STEP 1: Check the table of verification forecast indices for the region, time of year and lead time. If the score is above 2 continue to STEP 2. If the index score is less than 2, then the forecast is not recommended for your region for this period.
STEP 2: Continue to the YOUR TOWN’S AVERAGE RAINFALL button and scroll down to find your nearest location.
STEP 3: Select the rainfall figures for the chosen town for the required period
STEP 4: From the forecast map determine the forecast % range for the region nearest to your town
STEP 5: Enter the two range values in the boxes shown and click CALCULATE
STEP 6 : the resultant range of rainfall is the forecast in mm for your selected region and time period.
WORKED EXAMPLE
STEP 1. Say you are looking for a forecast for May June July (MJJ) for the SW Cape, and you need it 1 month ahead of time (i.e. you are currently in April or later). The Forecast Index is 2.3 which is MODERATE – go to STEP 2 STEP 2. Find the town required eg. Caledon STEP 3. Select the figures for MJJ: 55 67 64 (TOTAL: 186) STEP 4. From the forecast map find the forecast for the Caledon area – say 80-100% STEP 5. Type 80 and 100 into the 2 boxes and Click CALCULATE STEP 6. The resultant forecast is 149 – 186 mm for the MJJ period for Caledon.
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