Quantitative Precipitation Forecast
Issued by NWS
Issued by NWS
609 FOUS30 KWBC 160800 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 300 AM EST Sun Nov 16 2025 Day 1 Valid 12Z Sun Nov 16 2025 - 12Z Mon Nov 17 2025 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE SANTA LUCIA RANGE OF CENTRAL CALIFORNIA... A pair of deep shortwaves will impact much of California through the period today. The one that has been causing heavy rain across much of southern California is pressing inland this morning. Rates have come down a bit overnight due to waning instability, but much of central California and portions of southern California remain in more-or-less steady light to occasionally moderate rainfall. As the upper low departs to the east, the steady rain across much of inland California should diminish through this afternoon. Following this first shortwave, another vigorous, deepening longwave trough will track SSE out of the North Pacific and approach the northern California coast late tonight/early Monday morning. This second shortwave will have much more upper level energy with it by tonight than the first does now. This longwave trough will also have some instability with it. The result will be steady rain associated with the approaching low plowing into the northern California coast this evening, then spreading south in the form of a line of moderate rain with embedded thunderstorms capable of brief periods of heavy rain. It will cross the Bay area late this evening, then push south almost to Point Conception by 12Z Mon. The heaviest rain will push inland, reaching the central Sierra around the same time. Much of the Santa Lucia Range in central California have picked up between 5 and 8 inches of rain over the last week. Continued light to moderate rain may add another inch through this morning, but the heavy rains tonight with the cold front will likely drop another 1-2 inches. Rock and landslides have been reported from today`s rain. Thus with shifting winds and heavy rain tonight, it`s probable there may be additional impacts from the storms. In coordination with MTR/Monterey, CA forecast office, a Slight Risk upgrade was introduced with this morning`s update. Elsewhere the surrounding Marginal remains unchanged. ...Southwest Utah... The Marginal Risk area in southwest Utah also remains unchanged. Upslope flow into the Pine Valley Mountains may cause isolated instances of flash flooding as the area of rain currently over southern Nevada pushes east into the region, where enhanced upslope will cause the rain to intensify. The highest elevations above 8,000 ft or so may see snow, which will limit the flooding potential at lower elevations. Wegman Day 2 Valid 12Z Mon Nov 17 2025 - 12Z Tue Nov 18 2025 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF THE LOS ANGELES BASIN OF SOUTHERN CALIFORNIA... The deep and energetic trough that will be centered off the northern California coast at the start of the period will track southeast down the coast to over the San Joaquin Valley by early Tuesday morning. The trough will cut off into a second upper level low to impact the state by Monday afternoon. The heaviest rains will be out ahead of this cutoff low, where the overall flow is onshore out of the southwest. A line of heavy showers with embedded thunderstorms will move down the coast starting around Point Conception early Monday morning, reaching the L.A. Basin around midday. It will take between 2-4 hours for the heavy rain band to sweep through. During that time, rainfall rates peaking between a half and 3/4 inch per hour in the thunderstorms may cause widely scattered instances of flash flooding, especially on the south facing slopes of the Transverse Ranges down to the L.A. Basin. For this reason, the inherited Slight Risk remains in place with very few changes. At least some of the heavy rain will also penetrate inland into some of the California Deserts, including around Death Valley N.P. Given how recently the area saw heavy rains from yesterday, this additional heavy rain may also cause isolated instances of flash flooding. Thus, the Marginal Risk was expanded north and east to include a small portion of southern Nevada. Wegman Day 3 Valid 12Z Tue Nov 18 2025 - 12Z Wed Nov 19 2025 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR MUCH OF THE MOGOLLON RIM REGION OF ARIZONA INTO FAR SOUTHERN UTAH... A Marginal Risk area across portions of Arizona and southern Utah was introduced with this update. The cutoff low that will spread heavy rain across the L.A. Basin on Monday will slowly push east across southern California through Tuesday. Once again the heaviest rains associated therewith will be out ahead/east of the low center, putting Arizona and Utah in the area most likely to see heavy rain. Instability will once again be non-zero, peaking between 200 and 400 J/kg, which combined with above normal moisture will result in an area of training thunderstorms, likely along the Mogollon north and east of Phoenix. The southerly flow will continue across northwest Arizona and into southern Utah, where wet antecedent conditions from today`s rains will support additional flash flooding developing with heavy rains in the Pine Valley Mountains east to Lake Powell. Wegman 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