AWS, long rains end, quiet mountain

Our friend Simon (SENE*) made a trip to the summit caldera recently, and has shared some photos. He kindly detoured his climb to visit the Northern Icefield AWS and inspect our instrumentation. The upper photo illustrates snowcover on the glacier at the end of February. The red circle highlights a replacement temperature/humidity sensor, which with luck is accurately measuring these important variables again.

The second image shows a net 'long-rains' snow accumulation of at least 50 cm. Aside from footprints, the surface texture suggests that a week or more has passed since the last snowfall. On the ascent, Simon estimates ~60 cm of snow beginning below the caldera rim.

Below is a Sentinel-2 timelapse of snowcover between 18 May and 7 June. The transient snowline can be seen increasing in elevation, with thinning of snow on north-facing slopes. This pattern of ablation will likely continue in the months ahead, as rarely does the 'long-rains' season extend much into June.

Simon reports that the mountain is currently devoid of people. In the lower right-hand corner of the satellite image is a light-colored, circular area, which is "Barafu Camp" at 4,700 m. This is the last camp used by most climbers, and once the dry season gets underway it is bustling with hundreds of people. The lowest photo shows Barafu this year, with not a single tent visible; only camp infrastructure buildings can be seen.

*Tourism is severely impacting Tanzania, as the case with other destinations reliant upon international tourism. In preparation for a return to something approaching normal, SENE is offering special terms for future trips booked during June - safaris as well as Kilimanjaro climbs.  #TravelTomorrow 

Tanzania's President Magufuli has taken drastic steps to reopen the country, lifting the ban on flights and removing the required quarantine. Time will tell whether this early action was responsible...

 

Ski Africa!

From a satellite's perspective, Kilimanjaro emerged from thick cloud cover yesterday, revealing substantial snow blanketing the upper ~1300 m of the entire mountain (i.e., above about 4600 m / 15,100 ft). This is an area of ~50 km^2.

Distinguishing between fresh snow and thin, low clouds is difficult on this particular image - yet snowcover appears remarkably uniform. On such a big mountain, precipitation often varies spatially, reflecting interaction of the massif with regional circulation.

Not often is it possible to ski 1000+ meters at 3° south latitude. But if snow accumulation continues through May, as it typically does, this June might be a great time to ski the mountain - with appropriate COVID-19 precautions.

#seneadventures @christianpondella

April Update

Northern Icefield margin with "cloudcam" and AWS. At the edge, note the layer of seasonal snow overlying glacier ice (23 February 2020).

Mid-April is typically not a busy time on Kilimanjaro, midway through the so-called "low season" when climbers avoid what are often the wettest months, associated with widespread convection. However, April this year is unusually quiet, due to the global pandemic; as with National Parks around the world, Kilimanjaro is devoid of human visitors. Schools are closed, and residents are sheltering in place - many without employment. For a region so dependent upon tourism and foreign exchange, this is a devastating time. We empathize with guides and all the other mountain staff who eagerly await the return of clients, and the opportunity to share their mountain with visitors.

Since the short rains diminished in January, a series of snowfall events have maintained fresh snowcover on the glaciers (see images above and below). Summit caldera snowcover has varied between continuous (see 3 Feb image) and patchy (as seen on yesterday's satellite image, above). Snowcover appears to have been gradually decreasing over the past two weeks, as also occurred during February until restored by early March snow.

In most years the long rains continue through May, ending rather abruptly by early June. Precipitation between now and then will determine what climbers encounter once travel and group climbs are safe again. Although recession of the glaciers continues, seasonal snowcover creates an illusion of permanence. At some point during the dry season though (June-September), the snow is likely to completely ablate and the bright ice will again be in stark contrast to the dark volcanic ash - reminding us that the ice will likely be gone within a few decades.

Residual ice with Mawenzi in the background. Note seasonal snow layer on the ice as well as the crater surface (25 February 2020).

Stable weather returns [updated]

February weather on Kilimanjaro is often characterized by a dry interval, between the Short Rains of approximately Nov/Dec, and Long Rains within the Mar/Apr/May time period. As noted previously, the Short Rains brought considerable rain to the mountain this year, with snow up high, beginning in early October. That wet period appears to have ended.

The upper image from 2 February shows patchy snowcover on the upper 1000 meters of the mountain's south side, as viewed from above Moshi (Simon Mtuy credit). Distinguishing remnants of the former Southern Icefield from snowcover is difficult here.

The second image above was acquired today by the ESA Sentinel-2 satellite, revealing continuous snowcover within the summit caldera, and on the upper slopes. The stable-weather cumulus clouds visible here appear only slightly more extensive than those on the day before (top image).

Although telemetry of data from the Northern Icefield (NIF) weather station is not currently available (budget constraints), several recent reports from climbers confirm what the images depict. On 23 January, collaborator Sarah Konrad visited the NIF and measured a mean snowdepth of ~0.60 m around the weather station. Shortly thereafter (28 Jan.), Simon was above the Western Breach in the Furtwängler Glacier area, reporting "almost one meter of snow."

Images below show Simon's camp at Arrow Glacier on the 27th, looking south across the Western Breach, and a Furtwängler Glacier remnant near Crater Camp (Sarah Konrad credit). Finally, a photo of the NIF weather station from Sarah reveals that the equipment is overdue for a "service visit". Fortunately, planning is underway to visit the station later this month!

[UPDATE 02/04:  Our friend Timba keeps close tabs on Kilimanjaro weather from Moshi, in the interest of safety for the many guides and porters working on the mountain. It was Timba who inspired our analysis of how tropical cyclones might influence snowfall on the mountain (Collier et al., 2019).

Timba wrote today, emphasizing how wet the region has been in recent months, especially at the end of September and through most of October 2019. As he points out, this is the time when the Indian Ocean Dipole (IOD) was very strongly positive, a water temperature pattern associated with heavy rain in eastern Africa - and bushfires in Australia (read more here and here).

So, has stable weather really returned to Kilimanjaro? Although the IOD has returned to a neutral pattern, older friends of Timba's equate the current rainfall pattern with that of Oct. 1988 to June 1989 - when the two rainy seasons merged into one long wet season.]
 

More Snow

The wet 2019 short rains continue, according to both satellite imagery and reports from the Kilimanjaro region. Simon Mtuy wrote today that the mountain has been in clouds for the past three days, with heavy rain last night.

Above is a glimpse of the mountain two hours ago, from TPC sugar plantations (above Moshi).

Active convection continues over the anomalously-warm, western Indian Ocean. Tropical Cyclone 06A is forecast to move southwest to Somalia on a track toward Lake Victoria, with landfall on 6 December bringing heavy rainfall and high winds; not what eastern Africa needs this year.

In addition to cyclone 06A, another cyclone is forming on the other side of the Equator. Rarely do cyclones form on both sides (circulating in opposite directions). Read more about this situation, and the vigorous convection expected, here. [credit Severe Weather Europe]

Regional October precipitation

The upper photo provides another perspective on Kilimanjaro snow, complementing those of the previous post on this blog. It was sent recently by Simon of SENE, taken from Moshi in the first few days of November. On the satellite image above from 5 November, snowcover is reduced within the large summit caldera relative to that of 26 October, yet the snowline on the southwest flank appears even lower. Today's Sentinel-2 image (10 November, not shown) reveals a fresh dusting over the entire mountain, with higher amounts just west of Reusch Crater.

Simon wrote of anomalous October rainfall in the area, with a frequency more like that of the long-rain season. This appears to have also been the case for a larger region of East Africa, especially Kenya, southern Somalia and southern Ethiopia - and has led to flooding to the north and east of Kilimanjaro. The situation is shown clearly on a European Commission map for 5 November, from the Emergency Response Coordination Centre (ERCC). [Kilimanjaro can be seen, in shaded relief, where the northern border of Tanzania jogs a bit; it is southwest of the flooded area in Kenya (red dots).]

Why has the region been so wet during October? One good possibility is related to sea surface temperatures in the western Indian Ocean: anomalously warm water! Warmer than normal SSTs in the west, with cool SSTs in the east, sets up a positive Indian Ocean Dipole (IOD) event, associated with increased convection and precipitation over East Africa. During September the IOD strengthened markedly, becoming one of the most-positive events in many decades. Further information can be found here. Once precipitation data from the mountain are available, we will have a better understanding on how the 2019 IOD event is impacting the Kilimanjaro region.

Early short-rain snow

Snow conditions on Kibo have changed considerably over the past 10 days, as shown in the timelapse above. Very little seasonal snow was present on 16 October, nicely revealing the current distribution of glacier ice. Five days later the entire summit was blanketed by snow. A second-hand report from our friend Simon Mtuy indicates that the snowline on the 18th was below Kibo hut. (Simon's wonderful company is SENE).

Between the 21st and 26th, ablation of new snow appears to have dominated over additional accumulation. However, note extensive snow below the Western Breach on the 26 October image; this may have resulted from localized convection, typical on that side of the mountain. Simon was on the mountain last week, so it will be interesting to hear his observations. Low on the mountain (i.e., below 1800 m) he reports nearly non-stop rain since the beginning of October - an early beginning to the short-rains season!