Not a lot to report this morning (Tues 28th), with various model runs 'wobbling' quite a lot in the last 24 hours, but gradually starting to converge. As mentioned yesterday, the details will only become clearer in the next 12-18 hours, once the surface low has developed.
Light to moderate snow is likely over the SW-Cape ranges between 1400-1600m during the morning of Sat 1st (with more at higher elevations 1600-1800m), and spreading to the southern Cape mountain ranges during the day.
Recent model runs suggest less rainfall than initially predicted, due to a shift in the upper trough (which would have created upper instability). The latest SAWS forecast (11am on Tues 28th) has reduced the rainfall for Cape Town on Fri 31st from 40mm to a more realistic 30mm, but this is still a lot of rain in a 24 hour period!
Gale force winds (35 kts) are likely along the SW-Cape coast at times during Fri 31st, moving to the southern and Eastern Cape during Sat 1st. Moderate swells (4m) are likely (the relatively small size of the low will limit further development).
The front predicted for Sun 2nd and Mon 3rd seems likely to have minimal effects on Cape Town (though it will remain rather cold), but may have an impact on the southern Cape coast.
Edit: This afternoon (15Z on Tues 28th) the SAWS ship synoptic chart and EUMetsat Antarctic sector Airmass animation both show the developing low:
metzone.weathersa.co.za/images/articles/ma_sy.gif
oiswww.eumetsat.org/IPPS/html/MSG/RGB/AIRMASS/ANTARCTIC/
Edit: The low is currently positioned more than 3000km due west of Cape Town, and still has a very long time to evolve before landfall (72 hours or 3 days time). The models should now become a lot more consistent, with this detailed input data available.
Compiled by Gordon Richardson - Stormchasing SA
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