Fuego Volcanic Ash — Aviation Impact, November 2026: Advisories Every Day Since 20 October, Ash SFC/FL150 Drifting West, an Observed Ash Area Over Guatemala City (GUA) on 28 October — 1 of 742 on Record

A November page for an advisory run that did not stop. The October page closed on VAAC Washington's no-ash bulletin of 00:30 UTC on 10 October. Fuego did not wait: at 07:06 UTC that morning, 6.6 hours later, a new advisory reported an ash cloud drifting south-west from the summit on satellite, and 34 ash-bearing advisories followed to 18 October — in line with the three earlier no-ash bulletins in our record (18 and 20 May, 13 June), each followed by fresh ash within 4½ to 8 hours. Then came the one real pause since 11 May: a no-ash bulletin at 13:10 UTC on 18 October, and 49 hours with no Fuego bulletin at all, until 13:57 UTC on 20 October. Since then the sequence has run four or five advisories a day, 50 in all, every one carrying ash. This page therefore opens on the first advisory of November, not on a new eruption: the 04:19 UTC bulletin describes the kind of emission Fuego has produced all year — ash puffs seen on satellite, surface to FL150, carried west on the prevailing flow. What makes the late-October run worth a page of its own is where the ash went for five days of it, and on one morning in particular.

28 October: the first observed ash area over La Aurora in our record. At 10:51 UTC on 28 October VAAC Washington reported frequent emissions moving east and south-east on satellite, with the winds at ash level quickly backing. Its observed area for 10:10 UTC — surface to FL140, moving east at 5 kt — reached about 52 km from the vent and took in La Aurora International (GUA), about 3 km inside its north-east edge; the 16:00 UTC forecast area in the same advisory contained the airport too, about 2 km inside. The Tegucigalpa watch office's SIGMET 2, valid 11:00–17:00 UTC, drew the same area for the Central American FIR, and its 16:00 UTC forecast area also contained the airport. Testing the published polygons directly, it is 1 of the 742 observed and 1 of the 2,089 forecast Fuego ash areas in our record since 11 May that contain La Aurora; before that morning the closest had been about 10 km observed and about 2 km forecast, both on 20 September. By the next observation, at 15:40 UTC, the ash had fanned south to south-east up to 50 NM from the summit and its nearest edge was about 27 km from the airport; every later observed and forecast area has stayed 35 km or more away. On the ground, La Aurora's hourly METARs from 09:00 to 18:00 UTC reported CAVOK or 10 km visibility and no volcanic ash — none of its 4,305 METARs since 13 May has reported ash — and the network logged 140 movements there between 10:10 and 16:00 UTC, against 131 a week earlier. A drawn ash area is VAAC Washington's envelope for where ash is in the layer from the surface to FL140, not a measurement at the runway; we report the geometry and the observations side by side, and the operating calls that day belonged to the airport and the airlines. The morning was first reported on the GUA traffic brief.

Five days of easterly drift — the heading that decides exposure here. Distance tells you little at Fuego; the drift vector in each advisory decides who is downwind. Guatemala City sits about 40 km from the vent on a bearing of roughly 073°, and in the record to 9 October 53 of 646 observed areas (8%) moved north-east, east, south-east or south. Since 20 October it has been 19 of 50 (38%), in four runs: 17:54 UTC on 23 October to 23:42 UTC on 24 October (six areas moving north-east, east or south-east, the nearest edge to La Aurora about 18 km on 24 October); 11:09 UTC on 25 October to 12:19 UTC on 26 October (six, south-east and south, reaching about 68 km from the vent); 23:59 UTC on 26 October to 17:08 UTC on 27 October (four, south, up to 50 NM); and the three of 28 October — the east-moving area over the airport and two that swung south-east and south. The southward legs crossed the Pacific-coast airfield of San José (GSJ), 60 km south of the vent: it sat inside the observed areas of 17:08 UTC on 27 October and 16:01 UTC on 28 October and inside four forecast areas since 10 October; 3 of the 742 observed areas on record contain it, the first on 30 September. Every advisory since 02:24 UTC on 29 October — 14 of them — has the ash moving south-west or west; the widest area, at 16:43 UTC on 31 October, reached about 118 km west-south-west of the vent. That swing brings Retalhuleu (RER), 88 km west, back into view: the 22:28 UTC advisory of 31 October put it inside its 10:00 and 16:00 UTC forecast areas for 1 November, though no observed area has contained it since 16 September (32 of 742 on record) and the 04:19 UTC forecasts stop about 25 km short. None of this is a forecast we make — it is the published geometry, and the wind at ash level can turn.

FL140–FL160 is a low band — it matters in the terminal area, not at cruise. Fuego's summit stands at 12,346 ft, and every advisory since 20 October has reported ash from the surface to between FL140 and FL160 — roughly 14,000 to 16,000 ft pressure altitude, a few thousand feet above the crater: FL140 on 34 advisories, FL150 on 10 and FL160 on six (26, 29, 30 and 31 October), the first FL160 since 28 September. The current advisory reports FL150. The 90-day range is FL130–FL180, and nothing above FL160 has been reported since 13 September. Traffic crossing Central America at cruise passes far above that band, which is how a volcano can generate 735 bulletins in our record without touching the long-haul network. La Aurora's field elevation is 4,952 ft, so its arrivals and departures work through part of the band on every rotation — which is why an east-moving plume matters to Guatemala City in a way a west-moving one does not. The share of areas seen directly on satellite has risen: 19 of the 50 since 20 October were estimated from webcam and model winds under weather cloud, but 12 of the 15 since the evening of 28 October were observed. That is why dispatchers read the reported level and the drift line in each advisory, not the distance from the summit alone.

One FIR, two bulletin streams — read FIR-level signals as FIR-level. The VAAC advisory says where ash is and where it is forecast to go; the SIGMET is what an en-route crew is told. The Tegucigalpa meteorological watch office (MHTG) issues the volcanic-ash SIGMETs for the Central American FIR (MHCC), and it has issued 48 for Fuego since 20 October (a re-issue for the same validity period counted once) — tops of 14,000 ft on 34, 15,000 ft on 8 and 16,000 ft on 6 — with a Fuego SIGMET issued on every day since 1 July except 19 October. Our SIGMET record begins 1 July, so that is a floor. The current one, SIGMET 1, runs 05:00–11:00 UTC on 1 November, surface to FL150, moving west at 15 kt. The same office covers Santa María, 112 km west of La Aurora, which is under its own advisories (Santa María brief). Across the whole FIR, aircraft counted crossing it ran between 0.97× and 1.05× their weekday baseline on every day from 20 to 31 October — 1.05× on 28 October — and the 24-hour reading behind our ash map stood at −8% at 09:25 UTC on 1 November: FIR-wide figures spanning several countries, which we do not attribute to either volcano. Our detection layer logged five low-confidence tracking entries for this airspace after the October page closed (13, 13–14, 18, 21 and 22–23 October), each already past its end time; none since 23 October and none open. The FIR's NOTAM set, refreshed at 05:02 UTC on 1 November, carries no ash notice and no airport closure; its one airspace restriction is a route closure in Guatemalan airspace (ATS route R644, AUR–TIDER, surface to FL170) in force since 2 September, whose text gives no cause. The set holds current notices, so it cannot show one that has already lapsed.

What we watch for escalation. Three signals would change this page. Cadence: the run has held four or five advisories a day since 21 October; a sustained ten-plus a day would mark a different volcano — the busiest day in our record is six (4 July, 4 August, 10 and 14 September). Height: reported tops above FL180, the highest in our record (4 and 14 August). Reach: another observed area over La Aurora — it has happened once, on 28 October, when the drift backed east — or an observed area over Retalhuleu while the drift holds west. The 04:19 UTC advisory expects little change in the winds at ash level over the next 18 hours, which would keep the plume moving west. Automated multi-signal analysis checks all three every three hours, alongside observed airport movements and FIR-level traffic, and this page, the GUA brief and the live ash map update from the same cycle. The operating decision on any given day stays where it belongs — with the airport, the airline and the Guatemalan and Central American authorities.