Vocabulary in Context: Palpable

Read the following excerpt from a contemporary novel:

"As he wandered aimlessly through the labyrinthine streets of the old city, the shadows elongated under the fading light, casting a palpable sense of foreboding. Each turn of the cobblestone path seemed to deepen his unease, the remnants of laughter echoing faintly from afar, morphing into a cacophony of whispers that taunted him. The air was thick with an aroma of decay, stirring within him a visceral reminder of the fragility of joy and the inevitability of despair."

In this context, what does the word palpable most likely mean?