Lummi Island Rainfall DataLummi Island Rainfall Data39 Years of Rainfall Data from 4 Island Stations

Regional contextOlga, Orcas Island Rainfall Data

Washington Precipitation

Rain and Wind regimesRain Shadows

Wind DirectionsAugust 10, 2019Rainwater Catchment ProgramElizabeth Kilanowski -Raincoast Scientific

Tuttle Lane Rain Gauge

Daily Data Sheet

Created an electronic Record

Wrote Python computer programsfor analysis and graphs

West Shore Farm Rain Gauge

Annual Lummi Island Rainfall from 1980

Wet Month Rainfall Trends from 1980

Dots showmonths

Lines aresmoothed trends

Dry Month Rainfall Trends from 1980

Dots showmonths

Lines aresmoothed trends

Four Decades of Monthly Rainfall Trends

Bars indicateaverage trend foreach month overfour decades

First decade is fromone station

Olga, Orcas Island Rainfall From 1895

Bellingham Airport Temperatures From 1948

Washington Average AnnualPrecipitation(inches)

Great Variation Seattle – 36Tacoma - 41Forks – 119Sequim – 16Aberdeen – 84San Juan – 20Lummi Island – 35

MinnesotaSt. Paul, MN – 32Ely, MN - 29

Most storms in the PNW come off the Pacific Ocean

Rain hits the coastal mountainsOlympics – Vancouver Island

Drops precipitation and formsa rain shadow over the San Juans

Winter brings Fraser River Air -Cold, dry and continental

https://atmos.uw.edu/current-weather/northwest-radar/

Another Rain Shadow Example

Shifting winds relatedto climate change isan active area of research

Jet Stream – Polar Vortexwavy wind pattern

Warmer arctic – meansless temperature contrastbetween high and low latitudes.

The Take away:

Lummi Island may be getting a little wetter in the wet months and dryer in the dry months.

But there is a lot of natural variability in precipitation in thePacific Northwest because of the influence of the ocean.

Wind shifts may bring more or less rain to the Island over thecoming decades.