Quantitative Precipitation Forecast
Issued by NWS
Issued by NWS
431 FOUS30 KWBC 060730 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 230 AM EST Sat Dec 6 2025 Day 1 Valid 12Z Sat Dec 06 2025 - 12Z Sun Dec 07 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Wegman Day 2 Valid 12Z Sun Dec 07 2025 - 12Z Mon Dec 08 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. The inherited Marginal Risk aligned roughly along the Florida/Georgia line was removed with this update. A stalled out front over the area will act as a focal point for a corridor of mostly light to moderate rain through the day Sunday. Instability will be near zero, so any convection will be brief. Fast storm motion along the front due to an approaching 130 kt jet will ensure that any elevated convection will be short-lived. Finally, soils in the area are well below normal. The dry soils in this area will support any light rain being soaked right into the soil. This too will temper any flooding threat. Due to all of the above factors, the flooding threat was determined to be less than 5 percent, with the highest risk in the Jacksonville urban area. Wegman Day 3 Valid 12Z Mon Dec 08 2025 - 12Z Tue Dec 09 2025 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE PACIFIC NORTHWEST... The first in a series of Pacific lows will move into the coast of the Pacific Northwest on Monday. The combination of multiple days of heavy rain as low after low moves into the coast will slowly increase the flooding threat in western Washington and western Oregon. The slow increase of the flooding threat is due to the area`s general favorability for rainfall to quickly run off, resulting in a much higher threshold of heavy rain before there are flooding concerns. The trailing cold front south of a strong low that will move into British Columbia will be the focus for the heavy rain as abundant Pacific moisture slams into the coastal ranges and Cascades through the period. Soil moisture levels in this area are around normal for this time of year, but repeated days of heavy rain will cause the soils to saturate entirely. Thus, once the soils are saturated, all additional rainfall will convert to runoff very quickly. Moisture from the tropics will track northeast around the northwestern periphery of an expansive subtropical high off the California coast. This abundance of Pacific moisture from the tropics will support the elevated flash flooding threat over much of the upcoming workweek. Very few changes were needed to the inherited Marginal and Slight Risks. The Slight Risk area was trimmed away from Washington`s mountains, as the dominant precipitation type at the higher elevations will be snow on Monday morning. Both risk areas were also expanded south across west- central Oregon due to small southward adjustments in much of the guidance supporting heavy rain extending further south in Oregon. 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