FOUS30 KWBC 141601 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1201 PM EDT Sun Jun 14 2026 Day 1 Valid 16Z Sun Jun 14 2026 - 12Z Mon Jun 15 2026 ...THERE ARE SLIGHT RISKS OF EXCESSIVE RAINFALL FOR THE SOUTHERN PLAINS AS WELL AS FOR NORTHERN NEW ENGLAND... ...Southern Plains... A very slow-moving cold front will sink southward across Oklahoma and Arkansas today. Ahead of the front, an impressively moisture- laden air mass is in place over Texas and much of the Gulf Coast in general. Decaying MCS near the ArkLaTex will continue to drift southeastward and weaken this afternoon, allowing for some clearing in its wake. For the afternoon, plentiful southerly flow off the Gulf into southeast Texas will lead to widespread but largely disorganized shower and thunderstorm activity from the Houston and San Antonio metros north. Anywhere cell mergers or localized training features develop, localized flash flooding will be possible today, with urban areas more susceptible. A higher-end Slight Risk is noted across west Texas and the Hill Country where afternoon and evening thunderstorms will impact those areas. For the Hill Country, the main flooding threat will be tonight, as merging storms may yield an axis of heavier rain with potential rates of 2"/hr (20-60% chance from the 12Z HREF neighborhood probs). The storms will run into increasing resistance tonight in the form of a strengthening LLJ, which should slow down the forward speed of the storms as the traverse the Hill Country. Due to the flashy nature of the terrain in the Hill Country, the higher-end Slight was warranted. Back into New Mexico, afternoon and evening storms could interact with both the terrain features in the area, such as the Sacramento Mountains, urban El Paso, and any burn scars in the area. ...Northern New England... A Slight Risk is maintained for northern New England. The same cold front that will be impacting the Southern Plains will have a much easier time pushing eastward in northern areas, as a large upper level low over Canada pushes frequent shortwave disturbances east across the northeastern U.S.. Despite the progressive nature of the front, a surge of moisture will rapidly advect northward into New England ahead of the front, aided by increasing upper level support as a strong shortwave becomes more negatively tilted with time as it rounds the southeastern periphery of the upper level low. The moisture surge will also increase the instability, with MUCAPE values around 1,000 J/kg expected on average, and values up to 2,000 in some areas, including southeastern VT. The plume of moisture and instability will support numerous fast-moving thunderstorms training northeastward along and south of the Canadian border. The training storms will impact recently hard hit areas of northern New England, where soils are wetter than normal going into this event (FFG values around 1-2"/hr). While there's some question as to how strong the storms will get, the likelihood they will train along and south of the plume of greatest rainfall is high. The storms will train over northern New England for several hours before the cold front sweeps across from west to east tonight. The hilly terrain here can exacerbate rainfall rates and lead to flash flooding, especially in narrower river/stream valleys. ...Mid-Atlantic... Maintained the Marginal Risk for the Mid-Atlantic due to the continued chance for afternoon and evening storms feeding on the same moisture plume that will advance into New England. This could lead to localized instances of flash flooding, especially in urban areas along the I-95 corridor, though the severe threat appears greater. ...Florida... On the east coast of Florida, sea breeze interactions with the abundant moisture (PWATs around 2 inches) over the state should allow for a renewed development of afternoon and evening thunderstorms today. The storms will be nearly stationary, so mergers will pose the greatest threat for more prolonged periods of heavy rain, though all strong cells will be capable of localized heavy rain. Fracasso/Wegman Day 2 Valid 12Z Mon Jun 15 2026 - 12Z Tue Jun 16 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM SOUTH TEXAS THROUGH THE LOWER MISSISSIPPI VALLEY... As far as changes to the inherited forecast go, the day 2 forecast is the most similar to the prior forecast. A strong cold front over north Texas through southern Arkansas at the start of the day will continue making painfully slow progress south towards the western Gulf Coast on Monday. Meanwhile a surge of deep tropical moisture will actually further increase the amount of available moisture the storms will have to work with as they push south across Texas. The MCS from Sunday night along the Rio Grande will continue south into Monday morning along the Rio Grande and the Texas Hill Country. This MCS will weaken by midday, only to be replaced with far more numerous showers and thunderstorms all across southern and eastern Texas. These storms will form as the surge of moisture and plentiful instability from the Gulf advects north and west into southeast Texas. The storms from any morning MCs will quickly evolve into a slow moving line of storms from east Texas into Mississippi due to the abundant moisture and instability running into the very slow-moving cold front roughly near the AR/LA border. For some areas of east-central Texas, northern Louisiana, and western Mississippi, there may be no stop between any early morning rain from overnight MCS and the afternoon convection that quickly blossoms along the frontal interface. High FFGs and somewhat drier than normal surface soils going in to the Day 2 (depending on what happens today), should work to preclude Moderate Risk level coverage of flash flooding, but the whole area is in a higher-end Slight and a Moderate Risk upgrade is possible with future updates. For South Texas, the primary flash flooding threat for the period will occur overnight Monday night. While the abundant moisture will be in place in this region, there will be a lack of forcing, due to the distant cold front over the Hill Country, until the arrival of a potent upper level disturbance. This disturbance is likely at least in part the remnant circulation of former East Pacific tropical storm Cristina. As this feature pushes northeast out of the mountains of Mexico towards south Texas, it will not only increase the low level inflow of tropical moisture, but will provide ample forcing to organize the storms into slow-moving lines of training cells that track northwestward with time up the Rio Grande. PWATs will be 4 sigma above normal, exceeding 2.5 inches at times, so any and all storms will have impressive amounts of moisture to work with to produce heavy rain. Instability due to extensive cloud cover commensurate with such amounts of moisture will likely be the only limiting factor for coverage of heavy rain. A Moderate Risk may also need to be considered in south Texas should coverage of storms remain similar with more CAMs coverage and portions of this area get significant rainfall on Day 1/today. Wegman Day 3 Valid 12Z Tue Jun 16 2026 - 12Z Wed Jun 17 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE WESTERN AND CENTRAL GULF COAST... ...South Texas... The entire focus of heavy rainfall across South Texas Tuesday will be the speed of movement of the upper level disturbance which likely in part the upper level circulation of former east Pacific tropical storm Cristina. The global guidance is in alright agreement, but it could certainly be better. The EC is far slower with its movement than the GFS. For this period, the difference between the two is small enough that there is at least some confidence in the subsequent meteorological effects. Essentially the upper level Pacific moisture with Cristina will combine with exceptionally deep Gulf moisture along the western periphery of the Gulf, to raise PWATs to near record territory for this time of year for some areas of deep south Texas, particularly along the coast. With the disturbance in place, and strengthening with time, this abundant moisture will be focused into slow-moving bands of heavy- rain producing thunderstorms. PWATs will exceed 2.5 inches along the coast, with some areas even nearing 2.75 inches. The exact track of the slow-moving disturbance will be key as to who sees the most rain, as the storms ride north off the Gulf and into coast to the east of the center of circulation. Rain wrapping around the circulation will spread west across all of deep south Texas, right to the Rio Grande. This will lead to a second consecutive day with exceptional rainfall totals in spots, with areal average rainfall for the period likely exceeding 3 inches (with much higher localized amounts) from essentially Galveston south and west. At the moment, the heaviest totals look to concentrate for the portion of south Texas from Corpus Christi south and west to the Rio Grande, but again any change in track or speed of the upper low and any possible surface circulation will change this dramatically. Regardless, considering the overlap from the Day 2/Monday period, should this rainfall forecast remain similar with future updates, a Moderate Risk will be necessary as FFGs in this area will be much lower than they are now. Further, there will be urban flooding impacts from Brownsville to Corpus Christi as well. ...Louisiana into the South... Up the coast from south Texas, the plume of abundant Gulf moisture will continue to stream north into the slow moving front that will remain set up from east Texas through northern Louisiana and into western Mississippi. The good news for Tuesday is that the likely influence of the upper level low over deep south Texas/Mexico will make for downstream ridging, which should limit the coverage of heavy rain from Houston east across the South. That said, the front will still be a potent forcing feature, and training storms tracking east parallel to the front will still pose a localized flash flooding problem. Thus, the inherited Slight for this region remains in place, especially considering the likely much more favorable hydrology as this will be the second or third day (depending on where you are) of heavy rain for this region. This will likely offset the somewhat lighter rainfall totals expected Tuesday and Tuesday night. A faster forward speed of the upper level disturbance could also re-increase the rainfall forecast for this region and also push some areas close to Moderate Risk territory with future updates. Wegman Day 4 and Day 5 Valid 12Z Wed Jun 17 2026 - 12Z Fri Jun 19 2026 ...THERE ARE SLIGHT RISKS OF EXCESSIVE RAINFALL FOR PORTIONS OF MIDDLE MISSISSIPPI VALLEY, OHIO VALLEY, MID-SOUTH, AND GULF COAST ON DAY 4 AND DAY 5... An anomalous upper-level pattern will be the catalyst for active days 4-5 timeframe from the Gulf Coast on north to the OH Valley and as far east as the central Appalachians. Southeast TX and portions of the Deep South will also experience widespread thunderstorms. On Day 4 (Wed.) a robust 500mb vorticity maximum will spawn a strong area of low pressure at the nose of a 500mb jet streak. ECMWF SAT percentiles show show MSLP values that are among the lowest in the CFSR database (1979-2009) over the Midwest by 00Z Thursday that continue into early Thursday morning over the Great Lakes. 850mb winds will be roaring to the tune of 50 kts and potentially stronger than that over the OH Valley. The combination of highly anomalous low pressure over the Midwest paired with high pressure south of Bermuda will force Gulf moisture to race northward into the Middle MS Valley and on east into the OH Valley. With PWs also above the 90th climatological percentile, storms may be fast movers, but they will contain efficient warm rain processes. A Slight Risk was introduced from the MS Valley to as far east as central OH to account for the increased flash flood potential. Farther south, the pool of anomalous PWs accompanied by a strengthening southerly IVT over the western Gulf will keep the TX Coast at risk for Excessive Rainfall. While guidance still shows some differing solutions, the region will only continue to see soils grow more sensitive after multiple days of rain prior to Wednesday. A Slight Risk was introduced for the Lower and Central TX Gulf Coast, aligning with where the heaviest WPC QPF is located. For Day 5 (Thurs.), between the NAEFS and ECMWF SATs, the southerly winds within the 1000-500mb layer over the western Gulf are remarkable with the entire layer's southerly wind anomalies averaging at least the 97.5 climatological percentile. This means the Gulf is wide open for business, not just with low-level moisture but into the mid-to-upper levels as well. ECMWF and GEFS ensemble means on Day 5 have PWs above 2.2" over the central Gulf Coast with >90th climatological PWs as far north as the OH Valley. A strong cold front will trigger widespread thunderstorms within this environment that is likely to pose a flash flood threat in portions of the recently more sensitive soils of the OH and TN Valleys, leading to the issuance of a Slight Risk in these areas. Farther south, guidance shows varying solutions of what could transpire in east TX. The 12Z ECMWF EFI has a swath of >1 Shift of Tails (SoT) from east TX to as far north as northern MS, and even a small >2 SoT north of I-10 in east TX, indicating a signal for locally significant rainfall being possible in these areas. The details on the development of low pressure in the Deep South remain unclear. That said, there is no denying the copious amounts of moisture at these thunderstorms disposal and soils throughout the region will have only grown more sensitive after multiple days of Excessive Rainfall. A Slight Risk was introduced over the Upper TX coast on east into southwest LA where it aligns with not only the ECMWF EFI signal but the overlap with the more anomalous moisture content and the heavier WPC QPF within the TX/LA area. Mullinax 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 $$