Corridor Pressure
Elevated
Binding leg: Madeira.
The corridor is only as navigable as its most-pressured link.
Mainstem · Óbidos
Normal
Forecast 59.1th pctile (Normal) · observed 26th (Elevated) (days 1–26)
Amazon trunk (Óbidos) — the shared artery both barge legs feed into.
Tapajós · Itaituba
Ample
Forecast 69.2th pctile (Ample) · observed 20th (High) (days 1–26)
BR-163 → Miritituba/Itaituba → Santarém — the fast-growing Arco Norte leg.
Madeira · Humaitá
Elevated
Forecast 32.6th pctile (Elevated) · observed 64th (Normal) (days 1–26)
Porto Velho → Itacoatiara — Rondônia / west-Mato-Grosso soy & corn.
Alongside ENSO: The model's ENSO input is the Feb–Apr RONI (-0.44, cool — the season that best forecasts the Amazon low). But the Pacific has warmed since: the latest reading (JAS 2026) is +1.69 and still rising — a developing pattern, the same cool-late-winter start that preceded the record 2023 drought. If it holds into the dry season, compound low-water risk on the mainstem and Tapajós rises above the current Atlantic-led forecast. On the mainstem and Tapajós, a warm Tropical North Atlantic and El Niño compound — the severe lows need both. The Madeira leg responds to whole-basin Atlantic warmth and is largely ENSO-agnostic.
Red zone (≤10th) = Severe, amber (≤33rd) = Elevated pressure. Forecast is the modeled Sep–Nov low from the spring ocean state; Observed is the most recent river reading. A barge corridor is only as open as its weakest link.
Itacoatiara stage · Oct 2026 (days 1–26, ranked against the same days in past years)
4.3 m · 21th pctile
Elevated (observed) (−4.4 m vs the 1991–2020 average for the month)
Forecast — withheld · on a trend-refit (interannual) basis its LOO skill is r=+0.45 (n=28) against +0.80/+0.79 for the forecast legs on that same basis, and the 2026 fit is carried by a −1.43 sd extrapolated stage trend rather than by climate. Observed only until it earns a forecast.
Just below the mouth of the Madeira, the Amazon squeezes past the Passagem do
Tabocal — not a shifting sandbar but a fixed rock ledge that cannot be
dredged away. It sits immediately upstream of the Itacoatiara terminals, the point where
grain barges off the Madeira (Porto Velho) and the Tapajós (Miritituba) hand their cargo
to ocean-going vessels. When the dry-season low exposes the ledge, the whole corridor's
export throughput funnels through a single shallow gate: in the 2023 record drought a
tanker sat grounded here for 23 days and DNIT emergency-dredged an 8 km reach; in 2024
the government committed R$138 million to dredge a 12 km stretch at the Tabocal.
We read it off the Itacoatiara gauge — the mainstem stage right at the transfer point.
Its September–November low answers to the same North Atlantic and El Niño forcing that
drives Óbidos (out-of-sample skill +0.79), so this is a corroborating observed
gate on the mainstem; the mainstem forecast is anchored on Óbidos discharge above.
Corridor through-traffic · road exports beyond Paraguay
0 t
Road exports from Porto Murtinho to any destination beyond Paraguay, 2019 through Sep 2026. Not in use yet. What will count as use: any month with road-mode exports cleared there to a third country. Soybeans or corn would mean bulk grain is taking the route; beef or chicken would mean the protein trade is.
A new road bridge from Porto Murtinho into Carmelo Peralta, Paraguay, is due
around late 2026 (press reports; not officially confirmed). It opens a road from Mato Grosso do
Sul across the Chaco and the Andes to Chile's Pacific ports, the route USDA's October 2026
review credits with 30–40% lower freight to Asia (third-party estimates, not costed for any
specific cargo). Today Porto Murtinho is a river port, and its exports rise and fall
with the Paraguay River the way the Arco Norte's do with the Amazon. Comex Stat records each
export's exit point, mode and final destination, so the road layer below and the line
under it will show the corridor in use the month it starts. Destination is the final buyer:
a truckload bound for China via a Chilean port is recorded as China.
Comex Stat (SECEX/MDIC), exports by customs unit and mode; all four codes Receita Federal has used for Porto Murtinho. River exports are almost entirely soybeans barged down the Paraguay River to Argentina, and they swing with the river level (2023: 1.63 Mt; 2024: 0.13 Mt). Road volumes before the bridge are a few tonnes a year to Paraguay, too small to see at this scale; hover for tonnes.
The control. This trade is mostly beef ($408 M of $450 M in 2025) and today leaves through the southern border posts (São Borja, Dionísio Cerqueira, Foz do Iguaçu, Uruguaiana). If the corridor carries protein, this line leaves zero before anything else moves. Gaps = months with no road freight to Chile.
A warm Tropical North Atlantic pulls the Atlantic ITCZ north, starving the Amazon of
wet-season rain and deepening the dry-season river low. Measured in spring, it forecasts
the September–November low months ahead. On the mainstem and Tapajós, El Niño
compounds the Atlantic signal; the Madeira responds to whole-basin Atlantic warmth.
Boreal-spring (Apr–Jun) warmth in this box precedes the Sep–Nov Amazon low by ~3–5 months. The red band (≥ +0.4°C) is the dry-risk regime that drove the 2005, 2010 and record 2023 droughts. Self-computed from NOAA OISST v2.1, 1991–2020 baseline (see fetch_atlantic_index.py).
Óbidos mainstem discharge, leave-one-out (each year predicted from a model fit on all others). Every major drought (2005/2010/2023/2024, red diamonds) was flagged in the driest quartile months ahead. Points near the dotted line = accurate. Out-of-sample skill r ≈ +0.76.