Trough Much of NI and Eastern SI, 4th February
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- Tornado Tim
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Trough Much of NI and Eastern SI, 4th February
As people have mentioned in the January thread it looks like there is a possibility of storms for the eastern South Island and much of the North Island due to a trough.
With DTSH at around its peak there will be a large temperature gradient with the Southerly change in the eastern SI.The Storms that develop on the southerly change could be quite squally.
This setup might provide some good gust front shot's
Over in the NI, it looks like we are relying on the moisture and resultant latent heat,DTSH and trough for the trigger for this setup to pan out. Upper levels are not particularly cool (around -12 to -14°C @ 500mb).
With DTSH at around its peak there will be a large temperature gradient with the Southerly change in the eastern SI.The Storms that develop on the southerly change could be quite squally.
This setup might provide some good gust front shot's
Over in the NI, it looks like we are relying on the moisture and resultant latent heat,DTSH and trough for the trigger for this setup to pan out. Upper levels are not particularly cool (around -12 to -14°C @ 500mb).
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Re: Trough Much of NI and Eastern SI, 4th February
The set up is there for tomorrow but i do wonder just how much cloud cover there will be of mid/ upper level stuff, also with the low crossing central South Island in the early afternoon any clouds wont be going anywhere fast until the southerly kicks in.
So very squally as you say and messy thunder/hail set up for canterbury tomorrow.
So very squally as you say and messy thunder/hail set up for canterbury tomorrow.
Canterbury, home of good rugby and severe storms
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Re: Trough Much of NI and Eastern SI, 4th February
Storm Struck wrote: So very squally as you say and messy thunder/hail set up for canterbury tomorrow.
i'mmmmmmmmmmm , that could be on the cards for tomorrow,Jase
Will have to see what happens on the day, but should be much cooler afterwards and I hope for some good rain, about 14mm will do thanks. That' s my order I have put in to the rain gods.
Last edited by NZ Thunderstorm Soc on Sun 03/02/2013 18:42, edited 1 time in total.
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Re: Trough Much of NI and Eastern SI, 4th February
I think the deep layer moisture over the upper South Island and North Island is where the thunder risks are tomorrow.
500mb temps for 4pm tomorrow, very warm aloft.
500mb temps for 4pm tomorrow, very warm aloft.
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Re: Trough Much of NI and Eastern SI, 4th February
But i thought very cold air aloft was needed to produce storms,can someone explain the difference with tomorrow's set up.
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Re: Trough Much of NI and Eastern SI, 4th February
There will be an abundance of moisture I believe esp in the North Island, the moisture when lifted in convection creates latent heat which creates more CAPE and therefor more instability.Richard wrote:But i thought very cold air aloft was needed to produce storms,can someone explain the difference with tomorrow's set up.
It can therefor makeup for the warmer upper level temps.
Hope that helps
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Re: Trough Much of NI and Eastern SI, 4th February
Yes, really need plenty of moisture tomorrow for thunder to occur, that warm upper air tomorrow is a big negative for thunder.
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Re: Trough Much of NI and Eastern SI, 4th February
I am not surprised with the latest T-storm Outlook containing a low possibility of severe storms for the Canterbury area (Damaging wind with assoc squalls):
Over the western central North island, GFS has the instability holding throughout tomorrow night progressing into east of the North Island by 3 AM.
Tomorrow night you may get woken by Thunder...hopefully
The 00z GFS run is thinking the southerly change is a Canterbury Coast event.During Monday afternoon and evening, a sharpening trough, preceded by very humid northerlies and followed by much cooler southerlies, is expected to move across the country.
In the northwest of the South Island, the risk of thunderstorms diminishes to low, while much of the North Island is covered by a low risk. A moderate risk covers central parts of the North Island as the trough moves eastwards, as indicated on the chart. Any thunderstorms here are likely to be squally with gusts of 90-100km/h and accompanied by heavy rain of 10-25mm/hr.
In the east, very strong daytime heating ahead of the southerly change is forecast to make for very unstable conditions, and there is at least a moderate risk of thunderstorms from South Canterbury to Wairarapa with the change.Thunderstorms here could bring hail of 5-15mm and heavy rain of 10-20mm/hr.In Canterbury, there is an additional low risk that one or two thunderstorms may become SEVERE producing damaging wind gusts (in excess of 110km/hr) and hail in the 10-20mm range.
Over the western central North island, GFS has the instability holding throughout tomorrow night progressing into east of the North Island by 3 AM.
Tomorrow night you may get woken by Thunder...hopefully
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Re: Trough Much of NI and Eastern SI, 4th February
First rain here in weeks! And it's wonderfully heavy!:)
- NZstorm
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Re: Trough Much of NI and Eastern SI, 4th February
10mm in Grey Lynn.
49mm at Waiuku!
Looks like a warm front.
49mm at Waiuku!
Looks like a warm front.
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Re: Trough Much of NI and Eastern SI, 4th February
heavy here during the night!
38.7mm here, in 3 hours from 3am to 6am
due to a convergence line (the wind here changed to northerly from easterly) that intensified as it went south
lots more than I expected!
It was 20C with a 20C dew point all night too!
38.7mm here, in 3 hours from 3am to 6am
due to a convergence line (the wind here changed to northerly from easterly) that intensified as it went south
lots more than I expected!
It was 20C with a 20C dew point all night too!
Last edited by Manukau heads obs on Mon 04/02/2013 07:31, edited 1 time in total.
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Re: Trough Much of NI and Eastern SI, 4th February
A band of fog or low cloud visible along the foothills, seems to be coming up from the south;
looks like a NW arch behind it though.
Here, just high overcast, a few clear patches of sky, distant thin mist or haze.
14.3 degrees, 76% humidity.
looks like a NW arch behind it though.
Here, just high overcast, a few clear patches of sky, distant thin mist or haze.
14.3 degrees, 76% humidity.
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Re: Trough Much of NI and Eastern SI, 4th February
Pleased you fella's up north had some good falls over night,just hoping we can get some today now.
No misty cloud around this area and same temp as you Orion with a 14deg overnight low
No misty cloud around this area and same temp as you Orion with a 14deg overnight low
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Re: Trough Much of NI and Eastern SI, 4th February
Heaviest rain for a couple of months last night, a warm night with the all that humidity, min was 20C, current dewpoint 20C
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Re: Trough Much of NI and Eastern SI, 4th February
Nice to have 7mm of gentle warm rain, need way more though...
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Re: Trough Much of NI and Eastern SI, 4th February
10mm in the gage and steady rain falling now in Alex. The air smells very earthy and wonderful after 10 days of 30+ degrees. All windows and doors open!
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Re: Trough Much of NI and Eastern SI, 4th February
High cloud and mild light winds here in ChCh. We'll see for later on. There was a wee splash of rain in the night, not enough to wet the ground though
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Re: Trough Much of NI and Eastern SI, 4th February
wow 49 in waiuku!NZstorm wrote:10mm in Grey Lynn.
49mm at Waiuku!
Looks like a warm front.
im sure we had more than 3mm last night. will ask farmers around the area what they had. My rain gauge might be blocked with dust and spiderwebs
I was not expecting that rain at all, so was a nice suprise.
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Re: Trough Much of NI and Eastern SI, 4th February
I like this!!
Metservice:
A front is forecast to cross the South Island today and the North Island tonight or during Tuesday. This front is preceded by a warm, humid northerly flow bringing rain to much of the country, with some heavy falls, as per the latest Severe Weather Warning and Watch. The front is followed by a strong, colder southerly flow.
There is a moderate risk of thunderstorms over Westland, Buller and Nelson from later this morning through the afternoon, which could locally boost rainfall rates up to 25mm per hour and possibly more about the ranges.
There is also a moderate risk of thunderstorms from south Canterbury up to Wairarapa this afternoon and evening associated with the strong southerly change as it heads north. Thunderstorms here could bring hail of 5 to 15mm in diameter,locally heavy rain of 10-25mm/hr and strong wind gusts around 100 km/h. About parts of Canterbury and the Kaikoura Coast, there is an additional moderate risk that one or two thunderstorms may become SEVERE producing damaging wind gusts in excess of 110 km/hr, as well as hail of 10 to 20mm in diameter and possibly a small tornado.
Meanwhile, over the North Island, a trough ahead of the front, together daytime heating and very humid conditions is likely to produce thunderstorms in western areas later this afternoon and early evening extending across to Bay of Plenty tonight. There is a moderate risk of thunderstorms over this broad area,as indicated on the chart, with a lower risk extending into the ranges of Gisborne and Hawkes Bay. Thunderstorms here are likely to produce locally heavy rain up to 25mm per hour and strong wind gusts around 100 km/h. There is a low risk of one or two thunderstorms could become SEVERE in the west from Northland down to the Kapiti Coast producing downpours with rates over 25mm per hour,damaging wind gusts in excess of 110 km/h and possibly a small tornado.
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- Tornado Tim
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Re: Trough Much of NI and Eastern SI, 4th February
A very nice 23°C with a 21°C DP! Plenty of moisture out there today
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Re: Trough Much of NI and Eastern SI, 4th February
some gaps in the could would be great to get in some better heating. But yes plenty of moisture and it all gets cleared out tonight.
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Re: Trough Much of NI and Eastern SI, 4th February
A few spots of rain falling.
Bands of soggy-looking cloud to east and south.
17.7 degrees, 72% humidity.
Bands of soggy-looking cloud to east and south.
17.7 degrees, 72% humidity.
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Re: Trough Much of NI and Eastern SI, 4th February
Lacking two vital ingrediants for action at the moment here- sun and heating.
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