Difference between Portend and Predict

PORTEND vs PREDICT: NOUN

Make a prediction about; tell in advance
Indicate by signs
To state, or make something known in advance, especially using inference or special knowledge.
To believe or hold to be true in advance; forehold; surmise.
To foretell, foresee or prophesy.

To foretell something.
To state, tell about, or make known in advance, especially on the basis of special knowledge.

To indicate by prediction; forecast.
To indicate (events, misfortunes, etc.) as in future; to foreshow; to foretoken; to bode; -- now used esp. of unpropitious signs.
To stretch out before.
To serve as an omen or a warning of; presage.

Tell in advance
Make a prediction about
Indicate, as with a sign or an omen
Synonyms Prophesy, Presage, etc. (see foretell), foreshow, divine.
To foretell; prophesy; declare before the event happens; prognosticate; also, to declare before the fact is known by direct experience.

Loom, Signify, Foresee, Auspicate, Forecast, Prognosticate, Betoken, Predict, Omen, Prefigure, Augur, Bode, Foretell, Presage, Foreshadow

Promise, Call, Betoken, Omen, Augur, Prefigure, Bode, Presage, Forebode, Forecast, Portend, Foreshadow, Anticipate, Foretell, Prognosticate

Materialize, Bespeak, Precede, Allude, Forestall, Foresee, Auspicate, Forecast, Prognosticate, Betoken, Omen, Prefigure, Augur, Presage, Foreshadow

Forecasting, Speculate, Auspicate, Call, Betoken, Omen, Augur, Prefigure, Presage, Forebode, Forecast, Portend, Foreshadow, Anticipate, Prognosticate

It can be used to predict ASVAB scores.
Granted, no one can perfectly predict the future.
Will existing tests predict successful or superior performance?
The Old Testament prophets did not always predict.
Model scores predict the likelihood of consumers behavior.
Number of moles could predict breast cancer risk.
There is not sufficient information available to predict.
Often being able to predict both is useful.
Can perceptions of service quality predict behavioural intentions?
No one can predict fashion, so no one can predict future trends in programming languages.