In the local record maximum rain rate as 530mm/hour (sic 0.53m/hr) 00:15
27 Dec 2020 for a short duration. The owner , an ex metman , cannot
confirm it as genuine or not, but looks iffy. Later a short burst of
340mm/hr, overall 23mm in 6 hours. Could they be genuine extreme
rain-rate records?
If genuine it would explain why the local storm drain flap valve into
the local tidal river has been fully open , unnoticed, for a few months.
Flap nearly vertical, self weight holding it 20 degrees off vertical ,
backwards beyond vertical, against the hinge joint.
It was realised there was a problem because the lowest road drain water
traps had the level going up and down exactly with the highest tides.

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Global sea level rise to 2100 from curve-fitted existing altimetry data
http://diverse.4mg.com/slr.htm