在美国,气象学家预测任何数量的降水的概率下降。我们认为能接受的最小数量达到这个标准。01”。因此,我们预计100英寸的降水的概率下降位置。我们看从地面站观测数据,卫星和计算机模型,并将它与我们的知识结合起来的气象/气候和我们过去的经历相似的天气系统降水的概率。10%的机会下雨意味着10倍的100年,这种天气模式,我们可以预期至少. 01”在给定的位置。同样,90%的机会下雨意味着90倍的100年,这种天气模式,我们可以预期至少. 01”在给定的位置。同样,风暴预报中心问题严重威胁概率。你可以看到5%的机会龙卷风或15%的机会严重的冰雹。这仅仅意味着5 * 100在这种情况下我们可以期待一场龙卷风。100年或15倍你可以预期严重的冰雹和雷暴。 By definition, there is no difference in the amount of rain forecast by a 10% chance or a 90% chance. Instead, that information is defined elsewhere, typically by a quantitative precipitation forecast. Meteorologists are still struggling with the best ways to inform the public about the differences between high chance, low QPF events versus low chance, high QPF events, and everything else in between. Meteorologists are still human and have their own wet or dry biases that can hedge the chance of precipitation you see. Recently, forecasts are relying more on bias-correction techniques to remove the human bias from precipitation forecasts.