FOUS30 KWBC 111601 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1101 AM EST Wed Nov 11 2026 Day 1 Valid 16Z Wed Nov 11 2026 - 12Z Thu Nov 12 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR SOUTH FLORIDA... A small Marginal Risk was introduced to South Florida as thunderstorms develop near an approaching shortwave, remnant frontal boundary, and afternoon seabreeze. By 21-22Z, recent runs of the HRRR depict one or two cells with 2-3" rainfall totals near the urban corridor in South Florida, which could lead to isolated flooding in poorly drained urban areas later today. Asherman Day 2 Valid 12Z Thu Nov 12 2026 - 12Z Fri Nov 13 2026 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Kleebauer Day 3 Valid 12Z Fri Nov 13 2026 - 12Z Sat Nov 14 2026 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Kleebauer Day 4 and Day 5 Valid 12Z Sat Nov 14 2026 - 12Z Mon Nov 16 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF TEXAS AND THE WESTERN GULF COAST AS WELL AS THE OLYMPIC PENINSULA OF WASHINGTON... ...Southern/eastern Texas and western Gulf Coast... Strong high pressure over the eastern U.S. and an approaching southern stream upper-wave will help to lift a lingering frontal boundary back northward over portions of southern Texas and the western Gulf Coast day 4/Saturday and day 5/Sunday. This will allow for southeasterly moist Gulf return flow and set the stage for a renewed round of thunderstorms with the potential for locally heavy downpours. One complicating factor will be the timing and track of the initial southern stream upper-wave day 4 as well as a complex split-flow pattern upstream, with additional energy likely to translate eastward into the day 5 timeframe. This leads to significant differences in the latest global guidance, with highly variable QPF coverage/amounts both day 4 and day 5. However, when taken as a whole, the guidance does agree on the potential for heavy totals into the 2-4" range with locally higher amounts possible each day. For now, have opted to make only modest changes to the Marginal on day 4 (an eastward extension from south- central/southern Texas along the western Gulf Coast) as well as introduce a broad Marginal on day 5 a bit further east across portions of eastern Texas and the western Gulf Coast into western Louisiana given the uncertainty. These areas roughly cover where the heavier QPF amounts tend to cluster in those pieces of guidance that show heavier amounts for each day, respectively. Further areal adjustments are likely with subsequent forecast updates and a categorical upgrade may ultimately be needed once there is greater confidence in the location of heaviest rainfall. ...Western Washington... A second weak Atmospheric River is expected to impact western portions of Washington in the day 4/Saturday time frame. Wet antecedent conditions will be in place following an initial Atmospheric River mid- to late week, with the additional rainfall possibly leading to isolated flooding, particularly from the coast to the windward side of the Olympics. The latest guidance generally agrees on totals in the 1-3" range which are on the lighter side impact- wise for the region, and amounts with the initial Atmospheric River have trended downward a bit as well, so the risk may ultimately not materialize if current trends continue. Putnam 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 $$