Mud is still staining some of the streets around Stokes Valley \u2013 where residents were forced to clear mounds from footpaths, roads and driveways.<\/p>\n
Many were surprised by the sudden downpours and dramatic impacts in such a short space of time.<\/p>\n
Authorities said this event was a perfect example of why people should always be prepared.<\/p>\n
The Wellington Region Emergency Management Office\u2019s regional manager Dan Neely said it knew there could be the possibility of thunderstorms but that the actual warnings came suddenly.<\/p>\n
\u201cSevere thunderstorms are very difficult to forecast and severe thunderstorm warnings are issued by MetService at short notice.<\/p>\n
\u201cSometimes they pass with minimal impact, but as we saw today, when we had two back to back this morning, they can have significant impacts.\u201d<\/p>\n
MetService meteorologist Brain Mercer said this weekend the possibility of thunderstorms is embedded within the band of rain.<\/p>\n
This means they bring heavy spells, on top of the rain already forecast.<\/p>\n
\u201cIn these thunderstorms, there could be rainfall of between 10 to 25 millimetres per hour from an individual cell.\u201d<\/p>\n
But they are quite fickle.<\/p>\n
\u201cWe can get the correct setup for thunderstorms to happen, but every thunderstorm needs a trigger, needs something in order for it to actually fire off.<\/p>\n
\u201cSo the atmospheric conditions can be right for a thunderstorm, but you may not get that trigger.\u201d<\/p>\n
He said each storm might last for 30 minutes to an hour, and they tend to be very fast moving.<\/p>\n
MetService has a team of thunderstorm forecasters who track them.<\/p>\n
\u201cWhen they develop into severe thunderstorms, and by severe thunderstorms we mean they\u2019ve got very, very heavy rain, so falls sort of 25 to or above millimetres per hour, then we will issue a thunderstorm warning on that individual cell.<\/p>\n
\u201cHowever, each cell is quite short-lived.<\/p>\n
\u201cSo a thunderstorm warning will be in effect for an individual thunderstorm, but that thunderstorm may not last very long.\u201d<\/p>\n
He said that\u2019s why MetService issues a broader warning, saying there is a possibility of thunderstorms, because you can\u2019t track or issue warnings that far in advance.<\/p>\n