Thunderstorm Outlook
Issued at 6:47am 27/07/2024
Valid from 6:47am 27/07/2024 to Midnight 27/07/2024
No thunderstorms or significant convection expected during this period.
Issued at 10:03am 27/07/2024
Valid from Midnight 27/07/2024 to Midday 28/07/2024
A front is expected to move onto the South Island from the west during the morning. There is a low risk of thunderstorms from central Fiordland to central Westland during the whole morning, and for the rest of Westland to Buller after dawn. No other areas of severe convection or thunderstorms are expected.
Severe Thunderstorm Criteria
In New Zealand, MetService classifies a thunderstorm as severe if one or more of the following criteria are met:
Heavy rain (from thunderstorms):
Rainfall of 25mm/h, or more.
Large hail:
Hailstones 20mm in diameter, or larger.
Strong wind gusts (from thunderstorms):
Gusts of 110km/h (60 knots) or stronger.
Damaging tornadoes:
Fujita F1 - i.e. wind speeds greater than 116km/h (63 knots) or stronger.
Note: some tornadic systems such as funnel clouds, waterspouts and small land-based tornadoes are possible with thunderstorms that may not be classified as severe.
