21 20 19 |
Dew Point Temperature(º C)
Temperature(º C)
|
BAMOS March 2017 |
21 |
18 |
|
|
|
17 |
|
|
|
|
17:00 17:30 18:00 18:30 |
|
|
95 |
|
|
|
90
85
80
30
20
10
17:00 17:30 18:00 18:30
Wind Velocity( km hr-1) 0
17:00 17:30 18:00 18:30 1000.0
999.5
999.0
998.5
998.0
150
100
6
4
2
50
Wind Gust Velocity( km hr-1)
Relative Humidity(%)
Atmospheric Pressure( hPa)
17:00 17:30 18:00 18:30
Rain Rate( mm hr-1)
0 17:00 17:30 18:00 18:30
Rainfall( mm)
0 17:00 17:30 18:00 18:30
Time
Severe thunderstorm and hail storm in the Queanbeyan area 11 February 2016.
After our experience of a severe hailstorm on 29 January 2016 it was Queanbeyan’ s turn to be impacted by a similar event on February the 11th. While the thunderstorm skirted our site, I am providing data and observations on its effects here at Gilmore, about 8 kilometres to the south west of the Queanbeyan CBD.
The 9am Observations: The weather was partly cloudy with two octas cirrus / cirrostratus and two octas small cumulus at 2,000 feet, moving from the south southeast. Temperature was 21.5 º C, dew point temperatures 16.2 º C, relative humidity 72 % and wind, southeast at 6 km hr-1.
By 3:00 p. m. the temperature was 28.7 º C, dew point temperature 16.9 º C, relative humidity 46 % and wind, east north east at 15km hr-1. Cloud: a sky total of six octas consisting of three octas cirrus, four octas large cumulus, one octa cumulonimbus tops to west southwest, southeast and northwest. Thunder was heard at the time of observation. As was the case with the earlier storm in late January, moisture levels were higher than usual for the Canberra region.
The storm developed in much the same location as the earlier January storm and tracked northward towards the southern suburbs of the Tuggeranong Valley. The storm appeared from the radar to veer to the right as it approached the southern end of the Tuggeranong Valley and passed about 2 – 3 kilometres to the east of our site around 4:55 and 5:05 p. m. There was frequent lightning and almost continuous thunder during its passage.
Light and variable winds earlier became light northeast before a strong gust to 55 km hr-1 from the south south east occurred at 5:25 p. m. as the storm was located over Queanbeyan. Rainfall commenced at the station at 4:50 p. m. with a maximum rainfall rate of 12.2 mm hr-1 at 5:00 p. m. with some light small hail. Rainfall ceased by 5:15 p. m. with a total of 1.2 mm recorded. The winds veered from a northeast direction through east to southeast during the event. The temperature varied from 30.7 º C at 4:00 p. m. to a low of 20.4 º C at 5:00 p. m. rising to a secondary maximum of 25.0 º C at 6:00 p. m.
The dew point temperature fell sharply from17.0 º C at 4pm to as low as 10.5 º C at 4.55 p. m. before rising to 18.5 º C at 6pm( Figure 5). There was a corresponding rise and slighter fall in the relative humidity. As the storm moved over the Queanbeyan area, I estimated by trigonometry, that the top of the cloud was at about 43,000’. As reported in the media there was considerable damage in Queanbeyan from the hailstorm.
Figure 4. Evolution of meteorological observations from Gavin O’ Brien’ s personal weather station in Canberra, 1700 to 1850 AEDT 29 January 2016.