FOUS30 KWBC 230808 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 408 AM EDT Sat May 23 2026 Day 1 Valid 12Z Sat May 23 2026 - 12Z Sun May 24 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF EASTERN TEXAS AND WESTERN LOUISIANA... Convection across the Southern Plains early this morning will likely remain active in the post 1200 UTC period Saturday in an overall favorable convective pattern over the Southern Plains into the Lower MS Valley. There is a strong signal for widespread heavy precip day 1 across eastern/southern TX into southern LA as additional shortwave energy moving east northeastward from far northeast Mexico into southern and eastern Texas early Saturday enhances large scale uvvs. HREF and RRFS neighborhood probabilities are high for 1 and 2"+ totals day 1 in the slight risk area. Several of the latest CAMS, ARW2, GEM, NAMNEST and FV3LAM show potential for a period of training of cells across the Upper TX coast into southwest LA late morning into this afternoon. Across these areas, the HREF and RRFS neighborhood probabilities are high for 3"+ totals and the HREF probabilities high for 5"+ totals. There is potential for these heavier totals affecting the urban areas from Houston to Lake Charles, where an upgrade to a moderate risk was considered and will be re-evaluated after viewing the 1200 UTC hi-res guidance as per collaboration with affected NWS WFOs. No significant changes made to the marginal risk area from the Southern Appalachians into the Southeast. Southwest mid to upper level flow with embedded shortwaves will continue across these areas day 1. With PW values remaining well above average, 2 to 2.5+ standard deviations above the mean, additional widespread scattered convection will likely produce locally heavy rainfall totals. Both the HREF and RRFS show scattered areas of fairly high probabilities for 1"+/hr rainfall totals Saturday afternoon, supporting potential for isolated runoff issues. Over the Upper OH Valley region, a marginal risk area was added for potential for additional scattered convection and locally heavy rains into this afternoon. This additional scattered heavy precip will fall across areas that have received 1-2" of rain over the past 24 hours, raising soil moisture and stream flows and lowering FFG values. Isolated runoff issues possible across these areas. Oravec Day 2 Valid 12Z Sun May 24 2026 - 12Z Mon May 25 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE UPPER TEXAS COAST INTO SOUTHWESTERN LOUISIANA... A slow moving upper trof expected to amplify somewhat day 2 as it pushes from eastern Texas into the Lower MS Valley. This will likely help fire another round of convection in the vicinity of the Upper TX coast, eastward into southern LA. At the moment, it appears the best instability ahead of this next closed low will be suppressed southward into the northern Gulf in the wake of the active day 1 convection. This may support the heaviest rains being shunted southward and off the coast day 2, as suggested by the RRFS mean and the FV3LAM. There is still a lot of model spread, but WPC qpf has trended south, with the heaviest offshore. Subsequently, the previous slight risk area has been trimmed on the north end, confined to the far Upper TX coast into southwest LA. There may be overlap of the day 1 and day 2 heavy rain areas over the Upper TX coast into southwest LA. However, at the moment, the risk level was maintained as slight as there is still model spread with the day 2 heaviest qpf axis. No significant changes made to the previous broad marginal risk area extending northeastward from the Central Gulf Coast, across the South and into the Southern to Central Appalachians. Similar to the day 1 period, there will continue to be an axis of much above average PW values stretching across these areas, with embedded shortwaves in the broad southwesterly mid to upper level flow, supporting widespread scattered convection, locally heavy rains and isolated runoff issues. Oravec Day 3 Valid 12Z Mon May 25 2026 - 12Z Tue May 26 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE SOUTHERN APPALACHIANS... A small slight risk area was introduced in the vicinity of the Southern Appalachians from north Georgia into the Upstate of SC and far southwestern NC. A very broad region of much above average PW values, 2 to 2.5+ standard deviations above the mean, will stretch from the Central gulf coast, northeastward across the South, Tennessee Valley, Southern Appalachians and into the Southern Mid- Atlantic during day 3. Similar to the day 2 period, broad south southwesterly mid to upper level flow with embedded shortwaves will support additional widespread scattered convection across these areas. While locally heavy rains are likely across a large region in this anomalous PW axis, there is model signal for concentration of heavy precip into the upslope regions of the Southern Appalachians, with a small slight risk area depicted here. Included the Atlanta metro in the slight risk area given the sensitivity to potential urban issues. There may be additional slight risk areas in this anomalous PW axis depicted in future updates, but low confidence with placement at this time. Oravec 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