355 FOUS30 KWBC 242008 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 408 PM EDT Mon Mar 24 2025 Day 1 Valid 16Z Mon Mar 24 2025 - 12Z Tue Mar 25 2025 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF NORTHWEST WASHINGTON STATE AND ALONG THE CENTRAL GULF COAST... 16Z Update... Based on current radar trends and the 12Z HREF, made only minor adjustments, including to the recently introduced Marginal Risk area along the Gulf Coast. 13Z Update... ...Central Gulf Coast... Merging and training cells associated with a pair of linear complexes moving east across southern Louisiana into southern Mississippi and Alabama are supporting short-term heavy rainfall rates and a flash flooding threat. A Marginal Risk was added for areas where these storms may pose an isolated flash flooding threat into the late morning. Refer to WPC MPD #082 for additional information regarding the near-term heavy rainfall and flooding threat. Pereira Previous Discussion... ...Olympic Peninsula and Northern Cascades in Northwest Washington... A Marginal Risk of excessive rainfall will continue during Day 1 over the Olympic Ranges and across the foothills and western slopes of the northern Cascades, as the modest Atmospheric River slowly diminishes today and Monday night. Given continuation of the AR event, this too is a continuation of the previous (yesterday's) ERO, albeit with a drop in the category across the board. In other words, a Marginal Risk is in effect across areas where there was a Slight in yesterday's D1 ERO, while areas in yesterday's Marginal are now within the <5% probability of exceeding flash flood guidance. Latest guidance shows an atmospheric river continuing to impact the region, but also gradually waning through the period. The 00Z GEFS shows IVTs decreasing from ~500 kg/m/sec early in the period to 300-350 kg/m/sec, as a ridge continues to build and onshore flow into the region diminishes. As the AR diminishes, so will the potential for additional heavy precipitation. However, the continued moisture flux into the region early in the period may be sufficient for additional amounts of 2-3 inches, as indicated by the 00Z HREF. These amounts along with additional snowmelt may prolong runoff concerns. Hurley Day 2 Valid 12Z Tue Mar 25 2025 - 12Z Wed Mar 26 2025 The probability of rainfall exceeding flash flooding guidance is less than 5 percent. Pereira Day 3 Valid 12Z Wed Mar 26 2025 - 12Z Thu Mar 27 2025 The probability of rainfall exceeding flash flooding guidance is less than 5 percent. Pereira 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