Quantitative Precipitation Forecast
Issued by NWS
Issued by NWS
582 FOUS30 KWBC 121556 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1156 AM EDT Sun Oct 12 2025 Day 1 Valid 16Z Sun Oct 12 2025 - 12Z Mon Oct 13 2025 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF SOUTHERN ARIZONA AND NEW MEXICO AND PORTIONS OF THE COASTAL SOUTHEAST UNITED STATES... 16Z Excessive Rainfall Discussion Update... Given the amount of rainfall across parts of South Carolina overnight into the early portions of this morning...and satellite/radar imagery showing precipitation wrapping around the north side of surface low pressure off-shore...went ahead and introduced a Slight Risk area for parts of South Carolina and North Carolina. The expectation is that the system will gradually move away from the coast with decreasing chances of excessive rainfall with time. Until then...there will continue to be rain falling on areas which locally had more than 6 inches of rainfall and where the latest flash flood guidance has been lowered. The ARW run from overnight suggested rainfall persisting into the afternoon...also supporting the introduction of the Slight risk area in the short term. In the Southwest United States...maintained the Marginal and Slight Risk areas given latest radar imagery and the latest run of the HREF blended mean QPF. Radar imagery showed an area of rainfall over portions of Mexico that will move north of the international and into New Mexico...so a subtle eastward shift of the Slight Risk was made there. Overall...little change was made to the previous outlook reasoning. Bann 0830Z Excessive Rainfall Discussion... ...Southwest... Deep moisture, fortified with the remnants of Tropical Cyclone Raymond, will remain in place over portions of southern Arizona and New Mexico. This morning`s mesoanalysis shows PWs of 1.25-1.6 inches (3-4 std dev above normal) covering much of region. This moisture along with increasing large-scale ascent, provided by an approaching upper trough, will support another day of widespread showers and storms capable of producing moderate to heavy amounts. Maintained a Slight Risk covering much of southern Arizona and a small portion of southwestern New Mexico. Both the HREF and RRFS neighborhood probabilities indicate locally heavy amounts exceeding 2 inches are likely within this region, with some potential for amounts over 3 inches, especially across parts of southern Arizona. ...Eastern Southern Carolina and Southeastern North Carolina... The initial low of what is expected to evolve into a two feature system is forecast to linger along the coast in the vicinity of the North and South Carolina border today. Deeper moisture will remain as well, with many of the 00Z models, including the globals, showing a notable signal for locally heavy amounts developing later today. While instability will be limited, deep saturation through the column, and tall, skinny CAPEs are expected to support very efficient rains, promoting heavy amounts. Both the HREF and RRFS showing high probabilities for additional amounts over 3 inches today across parts of the region. These amounts may raise runoff concerns, especially for those areas where significant rains have already occurred. Therefore a Marginal Risk was introduced for areas where the hi-res ensembles indicate the heaviest amounts are most likely to fall. ...Northern Mid Atlantic to Southern New England Coasts... North of its parent, a secondary, triple-point low is forecast to develop near the northern Mid Atlantic coast. There remains some model uncertainty regarding if and to what degree this low will become the dominant surface feature. Despite the differences, there is broad agreement that strong, low level easterly winds, in combination with strong mid-to-upper level forcing, will support widespread precipitation from the northern Mid Atlantic coastal region to central New England, with heavy amounts expected along the coast. These heavy rains may compound what are likely to be poor ground conditions attributed to ongoing coastal flooding. Pereira Day 2 Valid 12Z Mon Oct 13 2025 - 12Z Tue Oct 14 2025 ...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL ACROSS PORTIONS OF SOUTHEASTERN ARIZONA, SOUTHWESTERN NEW MEXICO, AND SOUTHERN COLORADO... ...Southwest to the Central Rockies... Lingering deep moisture over southern Arizona and New Mexico will be drawn north ahead of an upper trough amplifying over California. This moisture along with the broad-scale ascent afforded by the upper trough will support one more day of showers and storms across the Southwest, but this time shifting a bit further east while extending north across New Mexico into the central Rockies. With drier air working into southwestern Arizona, the potential for heavy rain and the threat for flash flooding will become more limited across that area. However, further to the north and east, a Slight Risk was maintained along eastern portions of the Mogollon Rim into southeastern Arizona and southwestern New Mexico. There remains a notable signal for additional moderate to locally heavy amounts across that area. Also remaining is a Slight Risk in a portion of the San Juan Mountains, where models show deep persistent southerly winds, along with favorable upper forcing, supporting heavy totals as well. ...Northern and Central California.... Models remain in generally good agreement, showing an anonymously deep upper developing and dropping south along the West Coast from the Pacific Northwest to Northern California this period. Moisture with this system will be relatively modest initially, but enough to raise moisture anomalies to 1-2 std dev above normal along its axis of strong onshore flow. This along with strong forcing may be sufficient to produce locally heavy amounts, with isolated runoff concerns, especially in the upslope regions of the coastal ranges and the Sierra foothills below the snow line. ....Northeast... Questions remain as to how the low developing along the Northeast coast will continue to evolve, but most agree on at least a localized threat for heavy rain spreading north from southern New England up along the coast to areas perhaps as far north as coastal Maine. Given the uncertainty, kept the Marginal Risk centered to the area where the GEFS and ECENS both indicate that amounts exceeding an inch are most likely. Pereira Day 3 Valid 12Z Tue Oct 14 2025 - 12Z Wed Oct 15 2025 ...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL OVER PORTIONS OF CENTRAL TO SOUTHERN CALIFORNIA, NEW MEXICO, AND WEST TEXAS... ...Central to Southern California... A deep upper low will continue to dig south early in the period before turning east across California into the Great Basin this period. Before turning inland, this system will support an ongoing threat for heavy precipitation, with the focus shifting south along with its associated axis of deep onshore flow across Southern California into the southern Sierra Nevada. A Marginal Risk was drawn south along the Southern California Transverse Ranges, where 0.75-1 inch PWs interacting with favorable upper jet dynamics and orographic ascent are expected to support rainfall amounts of 1-2 inches along the favored terrain. These amounts may produce isolated runoff concerns, especially over vulnerable burn scar areas. A Marginal Risk was also maintained further to the northeast along the southern Sierra foothills, where similar amounts are expected below the snowline. ...New Mexico and West Texas... As drier air continues to spread east across Arizona into eastern New Mexico, PWs anomalies will remain high across portions of central New Mexico and West Texas where strengthening low level easterly winds will add to the lingering moisture. With the increase in moisture, the GFS shows PW anomalies remaining over 3 std dev above normal across much of the highlighted areas. This along with daytime heating will support additional shower and thunderstorm development, with some potential for locally heavy amounts and isolated runoff concerns. 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