Hydrometeorological Discussion National Weather Service / California Nevada RFC / Sacramento CA 810 AM PST Fri Nov 14 2025 ...MODERATE TO LOCALLY HEAVY PRECIP THRU SAT DUE TO A LARGE LOW CARRYING TROPICAL MOISTURE INTO THE REGION, T-STORMS ACROSS PARTS OF SRN CA TODAY/TOMORROW... ...WET PATTERN CONTINUES FOR NEXT WEEK AS ADDITIONAL SYSTEMS MOVE IN FROM THE NW... .METEOROLOGICAL CONDITIONS (FRI AM - THU AM)... An upper low now just offshore of the coast continues to funnel tropical moisture into the region this morning. TPW imagery has 1- 1.5" PW up part of the SJ valley down through se CA and out to sea. 12z morning sounding out of KOAK has dropped down below an inch as the moisture plume now focuses across southern CA. The sounding out of KVBG reported 1.12" PW and San Diego has 1.36". Radar and IR satellite have showers as far north as the central Sierra but the main focus is now from part of Santa Barbara County through LA County which over the past 4 hours has already gotten about 0.75- 1.50+". Over the past 12 hours parts of Santa Barbara County near Point Conception report upwards of 3". Another overnight hot spot included the central Sierra with about 1-3". The moisture plume will continue to gradually shift southward along the srn CA coast the rest of today carrying the heavier precip band with it as the low follows offshore. HREF exceedance probabilities are around 20-50% chance of at least 0.50"/hr rain rates diminishing later in the day. For the current time period, models appear to have underestimated the amount of precip over Santa Barbara/Ventura as they did for the overnight period. Bumped that up some due to the continued presence of moisture and favorable flow into the Transverse. Models continue to have the moisture plume stalling and then expanding back northward along the soCal coast tonight through Saturday morning spreading higher precip amounts with it. The heaviest time period for the rest of the system, other than the current one, looks to be 12-18z Saturday. This continues to be a period of particular uncertainty as models disagree on how far north to spread this precip and exactly how heavy it will be. They've come closer together compared to yesterday at least with the 00z ECMWF/06z GFS further northward compared to the NBM. Tried to blend this in a bit for that 6 hour block to show the northward shift. The GFS still insists on higher values across San Diego County at that time of around an inch while the ECMWF is half that. Went on the wetter side still but not as confidently as the GFS. Later Saturday, the low will halt its southerly trajectory and begin to head towards the coast. This will push more moderate precip back northward across the state. The upper low will head inland overnight with models now showing an embedded feature developing on the southwest side of the core of the low just offshore of the srn CA coast. This would generate another area of heavy precip potentially headed for San Diego. The GFS and the ECMWF have this band south of the CA border for now, but should the main low shift in position even a little north of what the det models predict this could end up right over San Diego Sunday morning. 24 hour QPF spread ending 18z Sunday is about 1.50". Confidence is generally low over San Diego as the GEFS 24 hr QPF spreads for Saturday approach 4". The rest of Sunday, expect scattered showers across much of the region as the low passes through on a sw to ne trajectory and the next system approaches right on its heels from the nw. An elongated trough stretching from the Gulf of Alaska to offshore of nrn CA should arrive some time Sunday afternoon or evening before forming a closed low by Monday morning. This would bring additional widespread precip to the area. Uncertainty for next week remains high as models disagree on the path of this system. Both the GFS and ECMWF also have another low pressure system headed our way mid week, but are very different on the timing with the GFS dry until after the end of day 6 and the ECMWF bringing in showers Weds afternoon. Bottom line, a wet pattern looks to continue into next week but still fuzzy on the particulars. The main focus of the morning forecast was on the next 48 hours with special attention paid to srn CA. Lots of finagling and model blending to try to paint a realistic picture. Confidence is low as moist southwest flow into coastal srn CA always makes pinning down QPF very difficult. Amounts went up by an inch at least down there compared to yesterday afternoon. QPF from 12z Fri-12z Sun: 1-4.50" central/southern Sierra, 4.50-9" Transverse, 2-4.50" coastal srn CA, 0.10-0.75" Bay Area, 0.50-1.50" central coast/SJ valley, and generally 0.10" or less for far nrn CA. For the rest of the period (12z Sun-12z Thurs), predicting another 0.75-2" across the Sierra, 0.50-1.50" for coastal CA (up to 2.50" or so Transverse), and 0.10- 0.75"+ across most of the rest of the state. Sierra freezing levels about 8.5-11 kft through Saturday lowering from sw to ne as the low moves inland. For this system levels will bottom out at about 6.5-8.5 kft Sunday before lowering further next week. Timing and numbers will change a good deal as the models right now very much disagree on where these systems will go and when which greatly impacts the freezing level forecast. Please Note: This product may NOT be routinely updated. Please refer to the following product issued by the CNRFC www.cnrfc.noaa.gov/Daily-Briefing for a graphical summary of weather and hydrologic conditions. |