Posted by Scott Rozenbaum (Rozewood Environmental Services, Inc.)
Lopez Island
May 9, 2025
Lopez Island
May 9, 2025
360.468.4448
360.202.0096 (cell)
360.202.0096 (cell)
Lopez Weather Summary - April 2025
May 9, 2025
Dear Folks,
Life has gotten crazier and there are too many deadlines before me, so this late April 2025 summary is tardy and may be shorter. Or maybe not? Sorry about that.
April 2025 was a drier than normal month overall. See attached map showing certain CoCoRaHS manual rain gauge data for April (our Aleck Bay gauge was partially off-line due to vacations). Overall, Lopez ran about 0.5 to 0.75 inches below average for April 2025 rainfall. In some ways it was welcomed, because our ground and soils were so darn wet and sodden from late March rains. My north-central gauge recorded 0.92” of rain (my 28-year average for April is 1.62”; Jack Giard’s 47-yr average for April is 1.60”; and the Oregon State University climate model ‘PRISM’ shows an April 30-year normal of 1.77” for my general location). Elsewhere on-island, cumulative rainfall amounts varied from 0.72 to 1.12 inches. There were a few outliers stations with 0.63”, 1.33”, and a cumulative measurement of 2.11” off of Lopez Sound Road that seemed unusually off. My cumulative evapotranspiration (ET) for April was 2.03”.
Temperatures were mainly typical for April, with highs in the 50s and 60s, and lows mainly in the 40s. Many of the online automated weather gauges, widespread across the island, showed roughly 15 days of daytime highs reaching 60° or warmer. That’s a little impressive! Did it feel a bit milder than typical April? I’m not sure; I wasn’t paying attention. I had had roughly 9 days reaching into the 60s, and for April, I did not hit the 70° mark, but many weather stations did reach 70 or 71 degrees on April 25th. My temperature extremes were 67° and 35°. I had very light, patchy frosts on April 13th and 22nd, but not enough to be damaging to plants or having to scape my car windows. I did finally break the 70° threshold on May 6th, but that’s for another report.
Regarding our wet late March 2025, I did receive many comments from islanders about the wetness, saturation, and sloppy conditions. So, because so many folks responded back, I had to throw out my dissertation of theories and keep my speculations simpler. So here are both science-based and the seat-of-my-pants ideas for the conditions we witnessed.
First, I don’t think the earthquake had any influence. There are situations where earthquakes can trigger conditions called ‘liquefaction’, a geologic process where soils and unconsolidated sediments can suddenly lose their shear resistance and “re-settle”, often causing saturated conditions to migrate upward and cause the sediments/soils to become structurally soft and unstable (especially for human foundation structures). That didn’t happen in March.
In hindsight, I think it was merely a coincidental chain of events: mainly having a wet late March, after a winter of typical rainfall and soils recharging with six months of ‘wet season’ rainfalls (even though January 2025 was definitely drier than normal).
Our island soils play a big role in our rainwater infiltration, water retention, water availability, good or poor drainage, and perched layers (lenses) of saturation during wetter times of the year. You might have heavier soil types, clay-rich soils or silt-rich soils, both (usually) have slower infiltration rates. Sandier soils are usually better drained. But all topsoil layers (well-drained or otherwise) can be influenced by a shallow, dense subsoil layer(s), which in winter and early spring can cause a layer of saturation to develop (caused by infiltrated rainwater building on top of the dense subsoil layer), and that saturated subsoil layer can thicken and reach the surface creating localized quagmires…..saturated, gooey, soft wet soils. And lord knows, Lopez has a large percentage of soils with problematic drainage, which some years is low-key, and other years it is wet, sloppy, and pretty miserable.
Given the varied comments I received, I think islanders in late March just experienced a wetter phase of late-winter / early-spring conditions with a lot of impeded rainwater (or runoff) infiltration, and layers of saturated upper soils creating all sorts of inconvenience.
Other causes of impeded drainage or new wetter areas can also be attributed to localized actions, problems with infrastructure, and other factors.
In my own lawn area behind my house, the gently sloping mowed grass became excessively wet, wetter than I’ve ever seen. This location happens to be where a buried tightline (solid PVC pipe) directs water into the forest (water from my house roof gutters and the house perimeter drain. I’m sensing the tightline cracked or uncoupled underground, and I’ll need to dig up a length to inspect and verify its damaged or non-damaged state. But some landowners may be having some maintenance issues with their curtain drains, perimeter drains, French drains, tightlines, and other forms of buried drainage infrastructure.
Have runoff patterns changed in your area of concern? A new segment of road or driveway, new building, new compacted pathway? Could runoff be following a new route or being concentrated to an existing area?
Are any actions, activities, or livestock changed in the immediate area and could those activities or livestock be compacting the soil? Are you driving your tractor, bulldozer, excavator, pickup truck, car, or even your riding lawnmower on soils that are still saturated or extremely moist? It can lead to increased compaction, which then affects how runoff and rain infiltration may operate in that immediate area or along that route or path.
While most folks might think that soil, made up of sands, silts, clays, and perhaps gravels, are the controller of how water moves through soil. Sandy soils equals well drained; clay-rich soils equals poorly drained, right?? Well, there is more to it than just soil texture (percentage of sand, silt, and clay). There is another soil science element to consider that affects aeration and soil water movement: soil structure. Soil structure is the natural aggregation of those sands, silts, and clays into combination secondary particles, units, or ‘peds’. Think dirt clods….you know, the thing you threw at your brother when you both were little kids! Types of soil structure include crumb, granular, subangular blocky, blocky, columnar, prismatic, and platy. There are tiny pores and gaps between the structural peds, and rainwater attempts to travel through those tiny pores / gaps. Good soil structure can assist in a soil having better aeration and being better drained or draining quicker after a heavier rainfall event. But here’s the kicker, certain types of soil structure are sensitive to disturbance, and especially when the soil is either wet or very moist. A tractor, truck, excavator, or livestock hooves concentrate a lot of weight underneath the wheel ruts, tracks, or hooves. During wetter or ultra-moist conditions, the peds are susceptible to crushing and compaction. It is possible to reduce aeration and the rate of water infiltration when using moderate or heavy equipment on ultra-moist soils. So can a resident, farmer, or contractor postpone soil work until the soils have dried out a bit? Ideally that would be a practical strategy to maintain soil structure. And yet, there are times when the person needs to do their work or task at hand. Just know that many actions have their positive and potentially negative impacts or consequences.
Other elements that affect our wetness levels are simply an increase in rainfall amounts and storm intensities. We’ll cover these at another time. Our April was drier than normal, and our early May is also being drier than normal. I’m hoping for some moderate rains soon. I’m not mentally prepared for the start of an early drought.
Life has gotten crazier and there are too many deadlines before me, so this late April 2025 summary is tardy and may be shorter. Or maybe not? Sorry about that.
April 2025 was a drier than normal month overall. See attached map showing certain CoCoRaHS manual rain gauge data for April (our Aleck Bay gauge was partially off-line due to vacations). Overall, Lopez ran about 0.5 to 0.75 inches below average for April 2025 rainfall. In some ways it was welcomed, because our ground and soils were so darn wet and sodden from late March rains. My north-central gauge recorded 0.92” of rain (my 28-year average for April is 1.62”; Jack Giard’s 47-yr average for April is 1.60”; and the Oregon State University climate model ‘PRISM’ shows an April 30-year normal of 1.77” for my general location). Elsewhere on-island, cumulative rainfall amounts varied from 0.72 to 1.12 inches. There were a few outliers stations with 0.63”, 1.33”, and a cumulative measurement of 2.11” off of Lopez Sound Road that seemed unusually off. My cumulative evapotranspiration (ET) for April was 2.03”.
Temperatures were mainly typical for April, with highs in the 50s and 60s, and lows mainly in the 40s. Many of the online automated weather gauges, widespread across the island, showed roughly 15 days of daytime highs reaching 60° or warmer. That’s a little impressive! Did it feel a bit milder than typical April? I’m not sure; I wasn’t paying attention. I had had roughly 9 days reaching into the 60s, and for April, I did not hit the 70° mark, but many weather stations did reach 70 or 71 degrees on April 25th. My temperature extremes were 67° and 35°. I had very light, patchy frosts on April 13th and 22nd, but not enough to be damaging to plants or having to scape my car windows. I did finally break the 70° threshold on May 6th, but that’s for another report.
Regarding our wet late March 2025, I did receive many comments from islanders about the wetness, saturation, and sloppy conditions. So, because so many folks responded back, I had to throw out my dissertation of theories and keep my speculations simpler. So here are both science-based and the seat-of-my-pants ideas for the conditions we witnessed.
First, I don’t think the earthquake had any influence. There are situations where earthquakes can trigger conditions called ‘liquefaction’, a geologic process where soils and unconsolidated sediments can suddenly lose their shear resistance and “re-settle”, often causing saturated conditions to migrate upward and cause the sediments/soils to become structurally soft and unstable (especially for human foundation structures). That didn’t happen in March.
In hindsight, I think it was merely a coincidental chain of events: mainly having a wet late March, after a winter of typical rainfall and soils recharging with six months of ‘wet season’ rainfalls (even though January 2025 was definitely drier than normal).
Our island soils play a big role in our rainwater infiltration, water retention, water availability, good or poor drainage, and perched layers (lenses) of saturation during wetter times of the year. You might have heavier soil types, clay-rich soils or silt-rich soils, both (usually) have slower infiltration rates. Sandier soils are usually better drained. But all topsoil layers (well-drained or otherwise) can be influenced by a shallow, dense subsoil layer(s), which in winter and early spring can cause a layer of saturation to develop (caused by infiltrated rainwater building on top of the dense subsoil layer), and that saturated subsoil layer can thicken and reach the surface creating localized quagmires…..saturated, gooey, soft wet soils. And lord knows, Lopez has a large percentage of soils with problematic drainage, which some years is low-key, and other years it is wet, sloppy, and pretty miserable.
Given the varied comments I received, I think islanders in late March just experienced a wetter phase of late-winter / early-spring conditions with a lot of impeded rainwater (or runoff) infiltration, and layers of saturated upper soils creating all sorts of inconvenience.
Other causes of impeded drainage or new wetter areas can also be attributed to localized actions, problems with infrastructure, and other factors.
In my own lawn area behind my house, the gently sloping mowed grass became excessively wet, wetter than I’ve ever seen. This location happens to be where a buried tightline (solid PVC pipe) directs water into the forest (water from my house roof gutters and the house perimeter drain. I’m sensing the tightline cracked or uncoupled underground, and I’ll need to dig up a length to inspect and verify its damaged or non-damaged state. But some landowners may be having some maintenance issues with their curtain drains, perimeter drains, French drains, tightlines, and other forms of buried drainage infrastructure.
Have runoff patterns changed in your area of concern? A new segment of road or driveway, new building, new compacted pathway? Could runoff be following a new route or being concentrated to an existing area?
Are any actions, activities, or livestock changed in the immediate area and could those activities or livestock be compacting the soil? Are you driving your tractor, bulldozer, excavator, pickup truck, car, or even your riding lawnmower on soils that are still saturated or extremely moist? It can lead to increased compaction, which then affects how runoff and rain infiltration may operate in that immediate area or along that route or path.
While most folks might think that soil, made up of sands, silts, clays, and perhaps gravels, are the controller of how water moves through soil. Sandy soils equals well drained; clay-rich soils equals poorly drained, right?? Well, there is more to it than just soil texture (percentage of sand, silt, and clay). There is another soil science element to consider that affects aeration and soil water movement: soil structure. Soil structure is the natural aggregation of those sands, silts, and clays into combination secondary particles, units, or ‘peds’. Think dirt clods….you know, the thing you threw at your brother when you both were little kids! Types of soil structure include crumb, granular, subangular blocky, blocky, columnar, prismatic, and platy. There are tiny pores and gaps between the structural peds, and rainwater attempts to travel through those tiny pores / gaps. Good soil structure can assist in a soil having better aeration and being better drained or draining quicker after a heavier rainfall event. But here’s the kicker, certain types of soil structure are sensitive to disturbance, and especially when the soil is either wet or very moist. A tractor, truck, excavator, or livestock hooves concentrate a lot of weight underneath the wheel ruts, tracks, or hooves. During wetter or ultra-moist conditions, the peds are susceptible to crushing and compaction. It is possible to reduce aeration and the rate of water infiltration when using moderate or heavy equipment on ultra-moist soils. So can a resident, farmer, or contractor postpone soil work until the soils have dried out a bit? Ideally that would be a practical strategy to maintain soil structure. And yet, there are times when the person needs to do their work or task at hand. Just know that many actions have their positive and potentially negative impacts or consequences.
Other elements that affect our wetness levels are simply an increase in rainfall amounts and storm intensities. We’ll cover these at another time. Our April was drier than normal, and our early May is also being drier than normal. I’m hoping for some moderate rains soon. I’m not mentally prepared for the start of an early drought.
