FOUS30 KWBC 121933 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 333 PM EDT Sun Jul 12 2026 Day 1 Valid 16Z Sun Jul 12 2026 - 12Z Mon Jul 13 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM PORTIONS OF KENTUCKY AND TENNESSEE INTO MID ATLANTIC... 1600Z Update: Relatively minor adjustments were made to the Day 1 ERO, most notably to extend the northern extent of the Slight Risk area farther north into WV-VA, based on the current observational/ mesoanalysis trends and the latest (12Z) CAM guidance. While now north of the quasi-stationary surface front, areas in VA-WV where the Slight Risk is now included continues to be modestly unstable (surface-based CAPEs 1500-2000 J/Kg) while PWs remain between 1.8-2.1 inches. While the bulk of the activity should remain farther south given the more impressive thermodynamic profiles will be (deep-layer instability), continued forcing (DPVA) ahead of the postively-tilted, quasi west-east upper trough trough should support some additional organized convective clusters farther north into northeast KY-southern WV and central VA. Both the 12Z HREF and REFS ensembles both show 1-3 hourly QPF exceedance probabilities that would support the Slight Risk, especially over KY-WV given the higher soil moisture and thus lower FFG. Hurley Previous discussion below.. ...Southeast Quarter of the Country... The Slight risk remains in place from portions of KY/TN into southern VA and the Carolinas. The mid level shortwave feature has evolved into a deeper closed low, with slow moving convection expected in the vicinity of that low across portions of KY and TN. While widespread convective organization is not expected, the slow storm motions combined with PW values between 1.75" and 2" will support locally heavy rainfall rates. FFG is lowered across this region due to antecedent rainfall, making isolated to scattered exceedance likely today. Further east from VA into the Carolinas, there is greater uncertainty regarding convective evolution within a messy mesoscale environment. Large scale forcing ahead of the mid level trough will interact with a slow moving backdoor front to trigger scattered convection. Stable air is filtering into southwest VA and central NC, while easterly flow off the Atlantic is pulling more instability into eastern VA/NC. Stronger instability exists over SC south of the front. So overall a messy setup and tough to pin down where stronger convection may focus long enough for flash flooding. The primary convective focus will probably be from far southern NC into SC where the instability is maximized near and south of the front. A secondary local max could materialize from portions of eastern/southeast VA into eastern NC where easterly flow enhances convergence. While instability should largely wane tonight persistent easterly upslope flow into the central and southern Appalachians overlapping with at least some weak instability could spark low topped convective development overnight somewhere across southwest VA or central/western NC. Overall the broad environmental setup within the Slight risk remains conducive to heavy rainfall given PWs over 2" and multiple low level convergence axes. While exact mesoscale boundaries remain to be pinned down, isolated flash flooding is likely, and a corridor or two of more concentrate impacts could emerge. Surrounding the Slight risk, a broad Marginal encompasses eastern NM, TX and much of the Southeast. A southward advancing cold front, the aforementioned mid level shortwave/low, and upper jet support will provide the necessary synoptic forcing for scattered convection. PWs over 2" and CAPE of 2000-3000 J/kg where daytime heating is maximized, will support heavy rainfall rates. While conditions are close to Slight risk thresholds across this corridor, regional FFG values are higher, and the latest HREF/REFS EAS probabilities do not highlight a well defined axis of higher convective concentration. Pockets of over 3" of rain are likely within this Marginal risk area, but overall coverage is expected to stay just below Slight risk thresholds. Consideration was given to a Slight risk upgrade for portions of north TX today, where a shortwave dropping south into the region should help focus convection. Localized flash flooding is likely here, particularly as an urban threat. However due to generally high FFG and spatial discrepancies with the current model guidance, we will hold at Marginal. ...Southwest... Monsoonal moisture and instability will expand northwestward on Sunday, necessitating a broader Marginal risk across AZ. While an embedded Slight risk may eventually be needed, lingering questions regarding storm coverage and organization keep the risk at Marginal for now. Current indications suggest that while robust convection will initiate over the terrain, it will propagate westward quickly, potentially limiting the threat to isolate instances of flash flooding. Chenard Day 2 Valid 12Z Mon Jul 13 2026 - 12Z Tue Jul 14 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF TEXAS INTO THE CENTRAL GULF COAST... 1930Z Update: Minimal changes were made to the Day 2 ERO. We did expand the Slight Risk area a little farther south over South TX on along the border with Mexico -- partly owing to the higher soil moisture content/lower FFGs in that region, but also due to the growing guidance consensus (esp with the CAMs) of heavier rainfall (higher HREF/REFS QPF exceedance probabilities) dropping farther south of DLF/Laughlin AFB. Hurley Previous discussion below... ...Texas and Central Gulf Coast... The Slight risk has been expanded deeper into TX with this update. Embedded shortwave energy is forecast to migrate westward underneath a sprawling upper level ridge centered over the Northern Plains. In the low levels we will see increasing southerly flow and moisture transport. However, with northerly flow prevailing aloft, cloud layer mean winds will become weak. Corfidi vectors will also be oriented north to south, opposite the lower cloud layer flow...which supports some backbuilding and training threat. PW values are forecast to exceed 2" over much of central and eastern TX, with values potentially topping 2.25" over east TX. Some instances of flash flooding appear likely in this setup. A favorable synoptic and mesoscale setup for training and backbuilding is forecast to align along the central Gulf Coast. Enhanced west to northwesterly low level flow south of the persistent shortwave/low over the TN/GA vicinity will converge with west-southwesterly inflow off the Gulf. This configuration is conducive for upwind propagation and some training convection. Based on latest model guidance, this threat may remain confined pretty close to the coast. A very moist airmass with PWs around 2.25" will support heavy rainfall rates. ...Southeast and Southern Mid-Atlantic... A broad Marginal risk remains from TN into the Southeast and southern Mid-Atlantic. Similar to day 1, a lingering shortwave and closed low will continue to interact with a a backdoor front. Model guidance show some spread regarding the exact positioning of these features and where the primary axis of instability will reside. An embedded Slight risk upgrade may eventually be needed as these mesoscale details clarify. At a minimum, localized flash flooding will occur, but the potential exists for a more concentrated flash flood threat to materialize. North GA into SC currently appear most at risk, but will see how todays convection evolves and what the new high res model show. ...Southwest... A Marginal risk is maintained from southern NM into AZ, southeast CA and southern NV. Deep monsoonal moisture will continue to push northwestward with isolated to scattered convection expected to result in at least a localized flash food threat. Chenard Day 3 Valid 12Z Tue Jul 14 2026 - 12Z Wed Jul 15 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF TEXAS... 1930Z Update: The notable adjustment to the Day 3 ERO was to expand the Slight Risk farther east to much of the Houston/Galveston Metro and southern portions of the Piney Woods. This as mesoscale-enhanced perturbations/vort lobes underneath the closed mid-level ridge meander slowly westward. One MCV in particular that continues to bear watching is the one expected to flare along and near the TX Big Bend and bordering northeast Mexico. With the 12Z run, the EC-AIFS once again continues to show a multi-day heavy-rainfall signal across this area, with a centroid of 2-2.5" mean QPF during day 3, and another larger area of 2.5-3.0" during day 4. ECMWF EFI using the 00Z run remains over 0.9 during Day 3 (and 4), with Shift-Of-Tails of 2+ for both days. Strengthening and persistent SE low-level flow will lead to a surge in low-level moisture flux/transport and positive TPW advection and forced upslope flow into the Edwards Plateau. Still enough spatial spread in the guidance to preclude an upgrade to a Moderate Risk in the current Day 3 ERO, but suspect if the guidance trends continue and the risk area becomes honed in a bit more, there will be an upgrade over the next forecast cycle or 2. Hurley Previous discussion.. ...Central TX... A Slight risk continues over much of central TX, with a setup similar to day 2. Model guidance forecasts strengthening 850mb southerly moisture transport interacting with a weak mean flow regime, keeping the threat of backbuilding and training convective clusters. There is the potential for at least locally significant flash flooding from the Edwards Plateau into portions of the TX Hill country. Higher end Slight risk probabilities are warranted for this corridor, and future upgrades to a MDT risk are possible. Notably, the AIFS has been highly persistent over multiple cycles in indicating a possible higher end event...and the AIFS has a good track record highlighting organized heavy rainfall events. This will be multi day threat over this region, and so hydrologic sensitivity should eventually elevate, increasing the risk for locally higher end impacts. ...Southeast... A Marginal risk is maintained across the Southeast as the same low/shortwave migrates slowly southwestward. Deep moisture will remain plentiful with PW value over 2". However, uncertainty exists regarding the position of the instability axis and overall convective organization, and model QPF signals are a bit more muted than on days 1 and 2. Nonetheless, because multiple days of rainfall may start to saturate soils and lower FFG thresholds, an embedded Slight risk area remains a possibility in future updates. ...Southwest into Northern Rockies... A Marginal risk stretches from AZ into MT. An expansive plume of deep moisture, featuring PW values near mid-July climatology maximums will extend across this corridor. The strongest instability will be focused at the ends of this axis, across AZ and MT, with weaker CAPE profiles in between. Cape should still be sufficient for isolate stronger cells and a localized flash flood threat. Central and eastern MT will need to be closely monitored for a potential Slight risk upgrade. An axis of strong instability is projected across the state, overlapping with increasing easterly low level moisture transport. While the mean flow is weak at 10-15 kts, cells could potentially grow upscale and forward propagate in this environment. Given the high rainfall rate potential, convective trends will be closely monitored. Chenard Day 4 and Day 5 Valid 12Z Wed Jul 15 2026 - 12Z Fri Jul 17 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF WEST TEXAS ON DAY 4 AND DAY 5... 2030 Update... Overall, the 12Z guidance did not present much reason to make significant changes to the previous outlook, therefore the update reflects mostly minor adjustments. There remains a notable signal for a potentially higher-end event beginning earlier in the week and continuing into the Day 4/5 period over portions of West Texas. NBM probabilities for amounts over 2 inches continue to increase for each day. As noted in the overnight discussion, portions of the region are being considered a higher-end Slight on Day 4. This area will continue to be closely monitored and an upgrade to a Moderate may be forthcoming, especially if the signal for successive days of heavy rainfall holds across the region. Pereira Previous Discussion... ...Texas... An increasing threat for excessive rainfall is becoming more and more pronounced as we move forward in time as consensus grows on a prolonged heavy rain setup across portions of west TX with emphasis on the Edwards Plateau, Big Bend, and parts of Hill Country. Dominant ridging over the top into the northern tier of the CONUS will give way to a broad upper trough migrating westward into the Southern Plains along the southern flank of the ridge as we move into the middle of the week. The introduction of troughing overhead will lead to weakening flow aloft and a myriad of smaller mid-level perturbations rotating under the dominant cyclonic flow. Lowering heights and regional forcing align to foster a more suitable convective environment across the western half of TX with an emphasis currently on west and southwest TX as noted via the multi- model consensus in both the deterministic and ensemble outputs. ML guidance has also been suggestive of the same threat with the last series of runs from both the AIGEFS and EC-AIFS ensemble coming in very aggressive with their interpretations in current D3-5 QPF output. This has also led to some correlation of elevated probabilities within the ensembles, both ML and standard NWP for 24-hr totals each period >2". 01z NBM probabilities for >2" have risen to between 30-50% for the D4 time frame with coverage extending from the Big Bend down into Maverick County, a span that includes some major population centers like Del Rio and Eagle Pass, TX. The 30-40% probs expand eastward into the neighboring Hill Country as well, an area of interest the prior D3 period, so there's a greater threat for overlap in this current pattern. When you begin factoring the cumulative threat of heavy rainfall, guidance has surely risen the bar in terms of the potential with incredibly aggressive presentations allotting several inches of rain for the D3-5 time frames. General maxima continues to be focused over the Lower Trans Pecos over into the neighboring Edwards Plateau and down through the central RGV where the pattern would allow for greater low- level convergence and prospects for organized convective clusters to sneak out of Mexico (Mexican State of Coahuila). Considering a solid agreement within the model suite this evening, felt confident enough to maintain a SLGT risk on D4 with a high-end SLGT prospect now being factored into the forecast as we move forward in time. Have also introduced a SLGT risk across west TX over into the Edwards Plateau and portions of the central RGV for D5 as the threat lingers into Thursday before finally beginning to disperse by Friday, beyond the D5 period. This is certainly an setup to monitor closely as significant rainfall potential is plausible in the current synoptic evolution being depicted, and further upgrades are not out of the question as we move closer to the window of impact. ...Western U.S... Very little change in the previous forecast with the pattern repeating on the new D5 leading to general continuity in both the D4 and D5 convective threat and risk areas. The Western U.S. will lie within the western flank of the broad ridge pattern over the Central and Eastern U.S which will provide a dominant southerly flow over the region allowing for continued moisture advection and enhanced surface troughing over AZ up through the Great Basin. This pattern is a continuation of the Monsoonal presence out west with a potential for increasing flash flood prospects as multi-day impacts could spur targeted opportunities for repetition of areas getting hit by convection in consecutive periods. This setup remains very stable in terms of the broad synoptic pattern in place over the western CONUS, however we will see a persistent moisture plume advect more formidable deep layer moisture poleward as we move into early-mid next week leading to PWAT anomalies pushing the 90-99th percentile according to the NAEFS and 00z ECENS outputs. The strongest anomalies will lie within the Great Basin up into the Northern Rockies on D4 with some modification by D5, but still very much entrenched within the upper bounds of the anomalies, especially over the Northern Rockies and Interior Northwest. Increased upper troughing migrating from the west will slide under the ridge across the Northern CONUS leading to an enhancement for convective potential over a broader scope by D4, carrying into D5 with widespread thunderstorm prospects aligned from the Canadian border in MT down through the Inter-Mountain West into the Southwestern deserts. This setup can lead to sneaky significant rainfall prospects for those in the interior with a more typical Monsoonal presentation in the convective coverage. With a very stable height field being depicted mid to late week, the threat for widespread convective activity over a large portion of the Western CONUS remains favored for a broad MRGL risk at the current lead. The threat will likely induce some upgrade potential on a day-to-day basis as we step forward in time and we get a glimpse at previous period impacts and any overlap in where activity could occur once again for areas hit previously. This is a relatively solid signal at range, so the risk was deemed reasonable as a MRGL with upgrades noteworthy once we get a better focus on potential inside 72 hrs. D4 and D5 maintained a MRGL risk in very similar areas with only minor deviations in the orientation of the risk from D4 to D5. 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 $$