Weekly Synopsis and Prognosis

Weekly Synopsis (15th Feb -21st Feb 2008)

On the 15th dry air was in circulation as a cold front approached from the west except for a pre-frontal cloud band that resulted in isolated afternoon thundershowers in the west ahead of a cold front. On the 16th isolated to scattered thundershowers resulted as the cold front passed south of the subcontinent inducing tropical moist air to be fed into the southern interior of the subcontinent. Scattered to widespread rain showers and thundershowers occurred on the 17th as moist tropical air continued to be fed into the subcontinent. Low-level moisture advection from the east coupled with convergence enhanced rainfall activities. On the 18th isolated thundershowers were observed due to convergence as a cold front brushed over the southern tip of the subcontinent.  Isolated thundershowers continued to be observed on the 19th due to low-level moisture advection from the east and convergence. On the 20th dry air was in circulation resulting in no precipitation. On the 21st convergence in the southern parts of the subcontinent resulted in moisture flow from the north into those areas and moderate to intense thundershowers resulted.

Weekly Prognosis (22nd - February - 29th February 2008)

ECMOn Friday 22nd a weak cold front will brush over the southern tip of the subcontinent with a continental anticyclone (IOA) situated over our area. Settled weather is thus expected with isolated evening thundershowers likely in the north and in the south as the cold front passes inducing little moisture influx of tropical air and afternoon convergence. On Saturday 23rd as the cold front progresses to the east there will still be little moisture circulation especially in the west and in the south following the progression of the cold front over the south-eastern interior. ECMWF also indicates convergence in the west. Isolated thundershowers in the west and in south are still anticipated. On Sunday 24th at 00Z the surface interior trough associated with steep upper level trough will advance into the interior of the subcontinent. By afternoon it is expected to deepen with a closed circulation (Low) centered over the south coast maintaining a strong south-westerly air flow over much of the interior. There will also be convergence west of our area, which is expected to extend over our area later increasing chances of precipitation. Scattered to widespread rain showers and thundershowers are anticipated. There is also a likelihood of hailstones and damaging strong winds. On Monday 25th convergence of winds is still anticipated in the east with the upper level trough slowly progressing to the east. Ex Tropical Cyclone IVAN will be adjacent to the north-eastern parts of the subcontinent forcing moisture to off-track from the interior of the subcontinent towards the disturbance. Isolated thundershowers are still expected becoming scattered in the east later on Monday. On Tuesday 26th little moisturewill be fed mainly in the north-east as more moisture will be injected into the depression (disturbance). Isolated thundershowers are still expected especially in the east. By Wednesday 27th dry air is expected to circulate in the interior of the subcontinent that will result in only partly cloudy conditions. On Thursday 28th convergence is anticipated in the far north and west of our area thus partly cloudy conditions will continue with little or no precipitation anticipated. By Friday 29th ECMWF is indicating convergence over our area especially to the northwest, which may spread to adjacent areas later. Tropical air is expected to flow into the interior of the subcontinent. Isolated to scattered thundershowers are likely to occur.