FOUS30 KWBC 131942 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 342 PM EDT Sat Jun 13 2026 Day 1 Valid 16Z Sat Jun 13 2026 - 12Z Sun Jun 14 2026 ...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR SOUTHWESTERN MISSOURI... ...Southern Plains, Mid-Mississippi Valley, western Ohio Valley... Maintained the Moderate Risk area for southwestern Missouri and adjoining areas with a continued signal for heavy rain this afternoon/evening and early overnight hours. A broader Slight Risk outline extends from the eastern half of Oklahoma northeastward to the far western Ohio Valley. At 15Z, a cold front extended from the Upper Midwest back to the central Plains and will continue to push southeastward today. In addition, a warm front extended from southeastern Nebraska across southern Missouri into the Tennessee Valley. Southerly flow from Texas and the Gulf will continue to supply warm/moist air to the region as dew points in the 60s/low 70s are common across the warm sector along with precipitable water values of 1.75-2.00 inches. Morning convection over central/southern MO (near and east of the warm front) will continue eastward this afternoon, allowing for some clearing to the west. By 00Z, cold front from the northeast will push into southeastern KS with an increase in the LLJ and an expected convective expansion into the Moderate Risk area. 40+kt 850mb southwesterly flow along/ahead of the surface cold front should favor sufficient growth with heavy rain rates of 2-3 inches per hour, especially where any training occurs if the cold front slows. 12Z CAMs still show potential for a fairly widespread 1-3" of rain and embedded 6+" totals over southwestern MO and far northeastern OK per some members. HREF mean signal has been consistent since 00Z and little change to the outlook area was made. The topography of the Ozarks across southern Missouri supports a heightened flash flooding threat as the mountains quickly funnel the heaviest rains into narrow valleys, worsening the impacts of any flooding that develops there. Will note the AI guidance from the ECMWF and GFS (though lower res at 0.25 deg) showed a QPF max over either eastern KS or northeastern OK rather than into MO, but their D1 skill is generally not as good as the traditional CAM guidance. A much larger Marginal Risk area exists from the southern Rockies all the way to the southwestern Great Lakes in the broad warm sector ahead of the front, with expected coverage isolated. ...Central/Eastern Florida... Trimmed the Marginal Risk area to remove the western portion of the peninsula. Westerly flow, though light, should favor convergence inland and over eastern areas. Moisture levels remain higher than climo -- near 2" -- and coupled with slow-moving cells may favor local flash flooding especially in urban areas. 12Z HREF neighborhood probabilities for at least 3 inches per hour are 10-40% (a little higher in the 06Z REFS) and 1-h FFG values are generally 3-4 inches per hour. Farther north into eastern/southeastern SC/NC inland from the coast, combination of sea breezes and incoming front to the north could support isolated heavier rain and very localized flash flooding should any convection remain slow-moving, though the coverage is likely less than the 5% threshold for a Marginal Risk outline. Fracasso/Wegman Day 2 Valid 12Z Sun Jun 14 2026 - 12Z Mon Jun 15 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR AREAS FROM SOUTHERN NEW MEXICO THROUGH WESTERN MISSISSIPPI... 21Z Update... Expanded the Slight Risk a bit farther south across TX with some more support for farther south QPF. Also included the Mid- Atlantic in the larger Marginal outline with the area to the north, and nudged that region into New England as well per some higher QPF in the models. Lastly, with little change in the synoptic pattern over FL, expect another change of sea-breeze-driven storms over the eastern portions of the Peninsula, where a Marginal Risk was added. Fracasso Previous discussion is below: A slow-moving but potent cold front will approach portions of north Texas through into Arkansas on Sunday. The MCS that caused the Moderate Risk flooding in Missouri Saturday night will be responsible for the heavy rains that elevate northeast Texas through the lower Mississippi Valley into the Slight Risk category. Associated heavy rain will be ongoing at the start of the period Sunday morning, and will weaken and dissipate by midday. Since the forward/southward progression of the heavies rains will slow after daybreak Sunday, some areas may see several hours of weakening but still heavy rains. Abundant moisture will remain in place south of the front, as PWATs rise as high as 2.25 inches. Thus, any cells producing rains will have no trouble doing so efficiently. During the afternoon and evening, this area may see additional widely scattered storms with the strong front stalled out in the area, but coverage will be somewhat in question as the stalled out front alone will not be enough forcing due to flow on either side of the front weakening to light and variable winds. Further west into west Texas and New Mexico, a shortwave trough running into some of the same Gulf moisture as further east should allow for scattered showers and thunderstorms to develop in clusters from the afternoon well into the evening. Topographic assistance by the Sacramento Mountains and other ranges may locally produce heavy rains, where any burn scars may take over at raising the flash flooding risk. The same front extends into the Appalachians and interior Northeast. While the storms will be racing in these areas, the abundance of moisture advecting north into the front will support the storms in their capability of producing heavy rainfall. The Marginal Risk for these areas was expanded along the Canadian border through northern Maine. The Marginal for portions of the Mid-Atlantic was split into 2 areas with this update. One for the I-95 corridor from DC to Philly, and a second for the Hampton Roads area. Abundant Gulf/Atlantic moisture in these areas will support fast-moving but training storms capable of producing heavy downpours. Due to ongoing drought, the threat really is focused on the urban areas where FFGs are lower. The intermediate rural areas were removed with this update as any training storms that occur over most of the Delmarva will be over rural and flood-resistant/flat areas. Wegman Day 3 Valid 12Z Mon Jun 15 2026 - 12Z Tue Jun 16 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR SOUTHEASTERN TEXAS EASTWARD TO THE LOWER MISSISSIPPI VALLEY... ...Southeastern Texas to southern Mississippi... Expanded the Slight Risk across much of Southeastern Texas to the Rio Grande with an increasing signal for heavier rainfall on Monday. Upper jet across the central Plains into Oklahoma will lie on the southwest side of a sprawling upper low over Hudson Bay, leaving Texas and the Lower MS Valley in the warm/moist sector to the south of a front. PWATs to 2.25 inches will be drawn northward due in part to a mid-level circulation out of coastal Mexico as well as energy exiting the southern Rockies. Combination of that forcing, ample moisture, and a nearby frontal boundary should support at least scattered heavier rain and some instances of flash flooding. FFG values decrease away from the coast, and highlighted these areas for now (despite the recent dryness which can act to increase runoff), in an arc from Laredo to Austin to College Station (then continuing into Louisiana like the previous ERO). ECMWF EFI QPF highlights SoT near 1 within this Slight Risk outline, suggesting even a higher-end Slight risk for areas near the TX/LA border but perhaps also near the Rio Grande. New 12Z CSU first guess ERO also showed an expansion of the Slight, in line with the updated changes. Model QPFs show some 4-8" amounts (and some >10" amounts) in this 24-hr period but the placement over southwestern/south Texas is uncertain (noting the AI guidance is closer to the coast). Potential exists for a further upgrade to a Moderate Risk somewhere in this region but would like to see the CAM guidance in future updates. Fracasso Day 4 and Day 5 Valid 12Z Tue Jun 16 2026 - 12Z Thu Jun 18 2026 ...A SLIGHT RISK OF EXCESSIVE RAINFALL EXISTS FOR PORTIONS OF THE SOUTHERN PLAINS, LOWER MISSISSIPPI VALLEY, AND THE SOUTHEAST... 20Z Update: General model consensus remains pertinent for a SLGT risk threat of flash flooding across portions of the Central Gulf Coast with emphasis along the I-10 corridor. Recent ensemble QPF distribution has shifted a bit further west with the corridor of heavier precip leading to agreement with the ML outputs from the EC-AIFS and associated ensemble. Given the overlap, increasing favor in flash flood prospects into southwestern LA with those areas between the Lower Sabine to Lafayette within the target for the D4 time frame. The SLGT risk inherited was extended west to reflect the agreement in the 12z ensemble/ML outputs. D5 continues to look very active with a higher likelihood of a complex of thunderstorms materializing with increasing flash flood concerns in-of the mid-Mississippi Valley to points east through the Midwest and Ohio Valley. Consensus on QPF being robust is solid, but exact placement is a bit fluid currently as models are still trying to distinguish exact placement downstream of initiation over the Midwest and northern/central Ohio Valley. Considering the forward propagation uncertainty, elected to maintain the MRGL risk with some minor adjusting on the northern and eastern periphery to reflect QPF orientation and pQPF 90th percentile forecast of >1.5" of precipitation. An upgrade in future forecasts is likely, but there is still time for further assessment and developing a better consensus. Kleebauer ..Previous Discussion.. The first half of the medium range will see two particular threats for flash flooding. First, along the Gulf Coast, a stationary front will work in tandem with with tropical moisture to develop thunderstorms capable of torrential downpours both on Day 4 (Tuesday) and Day 5 (Wednesday). There is greater confidence in Tuesday's flash flood threat given better model agreement in placement of QPF and the nearby frontal boundary remaining strong enough to help trigger numerous showers and thunderstorms. PWs will remain above 2.0" in many cases as well, allowing developing thunderstorms to contain highly efficient rainfall rates. Soils will be more saturated in wake of Monday's thunderstorms as well, making the region more susceptible to flash flooding. The forecast remains largely on track for Tuesday (Day 4) with only some minor tweaks to the inherited Marginal and Slight Risks to more closely resemble the latest WPC QPF. By Wednesday (Day 5) the frontal boundary will undergo frontolysis and the source of lift at the surface will weaken. However, ensemble guidance continues to show ample tropical moisture along the Central Gulf Coast, which at by Wednesday will have dealt with multiple rounds of Excessive Rainfall. A Marginal Risk was introduced along the I-10 corridor from the Houston metro on east to the FL Panhandle to account for the flash flood potential around the more urbanized communities along the central Gulf Coast. Farther north, Wednesday looks like an active day from the Midwest on east into the OH Valley. A 500mb shortwave trough racing east towards the Great Lakes late Wednesday will provide healthy upper- level ascent aloft to foster the development of low pressure. Meanwhile, a strengthening LLJ will direct anomalous moisture located over the South northward into the region. NAEFS shows an impressive IVT for mid-June that surpasses 750 kg/m/s over the eastern Corn Belt that will provide copious amounts of moisture. Guidance is not in agreement yet as to which locations are most favored to witness the heaviest thunderstorm activity. Fast storm motions should also help to limit residency times of developing storms. That said, PWs ranging between 1.75-2.0" will be the norm late Wednesday with storms likely containing efficient rainfall rates. A Marginal Risk was introduced to account for the localized flash flood potential on Wednesday from the Middle MS River on east into the OH Valley. 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 $$