FOUS30 KWBC 011936 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 236 PM EST Sun Nov 1 2026 Day 1 Valid 16Z Sun Nov 01 2026 - 12Z Mon Nov 02 2026 ...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE FOUR CORNERS REGION... ...Southwest... 16Z Update: No changes to the previous forecast as everything remains on track for a high-end MDT across portions of the Mogollon Rim and San Juan Mountains with a widespread MDT risk extending up through the canyon areas of northwest AZ into southwestern UT. HREF/REFS EAS signals for >2" of rainfall are both over 70% for areas of the Mogollon Rim and San Juan range with neighborhood probs for locally 5" or greater still running between 60-90% in both areas. This is consistent from the previous iterations of both hi-res ensemble suites, backing the current forecast and expectation for widespread flash and riverine flooding capable of locally considerable impacts across the outlined domain. Kleebauer ..Previous Discussion.. Few changes were needed to the ongoing risk areas across the Southwest. An anomalously strong atmospheric river is driving a plume of moisture and heavy rain into the Southwest from the Pacific. PWATs remain 4-6 sigma above normal for this time of year, with values between 3/4 inch and 1.5 inches. Further, essentially all of the Southwest has been in a very wet period, so this highly anomalous event is at the tail end of a long stretch of wet weather that has left the soils saturated already in most areas. Thus, all of today's rains will be converting to runoff, leading to numerous instances of flash flooding. Dry washes, arroyos, slot canyons, and burn scars will remain the most susceptible areas. The Moderate Risk for portions of Arizona into southern Utah remains largely unchanged as far as the area impacted, as for much of it, the risk area is tied to the terrain. That said, the latest guidance shows rainfall amounts have a 70-90% chance of exceeding the 100 year ARI. This is generally the threshold for considering a High Risk area, which remains possible. Ultimately, the rather fast forward speed of the plume of moisture, as well as a lack of instability will be two limiting factors which for this update will keep these areas shy of the High Risk threshold. Nonetheless, with the aforementioned highly anomalous moisture and strong upper level forcing from a pair of jet streaks and a vigorous trough following behind the rain, expect a widespread 3-5 inches of rain into portions of the Mogollon Rim, particularly areas most perpendicular to the southwesterly flow and in the core of the moisture plume. A higher-end Moderate risk is in effect for these areas, mainly north and east of Phoenix. Into Utah, the threat for flash flooding turns to the typical slot canyons and steep, rocky terrain, as well as numerous large burn scars that dot the southern Utah landscape. Each of these areas could see more severe flooding, despite not being quite in the core of the heaviest rainfall. A second Moderate Risk is in effect for the San Juans of southwest Colorado. Here too, due to a very high likelihood of exceeding 100-year ARIs, a higher-end Moderate Risk was introduced. For this area, the very recent high-impact flash flooding event from last week is top of the mind. Expect essentially a repeat, albeit with slightly lower snow levels. This might nominally mitigate any flooding concerns in river basins that drain the San Juans. It's likely that spot areas will see more total rainfall here than along the Mogollon Rim, due to steeper topography more efficiently wringing out the abundant moisture. Wegman ...South Dakota... 16Z Update: Low-end signal for isolated flash flood prospects remains over west-central to central areas of SD with the highest mean QPF distribution focused over the Black Hills up into north- central SD. Lower FFG's in the region aid in the potential, however, general rates will be 1"/hr or less, so the threat remains very isolated in the grand scheme. Expectation is for local 1-2" totals for the areas most impacted. Kleebauer ..Previous Discussion.. A small, low-end, and low confidence Marginal Risk was shifted north and west with this update. This will be remnant moisture from the major flooding event occurring over the Southwest, generally targeted at the post-midnight period tonight. Soils are around normal for moisture levels for this time of year, and instability will be nominal over this otherwise generally tough to flood area. Training cells are possible, which could lead to an isolated flash flooding risk. Wegman ...Southeast... 16Z Update: SLGT risk inherited over FL was maintained, but did adjust the northern periphery around Jacksonville where guidance has come into agreement on the heaviest precip potential focusing south towards St. Augustine down towards Miami. Still maintained the MRGL risk for the metro area of Jacksonville, however, but confidence in greater impacts has leaned higher further south. Expecting localized areas of 3-6" of rainfall over the southern half the state with the areas along the I-95 corridor signaling the best potential for exceeding local FFG's as an abundance of rainfall over the past several weeks has left the region along the eastern FL coast fairly saturated a bit more susceptible to flash flooding. Latest CAMs signal some pretty hefty totals in around West Palm down to Miami where the frictional convergence pattern and incessant convective approach off the nearby Atlantic will likely occur as has already been the case this morning. Expecting the threat to continue into the evening hours with even some heavier rainfall clusters entering the western coast by the early afternoon time frame and beyond. Further north into the Southeast U.S. between LA/MS/AL, scattered thunderstorms within a relatively saturated environment will provide the chance for isolated 1-2"/hr rainfall rates that could produce local 2-4" totals capable of isolated flash flood concerns. The greatest threat will be situated over the western half of MS into LA and along the northern periphery of AL with a conglomeration of moderate to heavy rain currently perusing the region. Best threat for flash flooding will still likely be within those urbanized zones, however pockets of places that have seen 6+ inches the past 24-36 hrs across LA/MS will be under the greatest threat locally due to significantly degraded FFG's from previous rainfall. MRGL risk remains for these areas. Kleebauer ..Previous Discussion.. A westerly wave that has been traversing the Gulf will move into the Florida Peninsula today. Abundant Gulf moisture will converge over the Peninsula as a weak upper level trough moves over the state, further increasing atmospheric lift. A widespread 1-3 inches of rain is expected over much of the Peninsula. This will be the latest in a string of days that has caused areas of heavy rainfall over the east coast. With heavier and more widespread rain expected today, areas where soils are already saturated from previous days remain in a Slight Risk, which generally covers the I-95 corridor from the Georgia line south through Miami. Some instability and an amazing history of isolated cells producing rains of 3+ inches per hour for 6+ hours have led to incredible rainfall totals in very isolated spots. This may potentially continue over the lower Mississippi Valley today. The Marginal Risk remains in place with some small expansions. Wegman Day 2 Valid 12Z Mon Nov 02 2026 - 12Z Tue Nov 03 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE EAST COAST OF FLORIDA... ...Florida... 20Z Update: The setup remains consistent among guidance for a continued threat of locally heavy rainfall in-of the eastern FL coast with the primary concerns being urban flash flooding in-of the I-95 corridor. Latest 12z HREF/REFS neighborhood probs remain elevated for >2" between St. Augustine down to Homestead with the consensus for heaviest precip between West Palm down to Miami. Overall, not much of a deviation between forecasts with the only adjustment being a trimming of the SLGT away from the Jacksonville area as the prob fields indicate a very low likelihood of appreciable precipitation in the vicinity of the metro corridor. Kleebauer ..Previous Discussion.. Continued easterly flow of deep tropical moisture from the Atlantic will allow for frictional convergence along the east coast of Florida Monday and into Monday night. Heavier totals are expected during the day Monday and across southeast Florida, where instability will be a bit higher, with better moisture. The highly urbanized I-95 corridor will also support widely scattered instances of flash flooding where nearly stationary storms can persist the longest. The inherited Slight Risk area was left largely unchanged. Rain should be lighter across the west coast, so the threat level will be much lower there. Wegman ...Midwest/Plains... 20Z Update: The trends continue in the trimming of the eastern extent of the MRGL with more of WI down through the immediate Mississippi Valley regions of IA/MO trimmed out of the risk as well as trends have been for a slower push of precipitation into the immediate area leading to less overall rainfall, and weaker rates. This is correlated well with the little to no risk of >1"/hr rates based off the latest HREF/REFS suite this morning, enough to warrant the removal of the risk in this general area. Areas across the Dakotas into northern MN still remain a focal point for moderate to locally heavy rainfall with the main prospects likely embedded heavier echoes in the vicinity of the maturing trowal on the north to northwest side of the surface cyclone. Further south, instability within the warm sector over the East- Central Plains of KS/MO down through OK/TX will provide the best opportunity for rainfall rates >1"/hr with some of the deterministic indicating 1-2"/hr rates over the course of late- Monday afternoon into the evening prior to the cold front approach from the west. Models have been keying on that area of southeast KS down through eastern OK and north TX as the main area of interest with the neighborhood probabilities between 40-70% for >2" with modest probs for >3" located over northeast OK into far southeastern KS. There's a potential for a small upgrade in this particular zone with the current look, but want to see future trends with the CAMs as this area is on the drier side and could very well handle local 2-3" of rainfall with the main concern over the more urban footprints. Kleebauer ..Previous Discussion.. The large Marginal Risk area in place across much of the Midwest and Plains was also left largely unchanged with this update. The greatest flooding threat within the Marginal will be for southern areas from Texas through Missouri, where greater instability and terrain concerns around the Ozarks should work to raise the flooding threat locally higher. Nonetheless the instability will remain near the lowest thresholds supporting convection. The nature and coverage of that convection will determine how high the flooding threat gets. Since those parameters remain uncertain, the Marginal remains in place. Further north across the northern Plains to the upper Lakes, there should be very little to no instability. However, steady rainfall will persist for far longer in this area, resulting in more widespread higher rainfall totals, but over a much longer period of time. Thus, the Marginal also remains in place there with few changes. A small trim on the eastern side of the risk area, to remove much of southeastern Wisconsin was made due to slower forward speed expected of the rainfall shield. Wegman Day 3 Valid 12Z Tue Nov 03 2026 - 12Z Wed Nov 04 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL PORTIONS OF THE LOWER TO MID-MISSISSIPPI VALLEY... ...Lower and Mid-Mississippi Valley... Surface low over the north-central CONUS will continue to move to the northeast with a trailing cold front extending down through the Plains, eventually maneuvering into the Mississippi Valley by Tuesday morning and afternoon. Warm sector into the area of the Lower to Mid-Mississippi Valley will be the focus of enhanced low- level convergence with the arrival of the front leading to an enhanced convective axis in the morning with further development during the afternoon prior to the frontal passage. Latest ensembles are bullish with a widespread 2-3" footprint located over the area of southeast AR through southwest TN, down into northern MS with the max located near the Memphis metro area. This is the most notable area given the propensity of flash flooding into the urban corridor, as well as an overlap of heavy rain into an area that was already heavily impacted by heavy rain over this weekend. Considering the setup and rainfall totals being forecast, this is more likely to be a flash flood concern for these particular areas with enough consensus among ensembles and ML guidance alike to add a small SLGT risk with the centroid placed over the Memphis metro. Kleebauer Day 4 and Day 5 Valid 12Z Wed Nov 04 2026 - 12Z Fri Nov 06 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE TENNESSEE AND LOWER OH VALLEYS TO THE SOUTHERN APPALACHIANS (DAY 4)... 2000 UTC Update: No changes were made to the Days 4-5 EROs based on the 12Z guidance/trends. Hurley While differences in the details remain, the latest model runs are showing better agreement with the evolution of an amplified upper trough and its associated frontal boundary that are expected to move east of the Mississippi Valley midweek. This system will continue to produce widespread precipitation, with the threat for areas of heavy rain and possible flash flooding continuing into early Thursday. Deep moisture (1.50-1.75+ inches) coinciding with strong southerly flow is expected to interact with an area of strong ascent, afforded in part by right-entrace region upper jet forcing, to produce widespread moderate to heavy rain (accums 1-2+ inches) across the Tennessee into the lower Ohio valleys and the southern Appalachians. While some models suggest a Slight Risk may be necessary at some point, dry soils (high FFGs) and remaining forecast uncertainty support maintaining the Marginal Risk at least for now. 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 $$