FOUS30 KWBC 141610 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1110 AM EST Sat Nov 14 2026 Day 1 Valid 16Z Sat Nov 14 2026 - 12Z Sun Nov 15 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS NORTHWEST WASHINGTON STATE IN THE AREA OF THE OLYMPIC PENINSULA AS WELL AS NORTH-CENTRAL TEXAS AND THE CENTRAL TEXAS COAST... North-Central Texas The trough responsible for heavy rainfall in California yesterday will dig into the Central/Southern Plains today. Shallow East Pacifc and Gulf moisture will converge along the leading edge of a digging upper trough. Thunderstorms will initiate over the Panhandle and propagate east/southeast through north-central Texas later tonight. A marginal risk (at least 5% chance) of excessive rainfall is in effect for the aforementioned area and is consistent with first guess fields. Soil moisture is fairly dry so some of the rainfall that occurs will be beneficial, but there's a small chance for storms to overperform the forecast. 1-2" exceedance probabilities are over 5% for the highlighted area as well. Coastal Texas A southern stream disturbance, responsible for this morning's rainfall/storms over portions of west Texas, will swing through southern Texas today. This mid-level vort max will be the impetus for convection along the central/southern Texas coastline this afternoon and continuing through the evening. These storms will access the same moisture (1-2" PWATs) and instablity (200-400 J/Kg MUCAPE) plume feeding the north-central storms. The potential for repeating rounds of storms along the coast is supported by multiple CAM guidance showing some 2-4" QPF maxes along the coast. RRFS 2-5" exceedance probabilities are over 5%+ for the highlighted area. Pacific Northwest A low pressure system will focus storms ahead of its attendant cold front as it arrives over the Pacific Northwest tonight. Some relatively modest instablility (100-250 J/Kg MUCAPE) will work its way into the region along with shallow moisture (0.5-1.5" precipitable water values). 2-3" 24 hour exceedance probablities are 5%+ over the Olympic Peninsula, which is consistent with the current marginal risk area. Kebede Day 2 Valid 12Z Sun Nov 15 2026 - 12Z Mon Nov 16 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF COASTAL TEXAS ON SUNDAY... Enough ingredients appear to be coming together to warrant a Slight Risk area on Sunday as convection associated with a mid-level trough approaches from the west/northwest early Sunday. Even if the models prove to be correct in keeping the highest rainfall totals off-shore...the there are an increasing number of signals that problematic rainfall amounts could develop inland (especially true in urbanized areas and where there is overlap with areas that received 1.5 to 4.0 inches of rain within the past week). Synoptically, low-level flow off the Gulf will be drawn northward across portions of the Upper and Central Texas coast early in the period in response to the approach of an upper level trough (potentially an upper low). The GFS and ECMWF both depict 30 to 45 kt flow with decent directional shear in the 925-700 mb layer...suggesting potential for organized convection. At the same time, precipitable water values approach 1.5 inches (or 1.5 to 2.0 standardized anomalies greater than climatology for this time of year). The models do show a plume of air with precipitable water values greater than an inch extending northward. Maintained the Marginal risk area here over questions about how much instability will be present. The upper system approaching from the northwest helps shnut the heaviest rainfall off the coast with time, Bann Day 3 Valid 12Z Mon Nov 16 2026 - 12Z Tue Nov 17 2026 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Bann Day 4 and Day 5 Valid 12Z Tue Nov 17 2026 - 12Z Thu Nov 19 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF NORTHERN AND CENTRAL CALIFORNIA WEDNESDAY... An upper-trough and accompanying cold front will progress eastward from the West Coast into the Interior West day 4/Tuesday. Increasing moisture along and with the frontal passage will lead to scattered showers and thunderstorms across the Desert Southwest and into the Four Corners Region. However, limited instability and modest moisture should keep rates low and the progressive nature of the system passage should limit rain totals overall. Another Atmospheric River (AR) will quickly follow in the wake of this previous system bringing heavy precipitation to northern/central California day 5/Wednesday. Snow levels will briefly increase with the approach of the warmer, moist Pacific air, though likely not reach levels seen with more significant ARs, particularly along the foothills of the Sierra given remnant colder air still in place from the prior system (~4500 feet). The AR is also expected to generally be on the weaker side and progressive overall. However, the forecast IVTs of ~ 500 kg/ms still should contribute to some heavy rainfall amounts, and the latest round of 00Z deterministic guidance all support areal average rainfall in the 1-2" range with locally higher amounts upwards of 3-4". This would be more than sufficient to raise isolated flooding concerns, and thus have introduced a Marginal Risk covering upslope regions of the northern/central Coastal Ranges and inland through the Bay Area to the Sacramento Valley and foothills of the Sierra. 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 $$