What happened on the San Diego River last week reminds me a lot of topological alignment during a fire, where you get a run because the wind, elevation and topology align in parallel with the fire’s spread.
Rough analogy, I guess, with how the precipitation fell directly into the watershed.
Except that Pacific storms have been carving the coastal mountains to fit for a very long time.
Summary:
- Dry and warm conditions into early Tuesday except a few showers possible over ther far north this morning. Temperatures around 5 to 20 degrees above normal with some recrod high max and high min temps possible.
- More widespread precip expected late Tuesday through Thursday as system moves through the region with showers lingering into Friday with trough over the region. Freezing levels around 9000 ft and higher on Tuesday then falling behind the cold front to around 3500-5500 ft over Nrn and Central CA by early Thursday and 4000-6000 ft over Srn CA and NV by Friday morning and down to around 1500-3000 ft over Nrn and Central CA Friday night.
- Significant rises are expected towards the middle of the week when a stronger storm is expected to impact much of California. Rivers will be highest along the north coast and Sacramento River system.
- The Colusa Weir and Tisdale Weir are expected to flow again this week, with the possiblity of Moulton Weir and Fremont Weir flow later in the week.
- Low level snow will continue to melt in advance of the storm system, but will have little impact on river levels.
Confidence: Medium
Staffing Level: Normal
Detailed Hydrometeorological Discussion: cnrfc.noaa.gov/discussion
Be aware that CAL OES is weighing in on social media about misinformation regarding expected impacts of this storm system and that impacts are forecast to be moderate. It appears that a few social media accounts are on an ARKStorm ride. This storm system is not projected to be of that magnitude.
Projected 5-Day total precipitation.
Flash flooding is as often a case of inches per hour as total rainfall over the course of a storm. These maps do not reflect those potential inches per hour numbers, that can be very localized, and have unexpected impacts in the watersheds they fall on.
British Columbia’s River Forecast Centre issued an upgraded flood warning for the Sumas River, a tributary of the Fraser River east of Vancouver on Sunday.
An updated bulletin says flows in the Sumas River are not anticipated to pose a hazard for flooding into Sumas Prairie, an area that was hard hit during the atmospheric rivers that swamped much of southwestern B.C. in November 2021, washing away bridges and spurring landslides that killed five people.
But in neighbouring Washington state, the bulletin says high flows on the Nooksack River have reached "local flood stage.’’
It says "spillover’’ into the Sumas River watershed has been observed near the community of Everson, Wash., about 20 kilometres south of Abbotsford.
The centre says the spillover should be "short-lived’’ as upstream areas of the Nooksack have already reached peak levels and are now receding.
Summary:
- A deep area of low pressure approaching the northeast Pacific will drag a strong cold front across CA and NV for Wednesday into Thursday with a round of moderate to heavy precip.
- Heaviest amounts will fall along northern/central CA coastal locations, the Shasta Lake drainage, and portions of the Sierra with 2" to 5" local to 6" at the wettest locations.
- Another storm system will approach the CA coast for the upcoming weekend, however, with model differences confidence is currently lower with this incoming precip event.
- Significant rises are expected on Wednesday and Thursday across much of California.
- Rivers will be highest along the north coast and Sacramento River system. Many locations are expected to exceed monitor stage, with several expected to exceed flood stage.
- The Colusa Weir and Tisdale Weir are expected to flow again this week, with the possibility of Moulton Weir and Fremont Weir flow later in the week.
Confidence: Medium then Lower this Weekend
Staffing Level: Extended (24 Hours Starting Wednesday Morning)
Detailed Hydrometeorological Discussion: cnrfc.noaa.gov/discussion
Cresting on the orange and yellow gages will occur Wednesday afternoon through Thursday morning.
Projected 5-Day Rain Totals
'kay. KSBY has a feature on debris flows and landslides in burn scars. A USGS Landslide Hazards Program team is working on the 2019 Cave Fire site. Soil saturation levels as covered in Hydrological Outlooks are another factor of risk. The language in the NWS issues is more specific about causes for pause.
Summary:
- Moderate to heavy precipitation will spread across the region today, lasting into Thursday with a deep area of low pressure off the Pacific Northwest coast and an associated cold front traversing CA and NV.
- Best precipitation totals will fall along the north coast down across the Santa Cruz mountains and Big Sur coast, along with areas inland over the Shasta Lake drainage with 3" to 5" local to 6". For the Sierra and coastal southern CA, totals will generally be from 1" to 3".
- Another area of low pressure making its way toward the coast from the southwest will impact the region Sunday into Monday. However, models show varying solutions at this point, resulting in lower confidence in the forecast.
- Beginning today, significant rises are expected across much of California.
- Rivers will be highest along the North Coast, Russian and Sacramento River systems. Many locations are expected to exceed monitor stage, with some expected to exceed flood stage.
- The Colusa, Tisdale, Moulton and Fremont weirs are expected to flow over the next several days heading into the weekend.
Confidence: Medium then Lower this Weekend
Staffing Level: Extended (24 Hours Starting Wednesday Morning)
Detailed Hydrometeorological Discussion: cnrfc.noaa.gov/discussion
The streamgages and real-time instruments used in the CNRFC, and other tools, are available as remote data resources. @ajohansson has a video posted with instructions for TAK (may apply to any KML app):
The video:
This dashboard has the virtue of 3D watershed depth layers. 1-Hour Radar Loop with approx inches per hour from NWS. The drainage down to the Navarro gage is visible, as is the watershed polygon south of Lake Mendocino and west of Clear Lake that drains to the Russian River, and later, points south and west to the Ocean.
I need to check on that KML, i know noaa made some changes on back end.
AJ
I gotta tell ya, dude, I have no clue how to recreate what USGS land and sea does to zoom the watershed definition datagraph value that changes the polygon with scroll altitude, or what REST message its sending, or what pull its doing with java voodoo. I was in Natural Resources, not the five json magics. Challenging, maybe somebody in TAK world is looking at it.
I feel like the easy way is to choose the most relevant watershed detail altitude as a single plane, in particular; the plane that aligns with NWS Watch and Warning polygons. See how that jibes with what you see with your Mk 1s. Use that KML layer in TAK. Feds have stacks of flood data and PDFs, I don’t imagine all of them are as plug and play as geolocated IAPs. Some of them might be. Some of them might be on Fed ArcGIS servers.
You need to keep it simple. You’re not underwriting an annual insurance estimate. You’re responding to an incident.
Ex. Last year, I used this map to evaluate the creeks around Camp SLO and the joint CalFire/CCC Toro Fire Center, located by the RC airstrip in the upper left. SLU has a TAK pilot, IIRC. As you mentioned, about NOAA, they move the racks around at the FEMA library.
Arroyo Grande Creek (of LPF Hotshots fame) and Oceano had flooding issues that tracked pretty closely to this map I hooked out of the Big Library.
Arroyo Grande Creek Watershed and Aquifers.
Ventura River Watershed and Aquifers. The bottom of the Ventura carries three large drainages that fall downwards to the beach.
Six Rivers National Forest, Eel River Watersheds. Sustained rainfall of 2.5"/hr. I dunno, I see alignment.
San Lorenzo River, Soquel Creek, Pajaro, Salinas River and Carmel Valley. Recent radar indicating rates of 2.5"/hr. Loma Prieta, above the San Lorenzo is 3700 ft.
Summary:
- Moderate to heavy precipitation has shifted across the southern Sierra down across coastal southern CA from Los Angeles to San Diego counties, as the cold front continues to sweep across the region. Precipitation totals will range from 1" to 3".
- Light to locally moderate precip will continue into Friday under onshore flow. Best opportunity for precip will be along the north coast and the northern/central Sierra with 0.25" to 0.75" local to 1".
- The next round of widespread moderate to heavy precip will spread across the region for the end of the weekend into early next week. Current thinking puts the highest precipitation totals from the Interstate 80 corridor southward across central/southern CA.
- Many river locations across Northern and Central California are cresting or beginning to recede this morning.
- River rises will continue today across Southern California and San Diego areas, where a flood stage is predicted for the San Diego River at Fashion Valley.
- Additional river responses are expected Sunday into Monday with the next system. Weir flow on the Sacramento system will continue heading into the weekend.
Confidence: Medium then Lower this Weekend
Staffing Level: Extended (Through Thursday Evening)
Detailed Hydrometeorological Discussion: cnrfc.noaa.gov/discussion
Ventura River FEMA Flood Hazard Layer
Cable Canyon Road to Highway 101
Ventura isn’t getting a very long spell as the storms move around Catalina. Current precip by Matilija Creek is a healthy 5 inches in 24 hrs. That could resume after one sunny day.
Summary:
- Light to locally moderate precip with scattered showers today, especially along the north coast and SE Shasta basin and northern/central Sierra. Light precip possible along the coast and Shast Basin and the Sierra and Nrn NV during the day Saturday.
- The next round of widespread moderate to heavy precip will increase along the Central CA coast Saturday night and spread across the region Sunday and continue into Tuesday. Highest precip amounts expected to generally be 6 to 12 inches along the transverse range and 4-8 inches along Central CA coast and along the Sierra for Saturday night through Tuesday.
- Most river locations across Northern and Central California are cresting or have started receding.
- Moderate to major river rises are expected in the next few days with the incoming system in the Southern California and San Diego area.
- Weir flow on the Sacramento system will continue heading into the weekend.
Confidence: Medium then Low Saturday night into next week.
Staffing Level: Extended (Through Thursday Evening)
Detailed Hydrometeorological Discussion: cnrfc.noaa.gov/discussion
Southbound Highway 101 at Ventura is currently closed due to flooding until Monday morning.
The chart shows a rise to approximately 11 ft on Thursday, not even close to the flood stage, yet significant flooding is present at the Highway. Storm surge from the Channel may be partially responsible for that, but I’m not actually there to say. The storm surge is expected to continue through the storm and a crest of 18.1 ft is forecast for Sunday night.
Tidal variation looks to be about 2-3 ft for today through Tuesday, Feb 6th. Waves to 12 ft or more have been forecast for the entrances to Morro Bay Harbor and Ventura Harbor.
Ventura County Fire Department (VCFD aka VNC) Basic Sandbag Tips
