FOUS30 KWBC 030028 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 828 PM EDT Tue Jun 2 2026 Day 1 Valid 01Z Wed Jun 03 2026 - 12Z Wed Jun 03 2026 ...THERE ARE SLIGHT RISKS OF EXCESSIVE RAINFALL ACROSS PORTIONS OF WEST TEXAS INTO NEW MEXICO AND THE DAKOTAS... 01Z Update: Main change from the previous D1 is the expansion of the SLGT risk further south into SD to cover for what has been an active afternoon and evening of heavy convection across the Black Hills area. Multiple shortwaves will continue to eject east- northeast out of the Front Range of WY leading to ongoing periods of thunderstorms to impact areas across southwest WY. Several flash flood warnings have already been issued over the region, so it stands to say the short term hydrologic state is at a point of favor when it comes to run off capabilities. The terrain is already a concern in the general sense, so this only added to the threat overnight. We will eventually see storms grow upscale and migrate eastward as cold pool mergers eventually transition convective modes to more multi-cell varieties, so the threat will dwindle after 06-09z, however the threat will remain elevated until the very end of the period which allowed for an expansion of the SLGT through a large portion of SD. Further south into the Southern High Plains, continued threat of heavy convection will occur this evening as large scale forcing will only stand to increase overnight with a rarer nocturnal convective evolution forecast across eastern NM into the western portion of the TX Panhandle down into parts of Southwest TX. The main focus will reside along the Rio Grande from El Paso down to the western Big Bend area where a robust instability maximum awaits allowing for stronger convective episodes to materialize and likely proceed without much in the way of forfeiting any instability in the process after the loss of diurnal destabilization. MUCAPE between 2000-3000 J/kg will reside between the Pecos river to the Rio Grande with a secondary max co-located between the Upper Trans Pecos to the Permian Basin which will align with the second area of interest across TX/NM. Cold pool mergers and sustained thunderstorm capabilities will drive an extended period of heavy rainfall through the above areas. The SLGT was generally maintained outside a minor adjustment southward along the Rio Grande in Southwest TX. Kleebauer Day 2 Valid 12Z Wed Jun 03 2026 - 12Z Thu Jun 04 2026 ...THERE ARE SLIGHT RISKS OF EXCESSIVE RAINFALL ACROSS WEST TEXAS INTO NEW MEXICO AND THE EASTERN DAKOTAS... ...2030Z Update... A few changes as well as a categorical upgrade have been provided for this update. First, the Slight Risk covering portions of the southern High Plains has been extended northeastward to include the eastern Texas Panhandle as well as portions of western Oklahoma. The now available hi-res guidance is suggestive of locally heavy rainfall totals in the 3-4" range along a north/south oriented axis of higher moisture south of an area of low pressure and attendant surface boundary. HREF probabilities of >3" are in the 25-45% range with low-end probabilities (15%) for > 5". The hi- res guidance is a bit more ambiguous to the southwest over west Texas and southeastern New Mexico, with the greatest potential for heavy rainfall similar to Tuesday across southwest Texas into southeastern New Mexico where an axis of higher/more anomalous moisture will reach further to the west into the higher Plains terrain and ahead of the Sacramento mountains. There may ultimately be a lull in storm coverage/intensity and attendant flash flood risk between these regions where relatively lower moisture is present, but have left a broad Slight Risk for now with the potential to further refine the outlook with additional forecast guidance. Second, a Slight Risk has been introduced for portions of the northern Plains covering southeastern North Dakota, northeastern South Dakota, and far western Minnesota. A more focused area of convection is expected ahead of a wave of low pressure along the cold front with the potential for upscale growth into an organized convective system. Now available hi-res guidance shows the potential for totals into the 2-3"+ range with low to moderate HREF probabilities of 3"+. The one caveat is that the more progressive nature of the front and subsequent convection compared to Tuesday may limit rainfall duration. However, there remains the potential for backbuilding convection to the southwest to compensate for the faster progression of the convection particularly if the surface wave helps to locally slow the front's southerly progress. Finally, a Marginal Risk has been included for South Florida. Another day of afternoon thunderstorms with the potential of localized totals into the 3-5" range could lead to isolated flooding concerns for urban areas. Putnam ...Previous Discussion... ...West Texas into New Mexico... Weak troughing aloft and the remaining relatively higher moisture in place across the region will likely promote the development of isolated to scattered thunderstorms again on Wednesday. The focus for the greatest concentration of thunderstorms and rainfall totals will shift a bit further east this day, likely along the NM/TX border into the TX Panhandle where amounts of 1-2" with isolated 3" totals likely. Isolated to scattered instances of flash flooding will be possible. ...Great Plains... An axis of higher moisture will be present ahead of an advancing cold front moving across the Northern Plains. Moist unstable air ahead of it will promote the development of several clusters of thunderstorms capable of producing intense rain rates between 1-2"/hr. Isolated to scattered flash flooding is anticipated with a possible upgrade to a Slight Risk needed for parts of eastern ND and far western MN if trends continue for a more concentrated area of thunderstorms and heavy rainfall. Taylor Day 3 Valid 12Z Thu Jun 04 2026 - 12Z Fri Jun 05 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE PLAINS, UPPER MIDWEST, AND TEXAS... ...2030Z Update... The previous forecast remains supported by the latest model guidance. There continues to be a signal for locally heavier rainfall ahead of the front across portions of the northern Plains/Upper Midwest potentially supportive of an upgrade to a Slight Risk. However, ensemble probabilities for rainfall totals greater than 1 inch remain very low. Additionally, spatial disparity of heavier totals in the deterministic guidance due to uncertainty of the position of the front do not provide enough confidence for an upgrade at this time. Putnam ...Previous Discussion... ...Northern Plains into the Upper Midwest... Shortwave energy ejects into the Plains during the period with the frontal boundary expected to become increasingly west to east oriented as it drapes across the Upper Midwest by Thursday. This will allow the moisture to pool ahead of it while also creating a more favorable setup for training/repeating thunderstorms that are expected to develop during the peak heating and continue into the overnight hours with the surging low level jet. While there remains uncertainty on placement (north solutions versus some that are further south), the ingredients appear to be in place for heavy rainfall from portions of the Dakotas eastward toward Minnesota. For now, a Marginal Risk remains in place but an upgrade to a Slight Risk may be needed in future updates if trends continue for a training thunderstorm scenario. ...Plains to Texas... A mid to upper level system slowly moving east out of western Mexico will approach the region during the period. As it does so, it will continue to pull into the area copious amounts of Gulf moisture. This will bring additional rounds of thunderstorms to the area, some of which will be locally heavy given the PWs in place and potential for repeating rounds. For now, will keep a Marginal Risk in place, but if greater organization of storms or confidence on specific areas rises, a Slight Risk may be needed for portions of western to central Texas with future updates. Taylor 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