The weather has the Met Service guessing again!

Manukau heads obs · Sat 17/07/2004 07:56

Just shows you how things dont always go to plan....or at the least the timing of things!

Parts of Northland and Auckland
could see 70mm of rain from Saturday morning through to early afternoon
and
Forecast issued at 0459hrs 17-Jul-2004 valid until 2359hr Saturday:
Manukau and Waitemata Harbours, Hauraki Gulf and Bream Head to Cape Colville
For the Manukau and Waitemata Harbours: Northeast 20 knots rising to 35 knots gusting 45 knots late morning,

That was issued last night.
This morning there is quite clear skies now, only 3mm in the early evening...and a light westerly!
Stuff all rain about the auckland/northland area now.,....
what has happened:

a low has moved north from the cook straight area, and is not west of auckalnd....and that has destroed the slow moving front that was supposed to have moved onto northland and auckland overnight (it did give some good rain to the coromendel overnight, and the BOP did have lots of rian yesterday from it).
BUT , the forecasted low has developed to the north of the NI now....AND it is moving south to SSE...but it looks like it will COMBINE with the low out to west of the NI.....
and that will see a clash!
becuase the low out to the west is a cold low....its only 9.5oC here now with the westerly associated with it.....and the low coming down from north is a warm low...with lots of warm most air on its eastern side directed down by the high to the east....
so, it could be quite explosive.....
we will have to wait and see!!
(and it just so happens its a new moon today

this is not intended as a moan at the met service,,...but just to point out how hard it is to get the timing of things right sometimes....and how things dont always go to plan.....NZ weather is not easy to forecast.....
its just a timing thing....the strong winds and rain look to be on the way,....but not until much later today by the looks

spwill · Unread post by **spwill** » Sat 17/07/2004 08:15

Great to see some blue sky this morning after yesterday .

I think Met service need to drop the heavy rainfall warnings atleast for Auckland, Northland.
Should see some convection showers up here today and a thunderstorm
is possible.
Distant cloud build ups can be seen to our west this morning.

Manukau heads obs · Sat 17/07/2004 08:32

WARNINGS NO LONGER IN FORCE

HEAVY RAIN WARNINGS HAVE BEEN LIFTED FOR: NORTHLAND AND AUCKLAND

they have just done that

but heavy rain warnings stil in force for other eastern areas, and that looks to be OK!

i didnt actualy want the rain....the ground is still wet enough....

but we might end of getting gale SWers.....

NZstorm · Unread post by **NZstorm** » Sat 17/07/2004 08:47

Have to say, I was happy to see the weather fine today. The forecast for 'long periods of rain' didn't appeal. The ECMRF model picked this a couple of days back. My interpretation of their modelling was that the low would be to far east for Auckland to get the rain.

Should see some convection showers up here today and a thunderstorm
is possible

Some convective showers look on the cards but very marginal conditions for deep cb's. Upper air doesn't look quite cold enough to me. Have to wait and see though.

Manukau heads obs · Sat 17/07/2004 08:51

yeah, i guess its not som much the timing...but the positioning....the slow moving front actualy drifted east instead of driting west....onto northland and auckland....that was what went wrong....the position of that front (which has not become more active quickly over the eastern coromendal and BOP....they will get alot of rain there.....but it will most likely wrap around the new low center...the combined low center....but over the waikato maybe...and so we will still miss it here in auckland....

its going to be an interesting 24 hours ahead!

Manukau heads obs · Sat 17/07/2004 09:15

reports coming in from my sister in whakatane....
alot of flooding there...100mm overnight, after lots of rain yesterday,....and its still raining there...and strong NE winds...
so thats where the action is at the moment!

see here:
http://www.weatherobservatory.bravepage ... ather.html

Michael · Unread post by **Michael** » Sat 17/07/2004 09:23

Its quite unusual the clouds are now racing from the south but is still mostly clear must be close either to a wind change or the low centre

Manukau heads obs · Sat 17/07/2004 09:28

very light westerly here michael, clouds only drifting in from the west
i.e i think its just a local warming/air movement thing,....and you will only be looking at low clouds....which seem to be moving fast,....but only becuase they are low....?

Michael · Unread post by **Michael** » Sat 17/07/2004 09:38

Yes they are very low probaby less than 1000 feet,they are clearing off quickly,I seen them do that in a Wellington anticyclonic northerly

Manukau heads observer wrote:very light westerly here michael, clouds only drifting in from the west
i.e i think its just a local warming/air movement thing,....and you will only be looking at low clouds....which seem to be moving fast,....but only becuase they are low....?

Manukau heads obs · Sat 17/07/2004 10:43

they have a new marine forecast out for the auckland harbours:
Forecast issued at 1039hrs 17-Jul-2004 valid until 1159hr Sunday:
Manukau and Waitemata Harbours, Hauraki Gulf and Bream Head to Cape Colville
For the Manukau and Waitemata Harbours, the Hauraki Gulf and from Bream Head to Cape Colville: Southwest 10 knots rising to 25 knots gusting 35 knots during the afternoon and to 35 knots gusting 45 knots in the evening. Sea becoming rough in the afternoon and rising to very rough in the evening. Fair visibility in showers but some heavy with poor visibility this afternoon. Poor visibility in rain at times Sunday morning.

But why could they not have issued an ammended forecast like that at that update they did at 5am....I mean the weather stations in the auckland/northland area showed there was light winds from the south or west at that time....and no NEer....
what I am getting at is that the weather data is there, and some of it is live....but the forecasters, in wellington, are not using it.....i.e its a case of not looking out the window
what do others think?
or am i too critical?
(just disussing things openly thats all, there is always room for improvement)

GraemeWi · Unread post by **GraemeWi** » Sat 17/07/2004 10:56

I've seen similar issues with the Darwin forecasts - the locals are being hit by squall lines and their local met office has fine conditions forecast despite the rain hammering on their windows.

I'm intending on enjoying this nice bit of weather today - no matter what is forecast or happens.

Cheers,

G

Manukau heads obs · Sat 17/07/2004 11:07

watching the sequence,
http://www.weather-display.com/windy/gb/moviegms.htm

the cloud /front coming down from the north is going to wrap around the low out the west of auckland......i.e the rain is going to get very close to auckland....
and the latest MSLA maps from the metservice has the new combined low focusing right over the waikato....and so auckland could get a bit of a harmmering from the SW, depending on how much it deepens, and how quickly...

its real dynamic at the moment!

Achten · Unread post by **Achten** » Sat 17/07/2004 11:43

For interest sake, this was recieved this morning

Michael · Unread post by **Michael** » Sat 17/07/2004 12:07

Clouds back to the NE again.Like a millpond here

Willoughby · Unread post by **Willoughby** » Sat 17/07/2004 13:19

Looking at the current average wind speeds on the weather channel, everywhere in the North Island is mostly calm apart from Wellington and Whakatane where there are gales...

NZstorm · Unread post by **NZstorm** » Sat 17/07/2004 13:30

According to latest Met Service MSL Prognosis, the air pressure will be around 1000hpa by midnight tonight at Auckland. Currently still 1015hpa.

Wellington looks like its got a humdinger day for tonights big game.
Currently S 25kts, rain, 10C. Wind will rise to 35kts this evening.

spwill · Unread post by **spwill** » Sat 17/07/2004 14:58

Cold rain with a howling Southerly in Wellington when the Allblacks are playing is very unusual.

Rather cold here with not much sun.

Some Cu showers about this Morning. Can see rain out to our east.

Michael · Unread post by **Michael** » Sat 17/07/2004 15:09

Wind now showing indications to the Gale Direction

tich · Unread post by **tich** » Sat 17/07/2004 15:16

Forecast rain hasn't reached Chch yet, but it has stayed cold after a morning frost; thin cloud cover hasn't increased much. As I said on anpther thread, inland warm advection snowfall could be a possibility should rain move down while the air is still cold in Canterbury.

It also looks like a major cold outbreak/snowfall event in developing in southeast Australia today according to the discussions on the Aussie weatherzone forum - snowfalls already reported to about 600 metres in southern and central NSW and 150 metres in Hobart.

NZstorm · Unread post by **NZstorm** » Sat 17/07/2004 16:39

It also looks like a major cold outbreak/snowfall event in developing in southeast Australia

Hobart freezing level today around 800m. Thickness 5221.
Macquarie Island thickness 5176 with fzl near the surface.

NZstorm · Unread post by **NZstorm** » Sat 17/07/2004 18:35

The low is now visible in the cloud imagery out to the ENE of the North Island. The ECMRF has turned out to be bang on. The model was predicting the low to form east of the NI (not over it) and that is what has happened.

A State of Emergency has been declared to two areas in the eastern BOP this evening for flooding. Will be interesting to see what rainfall totals are recorded.

ricky · Unread post by **ricky** » Sat 17/07/2004 19:56

Where do you find the ECMRF model outputs Steven?

...always looking for new information sources

NZstorm · Unread post by **NZstorm** » Sat 17/07/2004 20:36

According to latest Met Service MSL Prognosis, the air pressure will be around 1000hpa by midnight tonight at Auckland

8pm AK baro 1013hpa. Met Service modelling looks out.

Where do you find the ECMRF model outputs Steven?

http://www.ecmwf.int/products/forecasts ... 2004071700!!/

Michael · Unread post by **Michael** » Sat 17/07/2004 21:53

lots of rain on the telly in welly tonight

Manukau heads obs · Sat 17/07/2004 22:30

ahh, but the upper level spiral you might find is further east of the actual surface low....

its still a NNE at gisborne....

reports from my sister in whakatane is that its the worst in at least 40 years....
they are bringing in sand bags by helicopter.....

SWer just starting to pick up here now, and the barometer is starting to drop here now too...

we will know tomorrow morning just how much the low deepens and where it ends up