FOUS30 KWBC 020058 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 858 PM EDT Mon Jun 1 2026 Day 1 Valid 01Z Tue Jun 02 2026 - 12Z Tue Jun 02 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF THE NORTHERN ROCKIES, GREAT PLAINS, MID-SOUTH AND SOUTHEAST... We will maintain the Marginal risk areas with this update. The most organized convection overnight will likely be across KS and NE as upscale convective growth into one or two MCSs seems likely. Slow supercell movement has initially resulted in heavy rainfall totals over southwest KS, although do generally expect to see some increased forward motion off to the east with time as things grow upscale. Organized convection will also move across NE through the overnight hours. Both areas should see an eastward movement of activity helping limit overall duration...although some backbuilding will be possible. Overall expect the flash flood risk to remain isolated, but localized flood impacts are probable. Convection over portions of AR/LA/MS/AL should persist a bit longer into the night than typically supported diurnally as quite a bit of instability remains to go along with a few weak boundaries and a shortwave over the lower MS Valley. Generally expect this activity to be moving, although cell mergers could continue to result in a localized flash flood risk. The coverage of convection is decreasing over southeast NM and west TX, but a few stronger cells may persist for a few more hours and result in an isolated flash flood risk. Not really any flash flood threat over MT, but continued stratiform rain over saturated ground may continue to result in some minor areal flooding. Added a small Marginal to portions of SC and adjacent GA where some locally heavy convection is occurring, and we should see some additional development over the next few hours. An axis of enhanced low level convergence, combined with MLCAPE over 1000 j/kg and PWs around 1.8" to 1.9", will support locally heavy rates and an isolated flash flood risk where any cell mergers occur. Chenard 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