NZ Weather Forum

Both the GFS and ECMRF suggest an upper trough will lurk over northern NZ later in week. This suggests afternoon convection/thunderstorms on the way for inland North Island mid to late week. I would call this model output rather than a forecast at this stage. We'll see how the next few runs go.

GFS chart for thursday 4pm. 500mb heights and surface pressure.

sounds like some chase days coming up...been a long time coming!

Heres hoping that the Waikato might get something.
It has been soo quiet here, only 2 thunderstorms yet!
Just been looking at the CAPE Values for that time range not to good atm.

I'm busy Friday afternoon so that's when storms will fire, current GFS pointing that way.

Lifted index values of -4 and CAPE 800+ over inland North Island Friday afternoon. But I would ignore those kind of details this far out. They will change. But the general idea of an upper trough crossing the North Island toward the end of the week is the thing to watch out for. Hopefully successive model runs stay on track.

Indeed, Looks like the central NI might get something on Fri 1200 is the max level I saw.
Just asking for confirmation, is CAPE measured in j/kg?

yes,the unit for energy is j/kg.

What about Tuesday for the South and East of the South island with that cooler SW change moving through slamming into the muggy air?.
Cheers
Jason.

NZstorm wrote:yes,the unit for energy is j/kg.

Really? Joules per kilogram?

Cool!

Just looking at the MS 7 day rainfall. Not sure which model it is but it wants to set up a blocking high over the country that looks pretty sturdy from Friday till Monday. Doesn't quite look realistic at the moment...
Anyway, were it to eventuate, the current orientation would give prolonged rain to the West Coast of the South Island, and fine and settled weather for the North Island.

Great - need it fine for Lake Taupo Cycle Challenge on Saturday - well not raining anyway! Can put up with some wind, but we don't want it too hot as well!

blocking high over the country

Clearing for Saturday but the pattern looks progressive.

Models still suggest thundery convection possible Friday over northern half of NI. But this will be conditional on sufficient moisture as always. At the moment the GFS is going for 16C dewpoints Friday over Auckland! That would certainly be an unstable number if it happens. Sea breeze convergence will likely be the trigger.

Steven,
Have you looked at the CAPE levels for Tuesday Next week?
Looks like 1200 j/kg of CAPE will be hanging around Waikato area then too.
Lifted index also looks promising to with -4 values.
Yet it is a forecast so I will not take it seriously yet......

I think next week is too far out for looking at CAPE levels. Summer instability tends to be very conditional and often you don't know for sure until the day whether there will be instability/convergence.... and cb's can develop. Certainly looks to be a low risk over the inland ranges today, the risk increases for tomorrow by the looks.

There was some AC around this morning on my drive into work on the North Shore, good to see!

Wind Shear is apparent in the waikato today just saw some Altocumulus Undulatus.

Well ... it's nice to see but it's even better to shoot !
Some pictures pleazzzzz !!!

you could check out my web cam , pointing towards auckland city, to get an idea...

http://www.weather-display.com/windy/gb ... sbeach.htm
(with links there to movies of the clouds passing etc)

nice convection building up today, will be interesting to see what kind of heating we can get.

Lacertae,
Perhaps you should visit my website it is mainly photography and weather phenomena related site.
I update it on average every day.
Heres a link: http://web.me.com/gunnimacman/Tims_Weat ... bsite.html

Just looked South and some convection buildups are happening, looking W and NW significant buildups are happening as warm air goes over the Waikato tallish Hills such as the ranges looking East from Whitehill, that causes that trigger to push past the cap and that when thunderstorms start to eventuate from a Westerly direction.
Winds are NW at the moment so all of these buildups will come over Hamilton way.

pretty weak convection, nothing to get excited about
hopefully friday will be better

yea the heating never got above 21C.. still nice to look at tho

Up to 24C at GreyLynn, 14C dewpoints. Feels like summer has arrived.

The next few days could be interesting if moisture holds up and cloud cover from the trough to the NE stays away to allow for strong daytime heating.

Looks like we are getting the effects of cooler drier air with a SW in AK this morning. Looking like a convergence zone should develop this afternoon through the Waikato between an incoming SE and the SW. Whether there is enough moisture there for thunder is questionable but certainly a risk there late afternoon/early evening.

Tomorrow Friday sees drier SE flow now dominating and any thunder risk will be over Northland, maybe Auckland but chances look low atm.