FOUS30 KWBC 241554 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1154 AM EDT Sat Oct 24 2026 Day 1 Valid 16Z Sat Oct 24 2026 - 12Z Sun Oct 25 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF WEST TEXAS, NEW MEXICO, AND COLORADO INTO FAR WESTERN KANSAS... ...16Z update... Relatively minor changes were made to the outlook for this update across western CO/NM with a westward expansion of the Slight Risk to cover much of the San Juan Mountains into portions of northwestern NM. This was due to early morning convective development noted on 15Z satellite/radar across northwestern NM into southwestern CO out ahead of a slow moving closed low across the Southwest. Continued thunderstorm development is anticipated over this region during the day today with increasing instability resulting in multiple rounds of heavy rain. Given ongoing hydrologic sensitivities over the region, the addition of an inch or two of rain could exacerbate ongoing flooding in the vicinity of the western CO/NM border as seen in the 12Z HREF/REFS with 24 hour neighborhood (40 km) probabilities of exceeding 2 inches in the 50 to 80 percent range. Elsewhere, the Slight and Marginal risks over southwestern NE and northwestern KS were pulled back to the southwest a bit given an expected lack of instability. The latest model consensus indicates MUCAPE values staying generally below 250 J/kg through Sunday morning and the 12Z HREF/REFS show neighborhood (40 km) probabilities of exceeding 2 inches of rain in 24 hours to be less than 1 percent where the risk areas were removed. Otto ...previous discussion follows... ...West Texas to the Southern/Central High Plains... An upper level low will split off from the main upper trough over the southwestern U.S. early this morning. This feature will create favorable conditions downstream for scattered to widespread convection to develop from West Texas and New Mexico into the southern and central High Plains, and convection will likely be enhanced in coverage and intensity by an upper level shortwave lifting north across the region this afternoon and evening. Additionally, a strengthening south-southeasterly jet ahead of the system will increase moisture transport into the region, and instability will combine with this anomalous moisture to create a heavy rainfall threat. A Slight Risk of excessive rainfall was maintained for much of eastern New Mexico and southeastern Colorado and portions of West Texas and western Kansas. This area is expected to see the highest rainfall totals ranging from 1.5-3 inches, with higher amounts expected in portions of northeastern New Mexico and southeastern Colorado where the HREF and REFS show 50-75% chance of exceeding 3 inches in 24 hours. Rainfall rates in this region may reach 1-1.5 inches per hour, rivaling flash flood guidance, and could lead to scattered instances of flash flooding. Thankfully, the heaviest rainfall today should be displaced to the east of where the heaviest rain fell yesterday, but portions of north-central New Mexico and south-central Colorado have been included in the Slight Risk area to account for an elevated flash flood threat where locally heavy rain may fall over already saturated soils. The Slight Risk area also extends south into southeastern New Mexico and West Texas where the environment will be favorable for strong, organized convection later today. This area will see the highest CAPE and wind shear values this afternoon, and the vertically veering wind profile will be conducive for supercell development. Any supercells that develop will be capable of producing locally heavy rainfall that could cause flash flooding. These cells should be fairly quick-moving, which should help to somewhat limit the flash flood risk. The surrounding Marginal Risk area was expanded in West Texas to account for the potential eastward progression of convection this evening and for an upward trend in hi-res model QPF in this area. ...Four Corners region... A Marginal Risk of excessive rainfall extends back into the Four Corners region and includes portions of eastern and southern Utah and northern Arizona where convection in the vicinity of the upper low may result in isolated instances of flash flooding. Convection in this area should be fairly slow moving, and although snow levels will be dropping, they should remain high enough to allow for heavy rainfall. Models show some instability developing across Utah and Arizona during the afternoon hours, and there should be enough moisture to support widely scattered convection. Given the preceding days of heavy rainfall leading up to Saturday, the region may be more sensitive to additional heavy rainfall. ...East Coast of Florida... A mid/upper-level low will slowly move south over the Atlantic parallel to the Florida East Coast, which will generate scattered convection over the Atlantic that will migrate onshore with strong northeasterly flow on the northern and western sides of the circulation. A plume of anomalous moisture with PWATs of 1.3-1.5 inches will be aimed onshore by the low circulation and gradually shift down the coast throughout the day. The moist and unstable air mass will allow for heavy rainfall rates to develop and coastal convergence will focus rainfall over the urban I-95 corridor, which has been highlighted with a Marginal Risk of excessive rainfall. Isolated instances of flash flooding will be possible, especially in urban, low-lying, and poor drainage areas. Dolan Day 2 Valid 12Z Sun Oct 25 2026 - 12Z Mon Oct 26 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE CENTRAL AND SOUTHERN HIGH PLAINS AND SOUTHEAST FLORIDA... ...Central and Southern High Plains... The cutoff low will gradually progress northeastward, resulting in an expanding region of precipitation ahead of the system from West Texas through the southern and central High Plains. Similar to the setup on Saturday, anomalous moisture will stream ahead of the system into the Plains under favorable upper level conditions for scattered to widespread convection. The best instability should be focused over New Mexico and Texas, but there should be enough instability extending into the High Plains to support deeper convection with locally heavy rainfall. The highest flash flood threat will likely be located over portions of northeastern New Mexico, southeast Colorado, western Kansas, and the Oklahoma and Texas panhandles where there is a Slight Risk of excessive rainfall. There is still quite a bit of uncertainty surrounding rainfall totals, but the general consensus is for the highest amounts over the southern and central High Plains, and this is also where the REFS is flagging the highest probabilities for heavy rainfall. The western side of the Slight Risk area is where there is a chance that the heavy precipitation footprint may overlap with areas forecast to receive heavy rainfall on Saturday, which would make the area more susceptible to flash flooding with any additional rainfall. The broader Marginal Risk area surrounding the Slight Risk area was expanded in this forecast cycle to include more of southeastern New Mexico and West Texas. This region will have the best ingredients for heavy rainfall (CAPE greater than 1000 J/kg and PWATs of 1-1.5 inches) but will be slightly displaced from the best synoptic forcing with the main low. Any convection that develops in this area will have the potential to produce locally heavy rainfall. Given vulnerable terrain in southern New Mexico and heavy rainfall received yesterday and expected today, the expansion of the Marginal Risk area was justified. Soils over portions of Texas will not be as saturated, but given the favorable setup could still see a localized flash flood threat. The Marginal Risk area was also trimmed on the northern side to remove some of Nebraska and South Dakota where rainfall rates will be limited due to a lack on instability and where rain should be more stratiform in nature. ...East Coast of Florida... The mid/upper level low sliding down the coast will stall southeast of Miami, which will result in a prolonged period of moist, onshore flow across Southeast Florida. Showers and storms will form over the Atlantic and move over the Florida coast, which will result in heavy rainfall focused along the I-95 corridor. The heavy rainfall threat will shift south throughout the day, with the highest rainfall totals expected to accumulate over Southeast Florida once the system stalls. There is a Marginal Risk of excessive rainfall for much of the I-95 corridor south of Jacksonville and a Slight Risk for the I-95 corridor south of Melbourne. The Slight Risk area was expanded south to include more of the Miami metro area based on the latest model trends in QPF. Scattered instances of flash flooding will be possible, especially in urban, low-lying, and poor drainage areas. Dolan Day 3 Valid 12Z Mon Oct 26 2026 - 12Z Tue Oct 27 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE CENTRAL AND SOUTHERN HIGH PLAINS AND SOUTHEAST FLORIDA... ...Central and Southern High Plains... The upper level cutoff low will progress further, tracking across the north-central U.S. on Monday with a trailing frontal zone extending back across the central and southern High Plains. Scattered convection is expected to develop ahead of the system and will be able to tap into moisture flowing in from the Gulf and instability in the vicinity of the front. A shortwave is expected to move across the region on Monday and a strengthening jet along the frontal boundary will place the southern High Plains in the right entrance region, both of which should provide additional support for convective development. Compared to previous days, model QPF totals are modest, but the ingredients will be in place for at least a localized heavy rainfall threat. Therefore, the inherited Marginal Risk area was continued for the central and southern High Plains. ...Southeast Florida... Northeasterly onshore flow will continue across Southeast Florida, but the low pressure system will gradually weaken, resulting in precipitation tapering off on Monday night. Given heavy rainfall expected in Southeast Florida on Sunday, a Marginal Risk was maintained to account for isolated flash flood potential with locally heavy rain falling over saturated soils. Dolan Day 4 and Day 5 Valid 12Z Tue Oct 27 2026 - 12Z Thu Oct 29 2026 The probability of rainfall exceeding flash flood guidance is less than 5 percent. 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 $$