Jul
20.
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 is approaching the coast and will bring the chance of thunderstorms.. The graphics for days 1-3 show no frontal systems sliding into Oregon. The graphics for days 3-7 Wednesday through Sunday show a cold frontal system sliding into the Pacific Northwest Wednesday.
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Air Quality Index:
Eugene/Springfield: The Air Quality Index is 39 in the Good category measuring Ozone.
Oakridge: The Air Quality Index is 237 in the Very Unhealthy category measuring Particulate Matter.
Cottage Grove: The Air Quality Index is 29 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 AM TODAY FOR THUNDERSTORMS FOR THE CENTRAL OREGON COAST RANGE AND THE SOUTHERN WILLAMETTE VALLEY.
- A RED FLAG WARNING IS IN EFFECT FROM 5 AM UNTIL 8 PM TODAY FOR THUNDERSTORMS FOR THE NORTHERN OREGON CASCADE FOOTHILLS AND THE MT. HOOD NATIONAL FOREST REGION.
- A RED FLAG WARNING IS IN EFFECT UNTIL 8 PM TONIGHT FOR THUNDERSTORMS THE CENTRAL OREGON CASCADE FOOTHILLS, THE NORTHERN WILLAMETTE NATIONAL FOREST, AND THE SOUTHERN WILLAMETTE NATIONAL FOREST.
- A RED FLAG WARNING IS IN EFFECT UNTIL 8 AM TODAY FOR ABUNDANT LIGHTNING ON DRY FUELS FOR SOUTH CENTRAL OREGON COAST, THE UMPQUA BASIN, THE UMPQUA NATIONAL FOREST, THE SOUTHERN OREGON COAST, THE WESTERN SISKIYOU NATIONAL FOREST, THE WESTERN ROGUE BASIN INCLUDING THE ILLINOIS VALLEY, THE EASTERN ROGUE VALLEY, AND THE THE SOUTHERN OREGON CASCADES.
- A RED FLAG WARNING IS IN EFFECT FROM 2 PM UNTIL 11 PM TODAY 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 FROM NOON TO 10 PM TODAY FOR ABUNDANT LIGHTNING FOR THE DESCHUTES NATIONAL FOREST AND THE MINUS SISTERS RANGER DISTRICT.
- A RED FLAG WARNING IS IN EFFECT FROM NOON MDT TODAY UNTIL MIDNIGHT MDT SUNDAY 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.
- AN EXCESSIVE HEAT WARNING IS IN EFFECT UNTIL 11 PM MONDAY FOR BAKER COUNTY.
- A HEAT ADVISORY IS IN EFFECT UNTIL MIDNIGHT MDT MONDAY NIGHT FOR HARNEY COUNTY.
- AN EXCESSIVE HEAT WARNING IS IN EFFECT UNTIL 9 PM MDT TODAY FOR FOR MALHEUR COUNTY AND THE OREGON LOWER TREASURE VALLEY.
- A HEAT ADVISORY IS IN EFFECT UNTIL 11 PM TONIGHT FOR THE INNER PORTLAND METRO, THE EAST PORTLAND METRO, THE EAST CENTRAL WILLAMETTE VALLEY, THE LINN COUNTY LOWLANDS, THE LANE COUNTY LOWLANDS, THE WESTERN COLUMBIA RIVER GORGE, THE I-84 CORRIDOR, THE UPPER HOOD RIVER VALLEY, AND THE CENTRAL COLUMBIA RIVER GORGE -I-84 CORRIDOR.
- A FIRE WEATHER WATCH IS IN EFFECT THROUGH THIS MORNING ABUNDANT LIGHTNING ON DRY FUELS FOR THE SOUTH CENTRAL OREGON COAST, THE UMPQUA BASIN, THE UMPQUA NATIONAL FOREST, THE SOUTHERN OREGON COAST, THE WESTERN SISKIYOU NATIONAL FOREST, THE WESTERN ROGUE BASIN INCLUDING THE ILLINOIS VALLEY, THE EASTERN ROGUE VALLEY, AND THE SOUTHERN OREGON CASCADES.
- A FIRE WEATHER WATCH IS IN EFFECT FROM THIS MORNING THROUGH LATE SUNDAY NIGHT FOR LIGHTNING FOR THE BURNS BLM AND THE VALE BLM.
- A FIRE WEATHER WATCH IS IN EFFECT THROUGH THIS EVENING FOR DRY AND UNSTABLE CONDITIONS FOR THE CENTRAL BLUE MOUNTAINS.
- AN AIR QUALITY ALERT IS IN EFFECT UNTIL 5 PM MONDAY FOR KLAMATH AND LAKE COUNTIES.
- AN AIR QUALITY ALERT IS IN EFFECT UNTIL 5 PM MONDAY FOR GRANT AND MORROW COUNTIES.
- 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 sunny and hazy with a slight (20%) chance of AM thunderstorms, mostly sunny and cooler this afternoon, mostly clear tonight,
- Sunny and a bit cooler Monday, clear at night,
- Sunny and a bit warmer Tuesday, then clear Tuesday night.
- highs 86-84 warming to 89 Tuesday lows 53-49 warming to 52 Tuesday night.
- Sunny and a bit warmer Wednesday, mostly clear Wednesday night,
- Sunny and slightly cooler Thursday, clear at night,
- Then sunny and a bit warmer Friday and Saturday, clear Friday night.
- highs 90-87 warming to 89 Saturday lows near 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 cloudy and hazy with a slight (20%) chance of AM thunderstorms, partly cloudy and hazy and cooler this afternoon, mostly clear with evening haze, partly cloudy and hazy late tonight,
- Hazy with some AM clouds, sunny and a bit warmer Monday afternoon, clear at night,
- Sunny and a bit warmer Tuesday, then clear Tuesday night.
- highs 83-90 lows 59-55 warming to 57 Tuesday night lows 59-55 warming to 57 Tuesday night.
- Sunny and a bit warmer Wednesday, mostly clear Wednesday night,
- Mostly sunny and a bit cooler Thursday, clear at night,
- Then sunny and a bit warmer Friday and Saturday, clear Friday night,
- highs 92-88 warming to 90 Friday and Saturday lows 54-56 (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 a slight (20%) chance of AM thunderstorms, mostly cloudy and a bit cooler this afternoon, mostly cloudy and hazy with patchy fog late tonight,
- Mostly cloudy with patchy AM coastal fog, while inland AM haze and areas of fog, becoming sunny and slightly warmer Monday afternoon, mostly clear at night,
- Mostly sunny and a bit warmer Tuesday, then mostly clear Tuesday night.
- highs 69-72 lows 54-50.
- Mostly sunny Wednesday, mostly clear in the evening, partly cloudy Wednesday night,
- Mostly sunny Thursday and Friday, mostly clear both nights,
- Some AM clouds, then sunny Saturday afternoon.
- highs near 72 lows 52-50 warming back to 52 Friday night. (seasonal average high 67 low 54)
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Forecast for the Northern Oregon Cascades including the Cascades in Lane County:
- Mostly sunny and hazy with areas of smoke and a slight (20%) chance of thunderstorms and cooler today, mostly clear tonight,
- AM haze, sunny and a bit cooler Monday afternoon, mostly clear at night,
- Sunny and a bit warmer Tuesday, then mostly clear Tuesday night.
- free air freezing level above 16,000 ft. today through Monday, Tuesday, then above 16,000 ft. Monday night through Tuesday night.
- highs 82-79 warming to 84 Tuesday lows 52-46 warming back to 52 Tuesday night.
- Sunny and a bit cooler Wednesday, mostly clear Wednesday night,
- Sunny and a bit cooler Thursday, mostly clear at night,
- Sunny Friday, mostly clear Friday night,
- Then sunny and a bit cooler Saturday.
- free air freezing level above 16,000 ft. Wednesday through Thursday, 15,000 ft. Thursday night, 14.000 ft Friday, 15,000 ft. Friday night, then 14,000 ft. Saturday.
- highs 83-75 warming to 77 Friday lows 49-45.
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