Dorian wind speed and pressure



  • [31-Aug@16:30 UTC] Many news outlets are reporting that Dorian is currently nearing "Cat 5" intensity. But, using the Windy weather picker (in "Winds" mode), the max surface winds appear to be about 71mph (on the North side) and pressure (in "Pressure" mode) at the eye is 1004mbar (30 minutes ago it was 980mbar).

    In other words, Dorian seems to be barely Cat 1 intensity as currently rendered by Windy.

    What is going on? Is the Windy weather picker broken? Or is the strength of this storm being over-hyped by the mass media?


  • Sailor

    @af4ex

    This question has been raised many times, almost for every hurricane:

    https://community.windy.com/topic/4415/why-is-wind-speed-in-hurricanes-so-wrong

    In this long list of articles, some explain perfectly why global models can not predict the intensity of hurricanes. The others you can forget them.
     I would like to add that the ECMWF model, which is Windy's default model, uses the average wind speed over 10 minutes. The Saffir-Simpson scale is based on a sustained 1-minute wind which is about 15% higher.
     Then, if you compare GFS, ECMWF, and NAM, the higher the model resolution, the closer the speed to NHC's. If they send recon flights to hurricanes, there is a reason. Otherwise, they would only use weather models.
     For me, at least, the trajectory prediction by models is quite good and especially by ECMWF.



  • This is showing a 29 MPH wind near the center of hurricane Dorian. I installed this app to give me hurricane info. Right now, Dorian is a Cat 5 at 175 MPH winds.

    This app is doing me no good with such ridiculous "data".


  • Moderator

    @stanard Well 29mph is not that ridiculous because the wind at the very center of it should be equal to zero :)

    Just read the post above.
    No models can depict the real conditions in that kind of storms except very specialized ones which are used by scientists, running only in the area of the storm. Can you imagine? The wind changes 360 degrees in an area of 10km, from 0 to 180 mph and with a huge pressure drop... That is insane. No super computer can modelize this. We still need planes to investigate storms like that to really know what's happening.

    Moreover windy is not intended to predict wind in such phenomenom and I swear it's very accurate in your normal people life.

    ...

    Pray for the Bahamas... I was in the eye of hurricane Irma and I know that cat 5 hurricanes are some kind of monsters which haunt you forever, especially if experienced on a small island that is flat and not big enough to reduce wind speed and stop the convection... And on top of that extremely vulnerable to waves and storm surge... It's definitely a life threatening hurricane and some people are going to die there because of it. It's terrible to know it and having nowhere to run like on the "mainland" where you can follow evacuation routes.

    Stay safe!


  • Moderator

    @stanard said in Dorian wind speed and pressure:

    This is showing a 29 MPH wind near the center of hurricane Dorian. I installed this app to give me hurricane info. Right now, Dorian is a Cat 5 at 175 MPH winds.

    This app is doing me no good with such ridiculous "data".

    Windy does not create any forecast data but instead only visualises forecast and actual data received from various third party providers.

    Additionally, it is necessary to be sure and understand the difference between Forecast and Observed data.

    Unfortunately there does not seem to be any Weather Station sending (live) Reported Wind data from that part of the Bahamas, or the Weather Station is already damaged, which often happens during hurricanes.

    However, I still do not see the data that you mention. The data that I see from around 1 hour ago is displaying 156kn.

    This compares closely to the all the various data from the National Hurricane Center here: https://www.nhc.noaa.gov/cyclones/

    2019-09-01 18.16.56 - Windy_ Hurricane tracker - Google Chrome.jpg


  • Moderator

    National Hurricane Center here: https://www.nhc.noaa.gov/cyclones/

    Hurricane Dorian Forecast Advisory
    https://www.nhc.noaa.gov/text/refresh/MIATCMAT5+shtml/011455.shtml

    HURRICANE DORIAN FORECAST/ADVISORY NUMBER 33
    NWS NATIONAL HURRICANE CENTER MIAMI FL AL052019
    1500 UTC SUN SEP 01 2019

    ESTIMATED MINIMUM CENTRAL PRESSURE 913 MB
    EYE DIAMETER 15 NM MAX SUSTAINED WINDS 155 KT WITH GUSTS TO 190 KT.
    WINDS AND SEAS VARY GREATLY IN EACH QUADRANT.

    Hurricane Dorian Wind Speed Probabilities
    https://www.nhc.noaa.gov/text/refresh/MIAPWSAT5+shtml/011456.shtml

    HURRICANE DORIAN WIND SPEED PROBABILITIES NUMBER 33
    NWS NATIONAL HURRICANE CENTER MIAMI FL AL052019
    1500 UTC SUN SEP 01 2019

    AT 1500Z THE CENTER OF HURRICANE DORIAN WAS LOCATED NEAR LATITUDE 26.5 NORTH...LONGITUDE 76.8 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 155 KTS...180 MPH...285 KM/H.

    ...and Windy is displaying latest data of 156kn


  • Moderator

    Here is further detailed information regarding the modelling and forecasting of Hurricane Dorian:

    http://www.severe-weather.eu/tropical-weather/update-a-very-powerful-cat-4-hurricane-dorian-continues-towards-florida-but-latest-trends-suggest-it-may-shift-towards-se-us-coast/

    And some quotes:

    @www.severe-weather.eu:

    NOAA hurricane hunters continue scanning the hurricane with several aircraft, gathering important data needed for modeling the future track of Dorian

    @www.severe-weather.eu:

    The future track of Dorian based on NHC forecast suggests it may eventually even miss the previously forecast track which was pointing towards its landfall in ESE Florida on Monday. Latest trends put Dorian’s track towards the SE US coast by mid next week. Various model track trends are attached as well – quite a significant change from yesterday’s forecast and that said, the exact track of Dorian is yet pretty uncertain!


  • Moderator

    And the most recent update:

    http://www.severe-weather.eu/tropical-weather/looking-ahead-future-track-of-hurricane-dorian-for-bahamas-and-florida/

    @www.severe-weather.eu:

    The future track of Dorian is now generally well defined: it is expected to track due west across the northern Bahamas for the next 24 hours, until late on Monday (UTC). It will then make a very sharp northward turn, most likely tracking some distance off the eastern coast of Florida for the next 48 hours, until early on Thursday. There is still some uncertainty about its exact track, with some models pushing it close to the S-CNTRL parts of the eastern coast of Florida.

    @www.severe-weather.eu:

    Hurricane Dorian will remain an extremely powerful Category 5 hurricane as it tracks over the northern Bahamas. Expect similar destruction as seen during first landfall on Abaco Island today. After the northward turn there is still considerable uncertainty in its exact track and to a somewhat lesser extent its strength. The effect on Florida is still not certain, however, this is still a potentially extremely dangerous system for Florida

    I hope that this information helps give a better understanding of the difficulties involved in Modelling and Forecasting Hurricanes, especially the extremely powerful ones which often behave erratically.


  • Moderator

    Some general notes to add to this thread:

    Windy does not create any forecast data but instead only visualises forecast and actual data received from various third party providers.

    There are many useful but also complex and expert level tools and data available via Windy, therefore the user must always take care:

    • To understand what information they are displaying and viewing
    • To understand from where and when the information was sourced
    • To understand what this information actually means

    Comparing Forecast data with Actual data can be a common mistake.

    Hope this helps :)


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