FOUS30 KWBC 070057 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 857 PM EDT Sat Jun 6 2026 Day 1 Valid 01Z Sun Jun 07 2026 - 12Z Sun Jun 07 2026 ...THERE ARE SLIGHT RISKS OF EXCESSIVE RAINFALL FOR PORTIONS OF THE SOUTHERN PLAINS, OHIO VALLEY, AND CENTRAL GULF COAST... 01Z Update... Adjustments were made based on current radar trends, recent runs of the HRRR, and the latest HREF/REFS guidance. With the exception of the upper Texas Coast, Slight Risks from the previous issuance were left in place. Both model guidance and observation trends indicate at least some potential for additional heavy rain and flooding concerns in these areas through the remainder of the evening into the overnight. One area of potentially greater concern extends across portions of Central into North Texas. Supported by sustained low level inflow and deepening moisture, backbuilding along the southwestern flank of the ongoing line of convection may produce heavy amounts, with both the HRRR and HREF showing the potential for localized amounts in excess of 3 inches along an axis extending northeastward from the northern Hill Country toward the DFW Metro. Another area of greater concern is along the AR-TX border, where north-south training is expected to continue, resulting in heavy amounts. Here too the HRRR and the hi-res ensemble guidance show the potential for localized amounts over 3 inches. Pereira Previous Discussion... ...Southern Plains... A plume of deep tropical moisture will surge northward across the Southern Plains Saturday. The low level jet advecting this moisture north will run into an area of enhanced lift due to a nearby lingering upper-low, which will be lifting northeast to rejoin the jet. The result will be a series of rounds of storms moving north- northeast across portions of north/northwest Texas, Oklahoma, and western Arkansas. Highly efficient warm rain processes will dominate due to the presence of such abundant amounts of moisture, with PWATs close to 2 inches. For eastern Oklahoma/western Arkansas, rainfall is already ongoing and will persist for much of the day in the form of training lines of storms. To the west, another round of storms is expected to develop with daytime heating along the eastern periphery of the upper-low, with the expectation that repeated rounds of storm development and storm clustering/merging cold pools may eventually lead to a more organized convective system that will progress slowly to the east- southeast through the evening and overnight hours. An internal higher- end Slight covers from southwest of the Metroplex through it, and continuing into much of eastern Oklahoma and western Arkansas for the combination of two areas of persistent heavy rain. The latest convection allowing guidance (CAMs) show peak rain rates reaching upwards of 2-3 inches per hour with locally heavy totals into the 5-6+ inch range, more than sufficient for at least scattered instances of flash flooding despite some locally drier antecedent conditions. ...Ohio Valley... A very-slow moving cold front drifting south across the Midwest/Ohio Valley on Saturday will be the animus for multiple rounds of storms which will track east-southeast within the Slight Risk area roughly from central Indiana east to the central Appalachians. The front will form the leading nose of a plume of deep Gulf moisture tracking northward up the Mississippi Valley. The front will "shear" the moisture eastward in a narrow corridor, along which the storms will form and move. There is some uncertainty as to how persistent an ongoing complex of storms moving into central Ohio will be as they progress east- southeastward through the afternoon. However, even if storms do not maintain quite the same strength/organization as they move into the Mountains of western Pennsylvania and West Virginia, these areas have lower FFG thresholds and the risk for scattered flash flooding will remain a concern. Uplift along the western face of the Appalachians may also locally enhance rainfall rates. Another round of storms is expected along the boundary further west within the Slight Risk over central Indiana where the CAMS/HREF suggest heavier totals into the 3-5 inch range are possible. Additional storms are also forecast to develop further west along the boundary stretching through central Illinois and along the Iowa/Missouri border. However, these storms are forecast to remain more scattered/less organized with generally lower rain totals in the CAMS, keeping the flash flood threat more isolated compared to further east. ...Central Gulf Coast... No changes were needed to the Slight Risk area from New Orleans east to Pensacola. A strong front is in place across the eastern Gulf, characterized by very dry air to its east, rather than any significant temperature gradient. The dry air is 2 sigma below normal over portions of central Florida...under 1 inch PWATs. Meanwhile to the west from Louisiana through Texas, an abnormally moist air mass will be streaming north to the west of the high pressure area characterized by the dry air. Over much of Louisiana, PWATs will be over 2.25 inches or 3 sigma above normal. The front makes up the gradient between these extremely contrasting air masses. Through the day, the front will push east as the moist air mass gradually gains ground. However, the front will be the forcing along which numerous showers and thunderstorms pushing north out of the Gulf will form along. The front will be slow to move, allowing repeating rounds of storms to impact the central Gulf Coast. FFGs are high, about 4 inches/hour, but the repeating rounds of storms should rather quickly bring those numbers down, allowing for scattered instances of flash flooding to develop where the rains are most persistent by late afternoon, particularly for urban areas. HREF probabilities for rainfall exceeding 5 inches are also moderate to high (45-70%), with low end probabilities (~15%) of exceeding 8 inches. Storms are also expected west along and just to the north of the I-10 corridor between the Slight Risks covering southeastern and far southwestern Louisiana. However, more persistent forcing/greater storm coverage to the east and lower FFGs to the west suggest there will be a relatively more isolated threat in between. Similar to the Upper Texas Coast, nightfall should see a decrease in shower and storm activity, ending the flooding threat. Putnam/Wegman Day 2 Valid 12Z Sun Jun 07 2026 - 12Z Mon Jun 08 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF THE MID-MISSISSIPPI VALLEY, OZARKS, AND THE WESTERN TENNESSEE VALLEY... Minimal areal adjustments were made to the inherited Slight Risk based on the now-available convective allowing (CAM) guidance. Similar to today, scattered to widespread storms will develop with daytime heating across the Ozarks vicinity northeastward into the Mississippi Valley within an extremely humid airmass and under the influence of an upper-wave lifting slowly northeastward out of the southern Plains. Additional storms are expected ahead of the southeastern periphery of the upper-wave along a returning influx of higher Gulf moisture extending southeast into the western Tennessee Valley. The airmass characterized with PWATs of 2" will support highly efficient rainfall processes with rain rates of 2-3" per hour likely. Within the Slight Risk, two reasons for concern across the greater Ozarks vicinity are 1) the potential for storm clustering/cold pool mergers to result in more organized/expansive storm coverage as well as renewed development along remnant outflows and 2) that at least some of this region (particularly areas further south into eastern Oklahoma and western Arkansas) likely will have seen heavy rainfall today, better priming soils for potential flash flooding tomorrow. The first concern is supported by the now-avaialble CAM guidance indicating the potential for rainfall totals locally as high as 5-7". Elsewhere, a more isolated flash flood risk remains a concern with renewed storm development along a quasi-stationary frontal boundary along/north of the Ohio Valley. Similar to today, moisture pooling along/south of the boundary will support locally heavy rainfall rates upwards of 2"/hour, and an eastward extension of the Slight Risk may be needed with more confidence in storm coverage. In addition, the main upper-trough to the northwest will begin to overspread the northern Plains. Robust thunderstorms are expected to develop and grow upscale southward along a trailing cold front as surface low pressure intensifies in the lee of the Rockies. However, the progressive nature of the storms should keep the flash flood threat isolated. Putnam Day 3 Valid 12Z Mon Jun 08 2026 - 12Z Tue Jun 09 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE MID-MISSISSIPPI, LOWER OHIO, AND WESTERN TENNESSEE VALLEYS... ...2030 UTC Update... The previous forecast remains on track for the bulk of the Slight Risk from the Middle Mississippi Valley into the Lower Ohio/Tennessee Valleys. Increasing totals within the deterministic guidance (3-4" across the Lower Ohio Valley) and a similar set-up to the prior days all suggest a continued threat for scattered flash flooding and the potential for higher-end Slight impacts. The one caveat is that at least based on the current guidance the greatest potential for heavy rainfall Monday will be offset from areas that will see the heaviest rainfall on Sunday, leaving less concern about repeated rounds helping to prime soils. There is less confidence in the northward extent of the Slight Risk into northern Illinois and particularly southern Wisconsin depending on how far north the front retreats. Putnam ...Previous Discussion... On Monday, the excessive rainfall risk translates a bit further north and east into the Mid-Mississippi, lower Ohio, and western Tennessee Valleys. A strong front over the Great Lakes will retreat northeastward as the plume of anomalously deep moisture from the Gulf surges northeastward to replace the drier air mass in place over the Northeast. A slow-moving negatively tilted trough will also promote upper divergence and lift throughout the atmosphere over the Slight Risk area throughout the period. PWATs around 2 inches will be 3 sigma above normal for this time of year across the region, so many of the storms that form will consist of highly efficient warm rain processes, which will promote heavy rainfall. FFGs across the region will average around 2-2.5 inches, which will be easily overcome by many of the strongest cells, so long as their forward speed is kept in check. The Slight Risk area was nudged west over more of southeastern Missouri with this update, adjusted for expected heavy rainfall and likely lower FFGs in this region from the Day 2/Sunday period. Wegman 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