Tropical Cyclone Marcia May reach a Category 5 storm

tropical-cyclone-marcia-category-5

Tropical Cyclone Marcia Category 5

 

tropical-cyclone-lam-category-4

Tropical Cyclone Lam Category 4 heading for the Northern Territory

 
27381The Bureau of Meteorology has revised its forecast for Tropical Cyclone Marcia which is currently off the Central Queensland coast. The forecast has been revised in which it is expected that the storm may reach a Category 5 system before it crosses the coast.

The Bureau forecast model suggests that the storm should track south west and cross the coast somewhere between Mackay in the north and Gladstone to the south. Such a landfall would place the regional city of Rockhampton and the smaller centre of Yeppoon at risk.

The storm has potential to cause disruption to the region. This is already a strong storm and a weather station well off the coast close to the eye wall being Creal Reef recorded peak wind gusts of 189 km/h between 6.07 pm and 6.14 pm. In additional the lowest pressure recorded was 977.4 hectopascals.

This shows that this is a significant storm capable of causing considerable damage.

Comments

comments

  • Harley Pearman

    The revised forecast model by the Bureau of Meteorology is attached.

  • Harley Pearman

    When analysing some weather data from Tropical Cyclone Marcia, it is identified that some very unusual data was collected from the Creal Reef Weather Station that should be observed and recorded.

    In addition to a series of peak wind gusts of 189 km/h between 6.07 pm and 6.14 pm 19/2/2015, it is also identified that the air temperature was fluctuating wildly.

    Is it equipment failure however the weather station survived the onslaught and continued to record.
    Is it strong downbursts of cold wind.

    This raises questions as to what was occurring to cause the temperature swings as shown on the data. Some samples include:-

    Weather Station – Creal Reef ID 200736 – Latitude 20.53 S and Longitude 150.38 E (Height 1.7 metres ABS) for 19/2/2015.

    5.30 pm – Temp was 26C (Peak wind gust of 167 km/h).
    6.00 pm – Temp was 11.9C (Peak wind gust of 187 km/h).
    6.07 pm – Temp was minus 20.3C (Peak wind gust of 189 km/h).
    6.09 pm – Temp was 24.9C (Peak wind gust of 189 km/h).
    6.14 pm – Temp was Minus 30.2C (Peak wind gust of 189 km/h).
    6.15 pm – Temp was 24.3C (Peak wind gust 183 km/h).
    6.17 pm – Temp was Minus 15C (Peak wind gust of 183 km/h).
    6.20 pm – Temp was 21.7C (Peak wind gust of 183 km/h).
    6.30 pm – Temp was 24.7C (Peak wind gust of 178 km/h).

    For this 90 minute period, this is unusual in terms of temperature changes.

    The wind is from the SW direction.

    This continues throughout the evening period as the eye wall was close by.

    Another wild temperature swing occurs around 7 pm as follows:-

    7 pm – Temp was 23.6C (Peak wind gust of 172 km/h).
    7.03 pm – Temp was Minus 13.5C (Peak wind gust of 172 km/h).
    7.04 pm – Temp was 22.7C (Peak wind gust of 172 km/h).

    7.16 pm – Temp was Minus 10C (Peak wind gust of 178 km/h).
    7.17 pm – Temp was 1.5C (Peak wind gust of 178 km/h).

    Some wild temperature swings are observed around 7.30 pm:-

    7.30 pm – Temp was Minus 14.8C (Peak wind gust of 172 km/h).
    7.31 pm Temp was 8.1C (Peak wind gust of 185 km/h).
    7.36 PM Temp was Minus 48.8C (Peak wind gust of 185 km/h).
    7.43 pm Temp was 11.8C (Peak wind gust of 180 KM/H).

    This is the last plus 180 km/h winds recorded at this station.

    This activity continues through to 9.58 pm when this fluctuation ceases and the temperatures stabilizes around 25C.

    9.57 pm – Temp Minus 30.8C (Peak wind gust of 154 km/h).

    By 10 pm, the temperature returns to 25.4C with winds dropping steadily to 150 km/h.

    Winds drop below 100 km/h (Peak wind gusts after 12.02 am is 109 km/h) and no further gusts over 100 km/h.

    Air pressure during this period is as low as 977.4 hectopascals at 6.47 and 6.48 pm (Lowest reading observed).

    During this time, it is clear the eye wall has passed very close to this station and this station survived two bursts of plus 180 km/h winds.

    The unusual temperature fluctuations is interesting because the eye wall passed very close to another weather station – Middle Percy Island and this temperature fluctuation was not observed even though wind gusts reached 208 km/h.

  • Harley Pearman

    Prior to Tropical Cyclone Marcia coming ashore, the eye wall passed close to a second weather station which has also survived and given a great insight to wind speed just prior to land fall.

    This station known as Middle Percy Island presents an excellent insight into what was occurring as follows:-

    Middle Percy Island Weather Station ID 200001 Latitude 21.66 S and Longitude 150.27 E (Height 208.7 metres ABS) – For the 20/2/2015.

    12.40 am – First wind gust of 100 km/h from the SSE.
    2.26 am – Peak wind gusts of 139 km/h with sustained winds of 107 km/h.
    2.38 am – Peak wind gust of 150 km/h with sustained winds of 117 km/h.
    2.50 am – First plus 180 km/h peak wind gust (182 km/h) with sustained winds of 128 km/h.
    3.00 am – Peak wind gust of 165 km/h with sustained speeds of 133 km/h.
    3.09 am – Peak wind gust of 176 km/h with sustained winds of 141 km/h.
    3.28 am – Peak wind gust of 180 km/h with sustained winds of 145 km/h.
    3.30 am – Peak wind gust of 189 km/h with sustained winds of 145 km/h.
    3.39 am – Peak wind gust of 196 km/h with sustained gusts of 154 km/h.
    4.00 am – A 200 km/h wind gust is recorded with sustained winds of 156 km/h.
    4.17 am – Peak wind gust of 196 km/h with sustained winds of 141 km/h.
    4.24 am – A 200 km/h wind gust is recorded with sustained winds of 139 km/h.
    4.30 am – A 208 km/h wind gust is recorded with sustained winds of 141 km/h.
    4.46 am Peak wind gust of 176 km/h with sustained winds of 135 km/h.
    4.49 am Peak wind gust of 170 km/h with sustained winds of 130 km/h.
    5.00 Peak wind easing to 159 km/h with sustained winds of 113 km/h from the SW.

    Air pressure is as low as 971.6 hectopascals at 3.39 am.

    This station has survived 3 bursts of plus 200 km/h winds with a peak gust to 208 m/h. It is known that this storm without speculating on probable wind gusts had confirmed wind gusts to 208 km/h.

    The lowest temperature recorded to 5 am was 24.1C and winds swung from the SSE to SW during this period. The eye passed to the east of this recording facility but would have been close by.

    Humidity levels during this period was recorded at 100%.

  • Harley Pearman

    The coastal town of Yeppoon was hit hard by this system. Data from the local weather station being – Yeppoon The Esplanade – Latitude 23.14 S and Longitude 150.75 E (Height 5.5 metres ABS) shows the following:-

    Wind speeds

    10.18 am – First 100 km/h wind gust – Recorded at 111 km/h.
    10.30 am – Wind gust of 113 km/h.
    11 am – wind gust of 130 km/h.
    11.25 am – Wind gust of 141 km/h with the first sustained wind speed exceeding 100 km/h (102 km/h).
    11.30 am – Wind gust of 141 km/h.
    11.53 am – Peak wind gust of 146 km/h with sustained winds of 117 km/h.
    12 noon – Peak wind gust of 148 km/h with sustained winds of 120 km/h.
    12.30 pm – Peak wind gust of 156 km/h with sustained winds of 115 km/h.
    1 pm – Peak wind gusts of 146 km/h with sustained 115 km/h winds.
    1.21 pm – Peak wind gusts of 128 km/h with sustained wind dropping to 98 km/h.
    1.30 pm – Peak wind gust of 119 km/h.
    1.38 pm – Peak wind gust of 113 km/h.

    Winds drop below 100 km/h after 1.38 pm.

    The town was hit with 100 km/h plus winds for a period of 3 hours and 20 minutes.

    Wind direction varied from ENE throughout this period to north and this indicates the eye wall to the west of town towards Rockhampton.

    The lowest air pressure recorded with a now weakened system was 985.5 hectopascals at 12.30 pm.

    The town of Yeppoon also experienced rainfall of 122.8 mm for the 24 hours till 9 am 20/2/2015 and a further 88.2 mm until 6 pm 20/2/2015 (Combined tally of 211 mm from the storm).

    Rockhampton

    It appears the eye of a weakened tropical cyclone passed over the city which is showing up on the local weather station as follows:-

    11.43 am – First wind gust to 100 km/h.
    12.13 pm – Wind gust of 102 km/h
    12.22 pm – Wind gust of 111 km/h.
    12.30 pm – Wind gust of 111 km/h.
    12.50 pm – Wind gust of 113 km/h.
    1 pm – Wind gust of 100 km/h.

    Wind direction is from the east south east.

    There is a lull in wind and at 1.23 pm, winds are only gusting to 35 km/h and rainfall has eased.

    2.22 pm – Wind gust of 100 km/h.
    2.30 pm – Wind gust of 100 km/h.
    2.45 pm – Wind gust to 109 km/h.
    3 pm – wind gust to 113 km/h and this is the last 100 km/h wind gust.

    Winds are gusting from the west during this period and start to ease after 3.12 pm.

    The city weather station records 109.4 mm of rain to 9 am 20/2/2015 and a further 96 mm to 6 pm with a period of calm after 1 pm.

    Samuel Hill Aero

    This weather station closer to where the storm made landfall shows a maximum wind gust of 170 km/h at 9.36 am. This station records 181.2 mm of rain to 9 am 20/2/2015 and a further 88.2 mm to 2 pm where it eases off (A combined total of 269.4 mm).

    These are the highest verified wind gusts that I can find that are not speculative but verified by weather stations. If higher winds occurred, then they have occurred over areas but not recorded by functioning weather stations.

  • Harley Pearman

    Some rainfall tallies up until 9 am 20/2/2015 for this system includes the following:-

    Samuel Hill – 181 mm.
    Pacific Heights – 172 mm (Part of Yeppoon area).
    The Glen TM – 143 mm.
    Marlborough – 128 mm.
    Yeppoon – 122.8 mm.
    Williamson RAAF – 110 mm.
    Yaamba – 107 mm.

    After 9 am to 6 pm 20/2/2015, rainfall figures include:-

    Mt Seaview Alert – 176 mm.
    Callide Dam – 160 mm.
    Mundic Gully – 153 mm.
    Cedar Vale Alert – 106 mm.

    The areas and localities are south of Rockhampton and Yeppoon.

    The plot showing the rainfall is provided below for the 24 hours to 9 am 20/2/2015.

    This would event would have caused disruption and some damage such as power loss and I am aware of power loss and some damage around Yeppoon with emergency repair crews addressing the situation.

  • Harley Pearman

    I will add one further comment in relation to the Creal Reef Weather Station. When considering the temperature data fluctuations that was recorded, it does appear that the station was giving inaccurate temperature data at the time. The problem noted is that the temperature data is not accurate for the permanent records. This appears to be the only explanation for the unusual temperature swings noted at this station.

    In relation to wind, I have seen media reports of wind gusts reaching 295 km/h and even one report suggesting a wind gust of 324 km/h at Yeppoon. However when pouring over data from the weather stations in the path of the storm, I have not seen any evidence of wind gusts reaching this level. Thus far, I will not document this unless demonstrated by recording instruments.

    This leaves the highest confirmed wind gust by a recording instrument that I can find at 208 km/h.

    This storm has caused flooding in low lying areas and a sizeable clean up to commence around Rockhampton and Yeppoon and areas further south. I will report on the rainfall recordings in a separate post.

  • Harley Pearman

    Jeff thank you.

    I remember Tropical Cyclone Yasi. I remember being logged into a weather station close to the eye but it malfunctioned and stopped recording. I also remember obtaining a verified wind gust on the data set of approximately 183 KM/H (Give or take on either side) just before the instrument failed. I could not find anything higher than that.

    Since that event, I have been wondering as to where did the 285 km/h top wind gusts come from considering that I could not find anything to verify that level of winds. I never did see anything to verify this level of wind.

    It appears the same has occurred again. I am raising questions as to where are the incredible wind gusts coming from or what source. I have not seen any evidence of wind gusts over 208 km/h.

    In this storm, the core passed very close to two weather stations and the wind speeds appear to be consistent. There was a third station that was reasonably close too (170 km/h). The good news this time is that the two stations closest to the eye survived the onslaught without total failure.

    It is worth trying to find out if possible as to how are the 285 km/h winds are being obtained.

    I also saw a report suggesting winds of 200 km/h were impacting or likely to impact Rockhampton. However the maximum wind gust that I can verify on their instrument are two peak wind gusts of 113 km/h.

    I did see a media report of a 324 km/h gust at Yeppoon which is inconsistent with the official weather station being a single gust of 156 km/h at 12.30 pm and nothing higher. Notwithstanding that, there is damage in that area including some 1,500 power lines down but the damage is not that severe.

  • Jeff Brislane

    Hi Jimmy,

    No i haven’t. The BoM is using some sort of scale which corresponds air pressure with approximate wind speeds which you can ascertain by the wording in the report on cyclone Yasi where they say that the pressure of 929 hPa suggests wind gusts of approximately 285km/h. Seeing that there has been no reports of the pressure in Marcia dropping to 929 hPa i’m assuming that the wind speeds of Marcia do not support the Category 5 rating.

    I do not know where the BoM get’s it information to obtain a rating of category 5 for Marcia as it made landfall but I suspect it is being made solely on satellite imagery and not on any verifiable surface based measurements or either wind speed or barometric pressure. The only other way they could be measuring it is with radar and I doubt that would give true surface level wind speed indications unless the doppler was actually close to the core.

    I honestly hate BoM bashing when it comes to cyclones but I can’t help point out the inconsistencies in observations versus reported intensities of cyclones, meteorology is after all a science.

  • Jeff Brislane

    How interesting that now we have a comparible cyclone this season with which to compare Marcia! TC Olwyn has clipped Learmonth overnight with it’s eye wall and the station there recorded wind gusts to 180km/h and a central pressure of 969.5 hPa. I was forecast correctly as a category 3 system and it very closely matches Marcia in intensity.

    Do I need to say anything else? The BoM is playing with fire by over rating Coral Sea cyclones and this needs to stop. What we saw last night was an accurate forecast with no hype just facts and a cyclone measured that agreed with the forecast.

    Now they have played the Cat 5 card with Marcia though I can’t see how they can take it back.

  • Harley Pearman

    Jeff, there is a preliminary report now available on Tropical Cyclone Marcia at the Bureau of Meteorology website which is interesting to read. The critical summary of that report to note are:-

    Maximum sustained wind 205 km/h.
    Maximum wind gust – 295 km/h.
    Lowest pressure – 930 Hectopascals.
    Category rating – 5.

    It does not provide any new information.

    Problem is, there are no verified accounts in the statement showing the excessive wind speeds. The statement confirms the highest wind gust recorded of 208 km/h at Middle Percy Island. I do not know where the higher wind gusts written about is coming from.

    Tropical Cyclone Olwyn does indeed have verified wind gusts of 180 km/h. It seems this storm which I will write about in a separate post is more accurately predicted with the winds closely matching the forecast.

    I will look for more information on Tropical Cyclone Marcia over coming weeks to see what else is available.

s2Member®