A bit of botrytis. Cool, damp/rainy spring in your area? Don't dig; just let them go through their normal bloom and browning out cycle since you want to keep as many leaves as possible for next year's bloom. This is a natural occurrance and doesn't harm the bulb. I get it every so often but have not resorted to fungicides or chemical cures. Not worth it.

The stems will likley brown out earlier than usual. When they're really done and you begin your clean up - clean up thoroughly; don't any leave brown leaves or stem pieces since this is a fungus that sits on top of the soil or mulch.

Your clumps look like they could be divided - this would assist in bringing the humidity down, allow for more air flow and better circulation.

Good advice from duluthinbloom.