weather forecasting which is the continuous update and evaluation of available forecasting products at different scale. For example, a weekly forecast, in this case issued in the last week of October, was more accurate than the seasonal forecast issued 2 months earlier. Figure 1: Probabilistic above-normal (left panel) and below-normal (right panel) rainfall forecast for three overlapping seasons valid for the period of October 2013 to February 2014 The maximum temperatures (day temperatures) were forecast to become above-normal for both LP and NWP during the period of October to December. The tendency of warmer maximum temperatures was gradually expanded from the west of NWP during early spring (Figure 2). The minimum temperature (night temperature) forecast system indicated warmer 1

2 conditions than normal for most of LP and NWP, with the exception of the southwestern parts of NWP for which cooler conditions were expected during December 2013 to February 2014 (Figure 2). Above-normal minimum temperatures were expected to continue during the October to December 2013 and November 2013 to January 2014 periods. These conditions were expected to worsen the current drought conditions experienced in NWP if the expected November rain does not come early. Figure 2: Probabilistic maximum (left panel) and minimum (right panel) temperature forecasts for the three overlapping seasons valid for the period October 2013 to February 2014 Where can a farmer access the seasonal weather forecast? The South African Weather Service (SAWS) is the authoritative supplier of weather forecasts and information for South Africa. There are also other institutions outside the borders of South Africa issuing weather forecasts. We also have universities doing a lot of research and improving the models used for weather forecasting. Thirdly, we have private and public institutions developing models to best forecast the weather. Accessibility of seasonal weather forecasts is still a challenge in South Africa, especially for subsistence farmers, and lack of technology to access the information is a key factor. One of the major challenges is the understanding of weather forecast phenomena. The project on seasonal weather forecast dissemination methods is relevant because the main objective is to improve weather information dissemination methods and the understanding thereof. 2

3 How much rainfall was received in the month of September 2013? Figure 3 indicates an accumulation of 10-day rainfall surfaces created by a combination of ARC- ISCW and SAWS automatic weather station data with satellite rainfall estimates from NOAA CPC (National Oceanic and Atmospheric Administration Climate Prediction Center) available through FEWSNET (Famine Early Warning Systems Network). During the month of September 2013 most parts of LP and NWP received 0-5mm of rainfall and the north eastern parts of LP over soutpansberg received between 25 and 75mm. Figure 3: Total rainfall for September 2013 What is the seasonal outlook for the coming season (August to October)? Figure 4 indicate the probabilities for above-normal rainfall conditions over LP and NWP during the period from November 2013 to January The forecasting system indicates greater probabilities for below-normal rainfall conditions over NWP during January to March

4 Figure 4: Probabilistic above-normal (left panel) and below-normal (right panel) rainfall forecast for three overlapping seasons valid for the period of November 2013 to March 2014 Table 1: Climatic rainfall and temperature for Potchefstroom station, North West Province Potchefstroom JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Max Tem Min Temp Rainfall JFM FMA MAM AMJ MJJ JJA JAS ASO SON OND NDJ DJF Max Tem Min Temp Rainfall

5 Table 2: Climatic rainfall and temperature for Malamulela weather station of the ARC, Limpopo Province Malamulela Item JAN FEB MAR APR MAY JUN JUL AUG SEPT OCT NOV DEC MaxTemp Min Temp Rainfall Item JFM FMA MAM AMJ MJJ JJA JAS ASO SON OND NDJ DJF MaxTemp Min Temp Rainfall Table 3: Climatic rainfall and temperature for Lephalale station, Limpopo Province Lephalale JAN FEB MAR APR MAY JUN JUL AUG SEPT OCT NOV DEC MaxTemp Min Temp Rainfall JFM FMA MAM AMJ MJJ JJA JAS ASO SON OND NDJ DJF MaxTemp Min Temp Rainfall The maximum temperatures (day temperatures) are forecast to become above-normal for both LP and NWP during November 2013 to January The tendency of warmer maximum temperatures is gradually expanded from the west of NWP during spring (Figure 5). The minimum temperature (night temperature) forecast system is indicating warmer conditions than normal for most of LP and NWP, with the exception of the southwestern parts of NWP for which cooler conditions are expected during November to December (Figure 5). Above-normal minimum temperatures are expected to continue during the November to December period. These conditions are expected to worsen the current drought conditions experienced in NWP during late spring and the early summer months. 5

6 Figure 5: Probabilistic maximum (left panel) and minimum (right panel) temperature forecasts for the three overlapping seasons valid for the period of November 2013 to March

7 Maize production requirements in Limpopo and North West Province Table 4: Water and temperature impacts on maize production CLIMATIC IMPACTS Maize Minimum Range Precipitation Dry Land Water Requirements Critical Growing Stage Crop Damage During Drought Vegetative Pollination Stage Soft and Hard Dough Irrigation Critical Growing Stage Water requirements Soft and Vegetative Pollination Hard Stage Dough Minimum Summer Temperatures Extreme Requirements During Extreme Requirements During Long Days Germination All Growth Stages Maximum Summer Temperatures Germination All Growth Stages Temperature Requirements ( C) Germination Vegetative Pollination Stage Stage 2-3% Crop mm 7-10% Crop 4.5% Crop 5-19 C C Damage Damage Damage 4mm per per mm 5.7 mm Below 10 C 26 C per Wilting per Wilting day Wilting Day Day Day 13 C 30 C Summer Summer Summer Day Length Soft and Hard Dough Winter Short Days Drying of Kernels Winter Water and temperature play a major role in maize production. The minimum water requirements for maize production under dryland range from mm of rainfall and under irrigation the range is from mm per day during pollination stage. Why is this explanation and Seasonal Weather Forecasts of critical importance? Climate largely determines the success or failure of food production. More than 70% of food and nutrition insecure people are rural and therefore directly or indirectly dependent on agriculture for their livelihood. Seasonal weather forecasts as a planning tool can largely change food and nutrition insecurity to food and nutrition security. Growth originating in agriculture is almost three times more effective in reducing poverty than growth in any other sector of the economy. This was reiterated during a 2013 International Food Security Futures Conference. You are the farmers; you have the responsibility not only of food production but of food security, poverty reduction and economic growth in South Africa. The rural population is expected to peak between 2020 and 2050 which could mean intensified and exponential rural poverty and food and nutrition insecurity. Only you, our food producing farmers, can prevent a future catastrophe! Farmers would be wise to base their agricultural production planning on scientifically-based seasonal weather forecasts. Disclaimer The ARC-ISCW and its collaborators have obtained data from sources believed to be reliable and have made every reasonable effort to ensure accuracy of the data. The ARC-ISCW and its collaborators cannot assume responsibility for errors and omissions in the data nor in the documentation accompanying them. The ARC-ISCW and its collaborators will not be held responsible for any consequence from the use or misuse of the data by any organisation or individual. For further information please contact the following: Obed Phahlane PhahlaneO@arc.agric.za Pabalelo Radingoana RadingoanaM@arc.agric.za Mahlatse Phuthi MahlatseP@daff.gov.za Kentse Setshedi KentseS@daff.gov.za Adri Laas ISCWinfo@arc.agric.za 7