NOAA’s National Water Model, short-range run issued Sep 4, 6 PM CDT, for the 5 gauged tributary reaches feeding Lake Travis. The model routes rainfall that has already fallen plus near-term forecast precipitation.
Gauged inflow now
290
cfs · measured
Peak next 18h
419.6
cfs · ~12 PM CDT · modeled
Projected volume
535
acre-feet over 18h · modeled
Net lake effect
-0.07 ft
after 1,235 cfs out · inferred
Dashed = forecast. Values are at the gauges, not at the lake — water takes hours to a couple of days to travel downstream from the gauges to the lake. Flows are projected to rise meaningfully. National Water Model via NOAA/NWS · public domain.
The “net lake effect” nets the projected inflow volume against the water currently leaving the lake (1,235 cfs — Mansfield Dam, yesterday's average), held constant over the horizon, spread over the lake’s estimated surface area (before releases it would be +0.03 ft). It ignores travel time, channel losses, and any change the dam operators make — a scale reference, not a prediction. During floods, watch the live dashboard instead.