May 18, 2023
Note: Weather is a constantly changing phenomenon and weather forecasting is a combination of science, experience, and intuition. The accuracy of any given forecast can chance due to unexpected changes in atmospheric conditions, so there are no guarantees the the actual weather will conform to the projected forecast.
ADVISORIES
- NONE AT THIS TIME.
HEALTH ADVISORIES
A PERMANENT RECREATIONAL HEALTH ADVISORY IS IN EFFECT FOR THE SOUTH UMPQUA RIVER AND MAINSTEM UMPQUA RIVER. THE ADVISORY COVERS THE SOUTH UMPQUA RIVER FROM CANYONVILLE DOWNSTREAM TO THE CONFLUENCE OF THE MAINSTEM UMPQUA RIVER, AND THE MAINSTEM UMPQUA RIVER DOWNSTREAM PAST ELKTON TO LAWSON BAR. PEOPLE IN THE BEDROCK ALONG THE RIVERS EDGE ARE ARE KNOWN TO DEVELOP CYANOBACTERIA (BLUE-GREEN ALGAE) BLOOMS THAT CAN BE HARMFUL TO PETS AND PEOPLE IF ACCIDENTAL INGESTION OCCURS. SIGNS HAVE BEEN POSTED AT SEVERAL ACCESS AREAS ALONG THE RIVER.
THE WEATHER PATTERN
A large Upper Level High Pressure Ridge (“Arch” shape) still has a hold on the Pacific Northwest. Temperatures will cool off just for today. The graphics for days 1-3 show no fronts off the Oregon coast. The graphics for days 3-7 Sunday through next Thursday show a cold front moving through Saturday into next Sunday.
Note: Today is the anniversary of the major eruption of Mt. St. Helens 43 years ago on May 18, 1980.
Forecast For The South Willamette Valley Including Eugene-Springfield:
- A mix of clouds and sun and cooler this afternoon, mostly clear tonight,
- A mix of clouds and sun and a bit warmer Friday afternoon, mostly cloudy at night,
- AM clouds, then partly cloudy and a bit cooler Saturday and Saturday night.
- highs 77-80 cooling to 75 Saturday lows 52-54 cooling back to 52 Saturday night.
- A mix of clouds and sun and a bit cooler Sunday, partly cloudy Sunday night,
- Partly cloudy and a bit cooler Monday, partly cloudy at night,
- Partly cloudy and a bit warmer Tuesday, mostly clear Tuesday night,
- Some AM clouds, then mostly sunny and a bit warmer Wednesday afternoon.
- highs 72-69 warming to 73 Wednesday lows 46-44 warming back to 46 Tuesday night (seasonal averages high 69 low 44)
Forecast for the Umpqua Valley including Roseburg:
- Some AM clouds with patchy fog, sunny and cooler this afternoon, mostly clear this evening, partly cloudy late tonight,
- Some AM clouds, sunny Friday afternoon, mostly clear in the evening, becoming mostly cloudy late at night,
- Then mostly cloudy Saturday and Saturday night.
- highs near 80 lows 55-57 cooling back to 55 Saturday night.
- Mostly cloudy start, partly cloudy and a bit cooler Sunday afternoon, mostly clear Sunday night,
- Some AM clouds, sunny Monday afternoon, mostly clear at night,
- Mostly sunny Tuesday, mostly clear Tuesday night,
- Then mostly sunny and a bit warmer Wednesday.
- highs 73-75 lows 50-47. (seasonal averages high 72 low 48)
Forecast for the Oregon Coast including Coos Bay and North Bend:
- Mostly cloudy with areas of AM fog, partly cloudy and a bit warmer with areas of coastal fog this afternoon, mostly cloudy with areas of coastal fog late tonight,
- Mostly cloudy with patchy AM coastal fog while areas of inland AM fog, sunny and a bit warmer Friday afternoon, mostly cloudy at night,
- Then mostly cloudy and a bit cooler Saturday and Saturday night.
- highs 64-66 cooling back to 64 Saturday lows near 52.
- Mostly cloudy start, partly cloudy and a bit cooler Sunday afternoon, mostly clear in the evening, partly cloudy late Sunday night,
- Mostly sunny and a bit cooler Monday, mostly clear at night,
- Mostly sunny Tuesday, mostly clear Tuesday night,
- Some AM clouds, then sunny Wednesday afternoon.
- highs near 64 lows 47-45 warming back to 47 Wednesday. (seasonal averages high 61 low 48)
Forecast for the Northern Oregon Cascades including Willamette Pass:
- Some AM clouds, mostly sunny and cooler with a slight chance of showers and thunderstorms this afternoon and evening, just partly cloudy late tonight,
- Mostly sunny start, partly cloudy and a bit warmer with a (40%) chance of showers and a slight (20%) chance of thunderstorms Friday afternoon and evening, just partly cloudy late Friday night,
- Partly cloudy and a bit cooler with a slight (20%) chance of showers and thunderstorms Saturday afternoon and evening, then just mostly cloudy late Saturday night.
- snow level above 8,000 ft. today through Saturday night.
- highs 72-75 cooling to 73 Saturday lows near 47.
- A mix of clouds and sun and a bit cooler with a slight (20%) chance of showers Sunday afternoon, partly cloudy with a slight (20%) chance of evening showers, just partly cloudy late Sunday night,
- Some AM clouds, sunny and a bit cooler Monday afternoon, partly cloudy at night,
- Then mostly sunny and a bit warmer Tuesday and Wednesday, mostly clear Tuesday night,
- snow level above 8,000 ft. Sunday, 7,000 ft. Sunday night, free air freezing level 13,000 ft. Monday and Monday night, 12,000 ft. Tuesday and Tuesday night, then 11,000 ft. Wednesday.
- highs 62-48 warming to 63 Wednesday lows 35-37.