# 1) find every record‐breaking year ≥ 1980
post80 = ts.where(ts.index >= 1980)
current_max = -np.inf
record_years = []
record_values = []

for yr, val in post80.items():
    if np.isnan(val):
        continue
    if val >= current_max:
        current_max = val
        record_years.append(yr)
        record_values.append(val)

# 2) build ALL steps
all_steps = [(s, e, y) for s, e, y in zip(record_years, record_years[1:], record_values)]

# 3) filter to only multi‑year “flat” periods (>=3 yr)
steps = [(s, e, y) for (s, e, y) in all_steps if (e - s) >= 3]

# 4) pre‑compute limits & frame list
xmin, xmax = ts.index.min(), ts.index.max()
ymin, ymax = ts.min() - 0.1, ts.max() + 0.1
frame_files = []