Jul
21.
Here is my weekly weather quiz question for the last time. “What is the “Showalter Index?” Here is the correct answer. The Showalter Index(Abbrev. SWI) – is a stability index used to determine thunderstorm potential. The SWI is calculated by lifting an air parcel adiabatically from 850 mb to 500 mb. The algebraic difference between the air parcel and the environmental temperature at 500 mb represents the SWI. It is especially useful when you have a shallow cool airmass below 850 mb concealing greater convective potential aloft. However, the SWI will underestimate the convective potential for cool layers extending above 850 mb. It also does not take in account diurnal heating or moisture below 850 mb. As a result, one must be very careful when using this index.
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An Upper Level Low remains offshore and that means more onshore airflow. As it moves temperatures will slowly increase. The graphics for days 1-3 show a frontal system sliding into Oregon Monday. The graphics for days 3-7 Wednesday through Sunday show a cold frontal system sliding through the Pacific Northwest Wednesday.
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Air Quality Index:
Eugene/Springfield: The Air Quality Index is 33 in the Good category measuring Ozone.
Oakridge: The Air Quality Index is 23 in the Good category measuring Particulate Matter.
Cottage Grove: The Air Quality Index is 24 in the Good category measuring Particulate Matter.
Data courtesy of Lane Regional Air Protection Agency (LRAPA.org)
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ADVISORIES:
- A RED FLAG WARNING IS IN EFFECT UNTIL 11 PM TONIGHT FOR DRY AND UNSTABLE CONDITIONS FOR THE SOUTHERN BLUE AND STRAWBERRY MOUNTAINS AND THE CENTRAL BLUE MOUNTAINS.
- A RED FLAG WARNING IS IN EFFECT UNTIL 11 PM TONIGHT FOR ABUNDANT LIGHTNING ON DRY FUELS FOR THE SOUTH CENTRAL OREGON DESERT INCLUDING THE BLM LAND IN EASTERN LAKE AND WESTERN HARNEY COUNTIES.
- A RED FLAG WARNING IS IN EFFECT UNTIL 11 PM TONIGHT FOR ABUNDANT LIGHTNING FOR THE KLAMATH BASIN AND THE FREMONT-WINEMA NATIONAL FOREST.
- A RED FLAG WARNING IS IN EFFECT UNTIL 10 PM TONIGHT FOR ABUNDANT LIGHTNING FOR THE DESCHUTES NATIONAL FOREST AND THE MINUS SISTERS RANGER DISTRICT.
- A RED FLAG WARNING IS IN EFFECT UNTIL MIDNIGHT MDT TONIGHT FOR BURNS BLM AND THE VALE BLM.
- A RED FLAG WARNING IS IN EFFECT UNTIL 8 PM TONIGHT FOR THUNDERSTORMS FOR THE CENTRAL OREGON CASCADE FOOTHILLS, THE NORTHERN WILLAMETTE NATIONAL FOREST AND THE SOUTHERN WILLAMETTE NATIONAL FOREST.
- AN EXCESSIVE HEAT WARNING IS IN EFFECT UNTIL 10 PM MONDAY FOR THE EASTERN COLUMBIA RIVER GORGE OF OREGON, THE LOWER COLUMBIA BASIN OF OREGON, THE GRANDE RONDE VALLEY, WALLOWA COUNTY, THE NORTHERN BLUE MOUNTAINS OF OREGON, THE SOUTHERN BLUE MOUNTAINS OF OREGON, THE JOHN DAY BASIN, THE FOOTHILLS OF THE NORTHERN BLUE MOUNTAINS OF OREGON, AND THE FOOTHILLS OF THE SOUTHERN BLUE MOUNTAINS OF OREGON.
- A HEAT ADVISORY IS IN EFFECT UNTIL 8 PM MONDAY FOR THE OCHOCO, THE JOHN DAY HIGHLANDS, NORTH CENTRAL OREGON, AND CENTRAL OREGON.
- A HEAT ADVISORY IS IN EFFECT UNTIL 11 PM TONIGHT FOR THE KLAMATH BASIN, NORTHERN AND EASTERN KLAMATH COUNTY, AND WESTERN, CENTRAL, AND EASTERN LAKE COUNTY.
- A HEAT ADVISORY IS IN EFFECT UNTIL 9 PM MDT WEDNESDAY NIGHT FOR BAKER COUNTY AND HARNEY COUNTY.
- AN EXCESSIVE HEAT WARNING IS IN EFFECT UNTIL 9 PM MDT WEDNESDAY FOR MALHEUR COUNTY AND THE OREGON LOWER TREASURE VALLEY.
- A FIRE WEATHER WATCH IS IN EFFECT FROM THIS MORNING THROUGH LATE TONIGHT FOR LIGHTNING FOR THE BURNS BLM AND THE VALE BLM.
- AN AIR QUALITY ALERT IS IN EFFECT UNTIL 2 PM MONDAY FOR HARNEY AND MALHEUR COUNTIES.
HEALTH ADVISORIES:
- A PERMANENT HEALTH ADVISORY REMAINS IN EFFECT FOR THE SOUTH UMPQUA RIVER 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.
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Forecast for the Southern and lower Mid Willamette Valley including Eugene-Springfield and Albany-Corvallis:
- Mostly clear this evening, partly cloudy late tonight,
- Sunny and a bit warmer Monday, clear Monday night,
- Then sunny and a bit warmer Tuesday and Wednesday, mostly clear both nights,
- lows 54-49 warming to 52 Tuesday night and Wednesday highs 84-90.
- Sunny and slightly cooler Thursday, clear Thursday night,
- Sunny and a bit warmer Friday, clear at night,
- Sunny and a bit warmer Saturday, mostly clear Saturday night,
- Then sunny and a bit warmer Sunday.
- highs 87-90 lows 50-52 (seasonal averages high 86 low 52)
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EUGENE-SPRINGFIELD POLLEN COUNT:
GRASS: LOW (3)
TREES: LOW (3)
WEEDS: ABSENT (0)
Measured 7.18.24
Data courtesy of Oregon Allergy Associates.
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Forecast for the Umpqua Valley including Roseburg:
- Mostly clear with evening haze, partly cloudy and hazy with patchy drizzle late tonight,
- Hazy with some AM clouds, sunny and hazy and warmer Monday afternoon, clear and hazy Monday night,
- AM haze, sunny and a bit warmer Tuesday, mostly clear at night,
- Mostly sunny and a bit warmer Wednesday, then mostly clear Wednesday night.
- lows 59-55 warming back to 59 Tuesday night cooling to 57 Wednesday night highs 86-92.
- Mostly sunny and a bit cooler Thursday, clear Thursday night,
- Sunny and a bit warmer Friday, mostly clear Friday night,
- Then mostly sunny Saturday, mostly clear Saturday night,
- Then mostly sunny and a bit warmer Sunday.
- highs 87-90 lows 55-57 (seasonal averages high 87 low 58)
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Forecast for The South Oregon Coast Including Coos Bay and North Bend:
- Mostly cloudy and hazy with patchy coastal drizzle and coastal fog late tonight while inland haze with drizzle and patchy fog late tonight,
- Mostly cloudy and hazy with patchy AM coastal drizzle and fog while hazy with areas of AM inland fog and drizzle, becoming sunny and a bit warmer Monday afternoon, mostly clear Monday night,
- Inland AM haze, sunny Tuesday, mostly clear in the evening, partly cloudy at night,
- Mostly sunny and a bit warmer Wednesday, mostly clear in the evening, then partly cloudy Wednesday night.
- lows 54-50 warming to 52 Wednesday night highs 70-72.
- Mostly sunny Thursday, mostly clear Thursday night,
- Mostly sunny Friday, partly cloudy at night,
- Then partly cloudy Saturday through Sunday.
- highs near 72 lows near 52. (seasonal average high 67 low 54)
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Forecast for the Northern Oregon Cascades including the Cascades in Lane County:
- Partly cloudy and hazy with areas of evening smoke, partly cloudy and hazy late tonight,
- AM haze, sunny and a bit warmer Monday afternoon, mostly clear Monday night,
- Sunny and hazy and a bit warmer Tuesday, mostly clear at night,
- Sunny and a bit warmer Wednesday, then mostly clear Wednesday night.
- free air freezing level above 16,000 ft. tonight and Monday, above 16,000 ft. Tuesday through Wednesday night.
- lows 52-46 warming back to 52 Tuesday night highs 76-85 cooling to 82 Wednesday.
- Sunny and a bit cooler Thursday, mostly clear Thursday night,
- Sunny Friday, mostly clear at night,
- Sunny and a bit cooler Saturday, mostly clear Saturday night,
- Then sunny Sunday.
- free air freezing level 16,000 ft. Thursday, 15,000 ft. Thursday night, 15.000 ft Friday, 14,000 ft. Friday night, then 14,000 ft. Saturday through Sunday.
- highs 76-75 warming to 77 Sunday lows near 47.
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