Wednesday Dec 1, 2021 Update: I'm sure you've been enjoying our "balmy" weather, but that will soon change. Except for an isolated shower or sprinkles Saturday afternoon, no rain is expected through Sunday. High temperatures Thursday through Sunday will drop into the low-mid 50's with lows near 34-39. Light, mainly northerly, winds through Friday. Saturday could be a little breezy with some wind gusts up to 15-20 mph.
Monday: A series of low pressure systems are expected to pass through the region beginning early Monday morning and continuing through the middle of the month. Rainfall with Monday's storm looks to be around 3/4"-1". This isn't a particularly windy storm, so we'll probably only see a few southerly gusts to 20 mph or so. Snow levels on Monday will start off above 6000' then lower to 5000' during the late afternoon.
Wednesday Dec 8: Rain will develop during the morning, but this system appears lacking in moisture, so around 1/10" of rainfall looks like a good bet right now. No wind issues, snow levels near 4000'.
Thursday Dec 9: Rain should move in during the afternoon and continue through Friday morning. Still some uncertainties. Preliminarily, snow levels could be around 3000-4000'. Southerly wind gusts will probably stay under 25 mph, as this doesn't look like a windy storm. Total rainfall Thursday afternoon through Friday morning will likely be around 1/2-3/4".
Sat Dec 11 - Wed Dec 15: I'm watching this time period closely. Data is signaling that a strong and cold low pressure system may affect the area with potentially low snow levels on Saturday (Dec 11), followed by another colder system on Sun Dec 12 or Mon Dec 13 that could possibly drop snow levels to around 1000'. This is all still preliminary and I want to emphasize it is impossible to predict lowland snow this far into the future. If data continues to maintain the strong strength of the low pressure system on Sat Dec 11, strong winds could affect our area.
I avoid hyping because it gets us nowhere, and it's nearly impossible to predict snow beyond 3-days across the lowland areas. That said, there's little doubt that Dec 12-17, cooler air will come in and low pressure systems will become colder. Therefore, most models and their ensembles strongly hint at lowland snow possibilities sometime between Dec 12 and Dec 17. Think of ensembles as dozens of different modeled solutions for the weather pattern at a given time. The more that the ensembles have a similar outcome, better confidence exists with the favored prediction. By no means is this a slam dunk and it's low accuracy this far out but with a little more optimism since many model ensembles are on board for at least some potential for lowland snow. Next post is expected to be on Saturday Dec 4 and I'll be sure to update you on the snow potential. Here's one of the many ensemble's predicted snow:
Most models are similar to these projected temperatures. The takeaway message is that we'll trend cooler.
Where we stand with precipitation: November's going to close out with below average rainfall. Normal for the month is 6.92" and we've recorded 5.25" here in Cottage Grove. However, we had 4.55" of rainfall in October (start of the water year) when the normal is 3.67". Therefore for the Year-To-Date, we're really only behind 0.79" which is not bad at all (about another 1/5" (0.20") is expected on Monday). Storm systems with tons of moisture have been slamming into British Columbia, which has seen incredible amounts of rain and massive flooding. Undoubtedly, La Nina is having an influence on the weather patterns.
The week ahead: Monday, a low pressure system will clip our area and allow for light rain chances. Expect no more than 1/5" with light winds. Monday night through Friday (Dec 3) looks to be mainly dry with just a small chance of a light shower or two on Thursday. Low temperatures are expected to remain above freezing with no threats of frost through Sunday Dec 5 (scroll down for 10-day temperatures).
Wet and Cold? A major pattern change is looking more and more probable starting around December 4. A series of cold low pressure systems may begin to pass through the PacNW and into California (where precipitation is desperately needed). These systems are not only expected to be cold, but become progressively colder. Snow levels will likely start off at around 3000-4000' on Sat Dec 4 and could possibly be down to 1000-1500' by December 8th. Maybe lower, we'll see. Total combined rainfall through Dec 14 could be 3-5" with 2-4 FEET of new snow in the Cascades (if this all comes together as modeled). Some data is hinting that we could see some light snow here in Cottage Grove Dec 10-14.
System #1 Sat Dec 4: looks to have little moisture so don't expect much precipitation (snow levels probably 3000-4000').
System#2 Mon Dec 6: expected to be strong with lots of moisture and may be windy (snow levels might drop to 2000'):
System #3 Dec 8-9 (notice more purple, which is SNOW):
System #4 Dec 11-12 (notice the purple (SNOW) covers more of western Oregon):
IF high pressure doesn't break down as currently expected, then some of these low pressure systems may continue to be pushed well north of our region. Based on what I see right now, I do think the storm door will open for us. It should be noted, however, that computer model data are not in harmony and details will be sorted out over the next few days. I'll have an update out on Tuesday or Wednesday the latest.
Temperatures are expected to start trending cooler than average (normal) beginning around Dec 4:
Temperatures look to be "around" this over the next 10-days:
SNOW is possible! Models are starting to suggest lowland snow around Dec 10-14:
Wishing you all a safe and happy Thanksgiving! No hazards, high wind, or major snow impacts expected at this time. Tonight (Tuesday) through Sunday, snow is not expected over the passes at this time. Check road conditions at tripcheck.com
CASCADE PASSES: an insignificant amount, a dusting to 2" is possible to midnight tonight (Tuesday). NO SNOW is then expected Wednesday through Sunday. No significant wind impacts.
NORTH WA/OR: I-5 at the WA/OR border and northward through Washington, NO SNOW is expected through Sunday. No significant wind impacts.
SOUTH OR/CA: I-5 at the CA/OR border will have snow flurries or a dusting over the border pass mainly before noon today (Tuesday). This afternoon (Tuesday) through Sunday, NO SNOW is expected at pass levels. No significant wind impacts.
Major storms are not expected through Sunday. Later Thanksgiving evening or early night (Thursday), rain will develop as a storm system affects the region. Snow levels will be above 7000-8000' and therefore not affect the passes. Rain/showers will continue through Friday evening. Expect ~1/2" of total rain. Winds locally should stay under 15-20 mph. Night/morning fog is a possibility.
Small chances of showers will then exist Friday night through Sunday as a couple of storm systems pass to the north and may clip our area. Expect night/morning fog at times through Monday.
Temperatures: Frost is possible Wednesday and Thursday mornings (lows 28-32 tonight, then 30-35 Wednesday night). Patchy ice will be possible on some of the roads and bridges. Lows warm to above freezing and frost levels Thursday night through the weekend. Highs through Thursday will be in the upper 40's to low 50's, then warm to the mid 50's on Friday, and into the upper 50's-low 60's Sat-Sun. Normal high/low is near 50/36.
Looking ahead: Next storm system is expected to arrive on Tuesday Nov 30 with high snow levels. Another storm may then follow on Wednesday (Dec 1), but at this time most of the energy will probably be directed into northern Washington and British Columbia. It appears that La Nina is certainly influencing the weather patterns, as there's anomalous high pressure in the North Pacific and western U.S. This is affecting the jet stream by keeping it more north than what we typically see this time of year. However, it's still early in the rainy season, as there's still many months ahead which have the potential for plenty of precipitation.
No high wind concerns at this time. Monday and Tuesday morning, some snow is expected down to between 3500-4000'. Tuesday afternoon through Sunday Nov 28, snow is not expected over the passes at this time. Check road conditions at tripcheck.com
CASCADE PASSES: an insignificant amount, 1-3" is expected 8pm Monday evening through late morning or early afternoon on Tuesday.
NORTH: I-5 at the WA/OR border and northward through Washington is not expected to have snow impacts through Sunday Nov 28.
SOUTH: I-5 at the CA/OR border will have snow flurries or a dusting over the border pass mainly after 9pm Monday to sunrise Tuesday. This will be an insignificant amount and is unlikely to have any major impacts on travel. Tuesday afternoon through Sunday Nov 28, snow is not expected at pass levels (at this time).
Major storms are not expected through Sunday Nov 28. Three moderate to strong strength storm systems will affect the region. Dense fog will be possible at times through Wednesday morning. Frost is possible Monday morning, Wednesday morning, and Thursday morning. Patchy ice will be possible on some of the roads and bridges.
System #1: Later Monday, rain developing after 5:00pm. Tuesday will have some showers during the morning, with just isolated showers lingering through the afternoon. Total rainfall ~1/4". No wind concerns (under 20 mph). Dry Tuesday night and Wednesday.
Systems #2 and #3: Periods of rain and showers will develop Thursday morning (Thanksgiving Day) and continue through Sunday evening Nov 28. Thanksgiving day itself is expected to have 3/4-1" of rain. Some showers on Friday. More steady rain again Friday night through Saturday morning (another 1/2-1"). Light rain/showers on Sunday (Nov 28). Southerly winds can gust up to 20-30 mph at times (especially on Thanksgiving and Sat-Sun).
Looking ahead: Keeping an eye on later Monday Nov 29 and Tuesday Nov 30, as some preliminary data suggests a strong and windy storm may affect the region.
Temperatures look like this over the next 10-days:
If you're traveling during the Thanksgiving holiday period next week, no major weather impacts are expected through Saturday morning Nov 27. See below for later Sat Nov 27 and Sun Nov 28.
This afternoon through Friday: A low pressure system will bring periods of mainly light rain and showers to the area through Friday afternoon or early evening. Total rainfall from this system today and Friday looks to be 1/4"-1/2". It can get breezy at times later this afternoon or evening to about sunrise on Friday, with some wind gusts of 15 or 20 mph.
Friday night through the weekend: Looks dry, but low temperatures are expected to be around 30-35 (especially Saturday night and again Sunday night). Therefore, expect frosty mornings on Sunday and possibly Monday with some patches of ice possible on the roads (esp bridges). Some data hints that there could be some cloud cover overnight which could cause lows to be a little higher than forecast.
TRAVEL WEATHER NEXT WEEK: At this time, no major issues are expected through Thanksgiving Day. A couple of low pressure systems will bring regional rain and small amounts of snow (mainly above 5000-6000') later Tuesday into Wednesday morning. Major winter weather impacts are not expected through Saturday morning (Nov 27) over the Cascades and WA/OR + CA/OR border passes.
Thanksgiving day (Thur Nov 25) & Fri Nov 26: A storm system will bring rain and a small amount of higher elevation snow. Showers may continue into Friday (Nov 26). This doesn't look to be a particularly cold system, so all Oregon passes are not expected to have significant winter weather impacts (at this time).
Saturday Nov 27: A storm system may pass through with rain and high elevation snow (mostly above pass levels, no major winter weather impacts expected at this time).
Sunday Nov 28: A storm system with significant winter weather impacts may affect the PacNW. Note that there's large differences with the computer models right now, which should be resolved over the next few days. On or before Monday, I should have a better grip on this potentially powerful system that could impact return travel (or not).
Precipitation to date: As of 11:00am Thurs Nov 18, we've recorded 9.08" of rainfall since the start of the water year on October 1. So far for November, we've observed 4.53". Normal for the entire month is 6.92". Scroll below to see precipitation information, including snow pack.
Temperatures look like this over the next 10-days (not set in stone):
What: A storm system will bring rain and breezy to possibly windy conditions Monday morning and afternoon. Cooler/drier air mass moves in on Monday. Snow levels will be 3000-4000' Monday night and Friday night. Just a dusting to an inch below 4000' during this time period.
Timing: Rain develops around 10am-2pm on Monday. Winds start to pick up around predawn Monday and gradually increase throughout the morning and early afternoon. Winds will decrease late afternoon or early evening on Monday.
Hazards: Wind gusts of 30 mph can break a tree limb or two. High winds are expected to stay confined to the coast.
Total Rainfall: Expect 1/3"-2/3" (0.33-0.66") of total rainfall 11am-11pm Monday. Total average rainfall for the month of November is 6.92". As of 10:00am today (Sun Nov 14), we've recorded 4.03" so far this month and 8.58" since the start of the water year on Oct 1.
Wind: Southerly winds can gust up to 30 mph at times on Monday. Strongest winds 9am-3pm Monday.
Temperatures (5-days): Much cooler (and drier) air mass moves in on Monday. High temps Monday around 60, then ~50-55 Tuesday through next weekend. Lows: Monday night 33-37 // Tuesday night 29-34 // Wednesday night 33-37 // Thursday night 36-40. Normal high/low is near 53/38.
Fog: Patchy fog possible at times, especially Tuesday and Wednesday.
Snow Potential below 1000': Not going to happen.
Frost/Ice probability: Some frost is possible Tuesday morning. Frost, freezing temperatures, patchy ice on the roads are possible Wednesday morning. Temperatures are expected to be above freezing Wednesday night through the weekend.
15-day Outlook: Dry Tuesday and Wednesday. Next storm system comes in Thursday afternoon, bringing another round of rain and wind gusts to 25 mph. Friday evening through next weekend looks dry at this time. Thanksgiving week, a storm system may affect the area on Monday (Nov 22) with rain and mountain snow. Looks dry Tue-Wed (Nov 23-24). Another storm may affect the region on Thanksgiving Day (Nov 25) and Friday Nov 26. This is very preliminary. Timing will probably change and it should be noted that uncertainties exist from Mon Nov 22 through the Thanksgiving holiday weekend.
Seasonal Outlook (90-days, preliminary): Slightly better chances for near average precipitation, good chances for near normal temperatures for December.
Predicted temperatures look like this over the next couple of weeks:
Thursday Nov 11 Update: To those of you who are Veterans, thank you! As of 9:00am, we've had 1.40" of rain here in Cottage Grove (since 4:00pm yesterday). Most of that occurred 4pm - 9pm. Small chance of light rain today through tomorrow morning (Friday), then rain Friday afternoon-night. Heaviest rain stays to our north today and Friday. Don't be surprised if very little rain falls through Friday morning. About another 1/2" total combined rainfall today + Friday (mostly occurring Fri afternoon-night). Saturday+Sunday looks mainly dry, then some rain on Monday. Mild temperatures and humid through Sunday along with light southerly winds under 15 mph. Colder next week, freezing lows possible Tuesday night. November is our second wettest month (6.92"). We've had 3.73" so far this month and 8.28" since the start of the water year on Oct 1. Next 2-weeks have a higher probability of being more dry than wet (including Thanksgiving, subject to change).
Over the past day or so you've probably come across headlines of "heavy rain expected" and/or "hydrologic outlook." This is because a storm system will direct a narrow plume of moisture into the Pacific Northwest for an extended period of time, resulting in areas of heavy rain, potential for flooding, and mudflow possibilities around some of the burn areas. These types of systems are very complex and impossible to predict exactly where the north and south heaviest rainfall boundaries will be. Since the moisture plume is narrow, just a small 25-mile shift north or south results in more or less rainfall at the northern and southern edges. Initially through Thursday, our area will be on the southern edge of the moisture plume. As of this writing, the bulk of the moisture and heaviest rains will be directed north of us (into SW Washington and Salem north). Therefore, light to moderate rain is expected for the Cottage Grove area. Remember, any shift north or south of the main narrow moisture band will affect predicted rain totals. This image shows model-predicted accumulated rainfall. Notice the heaviest rain occurs north of our area.
What: Periods of rain through Friday night with high snow levels above 8000'. Maybe a rumble of thunder. Humid.
Timing: Rain is expected to develop at some point this afternoon, most likely between 3pm and 6pm. Periods of rain will then continue through Friday night.
Hazards: Heaviest rain is expected to stay north of our area. However, as stated above, any shift of the moisture plume could result in heavier rain across our area.
Total Rainfall: Expect 1/2"-1" through Friday night. If the moisture band shifts more to the south, rainfall totals will be higher. Total average rainfall for the month of November is 6.92". As of 10:00am today (Wed Nov 10), we've recorded 2.33" so far this month and 6.88" since the start of the water year on Oct 1.
Wind: No wind concerns. Southerly breezes at times are expected to stay under 15 mph.
Temperatures (5-days): Mild highs and lows through Friday. Highs 55-60 today (Wednesday), then 59-64 on Thursday and Friday. Lows will be 49-54. Normal high/low is near 54/38.
Fog: Patchy fog possible at times. Saturday and Sunday will likely have night/morning fog.
Snow Potential below 1000': Not going to happen.
Frost/Ice probability: Widespread frost, freezing temperatures, icy roads are not expected through Monday. Tuesday night through the middle of next week, lows may be in the low to mid 30's.
15-day Outlook: With the weekend looking dry, another storm will bring rain to the area on Monday (Nov 15). Tuesday night and the rest of next week is then expected to be dry. In fact, there's strong indications that we may have an extended period of dry weather through the days leading up to Thanksgiving, or possibly into Thanksgiving day (Nov 25). If data continues to hint at this, it would be highly unusual. After lows in the low-mid 30's during the middle of next week, temperatures rebound closer to normal at the end of next week.
Seasonal Outlook (90-days, preliminary): Slightly better chances for above average precipitation, good chances for slightly below normal temperatures for December.
What: Breezy tonight, with some wind gusts to somewhere between 20-30 mph. Light rain will develop later this evening with showers on tap for Tuesday. Total rainfall will be around 1/5-1/3" (0.20-0.33"). Snow levels above 6000' tonight, lowering to near 4000' Tuesday. Another couple of storm systems will bring periods of rain and showers through Friday, then Saturday and Sunday look dry.
Timing: A break in the rain may occur Tuesday night, Wednesday morning through Friday evening looks rainy/showery.
Hazards: Nothing significant. Heavy rain is possible later Thursday and on Friday.
Total Rainfall: Looking like 1/5-1/3" through Tuesday evening, 1/4" on Wednesday, then 1-2" possible Thursday through Friday evening. Total average rainfall for the month of November is 6.92". As of 11:00a today (Mon Nov 8), we've recorded 1.92" so far for the month and 6.47" since the start of the water year on Oct 1.
Wind: Breezy later this evening into early Tuesday morning. Winds can gust up to between 20-30 mph, especially between midnight and 5:00am.
Temperatures (5-days): Highs low-mid 50's Tue/Wed, then upper 50's-low 60's Thur-Sun. Lows upper 30's to low 40's through Thursday morning, then mid 40's Thursday night through Sunday night. Normal high/low is near 55/39.
Fog: Possible in between systems, especially Tuesday night and Friday night through the weekend.
Snow Potential below 1000': Not going to happen.
Frost/Ice probability: Widespread frost, freezing temperatures, icy roads are not expected over the next 7-10 days.
15-day Outlook: With the weekend looking dry right now, another storm will bring rain to the area on Monday (Nov 15). Things start to dry out later Tuesday of next week with hints that high pressure may become strong and therefore push the jet stream farther north. Although some uncertainty exists, it's possible that an extended dry period may occur from later Tuesday of next week (Nov 16) through around November 24. If high pressure becomes dominant across portions of the North Pacific and West Coast, our Thanksgiving might end up dry (low accuracy and preliminary). High temps look to be near to slightly above normal with lows close to normal.
Seasonal Outlook (90-days, preliminary): Slightly better chances for above average precipitation, good chances for slightly below normal temperatures for December-January-February (low accuracy and preliminary).
Current Snow Percent of Normal (Water Equivalent):
Most models indicate anomalous high pressure will become established across much of the west and parts of the North Pacific, including during all or part of Thanksgiving week. This model's ensembles shows just that (a bunch of "mini models" within a main model that predicts various outcomes - we look for an average or "mean" of these "mini models" to give us an idea of what may be to come in the longer range):
More or less, typical Oregon weather of periods of rain/showers through Wednesday (nothing to write home about). Total rainfall through Wednesday looks to be around 1/2"-3/4". Nothing concerning with southerly winds, which can gust up to 15 or 20 mph at times. Thursday through early next weekend, a couple storm systems could bring an additional 1-2" of rain to the area. However, there's some uncertainties with these late week-next weekend systems which should be cleared up for the next post on Monday. Also starting to see some signs that the middle of the month might be more dry than not due to strong high pressure possibly dropping anchor across the west coast. Temperatures look like this over the next 10-days (normal is 56/39):
As of 9:00am this morning (Sat Nov 6), 6.21" of rain has fallen since the start of the water year on October 1st. Normal to date is 4.90", so we're off to a good start. By comparison, at this same time last year we were only sitting at 2.39" of rain. Here's the water year to date precipitation percent of normal:
Regarding snow, it's still early in the season, but here's where we currently stand:
Our drought was so intense that all the rain we've had so far this fall hasn't yet made any sizable improvement:
Dry middle of November + Thanksgiving?
Around November 14, high pressure may strongly build into parts of the North Pacific and west coast states, pushing the storm track into far northern Washington or southern Canada. Interestingly and preliminary, the majority of the models are showing good odds that high pressure may affect much of the west coast from about November 14th through possibly Thanksgiving (Nov 25). I'll continue to address this with updates issued between now and then since Thanksgiving is traditionally the busiest holiday-travel period. Here's the two major models, which show anomalous western high pressure (red/orange = anomalous high pressure; blue/green = anomalous low pressure):