Cyclone season 2016/17

Discussion in 'Weather' started by Claude Cat, Jan 28, 2016.

  1. jeffx@stormwise

    jeffx@stormwise Active Member

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  2. Jellybeans1000

    Jellybeans1000 Dedicated Member
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    Nice monsoon low, isn't this the one that develops into a cyclone later on.
     
  3. jeffx@stormwise

    jeffx@stormwise Active Member

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    Yeah same one ec was proging over the topE,the models really struggle @ l/range in afura sea. Very similar to the GOM,totally its unpredictable until the tc forms.
    HPA@998 is a tc.
     
  4. trappers

    trappers Safety not guaranteed
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    Both access and gfs are predicting a cyclone, broadly aligned on track, just ~72 hrs different in formation time. Why are the models struggling with the timing?
     
  5. trappers

    trappers Safety not guaranteed
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    Latest AccessG and GFS runs have a cyclone forming on 21st and 23rd respectively in about the same place (NE Kimberly) and then intensifying. Begining to show on the 72hr BoM Regional model too.
     
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  6. jeffx@stormwise

    jeffx@stormwise Active Member

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    [​IMG]

    [​IMG]

    With the current vorticity North and the UL divergence cmc model above may be on the money as to track and where the low forms, as for timing?

    CMC is a 4VAR model meaning its better than the GFS.
     
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  7. trappers

    trappers Safety not guaranteed
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    Well cmc has it forming over Darwin on Tuesday and tracking inland. Can you explain what a 4VAR model is and why it is better than GFS?
     
  8. jeffx@stormwise

    jeffx@stormwise Active Member

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    4D-Va models are higher resolution traps than the GFS as far as i know still is using combination of 3D/ and
    some 4D var input. The mathematical formulation of 4D-Var.is advanced nested modelling. EC/UKMET/ACCESS CMC all use 4D. Current GFS is be totally scraped and replaced with full 4Dvar by 2019..
     
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  9. Rush

    Rush Pool Room
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    In 3DVar observed data is 'assimilated' at a singe point in time. Initial conditions are constructed which minimise forecast error between the model and observations at this single point in time. '3DVar' stands for three dimensional data assimilation.

    In 4DVar you repeat the 3DVar process at multiple points in time. At the UKMO (and BoM) they assimilate hourly (for the global and regional models) and initial conditions are computed which minimise forecast terror between the model and observations over a six-hourly window. This helps ensure that the short term evolution of the model atmosphere matches the evolution of the real atmosphere as closely as possible, which helps reduce long term forecast errors.

    I believe the ECMWF have a 12-hourly assimilation window for their global model.

    4DVar has nothing to do with spatial model resolution. ACCESS-G and ACCESS-R use the same executables to compute the initial conditions, despite having different spatial grids.

    Here is some reading material : http://www.ecmwf.int/sites/default/files/Ass_cons.pdf
     
  10. jeffx@stormwise

    jeffx@stormwise Active Member

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  11. jeffx@stormwise

    jeffx@stormwise Active Member

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    I did read on a thread here acess use's old ukmet data thats a croc and also just recently,
    i seen a post claiming the EC and UKMET are almost the same model thats even a bigger croc..

    ACCESS model.

    The offshore oil and gas industry in Australia's northwest operates in a harsh and remote environment, in which tropical cyclones pose a significant risk to safe and efficient operations. Improved forecasts offer a significant opportunity to mitigate this risk, and to this end we are developing a new tropical cyclone NWP system for the northwest. The new system builds on our experience with the existing operational system ACCESS-TC, but differs from it in being on a larger and fixed domain instead of relocatable, by running twice-daily instead of only when a cyclone has formed, by having higher resolution (4 km grid instead of 11 km), by forecasting to 5 instead of 3 days, and by including a one-way coupled wave model. The system is called ACCESS-TCX, with the X standing for “extended”, and aims to address specific issues around forecast length, tropical cyclogenesis and wave prediction. We have tested various ACCESS model configurations for this purpose over both northern Australia and the northwest Pacific Ocean, nested in either the global or regional ACCESS models. Intensity forecasts are substantially better than our existing tropical cyclone model, due to the combination of higher resolution and 4D-Var initialisation. Track forecasts are presently slightly worse, which may indicate that further tuning and calibration of the assimilation is required. We have also found that the system performance is sensitive to model resolution, physics, initial condition and lateral boundary conditions. The introduction of a new dynamical core to the model illustrated forecast sensitivity to the model dynamics, with the newer dynamical core producing stronger TCs. While we have demonstrated that ACCESS-TCX has the potential to provide good TC track and intensity forecasts, development continues to determine the best combination of model dynamics, physics, and data assimilation.
     
  12. Jellybeans1000

    Jellybeans1000 Dedicated Member
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    ACCESS is based on UKMO models.
    EC and UKMO are not "almost the same model" but they do share quite a lot of initialisation data.
    Maybe you should quote those posts?
    4D Var doesn't always mean higher resolution, but models that have it tend to have a higher resolution.
    Thanks for the heads up on ACCESS-TCX, sounds interesting.
     
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  13. Rush

    Rush Pool Room
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    Read the last slide. Spatial resolution is irrelevant (as I've mentioned previously). 4D-Var produces a flow dependent forecast covariance error matrix, 3D-Var doesn't.

    Don't confuse atmospheric model version and resolution with assimilation methodology. Newer atmospheric models have higher spatial resolution than the ones they replace, thus it is likely that new models use 4D-Var instead of 3D-Var.

    A 4D-Var atmospheric model with low spatial resolution could beat a 3D-Var model with higher resolution.

    In the UKMO (and BoM) a forecast consists of three steps. Observation processing (using the OPS executable), Variational Assimilation (i.e 4D-Var using the VAR executable) which generates a set of initial conditions for the forecast atmospheric model (the UK Unified Model executable).

    PS I began development of ACCESS-TCX for Jeff Kepert.
     
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  14. jeffx@stormwise

    jeffx@stormwise Active Member

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    http://forums.ski.com.au/xf/threads/sizzling-summer-thread.76883/#post-3179180

    Unified model is not similar to the EC., please clarify how it is with method.
     
  15. jeffx@stormwise

    jeffx@stormwise Active Member

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    Sorry but 3Dvar is old school, and that's why the MU is getting scrapped. Only a few country have the super computers to run 4DVAR models, the bom upgraded and runs the model.
     
  16. Jellybeans1000

    Jellybeans1000 Dedicated Member
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  17. Jellybeans1000

    Jellybeans1000 Dedicated Member
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    The BOM upgraded because it uses UKMO Models which are 4DVar.
     
  18. jeffx@stormwise

    jeffx@stormwise Active Member

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    I don't understand your point, It states above in the posts the BOM upgraded to 4var. I recollect telling you quite some time ago on a snow thread access is using ukmet core. If you know your stuff then you know GFS only use 4DAR on the FULL resolution model thus the difference in mslp and hpa..

    Also to the best of my knowledge the UKMET unified model ,is not the same as the UKMO
     
  19. jeffx@stormwise

    jeffx@stormwise Active Member

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    Sent a email to a friend who fix's modelling errors for noaa waiting for a response on what team did the programming on the Access upgrade. When i have the answer i will post the team..
     
  20. jeffx@stormwise

    jeffx@stormwise Active Member

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    That's not a answer showing why or how, please explain the reasoning behind your claim.

    And while your at it please explain where you believe a cyclone will form and the reason why
    and please dont just regurgitate what the current models show.
     
    #170 jeffx@stormwise, Dec 18, 2016
    Last edited: Dec 18, 2016
  21. Jellybeans1000

    Jellybeans1000 Dedicated Member
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    Yeah ACCESS does use a UKMO core, what is your point mentioning GFS into all of this?
    I was wrong. I make mistakes.
    Cyclones (Tropical) will form if they have access to warm seas (ie Tropics), instability, moisture, wind shear, part of an existing low pressure system and enough of the Coriolis Effect. Mate you just need to chill out a little, and we can get back to forecasting the weather.
     
  22. jeffx@stormwise

    jeffx@stormwise Active Member

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    Xingbao Wangy, Y Xiao D Kepert N. E. Davidson.
     
  23. jeffx@stormwise

    jeffx@stormwise Active Member

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    FYI
    UKMET model =UNIFIED
    UKMO model = GloSea5

    I think jelly you are confusing the access core model with the bergen ocean model .
    I dont need this shite jelly so over to you its all yours.
    .
    WOW traps you really opened a can of worms here.:)

     
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  24. Jellybeans1000

    Jellybeans1000 Dedicated Member
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    FYI UKMET and UKMO mean the same organisation. Thanks anyway though
     
  25. Seafm

    Seafm Dedicated Member
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    FIFY
     
  26. Rush

    Rush Pool Room
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    The 'ACCESS upgrade' is done by the UK Met Office. All the BoM do is download the source code, create suites to use our observational data bases (which use the MARS database developed at the ECMWF) on regional models in our part of the world, run the suite on our supercomputer (slightly different configuration to UKMO) and then archive the data onto our mass storage. Raw model output is then post-processed and handed to the forecasters to stuff it up ;)
     
    #176 Rush, Dec 18, 2016
    Last edited: Dec 18, 2016
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  27. Rush

    Rush Pool Room
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    You're getting confused. The UKMO 'Unified Model' a.ka. UM refers to an atmospheric model that can be used for weather forecasting, seasonal forecasting and climate projections. The physical and computational core is the same, however the parameterizations and physical timescales change depending on the application. However its still the same code and executable, thus it is 'Unified'.

    GloSea5 refers to the UKMO seasonal forecasting model, which uses the UM coupled to the NEMO ocean model to produce seasonal forecasts. This is implemented in the BoM as 'ACCESS-S'. The BoM however is using a different ensemble generation scheme and will in time use a local soil moisture assimilation scheme, and maybe some other goodies if I get around to it.
     
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  28. Jellybeans1000

    Jellybeans1000 Dedicated Member
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    When will ACCESS-S be released to the public? It looks really good from what I have seen.
     
  29. trappers

    trappers Safety not guaranteed
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    Sorry ;) I know some stuff about fluid mech / cfd but very little about met context, sorry if the question opened a can o!!

    Regardless, to now clearly on accessr over Kimberly. Seems little doubt something will develop.

    Has now been designated 90S too :)
     
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  30. Rush

    Rush Pool Room
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    Hopefully public products from ACCESS-S will be available Q2 2017.
     
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  31. trappers

    trappers Safety not guaranteed
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    Really warm SSTs 31 °C +


    MW images of 90S show some decent convection already.


    Really low v shear


    and tons of water vapour associated with a strong monsoonal trough ...


    All the ingredients are there for rapid and significant intensification. The only negative I can see is land interaction.

    I cant see any really strong steering influences (can anyone else?), but most of the models have it moving poleward so land interaction and loss of warm SSTs seems likely to kill it.

    But given I cant see any strong steering influences, what are the chances the models will get track wrong?
     
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  32. trappers

    trappers Safety not guaranteed
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  33. trappers

    trappers Safety not guaranteed
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    If you watch the low level cloud in the jospeh bonaparte gulf it is moving north west, but the low level cloud to the north of it is moving east ... could it hint at a LLCC under the convection already?
     
  34. jeffx@stormwise

    jeffx@stormwise Active Member

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    I know what it stands for, And also all the access lpha6 source code is available, a great resource .

    Unlike a few others about to dry up.
     
  35. Claude Cat

    Claude Cat Gone Fishing
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    Let keep this on topic - cyclone discussions for 2016;
    Happy to open up another topic regarding the models (it's interesting stuff) :D
     
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  36. Claude Cat

    Claude Cat Gone Fishing
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    EC and CMC still think we're in for some action. Although timing is somewhat different.

    [​IMG]

    [​IMG]

    Less likely on GFS on latest runs.
     
  37. jeffx@stormwise

    jeffx@stormwise Active Member

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    Shows a large monsoonal low.
    [​IMG]


    [​IMG]

    The Full resolution GFS , shows it as a mid-level circulation monsoon low. with no surface
    pressure just a weak mid-l @ 30hrs
    ON sat looking closely it would appear the low in question is just off the northern coastline.
     
    #187 jeffx@stormwise, Dec 19, 2016
    Last edited: Dec 19, 2016
  38. trappers

    trappers Safety not guaranteed
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  39. Jellybeans1000

    Jellybeans1000 Dedicated Member
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    [​IMG]
    [​IMG]
    Cyclone still looks dangerous, but there seems to be a time and strength difference with EC and GFS.
    EC thinks the cyclone will be deeper than GFS, coming from the monsoon low currently near Darwin.
    GFS thinks it comes from the low to the South of Bali.

    Thanks, need to proofread my posts!
     
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  40. trappers

    trappers Safety not guaranteed
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    Ignoring the models, the animated sat of the low south of Bali looks much MUCH more developed than the one in the bonaparte gulf. Some outflow clearly visible on it too.
    Animated sat image here

     
  41. trappers

    trappers Safety not guaranteed
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    Looking at the models they are all over the place. CMC has the two lows developing and then combining for a monster cyclone on Christmas eve! :(

     
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  42. jeffx@stormwise

    jeffx@stormwise Active Member

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    I was looking at the other one Traps on the gfs model 12.10S 129.44E the big broad circulation.
    Top NE corner JBG.
     
  43. jeffx@stormwise

    jeffx@stormwise Active Member

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    TIP
    You cant read cyclone strength off GFS MSLP 500mb plots, that's not the surface pressure.
     
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  44. jeffx@stormwise

    jeffx@stormwise Active Member

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  45. Jellybeans1000

    Jellybeans1000 Dedicated Member
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    [​IMG]
    [​IMG]
    The 00z run shows GFS with the low from South of Bali coming down. EC shows that low and the low near Darwin combining. But they aren't consistent with the dates.
     
  46. jeffx@stormwise

    jeffx@stormwise Active Member

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    [​IMG]

    CYCLONE Darwin @40hrs.
    Humm i forgot something must fix deltawx .
     
  47. POW_hungry

    POW_hungry Addicted Member
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    Perth Met office has pinned the tail on the donkey, on this evening's TC Watch outlook.

    [​IMG]
    More HERE
     
  48. jeffx@stormwise

    jeffx@stormwise Active Member

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    [​IMG]


    The 2
     
  49. jeffx@stormwise

    jeffx@stormwise Active Member

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    EVERE WEATHER WARNING
    for DAMAGING WINDS and HEAVY RAINFALL
    For people in the
    Daly,
    Tiwi and parts of the
    Arnhem districts.


    Issued at 4:44 pm Monday, 19 December 2016.

    WEATHER SITUATION:
    A developing tropical low in the Timor Sea, west of Bathurst Island, is combining with an active monsoon to produce squally showers and thunderstorms.

    DAMAGING WIND GUSTS of around 90 km/h are expected to develop late tonight or early Tuesday morning around the Tiwi District and coastal areas of the northern Daly and northwest Arnhem Districts.

    HEAVY RAIN which may lead to FLASH FLOODING is likely to affect the Tiwi and Daly Districts and coastal areas of the northwest Arnhem Districts.





    Locations which may be affected include Darwin, Jabiru, Cooinda, Maningrida, Wadeye, Wurrumiyanga, Nauiyu, Batchelor, Adelaide River, Milikapiti, Pirlangimpi and Milingimbi.





    The Northern Territory Emergency Service advises that people should:
    * secure loose outside objects and seek shelter when conditions deteriorate
    * pull over if it is raining heavily and you cannot see, park with your hazard lights on until the rain clears
    * avoid driving into water of unknown depth and current
    * create your own sandbags if there is flooding, by using pillow cases or shopping bags filled with sand and place them around doorways to protect your home
    * stay away from flooded drains, rivers, streams and waterways
    * ensure pets and animals are safe
    * be prepared in case of power outages, have an emergency kit with a radio, torch, spare batteries and first aid kit
    * for emergency help in floods, storms and cyclones, contact the NTES on 132 500. For more safety tips visit www.securent.nt.gov.au



    The next Severe Weather Warning will be issued by 11:00 pm ACST Monday.
     
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  50. nfip

    nfip Part of the Furniture
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    and bunker down Nadi !
     
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