235 FOUS30 KWBC 161927 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 227 PM EST Mon Feb 16 2026 Day 1 Valid 16Z Mon Feb 16 2026 - 12Z Tue Feb 17 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF CENTRAL AND SOUTHERN CALIFORNIA... 16Z Update... Newer 12z CAM suite and rapid refresh guidance continues to be on track with generally timing of the cold front as it progresses eastward across Big Sur through the California Bight later this afternoon. Recent satellite/RADAR trends show slightly stronger low level moisture flux given 925mb backed SSEly inflow per VWP to over 40kts compared to initial guidance and so recent HRRR/ARW have picked up on the potential for slightly higher rates with a few pre-frontal narrow updraft cells capable of up to 1"/hr rates along the Santa Barbara/SLO coastal region. This will shift onshore and maintain a slight uptick in totals, though most areas will see 0.5"/hr with 2-5" totals (highest values in the favored southern facing terrain of the Transverse Ranges) helping to further solidify the Slight Risk coverage potential. The intensity of the rates intersecting with urban/hard ground conditions will see an uptick of run-off, but shorter duration should limit the overall coverage and magnitude that the risk category continues to look solid. Minor adjustments to the upwind and downstream edges were made, but fundamentally the risk areas/categories remain the same. Gallina ~~~~Prior Discussion~~~~ A mid to upper-level trough will propagate into the West Coast, while a surface wave does the same this afternoon. Showers and scattered to isolated thunderstorms will spread south from the central California coast this morning down to SoCal tonight. The most impactful rainfall will likely occur between late morning and early evening. A combination of favorable upper and LLJ dynamics (120+ kts upper, 40-50 kts 850 mb respectively) within a relatively moist (0.75-1" PWATs representing the 90th percentile) and an unstable environment (100-300 J/Kg MLCAPE) will likely produce efficient rain rates this afternoon, especially over parts of the Central CA Coast down through the San Rafael Mountains and northern Los Angeles metro. HREF neighborhood probabilities indicate over a 25% chance of exceeding 2" in 24 hours by Tuesday morning across much of the aforementioned areas, with some embedded signals for 5"+ within upslope areas of the Transverse Ranges and Santa Lucia Range. Burn scars, urbanized and upslope areas will be especially susceptible to runoff. Progressive storm motion will mitigate flash flood risk. Kebede Day 2 Valid 12Z Tue Feb 17 2026 - 12Z Wed Feb 18 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF CENTRAL AND SOUTHERN CALIFORNIA... 20Z Update... Generally no changes to the synoptic scale setup for this period as the 12Z guidance agrees in allowing for additional Pacific shortwave energy and moisture transport to arrive across much of CA. By midday Tuesday, this new energy along with a cold front will drive a westerly low-level jet of as much as 40 to 50+ kts into the coastal ranges of central CA, including the Bay Area, with the front and onshore flow then settling south toward the Transverse Range by Tuesday night. IVT magnitudes are forecast to rise as high as 300 to 500 kg/m/s which coupled with warm advection and upslope flow into the terrain should foster some scattered instances of rainfall rates at least approaching a 0.50"/hour. Generally 1 to 2 inches of rain is expected for the lower elevations with 2 to 4 inches possible for the higher terrain and especially down across the Transverse Range. Given increasingly moist/wet antecedent conditions in the wake of the day 1 storm system impacting the region, these additional rains may foster at least some runoff concerns, with potential for renewed areas of urban flooding and at least an isolated flash flood threat near more sensitive sloped terrain and especially any burn scar areas. The Marginal Risk area was expanded just a bit, especially with respect to the Bay Area, but otherwise changes to continuity are minimal. Orrison ~~~~Prior Discussion~~~~ Another mid-level trough dives south along the West Coast on Tuesday, sending another round of showers and isolated thunderstorms into the central and southern California Coast. Ingredients will be less impressive on Tuesday than today, thus a marginal risk from the Santa Cruz Mountains down through the San Diego metro will suffice. Snow levels will also be lower so upslope portions of the Transverse Ranges will likely see snow where they see rain today. Saturated soils from antecedent rainfall will be an important factor in any isolated flash flooding that occurs within the marginal risk area. Kebede Day 3 Valid 12Z Wed Feb 18 2026 - 12Z Thu Feb 19 2026 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Orrison Day 1 threat area: https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt Day 2 threat area: https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt Day 3 threat area: https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt