General January Weather

[spwill]

I see both GFS and ECMWF have a Low affecting the north of the country at the weekend but quite a variation in timing between the two models, the ECMWF trend would have the low pass east of Northland Friday night/Saturday morning and move away quickly.

[Manukau heads obs]

M/S said it was almost out of the question yesterday Wilma could make it here...
WILMAAAA!!!!!

here she comes!

[Michael]

Fred Betty and Barney perhaps Mr Slate.
Theres anthony as well up there and ecmwf has some other one slamming into queensland but long way off.

M/S said it was almost out of the question yesterday Wilma could make it here...
WILMAAAA!!!!!

here she comes!

[NZstorm]

I heard NewtalkZB this morning running the story 'long hot summer starts today' and they have Bob Mcdavitt endorsing the story.

[Manukau heads obs]

La Nina will make that so for the SI...and the NI will be overall warmer , but does long hot summer cover occasional NW rain episodes?

[TonyT]

I heard NewtalkZB this morning running the story 'long hot summer starts today' and they have Bob Mcdavitt endorsing the story.

Thats hilarious

[Demchy]

Pardon me, but is anyone else seeing a disturbance forming to the NW of the NI in the outflow from Anthony?
Looks like Wilma is spinning up nicely too.

[dan]

Yes, do you mean this? Maybe some random Cb's.

[Demchy]

Thats it, it almost looked like Anthony leapfrogged down the outflow, am sure its just appearances but I see that his upper level cloud has all but disaapeared in the last few hours.

Certainly lots of convection up in the tropics, I am watching this site mainly...
http://www.goes.noaa.gov/sohemi/sohemil ... mscol.html

[Tim S]

Metservice must either not actually look at their own weather model or don't trust it at all, the latest SWW states:

On Friday a subtropical low is likely to move southeast to lie just east of Northland Friday night and move quickly away southeast Saturday morning.

yet their own weather model predicts this low to be around 600km away well to the North of Northland (the map is for 1am on Saturday morning, as the 7pm Friday night chart doesn't even have the low center on the map!):

90ba-12db92ead00-12dcc7e8600-12dba6a6a86.0.png

Please explain??!!

[spwill]

Metservice must either not actually look at their own weather model or don't trust it at all,

They will use more than one weather model and weather models can change with each run.

[Nev]

It shows on their hand-drawn 'Southwest Pacific Future Map' though.


Hmm, could be hope for one of us yet...

MetService - Severe Weather Outlook
Issued: 1:54pm Tuesday 25 January 2011

...Rain is all these areas is likely to clear quickly during Saturday morning as the low away.

[spwill]

MetService do mention there is considerable uncertainty about the anticipated track of this low.

[Michael]

Sometimes it appears they update one run then the next 6 hours you see it go "backwards" ie an older model then the next shows it as if the previous 6 hours was properly updated.

[Demchy]

This is probably quite a basic question but it appears that the warning text from the JTWC might be referring to what I mentioned earlier with the mention of a "Baroclinic Zone"

Is that term reasonably easy to explain?

Any help appreciated.

REMARKS:
250300Z POSITION NEAR 19.6S 160.5E.
TROPICAL CYCLONE (TC) 09P (ANTHONY) LOCATED APPROXIMATELY 865 NM
EAST-SOUTHEAST OF CAIRNS, AUSTRALIA HAS TRACKED SOUTH-SOUTHEASTWARD
AT 07 KNOTS OVER THE PAST SIX HOURS. TC 09P HAS WEAKENED OVER THE
PAST 06 HOURS AND HAS BEGUN TO SLOW AND TURN WESTWARD; MOTION OVER
THE PAST 03 HOURS WAS WEST-SOUTHWESTWARD. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY (MSI) DEPICTS A FULLY-EXPOSED YET WELL-DEFINED LOW-
LEVEL CIRCULATION CENTER (LLCC) WITH NO DEEP CONVECTION NEAR THE
SYSTEM. MSI ALSO SHOWS A WEAK BAROCLINIC ZONE JUST SOUTH OF THE
SYSTEM WITH A STRATOCUMULUS FIELD ADVECTING INTO THE NORTHWEST
PERIPHERY OF THE SYSTEM. A 242259Z TRMM IMAGE SHOWS THE
CORRESPONDING AREA OF DRY AIR ALONG THE PERIPHERY OF THE CIRCULATION
FROM THE SOUTH THROUGH THE NORTHWEST QUADRANT. TC 09P IS LOCATED
WITHIN A WEAK LOW-LEVEL STEERING ENVIRONMENT, HOWEVER, A DEEP
SUBTROPICAL RIDGE (STR) IS BUILDING OVER EASTERN AUSTRALIA AND IS
EXPECTED TO PROVIDE A WESTWARD STEERING INFLUENCE THROUGH THE
FORECAST PERIOD. MODEL GUIDANCE (ECMWF, GFS, NOGAPS, AND JGSM) IS IN
GOOD AGREEMENT EXCEPT FOR GFDN AND WBAR, WHICH INDICATE UNREALISTIC
TRACKS CONSIDERING THE BUILDING STR SOUTH AND SOUTHWEST OF THE
SYSTEM. THIS FORECAST IS CONSISTENT WITH THE PREVIOUS FORECAST AND
IS SLIGHTLY FASTER THAN THE MODEL CONSENSUS TO OFFSET GFDN AND WBAR.
TC 09P IS FORECAST TO WEAKEN WITHIN AN UNFAVORABLE UPPER-LEVEL
ENVIRONMENT AND IS EXPECTED TO DECREASE TO 30 KNOTS WITHIN THE NEXT
24-36 HOURS. THERE APPEARS TO BE A GOOD CHANCE THAT THE SYSTEM WILL
REGENERATE AFTER TAU 60 AS UPPER-LEVEL CONDITIONS IMPROVE AND THE
SYSTEM MOVES INTO A MOISTER ENVIRONMENT EAST OF CAIRNS. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 250000Z IS 13 FEET. NEXT WARNINGS AT
251500Z AND 260300Z. REFER TO TROPICAL CYCLONE 08P (WILMA) WARNINGS
(WTPS31 PGTW) FOR TWELVE-HOURLY UPDATES.//
NNNN

[Nev]

Was just about to post the above JTWC remarks on the 'Sth Pacific & Coral Sea TC Season' thread.

NOAA spotter-glossary definition:
Baroclinic Zone - A region in which a temperature gradient exists on a constant pressure surface. Baroclinic zones are favored areas for strengthening and weakening systems; barotropic systems, on the other hand, do not exhibit significant changes in intensity. Also, wind shear is characteristic of a baroclinic zone.

[Tim S]

Metservice must either not actually look at their own weather model or don't trust it at all,

They will use more than one weather model and weather models can change with each run.

Yeah but the SWW was issued less than an hour after the 7 day forecast model was issued, why would they issue two contradictory forecasts within an hour of each other?

I understand that MS use a multitude of sources for their SWW forecasts and their forecasts in general but it seems strange to me that they would issue one forecast that is completely different to what another forecast is showing.

Strangely the 7 day forecast has been a lot more accurate than their forecasts for Nelson of late, for example their forecast for Sunday only mentioned rain for us on Sunday a couple of hours after it started raining, however their 7 day rainfall outlook and their 3 day rainfall outlook both showed us getting rain in almost every run.

I'm not saying the 7 day rain forecast is going to be correct for this event (although it does agree with GFS) but it seems the MS don't have any confidence in their own forecast model, when it appears from here its doing a better job than them of late.

[Demchy]

... and in other news, is that an eye showing on Wilma now?

[Michael]

Yes it has an eye now.

... and in other news, is that an eye showing on Wilma now?

[Nev]

I've already posted a pic of Wilma's eye on the 'Tropical Cyclone Wilma' thread.

[spwill]

yet their own weather model predicts this low to be around 600km away

That model looks like the GFS, try this one http://www.metservice.com/national/maps ... future-72h

[Richard]

Great to see the topical South Pacific really coming alive after the last few years of boring cyclone seasons and its still early in the season yet.

Temp got to 30.5 before the arrival of the mod NW at about 3.00pm,the 15th 30+ for the summer so far,sitting on 29c now.

[Tim S]

yet their own weather model predicts this low to be around 600km away

That model looks like the GFS, try this one http://www.metservice.com/national/maps ... future-72h

So your telling me the model outlooks posted here: http://metservice.com/national/maps-rai ... cast-7-day aren't a metservice model but simply a republication of the GFS model? Surely if they did that they would have to disclose that, they do say they are 'computer generated' but don't specify they come from an external source.

[NZstorm]

The Met Service don't produce their own model. I have noticed them using ukmet.

Do BOM have their own model run or is it an NCEP product? I havn't taken much notice of their charts of late.

EDIT, I just read on weatherzone the BOM model is based on UKmet output.

[Manukau heads obs]

yes, I think the M/S like to use the Bracknel model?