Quantitative Precipitation Forecast
Issued by NWS
Issued by NWS
496 FOUS30 KWBC 170044 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 844 PM EDT Thu Oct 16 2025 Day 1 Valid 01Z Fri Oct 17 2025 - 12Z Fri Oct 17 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Locally heavy rainfall will continue across portions of far northwest KS into central NE this evening along a cold front. Hourly rainfall will occasionally exceed 1", and total rainfall may locally approach 2". While this rainfall could result in some minor runoff issues, the probability of flash flooding remains below 5 percent. Chenard Day 2 Valid 12Z Fri Oct 17 2025 - 12Z Sat Oct 18 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Gallina Day 3 Valid 12Z Sat Oct 18 2025 - 12Z Sun Oct 19 2025 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM NORTHERN ARKANSAS TO NORTHERN INDIANA... 21z update: 12z guidance trends depict a tightening of the two phasing shortwave features; with the northern stream digging a tad faster and the southern stream slowing and lifting northward. As such the initial rounding jet streak appears to be broadening and increasing overall diffluence across the Central MS Valley; further enhancing low level confluent flow toward 45-50kts and generally supporting of increased duration of enhanced flux within the training convective environment from the eastern Ozark Plateau across central IL toward L.P. of MI. The higher flux, slightly higher CAPEs to 500-1500 J/kg, and solid right entrance ascent and general diffluence while maintaining a parallel mean cell motion to the mean wind supporting SSW to NNE training along and downstream of the surface wave. As such, guidance has seen an increase in overall totals toward 2-3" though localized totals to 4"+. Instability reduces fairly quickly through the late afternoon, but the dynamics remain strong to have enhanced rainfall totals into the central Great Lakes. South of the base of the northern stream trof, cold front should be more progressive, dropping southeast. Deeper moisture pool and instability of 1000-2000 J/kg will allow for stronger/broader updrafts with higher rainfall intensity, but steering should limit duration with only exception to any right moving rotating updrafts that could locally reduce forward speed while increasing moisture flux convergence in speed and directional confluence. As such, narrower streets of enhanced rainfall totals are more likely than in the deformation zone further north. Along with higher FFG values, a broader Marginal Risk is preferred at this time/cycle. Gallina ~~~~Prior Discussion~~~~ By the beginning of Day 3 (12Z Sat), the southern stream shortwave traversing the Southern Plains will begin to merge with the northern stream shortwave digging into the Central Plains. As this occurs, by the end of the period (12Z Sun) there will be a strengthening upper level jet streak rounding the trough base, with a fairly vigorous and sizable accompanying vort center across the Lower MO and Mid MS Valley. As the upper shortwaves phase, the guidance remains consistent with the uptick in low-level moisture transport across the Mid South into the Lower OH Valley (confluence of the MS and OH Rivers). The 00Z GEFS in fact shows 850 mb moisture flux between 3-3.5 standard deviations above normal over the Slight Risk area, along an axis of TPW values between 1.7-1.9". Meanwhile, deep-layer instability, while not overly robust (MUCAPEs 500-1000 J/Kg per the 00Z GFS), will be sufficient for intense short-term rainfall rates considering the degree of synoptic forcing and available deep moisture. The main inhibitor to the excessive rainfall threat is the likelihood that the upper trough and associated surface cold front will become more progressive with time later in the period (Sunday night). Nevertheless, the setup continues to align with the expectations of a low-end Slight ERO Risk, as supported by the latest CSU ERO first-guess fields (UFVS verified) over an area where the current 3 hourly FFG is 2-2.5 inches. Hurley 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