13th December 2018
MetService weather maps show a few, almost stationary features currently around New Zealand, a low to the west and a
ridge to the southeast. This means we will have very similar weather days as we head into the weekend. As the low slowly
fills, another ridge moves over the country from the southwest during Saturday and Sunday.
“All the ingredients are in place for some significant afternoon thunderstorms over inland parts of both islands for the
next few days,” says Meteorologist Rob Kerr, “with northerlies pushing warmer, moisture laden air over the country close
to the surface, and a cold pool in the upper atmosphere causing enough instability for severe thunderstorms to develop.”
“As a result, MetService currently has a Severe Thunderstorms Watch for Thursday, and a Severe Thunderstorm Risk areas
for parts of both islands during Friday. Any region covered by a thunderstorm risk should prepare for localised
downpours,” he adds.
The ridge of high pressure moving over the South Island on Saturday and the North Island on Sunday does not flush out
the low-level moisture, but it will shut off the most vigorous shower activity by putting a cap on how high the air can
lift.
“We will continue the theme of low level stratus cloud in the mornings followed by bubbly cumulus cloud and even showers
for some places, but the chance of thunderstorms decreases as the ridge spreads northeast,” continues Kerr.
A notable exception from the shower activity this weekend will be the Summer’s first home cricket test at the Basin
Reserve, as the Black Caps face Sri Lanka under cloudy skies in the Capital Saturday morning, with more blue sky
appearing as the day goes by.
As we head towards Christmas and many people are making plans for the holidays, MetService are urging people to stay up
to date with the latest information at www.MetService.com or have their free MetService App handy.
•Warnings are about taking action: When severe weather is imminent or is occurring Issued only when required Recommendation: ACT Watches are about being alert: When severe weather is possible but not sufficiently imminent or certain for a Warning to be
issued Issued only when required Recommendation: BE READY Outlooks are about looking ahead: To provide advance information on possible future Watches and/or Warnings Issued routinely
once or twice a day Recommendation: PLAN
ends