Here is my weekly weather quiz question. What is the “Backwater Effect?” The first person to post the correct answer as a comment on this page will win a week of free personalized weather forecasts tailored to your needs.  Good luck.

________________

 

An Upper Level High Pressure Ridge (“Arch”shape with blue arrows) is still dominating our weather picture. The graphics for days 3-7 show a frontal systems moving in from the northwest Friday through Monday.

________________

Air Quality Index:

Eugene-Springfield: The Air Quality Index is 177 in the Unhealthy category measuring Particulate Matter.

Oakridge: The Air Quality Index is 129 in the Unhealthy for Sensitive Groups category measuring Particulate Matter.

Cottage Grove: The Air Quality Index is 84 in the Moderate category measuring Ozone.

Data courtesy of Lane Regional Air Protection Agency (LRAPA)

 

__________________

Advisories:

• A RED FLAG WARNING IS IN EFFECT FOR ABUNDANT LIGHTNING ON DRY FUELS FROM 2 PM THIS AFTERNOON UNTIL 10 PM THURSDAY FOR THE WILLAMETTE NATIONAL FOREST.
• A RED FLAG WARNING IS IN EFFECT FOR ABUNDANT LIGHTNING ON DRY FUELS FROM 3 PM THIS AFTERNOON UNTIL 10 PM FRIDAY FOR THE DDSCHUTES NATIONAL FOREST AND THE MINUS SISTERS RANGER DISTRICT.
• A RED FLAG WARNING IS IN EFFECT FOR ABUNDANT LIGHTNING ON DRY FUELS FROM NOON UNTIL 10 PM TONIGHT FOR THE UMPQUA BASIN, THE WESTERN ROGUE BASIN INCLUDING THE ILLINOIS VALLEY, THE SISKIYOU MOUNTAINS, THE EASTERN ROGUE VALLEY, AND THE SOUTHERN OREGON CASCADES, THE KLAMATH BASIN, THE FREMONT-WINEMA NATIONAL FOREST, THE SOUTH CENTRAL OREGON DESERT INCLUDING THE BLM LAND IN EASTERN LAKE AND WESTERN HARNEY COUNTIES.
• A FIRE WEATHER WATCH IS IN EFFECT FROM THURSDAY AFTERNOON THROUGH THURSDAY EVENING FOR ABUNDANT LIGHTNING ON DRY FUELS FOR THE SOUTH CENTRAL OREGON DESERT INCLUDING THE BLM LAND IN EASTERN LAKE AND WESTERN HARNEY COUNTIES, THE UMPQUA BASIN,  THE WESTERN ROGUE RIVER, THE SISKIYOU NATIONAL FOREST,  BASIN INCLUDING THE ILLINOIS VALLEY, THE SISKIYOU MOUNTAINS, THE EASTERN ROGUE VALLEY,  THE SOUTHERN OREGON CASCADES. THE KLAMATH BASIN,  THE FREMONT-WINEMA NATIONAL FOREST,
• AN AIR  QUALITY ALERT IS IN EFFECT UNTIL NOON FRIDAY FOR BENTON COUNTY, CLACKAMAS COUNTY, CLATSOP COUNTY, COLUMBIA COUNTY, HOOD RIVER COUNTY, LANE COUNTY, LINCOLN COUNTY, LINN COUNTY, MARION COUNTY, MULTNOMAH COUNTY, POLK COUNTY, TILLAMOOK COUNTY, WASHINGTON COUNTY, YAMHILL COUNTY,  CLARK COUNTY, DESCHUTES COUNTY AND JEFFERSON COUNTY.
• AN AIR  QUALITY ALERT IS IN EFFECT UNTIL NOON WEDNESDAY FOR GILLIAM COUNTY, GRANT COUNTY, MORROW COUNTY, SHERMAN COUNTY, UMATILLA COUNTY, UNION COUNTY, WALLLOWA COUNTY, AND WHEELER COUNTY.
• AN AIR  QUALITY ALERT IS IN EFFECT UNTIL NOON SATURDAY FOR DESCHUTES COUNTY AND JEFFERSON COUNTY.
• The Oregon Health Authority issued a Health Advisory today for Willow Creek Reservoir, located just east of the town of Heppner in Morrow County. Water monitoring has confirmed the presence of blue-green algae and the toxins they produce in the reservoir. These toxin concentrations can be harmful to humans and animals. People should always avoid areas with visible scum that looks foamy, scummy, thick like paint, pea-green, blue-green or brownish-red. Swimming and high-speed water activities such as water skiing or power boating where ingestion and inhalation exposure can occur is discouraged. Swallowing or inhaling water droplets as a result of these water activities in areas where a bloom has been identified, or an advisory issued, can expose people to the toxins being produced. Although toxins are not absorbed through the skin, people who have skin sensitivities that come into contact with a bloom may experience a puffy, red rash at the affected area. Drinking water directly from Willow Creek Reservoir at this time is especially dangerous. OHA Public Health Division officials advise campers and other recreational visitors that toxins cannot be removed by boiling, filtering or treating water with camping-style filters.
• The Oregon Health Authority has updated the Health Advisory issued July 28 for Howard Bay (also known locally as Howards Bay or Howard’s Bay), located in the southwest corner of Upper Klamath Lake, to include Shoalwater Bay to the north. These areas of Upper Klamath Lake are located off Oregon Route 140, 15 miles west of Klamath Falls in Klamath County. Water monitoring has confirmed the presence of blue-green algae and the toxins they produce in Howard Bay. These toxin concentrations can be harmful to humans and animals. People should always avoid areas with visible scum that looks foamy, scummy, thick like paint, pea-green, blue green or brownish red. Swimming and high-speed water activities such as water skiing or power boating where ingestion and inhalation exposure can occur is discouraged. Swallowing or inhaling water droplets as a result of these water activities in areas where a bloom has been identified, or an advisory issued, can expose people to the toxins being produced. Although toxins are not absorbed through the skin, people who have skin sensitivities that come into contact with a bloom may experience a puffy, red rash at the affected area. Drinking water directly from Howard Bay and Shoalwater Bay at this time is especially dangerous. OHA Public Health Division officials advise campers and other recreational visitors that toxins cannot be removed by boiling, filtering or treating water with camping-style filters.
• The Oregon Health Authority issued Health Advisory for Agency Lake, located just north of Klamath Falls along U.S. Highway 97 in Klamath County. Water monitoring has confirmed the presence of blue-green algae and the toxins they produce in the lake. These toxin concentrations can be harmful to humans and animals. People should always avoid areas with visible scum that looks foamy, scummy, thick like paint, pea-green, blue green or brownish red. Swimming and high-speed water activities such as water skiing or power boating where ingestion and inhalation exposure can occur is discouraged. Swallowing or inhaling water droplets as a result of these water activities in areas where a bloom has been identified, or an advisory issued, can expose people to the toxins being produced. Although toxins are not absorbed through the skin, people who have skin sensitivities that come into contact with a bloom may experience a puffy, red rash at the affected area. Drinking water directly from Agency Lake at this time is especially dangerous. OHA Public Health Division officials advise campers and other recreational visitors that toxins cannot be removed by boiling, filtering or treating water with camping-style filters.
• The Oregon Health Authority issued a Health Advisory today for Willow Creek Reservoir, located just east of the town of Heppner in Morrow County. Water monitoring has confirmed the presence of blue-green algae and the toxins they produce in the reservoir. These toxin concentrations can be harmful to humans and animals. People should always avoid areas with visible scum that looks foamy, scummy, thick like paint, pea-green, blue green or brownish red. Swimming and high-speed water activities such as water skiing or power boating where ingestion and inhalation exposure can occur is discouraged. Swallowing or inhaling water droplets as a result of these water activities in areas where a bloom has been identified, or an advisory issued, can expose people to the toxins being produced. Although toxins are not absorbed through the skin, people who have skin sensitivities that come into contact with a bloom may experience a puffy, red rash at the affected area. Drinking water directly from Willow Creek Reservoir at this time is especially dangerous. OHA Public Health Division officials advise campers and other recreational visitors that toxins cannot be removed by boiling, filtering or treating water with camping-style filters.
• The Oregon Health Authority issued a Health Advisory for Coffenbury Lake, located at Fort Stevens State Park about five miles northwest of US-101 ALT, Northwest Ridgefield Road near Warrenton in Clatsop County. Water monitoring has confirmed the presence of blue-green algae that can produce toxins in Coffenbury Lake. These blue-green algae levels are likely to be associated with dangerous cyanotoxin concentrations in the water that can be harmful to humans and animals.  People should always avoid areas with visible scum that looks foamy, scummy, thick like paint, pea-green, blue-green or brownish-red. Swimming and high-speed water activities such as water skiing or power boating where ingestion and inhalation exposure can occur are discouraged. Swallowing or inhaling water droplets as a result of these water activities in areas where a bloom has been identified or an advisory issued, can expose people to the toxins that can be produced. Although toxins are not absorbed through the skin, people with skin sensitivities who come into contact with a bloom may experience a puffy, red rash at the affected area. Drinking water directly from Coffenbury Lake at this time is especially dangerous. OHA Public Health Division officials advise campers and other recreational visitors that toxins cannot be removed by boiling, filtering or treating water with camping-style filters.
• The Oregon Health Authority has updated the Health Advisory issued June 30 for Lake Billy Chinook, located about 12 miles west of Madras in Jefferson County. The update lifts the advisory on those areas of the Deschutes and Crooked River of Lake Billy Chinook arms affected by the advisory, and confines the advisory on the Metolius Arm to Perry South Cove. Water monitoring has confirmed that the level of blue-green algae toxins are below guideline values for human exposure. However, OHA recommends that people remain cautious when using the lake, particularly with pets because toxins are still well above the very low exposure levels established for dogs.
• A Permanent Health Advisory remains in effect for the South Umpqua River and Lawson Bar. Pools in the bedrock along the rivers edge are known to develop Blue-green Algae (cyanobacterial) blooms that can be harmful to pets and people if accidental ingestion occurs. Signs have been posted along several access areas along the river.

________________

 

Forecast for the Southern and lower Mid Willamette Valley including Eugene-Springfield and Albany-Corvallis:

• A mix of clouds and sun with patchy smoke this afternoon, partly cloudy with patchy smoke tonight,
• Partly cloudy with patchy smoke Thursday and at night,
• AM clouds, mostly sunny and a bit cooler Friday afternoon, then partly cloudy Friday night.
• highs 90-87 lows near 58.
• Partly cloudy and a bit cooler Saturday, partly cloudy with a slight (20%) chance of showers Saturday night,
• Mostly cloudy with a slight (20%) chance of showers Sunday and in the evening,  just mostly cloudy late Sunday night,
• Partly cloudy with a slight (20%) chance of showers Monday, then just partly cloudy Monday night and Tuesday.
• highs 86-78 lows 56-52. (seasonal averages high 84 low 52)

________________

Eugene-Springfield Pollen Count

Grass………. Low (3)
Trees………. Low (3)
Last Counted: 8/2/17
Data Courtesy of Oregon Allergy Associates.
Note: It would seem the pollen season is over.

________________

Forecast for Roseburg:

• Partly cloudy with patchy smoke and a slight (20%) chance of isolated thunderstorms and a bit cooler this afternoon, patchy smoke with isolated evening thunderstorms, a (40%) chance of isolated thunderstorms with patchy smoke late tonight,
• Partly cloudy with patchy smoke and a bit cooler with a slight (20%) chance of  thunderstorms Thursday and evening, patchy smoke at night,
• Partly cloudy and a bit cooler Friday and Friday night.
• highs 95-90 lows 62-64 cooling to 60 Friday night.
• Sunny and a bit cooler Saturday, mostly clear with a slight (20%) chance of thunderstorms at night,
• Sunny Sunday AM, partly cloudy with a slight (20%) chance of showers and a bit cooler in the afternoon and evening, mostly cloudy with a slight (20%) chance of showers Sunday night and Monday AM, then partly cloudy and a bit cooler Monday afternoon through Tuesday.
• highs 88-82 lows near 56. (seasonal averages high 86 low 56)

_____________________

Forecast for The South Central Oregon Coast Including Coos Bay and North Bend:

• Mostly cloudy this afternoon patchy inland smoke, partly cloudy this evening and mostly cloudy with patchy inland smoke and a slight (20%) chance of isolated inland thunderstorms tonight, patchy fog late at night,
• Mostly cloudy with patchy AM coastal fog while patchy inland fog and smoke inland, partly cloudy Thursday afternoon and evening, just mostly cloudy late Thursday night,
• Mostly cloudy in the AM, partly cloudy Friday afternoon and at night.
• highs near 65 lows near 55.
• Partly cloudy Saturday, a slight (20%) chance of showers Saturday night,
• Partly cloudy and a bit warmer with a slight (20%) chance of showers Sunday afternoon through Monday AM, then just partly cloudy and a bit cooler Monday afternoon through Tuesday.
• highs near 65 lows near 55. (seasonal averages high 65 low 53)

________________

Forecast for the Cascades in Lane County:

• Partly cloudy and a bit cooler with patchy smoke and a (40%) chance of scattered showers and thunderstorms this afternoon and evening (under 0.10 in. of rain possible, more in storms), patchy smoke with a slight (20%) chance of showers and thunderstorms late tonight (under 0.10 in. of rain possible, more in storms),
• Partly cloudy with patchy smoke and a bit warmer with a (40%) chance of showers and thunderstorms Thursday afternoon (under 0.10 in. of rain possible, more in storms), patchy smoke with a good (50%) chance of showers and thunderstorms in the evening, patchy smoke with a slight (20%) chance of showers and thunderstorms late at night,
• Partly cloudy with patchy AM smoke and a slight (20%) chance of showers, a (40%) chance of showers and thunderstorms and a bit cooler Friday afternoon, a slight (20%) chance of evening showers and thunderstorms, then just partly cloudy late Friday night.
• snow level above 8,000 ft. today through Friday evening, then free air freezing level above 12,000 ft. late Friday night.
• highs near 78 lows 56-53.
• Partly cloudy in the AM, mostly sunny and a bit cooler with a slight (20%) chance of showers and thunderstorms Saturday afternoon and evening, partly cloudy late at night,
• Partly cloudy and a bit cooler Sunday with a slight (20%) chance of showers in the afternoon and Sunday night,
• Partly cloudy and a bit cooler with a slight (20%) chance of showers Monday and in the evening, then just partly cloudy late Monday night and Tuesday.
• free air freezing level above 12,000 ft. Saturday AM, snow level above 8,000 ft. Saturday afternoon and evening, free air freezing level above 12,000 ft. late Saturday night through Sunday night and Monday, then free air freezing level 11,000 ft. rising to 12,000 ft. Monday night and Tuesday.
• highs 74-63 warming to 65 Tuesday lows 49-43.

 

________________

**Because weather forecasting is a combination of science, intuition, and timing there can be no absolute guarantees that individual forecasts will be 100% accurate. Nature is in a constant state of flux and sudden unexpected weather events can happen.

________________

Get your local Eugene-Springfield and Lane County news on-line at eugenedailynews.com.

________________