FOUS30 KWBC 201602 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1202 PM EDT Mon Jul 20 2026 Day 1 Valid 16Z Mon Jul 20 2026 - 12Z Tue Jul 21 2026 ...THERE ARE SLIGHT RISKS OF EXCESSIVE RAINFALL FOR PORTIONS OF THE SOUTHWEST AND NORTH CAROLINA... ...Southwest... 16Z Update...little change, more Marginal in western CO. Monsoonal moisture continues to stream across the Southwest into the Great Basin with renewed diurnal convective coverage again today. The eastern end of the threat area is bounded by a shortwave low over west Texas. Elevated moisture with PW of 2 to 2.5 standard deviations above normal and limited cloud cover from overnight allows good coverage of convection. Focus of heavies along the Mogollon Rim, southeast AZ and southern NM. West Texas is less certain for needing a Slight given ongoing clouds/precip this morning. ...Southern Mid-Atlantic to southern Appalachians... A warm front on leaving edge of deep tropical moisture plume extending northeastward from the tropical depression in the Gulf. The front will provide enough forcing across much of eastern North Carolina to allow for a renewed round of widespread showers and thunderstorms in the area. Soils remain generally dry over most of the area, despite storms impacting some of eastern North Carolina yesterday. Above normal moisture for the storms to work and the front providing some forcing warrants continuation of the Slight Risk. Trimmed southern NC from the Slight given consensus in the 12Z HREF/REFS. ...Gulf Coast... The outermost western periphery of Tropical Depression Two continues to impact the Gulf Coast of Florida, through the Panhandle into southern Georgia, and over to southeastern Louisiana. Banding is occurring, so localized multiple inch per hour rates. Regardless, the center remains far enough offshore, with drier air aloft working to significantly cut down on the overall coverage of storms. Considering the dry soils and high FFGs typical of the immediate Gulf Coast, even periods of heavy rain should only result in isolated instances of flash flooding. Thus, there was little change to the Marginal Risk area. ...Midwest... The Marginal Risk across much of the Midwest and upper Great Lakes also remains largely intact with updated progression for ongoing activity. There remains considerable uncertainty as to coverage of storms impacting the area today into tonight. It appears the most likely areas to be impacted this afternoon/tonight are from central Iowa east across northern Illinois. Dry soils highlight this area, so this being the height of the growing season should mitigate the flash flood risk. Jackson Day 2 Valid 12Z Tue Jul 21 2026 - 12Z Wed Jul 22 2026 ...THERE ARE SLIGHT RISKS OF EXCESSIVE RAINFALL ACROSS PORTIONS OF ARIZONA AND UTAH, AS WELL AS THE UPPER OHIO VALLEY AND INTO THE MID-ATLANTIC... ...Arizona into Utah... Increasing monsoonal moisture, particularly into southern Arizona will combine with an approaching upper level shortwave trough to further increase convective converage across portions of the Southwest on Tuesday as compared with previous days. The introduction of a northwestward-moving shortwave trough will allow the convective activity to wane over eastern New Mexico and west Texas, and instead promote more activity into eastern Nevada, Utah, and portions of Colorado and Wyoming. Numerous highly flash-flood prone slot canyons, dry washes, and rocky soils will allow the many storms that form over the region to cause scattered instances of flash flooding. The Slight Risk area was expanded north to include much of Utah and into eastern Nevada for this region. The greatest convective coverage and most impactful flash flooding is expected over portions of Arizona and the boot heel of New Mexico. A higher-end Slight remains in effect along the Mogollon Rim, but has been expanded to the Mexico border along the AZ/NM border with this update. ...Upper Ohio Valley through the Mid-Atlantic... A strong cold front pushing south across the Midwest will run into plentiful tropical moisture being drawn north from Tropical Depression 2 in the Gulf. The front will act as a catalyst for numerous segments of mostly fast moving thunderstorms across the Mid-Atlantic and Ohio Valley on Tuesday. With PWATs ahead of the front over 2.25 inches in some instances, and in most areas above 2 inches, the storms will have plentiful juice to work with, allowing for heavy rainfall to impact most areas from the central and northern Appalachians to the urban I-95 corridor from Richmond up through Boston. The fast moving nature of the storms should mean most areas have severe concerns as higher priority than flash flooding. However, it's likely that backbuilding and training storms on the book ends of any segments could cause widely scattered instances of flash flooding. Thus, the Slight Risk inherited over much of the Mid-Atlantic remains in place with few changes. ...Gulf Coast... Tropical Depression 2 is expected to gradually drift west, with the center following near the Gulf Coast. All of the guidance suggests that northerly shear and dry air entrainment will push any meaningful associated heavy rainfall south of the center over the Gulf, leaving very little rainfall to impact the immediate Gulf Coast. Thus, despite being a tropical cyclone with local PWATs up to 2.5 inches, the distinctive lack of rainfall for most land areas, especially away from the immediate coast remains an unusual feature with TD2. The Marginal Risk in place over most of the northern Gulf Coast from the Florida Panhandle west through southeast Louisiana remains in place with few changes. Wegman Day 3 Valid 12Z Wed Jul 22 2026 - 12Z Thu Jul 23 2026 ...THERE ARE SLIGHT RISKS OF EXCESSIVE RAINFALL FOR THE CAROLINAS, PORTIONS OF THE INTERMOUNTAIN WEST, AND THE CENTRAL GULF COAST... ...Carolinas into Southeastern Virginia... A strong cold front that impacted much of the Mid-Atlantic on Tuesday will stall out over central Virginia on Wednesday. Ahead of the front, abundant Gulf moisture will continue streaming northeastward from Tropical Depression 2, likely to be centered south of the Mississippi Delta. Since the front will remain strong, and the moisture will remain well above normal for the Carolinas, as PWATs spike above 2.25 inches at times, the front will act as a train track for numerous training and backbuilding thunderstorms. The focus for these storms will be where the front interacts with the deepest moisture, which is expected from central North Carolina northeast through the Tidewater of Virginia. This area should get a break in the rain on Day 2/Tuesday, such that by the time the heaviest rains impact NC and VA on Wednesday, some draining from prior days' storms should work to limit the flash flooding risk somewhat. Thus, for now the area remains in a higher end Slight. The forecast rainfall will continue to be monitored as a Moderate Risk upgrade remains a possibility. ...Central Gulf Coast... Tropical Depression 2 is expected to be drifting west to the south of Louisiana on Wednesday. The conditions impacting the system will remain much the same on Wednesday as on prior days. Northerly shear will remain in place, pushing most of the associated convection south of the circulation center, keeping nearly all of the heaviest rains over the Gulf. Only a tiny fraction of the storm's overall rainfall will impact land areas, with the best chance expected along the immediate Gulf Coast of southeastern Louisiana. The inherited Slight Risk was trimmed to just the immediate coast, dropping the threat for metro New Orleans, in coordination with LIX/Slidell, LA forecast office. Of course, trends in the storm will continue to be monitored, as subtle changes in the environment around the storm could result in large changes in the rainfall forecast. ...Intermountain West... The combination of well above normal moisture across much of the intermountain West on Wednesday, strong upper level disturbances tracking northeastward ahead of a longwave trough over the Pacific Northwest, and numerous mountain ranges will all work to promote a much higher than normal flash flooding potential over the area from the 4 Corners north through much of southeastern Idaho. The Slight Risk for Idaho and Wyoming was expanded south due to yet another day of expected showers and thunderstorms impacting the highly flash flooding prone areas of Utah and western Colorado. The greatest rainfall totals are likely into northwestern Wyoming, from Yellowstone south. Few changes were needed north of Wyoming's southern border. Wegman Day 4 and Day 5 Valid 12Z Thu Jul 23 2026 - 12Z Sat Jul 25 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE CENTRAL PLAINS TO LOWER MISSOURI VALLEY, THE CENTRAL TO WESTERN GULF COAST, AND THE EASTERN CAROLINAS ON DAY 4... ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE LOWER MISSOURI AND MID MISSISSIPPI VALLEYS, AND THE EASTERN CAROLINAS ON DAY 5... ...Southeast... A moisture-laden front will continue to sink slowly south across the region. While the overnight guidance continues to present differences on the timing of the front and corresponding precipitation, there remains a strong signal for additional heavy amounts impacting parts of the region, especially for portions of the Carolinas. PWs remaining around 2.25 inches along with periods of enhanced ascent will raise the threat for additional heavy amounts most likely centered over eastern North Carolina into northeast South Carolina Thursday into early Friday. Due in part to model differences and forecast uncertainty, maintained a Slight Risk. However, this has the potential to be a second day in-a-row, and the fourth day this week for heavy rains impacting parts of the region. Therefore, if forecast confidence increases and the signal for a multi-day heavy rainfall event holds, future upgrades may be required. For Friday into early Saturday, it remains a question whether the front will continue to push south, bringing drier conditions into the Carolinas as the GFS/UKMET indicate, or continue to hang up well to the north as shown by the ECMWF and Canadian. Opted for a Slight Risk on for the Day 5, centered similar to the Day 4 area, which presents a compromise between the two camps and lined up with the higher probabilities from the most recent ECENS. ...Gulf Coast... Shear across Tropical Depression Two is expected to keep the heaviest rainfall amounts associated with the system mostly south of the center and offshore. However, cannot rule out the threat for onshore flow supporting some locally heavy amounts along the coast, especially if the trends support a stronger system and more northerly track. Therefore, the a Slight Risk was maintained along the Louisiana to the upper Texas Coast on Day 4. A Marginal Risk was drawn for Day 5 from the upper Texas Coast inland toward south-central Texas, where heavy amounts are possible if the storm remains organized and continues to track west. ...Central Plains to the Mid Mississippi Valley... Models continue to show a well-defined shortwave sliding southeast off of the top of the western U.S. ridge through the northern Plains and into the mid Mississippi Valley on Day 4. Organized heavy rain may develop late Thursday into early Friday as this energy interacts with a deepening moisture pool fed by a strengthening southwesterly jet. A Slight Risk was maintained on Day 4 over parts of southeastern Nebraska into adjacent parts of Kansas, Iowa, and Missouri, where models indicate the deepest moisture, better forcing and greater potential for localized training will center. Storms continuing through Friday morning and possibly redeveloping later in the day downstream will extend the threat across across a greater part of the mid Mississippi Valley on Day 5. ...Southwest/Great Basin/Central and Southern Rockies... Monsoon moisture will continue to fuel diurnal activity, however the footprint is expected to diminish especially by Day 5 as moisture anomalies drop off and heights build across the Southwest. Pereira 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 $$