joliver657 wrote:I dont know how accurate the MS 3 day maps are but they are forecasting this to be very nast for the S. Island east coast
The Metservice 3 day maps are GFS generated so they are pretty much reflecting in a 3 hourly breakdown what the Metvuw charts (perhaps moderated). They are just more detailed really.
Anyways latest model run showing around 30-35mm for Christchurch. It is focusing the bulk of the rain for Eastern South Island around Eastern Otago now with 60mm being put out for Dunedin.
Reporting Live from Southern Christchurch
Leighton Thomas
Yes, looks like a rain event now but with warm advective snow possible over inland Southland/Otago Sunday/Monday.
Not sure of the snow level but 500m seems a good guess.
Forecast sounding below for inland Otago on Sunday showing the over running of airmasses.
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Last edited by NZstorm on Fri 03/05/2013 07:37, edited 1 time in total.
Yes to warm for any low level snow in Canterbury by the looks of it with thickness of around 545+ and 850mb temps of +5 so don't get to carried away peoples.
CHCH Weather Chaser wrote:
Anyways latest model run showing around 30-35mm for Christchurch. .
Yes because its looking more like a SE wind flow event now,Christchurch does get sheltered some what from BP,but there should be higher totals than that away from the city.
CHCH Weather Chaser wrote:
Anyways latest model run showing around 30-35mm for Christchurch. .
Yes because its looking more like a SE wind flow event now,Christchurch does get sheltered some what from BP,but there should be higher totals than that away from the city.
Latest 3 runs have all suggested in the 30-40mm range for the city and as you say with the more SE flow the city will get sheltered so perhaps knock a bit of that as the models dont take that into account so well. Inland totals will be higher from the onshore flow. Hopefully the next run moves the bulk from Eastern Otago a little further north. I feel like a decent heavy rain event!
Reporting Live from Southern Christchurch
Leighton Thomas
Things have certainly changed in the last 24 hours. Now the developing low is further north still a cold airstream too. Heavy rain and severe winds snow above 500 or 600metres maybe. Looks more like sunday and Monday event now too. GfS painting a different picture every update. No wonder the MS seem abit confused . Hard to forecast this weather event by the looks.
I think you will find it starts off as a SE event with the positioning of the low, once it crosses the top of the south island and into the southern ocean a more direct southerly flow will get organised therefore directing the bulk of the activity over Canterbury northwards.
This is the second run that has it in a simular outlook so tonights run will be interesting to see if it changes, the air is still being dragged from quite far south regardless so that and a few other factors we are going to see that snow level sneak down from what the models pick.
Run just through putting out 40mm now for Christchurch and 63mm for Dunedin so slight increase for both but still a bit of variation in the positioning and timing of everything.
Reporting Live from Southern Christchurch
Leighton Thomas
Very dissapointing weather system. I was counting on it snowing to at least 300msl in Mid Cantrbury but appears it will be more a 500msl plus system. Damn
M/S Canterbury mountain forecast now has snow to 1600m on sunday and 1000m on Monday so much more inline with what charts a picking for us.
Here in Rangiora we may get good rain being away from Chch's BP rain shadow and much closer to the foothills.
So i wonder why the mountain forecast is different to the plains?, is that because the bulk activity is in the plains/foothills region where the S-SE flow will affect.
The metrogram is pushing over 540 on the THK now so probly no lower than 500m unless it changes , its still going to be interesting anyway.
Its just the stupidity of the M/S forecasting system they use on there website with to many products to display, they all come together to contradict each other and it often happens.
I would think that the mountain forecast needs to be very good given the position people put themselves in in that environment and the possible outcomes, the difference between 500m, 1000m and 1600m is huge when tramping or driving and snow forecast to fall to 1600m that then falls 500m could mean a safe tramp turns into a helicopter trip home- well it does these days anyway.
Latest run has backed off totals for here. Seems the bulk is consistantly plotted for Eastern Otago. Dunedin still looking around 60mm for the 3rd run straight. Also looking like decent falls around Cheviot to Kaikoura region.
Reporting Live from Southern Christchurch
Leighton Thomas
melja wrote:Its just the stupidity of the M/S forecasting system they use on there website with to many products to display, they all come together to contradict each other and it often happens.
I would think that the mountain forecast needs to be very good given the position people put themselves in in that environment and the possible outcomes, the difference between 500m, 1000m and 1600m is huge when tramping or driving and snow forecast to fall to 1600m that then falls 500m could mean a safe tramp turns into a helicopter trip home- well it does these days anyway.
Yes, there is too much repeativeness on the MetService website, as discussed in another topic on this forum.
Last couple of runs have backed off the intensity of this system and we are getting close now. The Metservice 3 day maps though show some very heavy falls especially for inland Canterbury (darfield 90m in 8 hours) but they havent updated that yet to the latest run. That is based on the model run early evening yesterday - that normally happens in the next 3 hours or so. Latest only going low 20's here.
Reporting Live from Southern Christchurch
Leighton Thomas
Well the day is almost here. Some steady rain for Wellington Region by the looks, still cold air flow too. Maybe some snow for higher altitudes in the south and north of both islands good start for the ski season. 984hp still pretty lowish for this weather system so there will be some reasonable intensity for some areas exposed.
Richard wrote:I see now that MS are only talking 7.2mm in total for CHCH
Where are you seeing that Richard? Under Christchurch in extended 2 hourly rainfall graphs it shows a lot more than that. Nothing huge but still fair bit more. GFS just through hour ago showing approx 30mm.
Reporting Live from Southern Christchurch
Leighton Thomas
Still and brooding out here too. MetService has about 90 mm for Dunedin until tomorrow morning. If it fell that would be enough to let the Leith give its new flood protection scheme a test drive. That was the forecast from last night and the way they've been bouncing around I would not be suprised, but bitterly dissapointed if we end up with about 15mm.
, its still going to be interesting anyway.
