FOUS30 KWBC 062025 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 325 PM EST Fri Nov 6 2026 Day 1 Valid 16Z Fri Nov 06 2026 - 12Z Sat Nov 07 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF SOUTHEASTERN NEW ENGLAND... ...Southeast New England... Only very minor edits were needed to the inherited Slight Risk stretching from eastern Connecticut/Long Island northeastward through Rhode Island and into portions of eastern Massachusetts. As the mid/upper trough takes on a more neutral to negative tilt, mean low- mid layer flow will back more southerly (parallel to the surface front), thereby prolonging the favorable moisture flux off the Atlantic Gulf Stream and thus axes of heavier rainfall through the day and into the evening hours. TPWs approaching 1.75" is close to 3 standard deviations above normal for early November, while IVT values exceed 750 KG/m/s through late afternoon per both the GFS and ECMWF. The latest 12Z HRRR and RRFS suite of guidance show areal average rainfall in the 2-3" range with locally heavier totals of 5" possible, supported by the impressive influx of moisture off the Atlantic. A slower progression of the front as the flow backs will also help to maintain storm development/coverage over the region for a longer period of time increasing the chance for these heavier totals. Some storms are also possible further north along the coast of Downeast Maine depending on when the front clears the coast. However, given dry antecedent conditions and proximity to the coast do not expect a notable flood threat. ...Southeast VA into Northeast NC, the DelMarVa, and coastal NJ... Further south, another maxima of heavy rainfall is expected across portions of southeastern VA and perhaps into northeastern NC. The latest hi-res guidance continues to show the potential for some locally heavier totals in the 3-5" range. Modest instability (~1000 J/KG CAPE) should lead to some more robust storms with waves along the front potentially helping to slow its progression and allow for at least brief training potential, both contributing to higher totals. Locally backed and enhanced southerly flow will also aid in increased moist flow from the Atlantic and enhanced convergence. This would result in a greater concern for scattered flash flooding particularly for the more urban areas around Norfolk/Virginia Beach. However, given the relatively isolated nature of the threat and drier conditions overall, have maintained a Marginal Risk. See additional details in WPC Mesoscale Precipitation Discussion (MPD) #1558. A Marginal Risk extends both further north through the DelMarVa and southwest through eastern North Carolina where additional, ongoing storms along the front will continue to lead to heavy rainfall, though the progressive nature of the front should keep any threat of flash flooding isolated. ...Southeastern AZ/Southwest NM... A targeted Marginal Risk remains across southeastern Arizona and far southwest New Mexico. A developing upper-level wave in the southern stream will pass over the region today leading to isolated to scattered thunderstorm development. While not quite as anomalous as recent events, increasing moisture as well as modest instability could lead to a few more robust downpours producing ~1-2" or so of rain, which is more than sufficient for at least isolated flash flooding concerns, especially for more sensitive terrain and urban areas. Putnam/B Hurley Day 2 Valid 12Z Sat Nov 07 2026 - 12Z Sun Nov 08 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF SOUTH, CENTRAL, AND WEST TEXAS... Have maintained the Marginal Risk across much of south to south- central and west Texas for Saturday. Expect a slow ramp-up of storms through the day with the approach of the southern stream upper-wave from the west and increasing low-level flow from the Gulf, which will likely leave the chance for more widespread, intense rainfall for Sunday. There were a couple corridors of potentially heavier rainfall noted in the now available hi-res guidance. The first is with the potential for modest instability to develop through portions of the lower Rio Grande Valley leading to a cluster of more intense storms as indicated by the HRRR. The second is with enhanced upslope flow into the higher terrain of northeast Mexico increasing storm coverage and potential rainfall along the south Texas Plains/Rio Grande as noted by the suite of RRFS guidance. However, given the bi-modal distribution of circumstances and potential rainfall, as well as the concern some of the heaviest rainfall could ultimately end up mostly in Mexico in either case, the risk for flash flooding broadly remains isolated for now. Putnam Day 3 Valid 12Z Sun Nov 08 2026 - 12Z Mon Nov 09 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTH- CENTRAL AND SOUTH TEXAS... ...2030 UTC Update... The prior forecast reasoning remains on track on a possible eventful day across south to south-central Texas. The latest global 12Z guidance continues to show the potential for areal average rainfall in the 2-3" range and locally heavy totals in the 4-8" range. However, there remains a higher than normal amount of uncertainty with where the heaviest rainfall and flash flood risk may occur. The guidance shows several scenarios including a coastal convergence focus along the Gulf (GFS), an enhanced low-level jet from the Gulf further inland across south Texas (ECMWF), or enhanced upslope flow into the higher terrain of northeastern Mexico with a heavy rain focus along the south Texas Plains/Rio Grande (CMC/UKMET). The risk could also be influenced by a combination of these factors, including both along the coast and with enhanced flow inland through south-central Texas, that lead to multiple enhanced corridors of rainfall. The Slight Risk will likely need adjustment including potentially trimming regions where the threat ultimately is not as high, but for now have left the risk rather broad until there is more clarity in the forecast. Putnam ...Previous Discussion... ...South Texas... A anomalous upper pattern over the Southwest will shift focus to the South-Central Plains with eyes on the southern half of TX as we head into Sunday. Digging mid-level trough out of the Southwestern CONUS will eventually close off over northern MX and drift eastward leading to increasingly diffluent flow over west TX and points south and east. At the surface, modest surface ridging to the north will send a cold front southward, gradually, with eyes on Deep South TX by the end of the period. The synoptic evolution lends to a classic isentropic pattern situated over the Edwards Plateau through Hill Country, sinking southward into South TX as we move into the back half of Sunday. Prevailing southeast between the surface to 850mb will lead to an ushering of low-level moisture that will send PWATs surging between 1.5-2.1" with the highest moisture prevalence located over the Southern RGV over to the Gulf Coast, mainly south of Corpus Christi. Directional shear will entice the potential for mesocyclone development and the ability to sustain convection, even elevated to the north of the front leading to enhanced precipitation rates with longevity due to the persistence in the diffluent flow aloft. This whole setup will materialize and become a fixture for at least 24 hrs with a broad area of moderate to heavy rainfall with embedded convection situated across Southern TX with the core located along and south of I-10. Models are consistent in the presentation of bouts of heavy rainfall throughout the period with some enhancement expected in the afternoon and evening as the ascent pattern is maximized with the mid and upper level evolution, as well as the additional diurnal instability element that will occur south of the cold front. Widespread 2-4" with locally higher totals are already being forecast within the numerical suite, even the ML coming in with a solid 1-3" from northwest to southeast with the max focused over the lower Rio Grande Valley (RGV). Despite some of the higher FFG indices, this type of setup can surprise and offer some sneaky flash flood prospects, especially within more urban settings and locally flashier creeks and arroyos across the region. In coordination with the local WFO's over South TX, a SLGT risk was added for those areas along and south of I-10 down to the lower RGV. Main areas of concern will be that area of South-Central TX near San Antonio and the RGV areas between Eagle Pass down to Brownsville. Kleebauer Day 4 and Day 5 Valid 12Z Mon Nov 09 2026 - 12Z Wed Nov 11 2026 2030Z Excessive Rainfall Discussion... An overall downward trend is expected across Texas on Monday...especially during the latter part of the period. The signals for heavy rainfall in the Pacific Northwest remain muted so was not inclined to introduce an outlook area at this time. Bann Previous Excessive Rainfall Discussion... ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL SUNDAY ACROSS DEEP SOUTH TEXAS ON DAY 4... D4 will be the period where the pattern breakdown over TX and the threat for heavy rainfall begins to dwindle from north to south with the loss of the primary ascent, along with more stable air advecting into the region post-front. There is some discrepancy in the amount of lingering heavy rain/convection in the region from the deterministic output with some lighter amounts overall in the various ensembles. Leaning towards a MRGL for South TX with mainly areas along and south of a line from Laredo to Corpus Christi. Rainfall totals will vary in terms of magnitude with perhaps even a threat for an additional 1-3" according to some global deterministic outputs. Eventually, this setup will translate into a quieter pattern and limited impacts are anticipated for the back- half of D4 and beyond for TX. Across the Pacific Northwest, our first true atmospheric river of the season will impact the region with a steady stream of heavy precipitation into northwest WA, sinking south into northeast OR and the neighboring Cascades between WA/OR. Current setup is not conducive for flash flood scenarios at this time as the antecedent soils in the area lean dry and capable of the initial intake of heavy rainfall in the region. A nil ERO is forecast for D5, but will keep an eye on trends for this period and beyond as the synoptic pattern unfolds and rainfall continues into the second half of next week. Kleebauer 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 $$