FOUS30 KWBC 012000 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Mon Jun 1 2026 Day 1 Valid 16Z Mon Jun 01 2026 - 12Z Tue Jun 02 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF THE NORTHERN ROCKIES, GREAT PLAINS, AND MID-SOUTH... 16Z Update... ...Central Gulf Coast... The Marginal Risk area over the Mid-South was expanded southward to the central Gulf Coast for this update. Soils remains quite saturated in eastern LA, southern MS, southern AL, and the western FL Panhandle with NASA SPoRT-LIS 0-40cm soil moisture percentiles above the 80th percentile. The MCS propagating south from western TN is likely to continue triggering additional storms this afternoon and evening, likely along its remnant outflow boundary. Plus, radar and surface observations show the sea breeze moving inland over eastern LA, which is likely to kick-start more storms this afternoon. The 12Z LIX sounding measured a 2.11" PW and MLCAPE approaching 2,000 J/kg. Steering flow is light, so storms will be pulse-like in nature. However, given the moisture and instability present, combined with the lingering sensitive soils, storms could produce >3" amounts locally. This is supported by the new 12Z HREF guidance showing moderate-to-high chances (50-80%) for rainfall totals >3" through this evening along the I-10 corridor in southeast LA. Localized flash flooding is possible this afternoon, particularly in areas that drain poorly, where soils are overly saturated, and in more urbanized settings. Aside from some minor tweaks to the Marginal Risks in northern MT, the central Plains, and west TX/eastern NM, the latest forecast guidance continues to support the Marginal Risk outlooks this afternoon. Mullinax ---Previous Discussion--- ...Northern Rockies... A closed mid-level system will continue to slowly move across Montana during the period, bringing an additional 1 to 2 inches of rainfall. The Marginal Risk for isolated / localized flooding was maintained with minimal adjustments based on the 00Z guidance. ...Mid-South... Early morning MCS across eastern Kansas and Missouri is expected to continue to move east/southeast through this morning toward the TN Valley and Mid-South. Forward propagation after 12Z should overall limit widespread heavy rainfall, but some elements may locally train/repeat over the same area bringing a risk of flash flooding, particularly early in the period across eastern Missouri. While that activity is likely to wane by late morning, additional thunderstorms are expected to fire up along remnant outflow boundaries to the south and west across Mississippi and Alabama. Pockets of 1-2" in a short duration may result in isolated flooding, with the overall threat maintained at the Marginal Risk level. ...Central Plains... Broad upper level forcing across the region along with modest southeasterly low level flow will bring isolated to scattered diurnally driven convection today across the High Plains that will gradually track eastward through south central Nebraska and western to central Kansas into this evening and overnight. The Marginal Risk was maintained with a few adjustments based on the latest model guidance. ...West Texas into New Mexico... Modest forcing for ascent across the region combined with low level southeasterly flow will bring westward Gulf moisture. Diurnal convection is expected across the Davis and Sacramento Mtns. Based on the 00Z hi-res models, some of this convection may spread away from the terrain, but overall expected to be isolated in coverage with a localized flash flood risk today. Taylor Day 2 Valid 12Z Tue Jun 02 2026 - 12Z Wed Jun 03 2026 ...THERE ARE SLIGHT RISKS OF EXCESSIVE RAINFALL ACROSS PORTIONS OF WEST TEXAS INTO NEW MEXICO AND NORTH DAKOTA... 20Z Update... ...North Dakota... Guidance started coming into better agreement on the clustering of thunderstorm activity across ND Tuesday afternoon and into Tuesday night. A tongue of >1.2" PWs, which is above the 90th climatological percentile, will reside over the Northern Plains with MUCAPE >1,000 J/kg supplying plenty of instability. Various model model members using area-averaged sounding Tuesday afternoon show increasingly saturated profiles with within a highly sheared environment. Thunderstorms are likely to contain mesocyclones that enhance rainfall rates, with discrete cells initially transitioning to more linear structures overnight as the low-level jet strengthens across the Dakotas. 12Z HREF probabilities show moderate-to-high chance probabilities (50-70%) for >3" of rainfall in east-central ND with the bulk of the rainfall occurring 21Z Tues and later. FFGs may recover somewhat, but given the potential for up to 2"/hr rainfall rates in an area susceptible to those kind of Excessive Rainfall rates, a Slight Risk was introduced in the heart of ND this forecast cycle. Elsewhere, the inherited Slight Risk in eastern NM/west TX and the Marginals in place across the South were adjusted for the latest WPC QPF and some 12Z CAMs. The meteorological rationale provided by the overnight shift remains on track at this time. Mullinax ---Previous Discussion--- ...West Texas into New Mexico... By Tuesday, the latest model guidance suggests greater moisture will expand westward toward the region (compared to today) with PW anomalies approaching 1.5 to 2 std deviations above normal. Another round of terrain driven convection is expected that spreads east across the area. Overall, pockets of 1 to 2 inches are possible with resulting isolated/scattered flash flooding, particularly for any sensitive locations such as burn scars and steeper terrain. ...Great Plains... Large scale forcing for ascent across the High Plains will work with an increasing amount of low level moisture to produce several clusters of thunderstorms during the period capable of producing heavy rainfall - one area of concern is across eastern to central Kansas where the latest guidance has pointed toward the potential for several repeating clusters of intense rain rates. Some of this additional rainfall may fall on areas expected to see heavy rainfall today. A second area of concern is the Northern Plains where there is likely to be better forcing with the proximity to the mid/upper level feature. Here, moisture isn't as high and storm motions may be faster, but potential exists for intense rain rates and locally heavy rainfall. Both of these areas (Dakotas and western/central KS) may need upgrades to Slight Risk if trends continue with future model cycles but for now, have maintained the Marginal given some of the uncertainty heading into Tuesday. ...North Florida through the Gulf Coast... A cold front will slowly advance southward across the region during the day Tuesday, with copious amounts of moisture pooling along and ahead of it. Thunderstorms are likely to develop, particularly focused on the Florida Panhandle to northeast Florida where the latest guidance points to the potential of 1-3" locally. Localized / isolated flash flooding will be possible due to the expected intense rain rates and overall slower storm motions. Taylor Day 3 Valid 12Z Wed Jun 03 2026 - 12Z Thu Jun 04 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF WEST TEXAS... 20Z Update... Reviewing 12Z guidance, the Slight Risk in West TX and eastern NM was expanded farther north into the TX Panhandle with WPC QPF and several model members showing a slightly farther northward extension of heavier rainfall totals. Otherwise, the forecast reasoning in the previous discussion remains valid with eastern NM into west TX most prone to flash flooding on Wednesday. Mullinax ---Previous Discussion--- ...West Texas into New Mexico... A greater signal exists for a stronger mid-level shortwave to move across the southern High Plains on Wednesday. This feature, combined with the continued relatively higher moisture in place, should result in robust convection to develop across far eastern New Mexico into western Texas, particularly across the TX Panhandle. A Slight Risk was maintained for the potential of isolated to scattered flash flooding, some of which may fall on similar areas as Tuesday. ...Great Plains... The active pattern across the Plains is expected again on Wednesday with a plume of relatively higher moisture extending from Texas all the way north into the Northern Plains. Daytime convection is expected to fire up across the Plains and then move east/southeast into the evening/overnight hours. Several organized clusters of convection are likely with pockets of locally heavy rainfall. For now, a broad Marginal Risk remains in place for isolated instances of flash flooding. Taylor 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