Canterbury

The situation

Issued at 6:25 am on the 17th of August by Leighton Thomas

MOSTLY FINE DAY, WITH MILD CONDITIONS (EARLY SPILL OVER RAIN FOR INLAND AREAS WILL CLEAR THIS MORNING)

(RAIN, SNOW & COLD CONDITIONS ON TRACK FOR THE WEEKEND)

Good morning. An active high powered front is moving up the West Coast of the South Island, bringing heavy rain near the Main Divide and scattered spill over rain for the High Country & Foothills. Out east it’s mostly fine with high cloud, gusty NW winds and mild temperatures, in-fact our current temperatures look like day time ‘highs’ for middle stages of August.

Get out and make the most of this spring like weather, with rain, colder temperatures and even snow for the High Country this weekend. We currently have an ‘Extreme Weather Outlook’ in place, with full details, there has been some slight changes overnight, with the heavier, more persistent rain set for North Canterbury & the Kaikoura District, especially about the foothills.

(CURRENT TEMPERATURES 6:15AM) Christchurch 12, Ashburton 12, Timaru 9, Kaikoura 15, Mt Cook Village 7, Darfield 14, Methven 11, Culverden 16, Twizel 8, Hanmer Springs 13, Castle Hill Village 8, Arthur’s Pass Village 8, Oxford 14.


KEY POINTS FOR YOUR THURSDAY MORNING.

Spill over rain is affecting many inland areas this morning, mostly about the Canterbury Foothills; this will gradually ease through the morning. Low chance of the odd spot reaching the coast.

Enjoy the next couple of days of mostly fine weather, in-fact today, our milder NW airflow will push many eastern towns into the high teens. While it be mostly dry, mild and sunny out east, heavy rain will fall near the Main Divide & Headwaters over the next 60 hours  = our main rivers systems will be running high.

We’re looking at a nasty system of weather this weekend, which will be more confined to areas north of Christchurch. Conditions will deteriorate Saturday afternoon from the north & continue through until middle stages of Monday in some areas. This is a complex set-up, with a number of moving ‘parts’ for the better word = this system demands respect, for areas already struggling, with excess water. At this stage we expect the heavier rain to be for northern parts of the region, Amberley north.

Snow is likely to fall in the High Country, affecting Alpine Passes & the High Country, with significant snow accumulations at higher altitudes.  In addition rain may cause more surface flooding concerns, for many areas north of Amberley, with up to 80mm possible for inland parts of the region. At this stage snow is not likely to drop below 500/600m. Many ski fields should receive in excess of 60cm.

We currently have an ‘Extreme Weather Lookout’ in place, with more details; this will most likely be upgraded to a full ‘Warning’ & ‘Watch’ this evening

People working, living & ‘operating’ in the High Country should prepare for the possibility of heavy snow, rain and bleak conditions, over an extended period of time. This isn’t your traditional cold snap, with 15-25mm and a dusting of snow on the foothills.

We’ll continue to watch this closely over the next 48 hours and make adjustments to town forecasts and ‘Warning ‘content.

CWU cater for 23 towns across the region; please remember there are significant differences in weather across the region during any system of weather.


GENERAL SUMMARY ACROSS THE REGION – CHECK TOWN FORECASTS FOR MORE SPECIFIC & DETAILED INFORMATION.

 

All town forecast pages will be updated this morning & again this evening, based on all the very latest maps/models & data.

 

TODAY: Mostly fine out east, with extensive high cloud at first. Spill over rain in the morning; more likely about the foothills & High Country (Some rain could be heavy for a time) Gusty NW winds about the High Country will spread across the Plains and likely to reach coastal areas from afternoon. Heavy rain and gales near the Main Divide, with snow above 1200m. East is best tomorrow. Enjoy the mild & dry conditions across the Canterbury Plains & Coastal areas. H: 16-19 L: 5-8

 

FRIDAY: Mostly fine and mild out east, with high cloud and sunny skies. Rain, heavy at times near the Main Divide, with strong to gale force NW winds. H: 15-17 L: 4-6

 

SATURDAY: Mostly fine start, before conditions deteriorate from the north and south. Showers & periods of rain developing by evening, with heavy rain setting in overnight about North Canterbury. Snow above 900m, lowering to 700m by Sunday morning. Becoming colder overnight. Fresh cold southerlies developing & becoming strong about coastal areas. H: 9-11 L: 1-3

 

SUNDAY: Rain, steady at times through the day, with heavier falls near the Canterbury Foothills. More persistent heavy rain north of Amberley. Snow lowering to 700m, with heavy falls about the High Country. Rain more occasional in South and Mid Canterbury. Fresh cold southerlies, strong about coastal areas. H: 6-9 L: 0-2

 

Monday: Rain or drizzle during the morning, more persistent in North Canterbury, with snow about the High Country above 700m.  Fresh cold southerlies across the region. Conditions gradually easing by midday & clearing late in the afternoon.  Severe frosts at night, especially inland. H: 7-9 L: -3, -1

 

TUESDAY: Mainly fine day, with sunny skies. Light winds inland, with NE winds freshening about coastal areas. H: 11-13 L: 1-3


‘Situation’ will be reviewed & updated around 7:30pm Thursday evening.

 

Weather Analyst: Russell Voice

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