866 FOUS30 KWBC 152024 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 424 PM EDT Thu Oct 15 2026 Day 1 Valid 16Z Thu Oct 15 2026 - 12Z Fri Oct 16 2026 ...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF WEST TEXAS... 16Z Update... Overall, the 12Z HREF and REFS did not present any reason to make significant changes to the previous outlook. Therefore, made mostly minor adjustments based on this latest guidance. These changes included trimming some of the western extent of the outlook areas north and west of the Davis Mountains where both the HREF and REFS agree that the potential for additional heavy amounts will be limited. Both suites continue to show a strong signal for heavy amounts developing this evening and overnight within the Moderate Risk area, with high neighborhood probabilities (above 70 percent) for amounts exceeding 5 inches centered within this area. A more immediate threat for flash flooding is farther to the north where rain continues across some parts of Northwest Texas where heavy amounts have already occurred and 3-hr FFGs have dropped below 0.25 inch in some of the most impacted basins. While considered a 'high-end Slight' in the near-term, conditions are expected to improve as a cold front moves steadily through the region this afternoon. Refer to WPC MPD #1498 for additional information regarding the near-term heavy rain and flash flooding threat across western to northwestern Texas. Across the central Appalachians-Ohio Valley, extended the Marginal Risk west to include portions of eastern Kentucky, where this morning's activity in addition to possible further activity this afternoon may produce some localized 1-2+ inch amounts across a relatively sensitive/low FFG area. Pereira Previous discussion... The setup for Thursday into early Friday morning continues to trend towards a very active period across portions of the Southern Plains as a cold front drives south with the aid of a strengthening surface ridge emanating out Canada. Complex longwave evolution will generate quite a strong surface response with high pressure nosing out of western Canada, eventually strengthening into a 1040+ mb high centering over Montana by later this afternoon. This will finally push the front bisecting the Plains through the Ohio Valley southward creating a focused area of low-level convergence as it interacts with rich theta_E air positioned over the Southern Plains of OK/TX. Current surface analysis maintains our ridge across the Lower Mississippi Valley with a prevailing south to southwest fetch out of the adjacent Gulf, leading to a fairly pronounced deep layer moisture source across much of the Lone Star state and the eastern half of OK. PWATs centered over west TX up through OK remain very much elevated with the 00z RAOB's out of both KOUN and KMAF indicating PWAT anomalies encroaching on +2 to +3 standard deviations when accounting for climatology. This is also well above the 90th percentile with the NAEFS outputs signaling closer to the upper 97-99th percentile when adjusting for seasonal climo, so the environmental conditioning is more than favorable for prospects of heavy rainfall in any convective regimes. Streaming mid- level vorticity within the western flank of our ridge over the Southeast CONUS will continue for at least another 24 hours before the general pattern, both at the surface and aloft, finally shifts and the threat for significant convective coverage and associated impacts diminishes across the region. Classic low- level convergence regime with the front will allow for the standard continuation of convection over the Southern Plains the first part of Thursday with the eventual decay in the magnitude for a short time late-morning into the afternoon. By the mid to late-afternoon time frame, we'll begin seeing our front take a dive south as it begins feeling the pressure gradient pattern building over the Plains and Northern Rockies thanks to our maturing high out of the Canadian Prairies. By the following evening (Thursday night), the nocturnal LLJ will respond ahead of the approaching boundary leading to enhanced low to mid-level convergence from the eastern Permian Basin down through the adjacent Concho Valley, into the Big Bend and Lower Trans Pecos. The further south the setup, the more prolonged the heavy convective regime will last creating a cumulative effect of all the heavy rain occurring during the period. A noteworthy precipitation gradient can be seen within the ensemble means with heavy QPF signatures over the Big Bend to Lower Trans Pecos with a gradient decline as you move northward. Areal average QPF between 3-5" with locally higher amounts are anticipated along and south of I-10, mainly east of the Davis Mountains with the maxima centered over the Lower Pecos River basin between Sanderson to north of Del Rio. 00z HREF/REFS neighborhood probabilities continue to pinpoint 70-100% exceedance probs for >3" with even a pocket of 50-80% for >5" positioned over Terrell county in the Big Bend up through portions of the Lower Concho Valley. This is the area where the convective pattern will linger the longest before the eventual frontal progression pushes the front through the area, but it's also the area with the greatest instability and deep layer moisture presence when assessing raw PWAT indices being forecast. Considering such a robust signal, the previous MDT risk forecast is still very much in play with only minor modifications to the risk itself from the previous issuance. Continuity and the enhanced probabilities maintain a favorable prospect for widespread flash flooding across the aforementioned areas with even a threat for areas north around the central Concho Valley, including the San Angelo area and surrounds. The SLGT risk extends further north into southern OK with the initial convective threat carrying over from the morning hours and some overlap in the afternoon on initiation before the front finally pushes through the air and dry air advection in wake of the front puts an end to the threat. DFW metro will be right on the edge of seeing more appreciable rainfall, but current progs are the worst stays just outside the metroplex this period. Will be something to monitor moving forward, but the area remains in the MRGL encompassing the outskirts of the main axis of heavier precip and associated SLGT risk. Kleebauer Day 2 Valid 12Z Fri Oct 16 2026 - 12Z Sat Oct 17 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF CENTRAL AND SOUTHERN FLORIDA... Flow across the region will become more southerly ahead of an amplifying trough moving into the easterly U.S. This will support increasing moisture, with PWs climbing to at or above 2 inches (or around 2 std dev above normal) across much of central and southern Florida on Friday. This will support efficient rain-producing storms, with slow storm motion raising the threat for localized heavy accumulations. The Marginal Risk highlights the area where the HREF and REFS both generally show higher (greater than 50 percent) probabilities for accumulations exceeding 3 inches. Pereira Day 3 Valid 12Z Sat Oct 17 2026 - 12Z Sun Oct 18 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ALONG PORTIONS OF THE FLORIDA EAST COAST... 20Z Update... No changes were made to the previous outlook. Pereira Previous discussion... Cold front will be pushing through the Florida Peninsula by Friday night and maintaining slow progression southward through Saturday with a bit of a frictional convergence regime along the east coast. Surface ridging to the north coupled with the front will allow for prevailing east to northeast flow off the nearby Atlantic with focused convergence along the front as it motions south. Current progs are for the front to be aligned between Melbourne and West Palm Beach by Saturday afternoon which should coincide with the diurnal max instability. As of now, the signal shows convection confined right along the coast with little progression inland, so the threat for any heavy rainfall is along that immediate coastal plain. That said, that's the main population center with urban sprawl up and down this area of the state, and with the environment conducive for locally 2-3"/hr within any convective cores, imagine isolated totals of 4-6" are very much plausible in this scenario. It's a tricky setup with low areal coverage of heavy rain potential given the expected proxy to the coast. Considering the marginal signal within the global deterministic and ensemble bias correction, the previous MRGL risk was maintained with no adjustment. Kleebauer Day 4 and Day 5 Valid 12Z Sun Oct 18 2026 - 12Z Tue Oct 20 2026 ...MARGINAL RISKS OF EXCESSIVE RAINFALL EXIST FOR THE GOLD COAST OF FLORIDA SUNDAY & PORTIONS OF THE EAST COAST MONDAY... 2000Z Update: Only minor changes made to the Day 5 outlook. The Marginal Risk area along the Mid Atlantic Coast is still predicated on the trends in the AI guidance, especially with the 12Z ECAIFS, which came in much wetter (low closer to the Mid Atlantic Coast) at 12Z compared to 06Z. Hurley Previous discussion.. ...FL Gold Coast... A well defined cold front is expected to press southward, becoming stationary across Cuba on Monday. Moderate to strong Low level east northeasterly flow exist near the east coast Florida Sunday, nearly antiparallel to the flow aloft. Precipitable water values are forecast to be 1.5-2". Strong boundary layer convergence maxima likely along the east central coast of Florida, which would be strongest overnight. This will support potential for locally heavy rains from well defined rain bands that may train for periods early Sunday, with isolated runoff issues possible along the east central coast of Florida, especially in urbanized regions. The guidance is slowly trending downward with amounts as the front trends faster due to more of a signal in a low near the East Coast, so there is a chance that later shifts may be able to drop the Marginal Risk. Stay tuned. ...Eastern NC/Southeast VA... The guidance is trending towards an occluded low, which could have some interior convection, somewhere across the western subtropical North Atlantic between the Southeast Coast and Bermuda. The 00z GFS is the farthest east, but the 00z ECMWF/Canadian/UKMET are much closer to the 12z EC mean/00z GEFS mean in more coastal solutions. This could allow for heavy rainfall near the NC Outer Banks and Southeast VA as moisture/instability pivot back to the coast from the Gulf Stream within its comma head or TROWAL. The 00z UKMET has the strongest signal while the 00z ECMWF is slightly offshore. Since the ensemble means indicate more western solutions may have merit, raised a Marginal Risk as a course of least regret. Roth 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 $$