Severe Weather & Rainfall Alert Friday the 15th of November, 2013 for Logan Todays Severe Weather Threat Is Low Discussion: An upper trough will strengthen over the southeast corner of the state today and combine with a stalled surface trough close to the coast producing some moderate to strong instability over the region. Overall the atmosphere will be a little drier today and this coupled with a stronger stable layer of air above the surface means that storms are expected to be much more isolated than yesterdays line - however the strengthening upper trough and more favourable wind shear profile is supportive of severe storm development. As such, while storms will be more isolated and a little less likely than yesterday (so the chance of a storm moving over any one location) is lower, the chance of the storms that do occur being ! severe is higher. Damaging winds and large hail are possible in storms today - but there may be quite a few areas today that receive no storms at all (and if the stable layer of air is not broken, there may be no storms at all in the region, though any early afternoon shower development on the ranges/eastern Downs would be a sign that at least some storms will occur). Two main scenarios exist - given the drier air, storms may favour the coastal ranges (Gold Coast and Sunshine Coast Hinterland, possibly also initiating in the Brisbane Valley). This means areas east and northeast of the ranges would be at risk from these storms (keeping Brisbane southern suburbs/Logan area generally clear). However a small mid level moisture tongue may initiate convection over the eastern Darling Downs, and if this occurs then all areas of the Southeast Coast region could experience some isolated storm activity (but these would be stronger closer to the coast, especially east of a line from Esk to Boonah). Storms will move towards the east at 30-40km/h, but stronger storms will move NE or possibly N/NE. Otherwise the Gold and Sunshine Coast areas are slightly more favoured for storms than the surrounding regions. Tomorrow storms will be more likely and potentially quite severe - due to the upper trough strengthening further and possibly bringing some very strong instability across the region. However conditions over the western half of the Southeast Coast district will be a little drier meaning that storms will be stronger close to the coast once more. Storms should remain isolated and somewhat hit and miss, but the storms that do occur have quite a good chance of being severe with damaging winds and large hail and even the preliminary indication of high end severe storms occurring. Variability still exists for Sunday - but at this stage expect a few showers developing with a possible storm during the afternoon. However some of the latest forecast trends are predicting slightly drier air in the upper atmosphere in the morning (which would be supportive of more traditional thunderstorms during the afternoon), but stronger consensus is for overnight rain and some isolated storms to also occur with the preliminary indication of some moderate to heavy falls occurring late on Sunday. Rain areas will continue into Monday before easing during the middle of the day to a couple of showers. Tuesday will then become fine as this system pushes out to sea. Weatherbrief Friday 15th Saturday 16th Sunday 17th Monday 18th Tuesday 19th Temperature 30 19 28 18 26 18 24 17 27 Brief Forecast Chance late shower or storm Late shower or storm Showers, chance storm Rain periods, showers - easing Fine Max Rainfall Chance (9am to 9pm) 35% 60% 70% 75% 0% Chance Thunderstorm Low Moderate Low Very Low N/A Chance of Rainfall Friday 15th Saturday 16th Sunday 17th 0900-1200 0% 0% 20% 1200-1500 15% 30% 40% 1500-1800 35% 60% 70% 1800-2100 20% 60% 70% 2100-0900 0% 55% 80% 24 Hour Rain 3-6mm 10-15mm 20-40mm Severe Weather Threat - Next 24 Hours Chance Hail 2cm Chance Wind Gust 65km/h Chance Wind Gust 90km/h 0900-1200 0% 0% 0% 1200-1500 15% 15% 15% 1500-1800 20% 35% 20% 1800-2100 5% 5% 0% 2100-0900 0% 0% 0% Negligible 5% or less Low 5 - 30% Moderate 30 - 60% High 60% or higher
Posted on: Fri, 15 Nov 2013 02:23:39 +0000
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