4月28日北京快讯 转眼间，“谷雨”节气已至。刚刚进入到本周（4月26日-5月2日），天气舞台画风又转。在专家看来，周内的形势变化可以说是大开大合，波澜壮阔一般。冷空气在经过近几日的“折腾”后，逐渐减弱南压。南北方的气温，将迎来一波大回升。而对于前期一直热度不减的云南来说，随着冷空气的介入，对流天气也趁虚而入。

April 28 Beijing express in the twinkling of an eye, "Guyu" solar term has arrived. Just entering this week (April 26 - May 2), the weather stage painting style has changed again. In the view of experts, the change of the situation during the week can be said to be a grand opening and closing. After several days of "tossing" in the cold air, the southward pressure gradually weakened. The temperature in the north and South will usher in a big recovery. For Yunnan, which has been hot in the early days, with the intervention of cold air, convective weather also takes advantage of the situation.

“民声君”注意到，有本栏目粉丝发来视频及图片表示，今天（28日）午后，云南文山境内突降冰雹，密集的冰雹随着雨点一同落下，街道很快被铺满一层，汇聚成“冰雹河”。当地居民称，降雨和冰雹持续了1个小时左右，看到最大的颗粒有拇指大小。当地气象部门监测数据则表明，此次过程约为20分钟。

"Minshengjun" noticed that some fans of this column sent videos and pictures to show that there was a hail storm in Wenshan, Yunnan Province this (28th) afternoon, and the dense hail fell with the rain. The streets were soon covered with a layer and gathered into a "Hail River". Local residents said the rain and hail lasted about an hour, and the largest particles were thumb sized. Local meteorological department monitoring data show that the process is about 20 minutes.

本还是艳阳高照，瞬间就冰雹来袭，这样的“鬼天气”，着实令不少人感到猝不及防。对此，专家解释称，就是因为当地前期热，对流能量足，冷空气进来，触发了对流。公众须知，强对流的触发，是具有一定的随机性和不确定性。

This is still sunny, instant hail attack, such a "ghost weather", many people feel caught off guard. In this regard, experts explained that it is because the local early heat, enough convective energy, cold air in, triggered the convection. It should be noted to the public that the triggering of severe convection has certain randomness and uncertainty.

值得注意的是，业内人士强调指出，有时候潜势存在，但却没有对流的情况也很普遍。这就相当于子弹上膛，没有扣动扳机，这就是有潜势，但是没动手。对流也一样，有时一切具备，就差一个扣动扳机的。这个对流抑制的能量越强，相当于阻挡扣扳机的力量越大，触发越难。但如果对流有效位能很高，就是不鸣则已一鸣惊人。

It is worth noting that people in the industry emphasize that it is very common that there is potential but no convection sometimes. This is equivalent to loading a bullet without pulling the trigger. This means that there is potential, but there is no action. It's the same with convection. Sometimes all you have is one to pull the trigger. The stronger the convection suppression energy is, the greater the blocking force is, and the harder the trigger is. However, if the convective effective potential energy is very high, it will make a big splash if it doesn't.

气象北京 最新消息，门头沟灵山飘雪。

Beijing's latest weather news, Mentougou Lingshan snow.

北京市气象台30日6时发布：今天早晨到白天阴（大部地区有小雨）转晴，北转南风二三间四级，最高气温16℃；夜间晴间多云，南风二级转北风三四级，最低气温7℃。今天早晨到上午有小雨天气，外出雨具随身，注意交通安全。气温有所下降，可适当调整着装，谨防感冒。明天白天北风较大，注意防范。

Beijing Meteorological Observatory announced at 6:00 on the 30th: from this morning to the daytime, it will be overcast (with light rain in most areas) and clear, with north to south winds of two, three and four levels, and the highest temperature of 16 ℃; During the night, it is sunny and cloudy, the south wind is grade 2, the north wind is grade 3 and 4, and the minimum temperature is 7 ℃. There is light rain from this morning to this morning. Take rain gear with you when you go out and pay attention to traffic safety. If the temperature drops, you can adjust your clothes properly to avoid catching cold. There will be a strong north wind in the daytime tomorrow. Take precautions.