For autumn 2016 ,ond
The PWD seasonal forecast is as under. Due to being a post el Nino year 2016 would have many properties of a la Nina years one of the few reasons which we can identify is upper oceanic heat content anomalies near dateline up to the depth of 300 meters, these anomalies pose significant effects on subcontinent weather as evident from several statistic-based research articles, though the exact mechanism of action is not well understood and is part of ongoing research, another thing that we have been experiencing since the start of the year that north Arabian sea Sst is warmer than normal and MSLP is slightly less than normal, the warming of Sst was more pronounced in monsoon season but lack of typical Arabian high may be as a result of warmer Sst was main moisture blocking effect for Pakistan through out the year including ms and the trend is likely to continue till the end of this year. Most reliable international models do not forecast a la Nina in the coming month except one model out of eight as surveyed by Bom, but from cool subsurface water under equatorial Pacific, we cannot completely rule out a la Nina but even if it occurs it would not be moderate or strong. Another factor that influences non-ms months rain is the ao index which is currently running in the negative phase but this index forecast for the next 3 months is not publicly available, so we would also get some idea from NMME an ensemble model of most of Lrf international models like Cfs, NASA, Cmc, etc. Slightly below normal precipitation of order of – 10 % with slightly above normal temperatures of the order of 1 to 1.5 c above normal expected during October to the end of December for the country as a whole for the year 2016.
