Telemetry from the Northern Ice Field shows a snowfall event last month, likely associated with the seasonal increase in humidity, the transition from dry season to the short rains. This was the first noteworthy, accumulating snow since early May.
Snow sensors indicate that the event began on 19 September and continued
through the 27th. Averaging two series of measurements suggests 9-10 cm
of accumulation. This snow isn't likely to persist, due to
densification (settling) and ablation. The climate at this time of year
remains quite dry and sunny, and several centimeters of surface lowering
occurred on a single day, 5 October. Nonetheless, a 10 cm snowfall is
sufficient to dramatically increase albedo and thus reduce the amount of
solar radiation absorbed. The net effect is a reduction in the rate of
ablation - for a period of perhaps weeks.
At the Northern Ice Field site where our measurements are concentrated,
there has been effectively no net change in glacier thickness (mass
balance) for 2 years; accumulation has balanced ablation. This will
change if the 2013 short rains are delayed, as ablation can be rapid
during October - November. We will visit the glaciers later this month,
and are looking forward to seeing surface conditions and assessing the
spatial variability of mass balance over the past year.