FOUS30 KWBC 132030 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 430 PM EDT Mon Jul 13 2026 Day 1 Valid 16Z Mon Jul 13 2026 - 12Z Tue Jul 14 2026 ...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL OVER SOUTH- CENTRAL TEXAS WEST OF SAN ANTONIO... ...16Z Update... ...Texas... The incoming 12Z guidance continues to paint a bleak picture for flooding potential across a portion of south-central Texas, generally in the area from San Antonio west to the Rio Grande River. A strong low level jet transporting plentiful deep tropical moisture northward up the Rio Grande Valley into South Central Texas. As that moisture hits the southern edge of the Edwards Plateau, uplift from the Plateau combined with some instability around 1,000 J/kg, and weak flow aloft will support training and backbuilding thunderstorms developing in this area from the late evening and through the rest of the overnight. Earlier rainfall in this area over the past 24 hours or so on the order of a half-inch to 2 inches in spots has already saturated the soils, especially along the Rio Grande near Del Rio. The expectation of multiple inch per hour rainfall rates with the strongest storms are likely to result in flash flooding, especially the rivers draining the southern Edwards Plateau. Much of the greatest flooding impacts are expected with the ongoing heavy rain that continues into the Day 2 period in this region, but the increased heavy rainfall forecast in these area prior to the 12Z end of the Day 1 period and favorable hydrology both were contributing factors to the Moderate Risk upgrade. Elsewhere, the risk levels were left largely unchanged, both in the Southwest with the developing monsoon as well as across much of the Southeast, where widespread but widely scattered clusters of storms are likely to produce localized flash flooding, but with low confidence on where those storms will form and how much rain they will produce. Wegman ...Texas into Louisiana... Front analyzed over OK/AR will slip southward as we move into Monday with an increasing axis of low-level convergence along and ahead of the boundary. Environment across the Southern Plains into the Lower Mississippi Valley can be best described as oppressive as deep layer moisture from Gulf origin has made its presence known over much of the South with much of TX into Louisiana as no exception. Upper pattern across the CONUS will be liable to cause some headaches over much of the southern tier of the U.S. as broad upper ridging focused over the Northern Plains will lead to more east to west migrations of disturbances rounding the base of the ridge and entering these suitable convectively allowing environments. The 00z HREF continued a trend of widespread convective coverage anticipated in the D1 time frame with multiple areas of interest spanning from the Carolinas over into the Southern Plains. The primary targets for enhanced rainfall are currently positioned within the Lower Mississippi Valley extending west through Central TX, eventually with the western fringes located in the terrain of southwest TX. Prob fields have become very bullish on the prospects of locally heavy rainfall in several areas spanning west TX into LA with the greatest neighborhood probs for >3" (50-80%) and >5" (40-70%) located over east TX into the Sabine with an extension along the I-10 corridor between Lake Charles to Lafayette. This trend has been noted in successive HREF outputs with the ensemble mean QPF now upwards of 2-3" over a large area east of I-35. Make no mistake, however, the threat for excessive rainfall totals over 3" does not stop in these areas as multiple CAMs deterministic signatures indicate a potential for significant rainfall in-of the I-35 corridor extending west into Hill Country and the Edwards Plateau the back half of the period. This setup would transpire later in the evening with the additional support stemming from an approaching mid-level shortwave migrating southwest under the guide from the general 500mb pattern across the Central and Southern CONUS. Weak LLJ will likely develop after 00z Tue across the RGV and South TX with that evolution likely providing a bit more enhancement in the boundary layer convergence scheme. Timing of any energy and overall positioning of the front will be a major dictator of what could transpire in the back half of the forecast, so currently went with a high-end SLGT to cover the primary concerns from southwest TX through central and southwestern LA with a broad SLGT extending further east through the rest of the Southeast and Southern Mid Atlantic (More of this area below). This is a setup that could spell surprises considering a very favorable environment in place that will likely assert some very prolific rainfall rates at times as deterministic samples from CAMs already indicating the possibility of >3"/hr rainfall prospects across a good portion of TX into LA. ...Southern Mid Atlantic into the Southeast U.S... Current UA and WV satellite analysis indicates a weak closed-low located over central TN and a slow-moving quasi- stationary front at the surface positioned over the Carolinas through the southern Tennessee Valley into the Southern Plains. Sprawling upper ridge centered over the Northern U.S. is really driving this anomalous pattern with surface ridging extending from the Ohio Valley and Northeast down towards the area of the front. The entire setup provides a strong low to mid-level convergence pattern that is driving quite an axis of heavy convection over the Carolinas this evening with a ton of convection occurring earlier Sunday over much of the Southeast. Generally persistent 500mb setup will allow for a repeat of widespread convection during the daytime hours, Monday, with perhaps a small shift in the northern periphery of the coverage further south compared to Sunday as high pressure filters in over much of VA/WV and the Central Mid Atlantic. HREF blended mean QPF remains bullish with widespread 1-2" totals located across western and southern NC down through SC where the areal maxima is positioned squarely along the eastern fringes of the Piedmont into Low Country. A strong neighborhood and EAS signature exists within the latest 00z HREF for >5" and >2", respectively, a textbook indicator of at least scattered flash flood prospects over the area in question. The most prominent signatures reside in SC with more modest interpretations in the prob fields located over the Southeast towards the northern half of GA/AL into MS. Despite widely scattered coverage this past afternoon, several flash flood warnings were necessitated thanks to a very efficient warm rain process for much of the Southern U.S. as deep layer moisture and very high regional theta_E's offered deep warm cloud layers noted via widespread WBZ heights >14k ft when assessing both observational RAOB's and forecast soundings from various CAMs. In any case, this is a textbook, widespread SLGT risk prospect considering the variables above and a general persistence in the pattern. A SLGT risk now extends through much of the Southern Appalachians, southern NC, and points south with the inclusion of the western FL Panhandle and Central Gulf coast areas. ...Southwest U.S. into the Sierra's... As the upper pattern remains persistent for areas further east, the Southwest U.S. will lie within the western flank of the ridge allowing for prevailing southerly flow aloft to advect deeper moisture north and northwest allowing for greater convective potential over a larger area as we move into Monday. Instability fields are primarily weak for areas within the Great Basin and interior CA, but are much more favorable for locations within the Desert SW of AZ into the Mogollon Rim region. The combination of increasing moisture (+2 standard deviation PWATs) and increasing thermodynamic influences noted via improved MUCAPE fields will lead to scattered heavy rain prospects across the more susceptible flash flood areas located from the Sierra's down through the Desert Southwest of CA/AZ for Monday. A MRGL risk is in place for the period at these locations with the best threat likely over southeastern AZ into the Mogollon Rim according to the latest HREF prob fields for 1 and 3-hr FFG exceedance forecast. Kleebauer Day 2 Valid 12Z Tue Jul 14 2026 - 12Z Wed Jul 15 2026 ...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE EDWARDS PLATEAU, CENTRAL RIO GRANDE VALLEY, AND HILL COUNTRY... ...2030Z Update... ...Texas... With CAMs guidance, confidence continues to increase in a multi- night significant flash flooding event across a portion of south- central Texas. Essentially, an upper level low over northern Mexico will help funnel abundant Gulf moisture northward into the Edwards Plateau both continuing into Tuesday morning from Monday night's event, and then a renewal of storms causing flash flooding again Tuesday night into Wednesday. A second mid-level disturbance, currently over northeastern Texas, will drift southwestward through the day and merge with the ongoing disturbance over far northern Mexico just east of the Big Bend. This should help renew the forcing for thunderstorms again for more storms Tuesday night. There is reasonably good confidence that if storms form, it will be over the same areas Tuesday night as will be hit tonight. So the question becomes how widespread and strong those storms will be, and on that note there are different camps in the guidance, with some showing another very active night of heavy flash flooding rains, and others showing far less-so, with the main action being tonight into Tuesday morning. How this resolves with future forecast updates will ultimately be the deciding factor as to whether or not a High risk upgrade is needed, likely targeting the area between San Antonio and the Rio Grande River along the Balcones Escarpment. Regardless of what happens with the heavy rains on Tuesday night, tonight's event looks to be in the cards with high confidence on multiple inches of rain, which will continue into Tuesday morning. Hydrologically, the area is extremely flash-flood prone, given enough heavy rainfall, likely one of the most prone areas of the country. Thus, almost regardless of what happens again Tuesday night, tonight's event will be significant for the area. Thus, in addition to the Day 1 Moderate, the Day 2 Moderate area is for the likely ongoing flash flooding impacts expected in this region through Tuesday morning. In collaboration with the EWX/New Braunfels, TX forecast office, a higher-end Moderate is in effect for the area from U.S. 57 north almost to I-10, all west of the San Antonio Metro. ...Mississippi and Alabama... A Slight Risk upgrade was introduced with this update for portions of central Mississippi and Alabama. In a similar fashion as further west in Texas, a mid-level low will be moving over a very moisture-rich environment across the South. However, unlike further west in Texas, no topography and most of the storms occurring at peak heating from late morning through early evening make this event a bit different than further west. The disturbance will provide enough forcing, given ample instability, to produce widespread shower and thunderstorm activity across Mississippi and Alabama. The disturbance will act as a focus, allowing the activity to organize, which in turn increases the potential that cold pools and other local forcings will allow for training and backbuilding of convection. In addition to storms impacting the area now, recent heavy rains from past days have also saturated the soils in this area, which have in turn lowered FFG thresholds across the Slight Risk area. With more widespread convection expected Tuesday afternoon, widely scattered instances of flash flooding are expected. Wegman ...Previous Discussion... ...Texas... A significant, multi-day threat for heavy rainfall will begin on Tuesday across portions of west TX with the threat looming largest over the areas along and west of the Rio Grande near and south of I-10. There has been a growing consensus over the last several days of significant rainfall potential brewing across the Edwards Plateau and surrounding areas with the setup a textbook case of primed low- level convergence thanks to frontal positioning and the threat of an approaching MCV complex migrating westward from Central TX. Latest CAMs are finally in range of the threat, at least the initial setup leading into what will be a very active Tuesday night and Wednesday morning across areas west of I-35 along and south of I-10 into Hill Country. Disturbance moving into the region will only act as a provider for sufficient low-level convergence in an already buoyant environment situated over much of the southern half of TX. LLJ enhancement over the RGV will only act as a beneficial product for low-level moisture transport and convergence which will allow for a focused axis of heavy rainfall to materialize and slowly drift over the same areas for several hours once the activity initiates. ML guidance and global ensembles have been extremely consistent in their interpretations of what will transpire with little wavering in the axis of heaviest QPF and only providing greater magnitudes as we move closer in time. Mean QPF for the D2 time frame is now upwards of 3-4", locally higher across much of the Edwards Plateau with the focus over Del Rio and points east into Hill Country. Bias corrected ensemble is also indicating some 4-5" totals as of the latest iteration, a signature generally seen for events of upper echelon potential. Considering the favorable environment and likely efficient rainfall given PWATs between 2-2.2" forecast, prospects for >2"/hr rainfall are not only certain, but there's a threat for even some 3-4"/hr rates in the strongest cell cores that could push totals for the first day of the event to >5", as noted via modest probs within the NBM over the area. In coordination with the local SJT and EWX offices, a MDT risk was added across the aforementioned areas with emphasis on the Edwards Plateau where the most consistent signals for >3" rainfall exist among all ensembles. Across central and southwest TX, locally heavy rainfall prospects will only continue, with the latter the most likely to see some type of overlap in the general convective coverage as thunderstorms focus over the regional topography from the Davis Mtns. into the Stockton Plateau. Central TX is a toss-up currently with the greatest threat likely to be in proximity to the quasi-stationary front and any lingering outflows that materialize from convection the previous period. Models are generally aggressive in-of San Antonio and the I-10 corridor for the first half of the forecast, so it will be interesting to see the trends as we step forward in time. For now, a broad high-end SLGT is forecast over the above areas, but there is potential for an upgrade in either area, pending trends in hi-res guidance and observational trends as convection occurs from the end of D1 into D2. ...Southwest U.S. into the Great Basin... Continued impacts from lying into the western flank of the ridge centered over the Northern U.S. as prevailing southerly flow will just maintain a prevalent moisture advection regime poleward over the Desert Southwest into the Great Basin. Models remain consistent in their interpretations of locally heavy rainfall over both regions with the heaviest QPF centered over AZ, but potentially greater impacts in those more flash flood prone areas located in the interior west, including those slot canyons over UT/NV. Rainfall rates will be the driving factor for flash flooding in this scenario with instability generally favorable (>750 J/kg MUCAPE) over a large portion of the Western CONUS. The combination of PWAT anomalies >2 deviations above normal and elevated instability favors at least widely scattered flash flood potential, which this setup is leaning into the textbook signature as forecast. The previous MRGL risk was maintained with some expansion further north around the area of the Sierra's. ...Northern Rockies... PWATs encroaching the 90-99th percentile over the western half of MT coupled with favorable instability and approaching mid-level troughing to the west will allow for scattered to perhaps widespread convection to materialize over the Northern Rockies Tuesday afternoon and evening. Totals are currently relatively meager in an areal average sense, however some of the deterministic are producing some local 1-2" amounts with impacts realistically only a few hours, at best when convection occurs. These types of rates are historically favorable for flash flood prospects across the Northern Rockies, so the previous MRGL risk was maintained over the area as the signal remains consistent. ...Northern Vermont and New Hampshire... A strong closed low over Northern Quebec will pinwheel southeast, well north of the Canadian border in New England, but will aid in a broad brush of robust mid-level vorticity over the northern tier of both VT/NH during peak diurnal heating. MUCAPE between 2500-3500 J/kg will be located across the northern tier of both states leading to a targeted area for locally heavy rainfall with rates likely to approach close to 2"/hr as noted in the latest HREF prob fields. A quick 1-3" is forecast across this small area of New England, however this area is notorious for local terrain influences that could cause issues with any appreciable rainfall in that short period of time. A MRGL risk was added for the threat in the above area. Kleebauer Day 3 Valid 12Z Wed Jul 15 2026 - 12Z Thu Jul 16 2026 ...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE LOWER TRANS PECOS, EDWARDS PLATEAU, RIO GRANDE VALLEY, AND HILL COUNTRY... ...2030Z Update... ...Texas... The Moderate Risk area has been expanded this afternoon in coordination with EWX/New Braunfels, TX, SJT/San Angelo, TX, and MAF/Midland-Odessa, TX forecast offices. As mentioned in the D2 discussion, while there remains some disagreement in the guidance as to how heavy ongoing rainfall into Wednesday morning will be across the region, it remains likely that there will be heavy rainfall to some degree along the Edwards Plateau region on Wednesday morning, with another round likely to impact portions of the area again Wednesday night into Thursday. Given the expected heavy rainfall on both days 1 and 2, should the forecast remain similar in the coming days as this period moves into the CAMs guidance range, it appears probable a High Risk upgrade will be needed. By Day 3, as usual, uncertainty increases both with the magnitude of the expected heavy rainfall, especially into Wednesday night, as well as the location. Some good news is that for now the guidance appears to suggest the heaviest rainfall by Wednesday night will be shifting westward up the Rio Grande, impacting generally from Del Rio westward. Meanwhile the heaviest rains expected tonight and again Tuesday night are expected to focus mostly east of Del Rio along the Balcones Escarpment. This shifting of the heaviest rains will be huge for avoiding High Risk level impacts, though despite the heavy rains expected to impact some portion of that area Wednesday night, the area east of Del Rio will not be entirely rain-free, just in all probability experiencing lighter rains as the focus shifts west. That said, guidance usually shifts south and east with time, especially once it gets into the CAMs range, so there still is plenty of concern that Wednesday night's rainfall event will also focus in the same region. A higher-end Moderate Risk area was introduced with this update from west of San Antonio (mostly due to impacts from Wednesday morning) almost to the eastern edge of Big Bend National Park, including Del Rio. The surrounding Moderate Risk also includes metro San Antonio. At the moment this threat is a combination of urbanization, some heavy rainfall impacting the metro at times on both Days 1 and 2, and finally, afternoon convection that likely marks the start of the heavy rainfall event into the overnight period Wednesday night as the storms move west with time. ...Mogollon Rim region of central Arizona... In coordination with the FGZ/Flagstaff, AZ; PSR/Phoenix, AZ; and TWC/Tucson, AZ forecast offices, a Slight Risk area from the Mogollon Rim south was introduced with this update. While monsoonal rains will impact this area on both later this afternoon and again Tuesday afternoon, the moisture and forcing will both increase further by Wednesday afternoon. Any storms will form along the Mogollon Rim itself, with some probability due to topography, cold pools, or other local forcings, that the storms will backbuild south off the topography. For now it appears this activity will not impact metro Phoenix with widely scattered flash flooding, but the area just to the north in the foothills leading to the Mogollon Rim are the areas most likely to see impacts. Wegman ...Previous Discussion... ...Texas... Setup from the D2 will linger into D3 a our mid-level disturbance is likely to meander for at least one more period leading to low- level convergence pattern continuing across the same areas impacted in the D2. Models are consistent in the signature for an additional round of heavy rainfall centered over the Edwards Plateau with a bit more of a northern extension into the Lower Trans Pecos and lower Concho Valley. Considering the overlap from the previous period, multi-day totals are upwards of 6-8" currently with areas of 10+ inches plausible when you consider the low-bias in some of the global deterministic outputs when it comes to convection. The setup is one that signals significant flash flood concerns given the multi-day impact and the forecasted totals in place. A MDT risk was introduced for the above areas to account for the impacts on back-to-back days, as well as the agreement in ensembles and ML outputs that can be traced back to the last 3-4 days exhibiting a consistent result. This period will need to monitored for further upgrades as we move forward in time as a lot will stem from what happens the prior periods. ...Western U.S... Broad upper ridge centered over the Northern U.S. will continue to provide significant moisture advection into the interior west leading to scattered convective signals from the Canadian border down into the Desert Southwest with flash flood concerns in those more susceptible areas out west. This setup is is a continuation from the previous period, but the expansion of heavy rainfall is further east comparatively as the ridge nudges eastward and shifts the general pattern in tandem. Broad MRGL risk exists for the period across the West. Kleebauer Day 4 and Day 5 Valid 12Z Thu Jul 16 2026 - 12Z Sat Jul 18 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF CENTRAL AND WEST TEXAS ON THURSDAY INTO THURSDAY NIGHT... 2030Z Update... Daytime guidance did not present any reason to make significant changes, therefore only minor adjustments were made to the outlook areas, including the higher-end Slight Risk on Day 4 from the Edwards Plateau into portions of the Concho Valley and Hill Country. Pereira ...Texas... A Slight risk is maintained over portions of central and west TX for Thursday (day 4), marking a continuation of a potentially significant multi-day flash flood event. The environmental setup remains favorable for organized cell training and backbuilding. Notably, an increase in low level wind fields should yield even stronger 850mb southerly moisture transport than seen on preceding days. However, given this will be day 4 of the event, inherent mesoscale uncertainties exist regarding the exact positioning of the remnant MCVs and the spatial alignment of the instability field. Furthermore, the broader environmental moisture field is forecast to become somewhat less robust, with a smaller areal coverage of 2" PW values. With that said, antecedent soil conditions could be highly saturated over portions of the region by this time, heightening hydrologic sensitivity. This is considered a higher end Slight risk from the Edwards Plateau into portions of the Concho Valley and Hill Country. The potential is certainly there that the MDT risk currently valid for days 2 and 3 may need to be extended into day 4 (Thursday) as well. By day 5 (Friday), the model signal becomes a bit less pronounced for this multi-day heavy rainfall event. Convective evolution is less certain by this time, and global deterministic and ensemble QPF signals become more muted. Thus we will keep the risk at a Marginal level, although certainly a chance the multi-day event continues into Friday, with Slight risk upgrades a possibility as we get closer. ...Western U.S... A broad active monsoonal pattern will continue across much of the western U.S. Thursday into Friday. An anomalous PW axis stretching from AZ northward into MT is forecast to remain above the climatological 90th percentile, and locally higher in some spots. This airmass will sustain a localized flash flood threat across an expansive corridor spanning from portions of eastern CA, AZ, and NM northward to MT. The highest absolute moisture and instability values during the period are forecast from portions of southeast CA into AZ. Model guidance indicates some uptick in instability as well, with peak CAPE values currently expected on Friday. Similarly, deterministic and ensemble QPF footprints gradually ramp up through the period, peaking across AZ on Friday. While a broad Marginal risk currently covers the multi-day isolated flash flood risk, embedded Slight risk upgrades may eventually be required. Friday currently presents the stronger signature for a more concentrated flash flood threat, particularly over southeast CA, AZ and southern UT, and trends will be monitored closely. Chenard 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 $$