


Area Forecast Discussion
Issued by NWS Omaha/Valley, NE
Issued by NWS Omaha/Valley, NE
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565 FXUS63 KOAX 182327 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 627 PM CDT Fri Jul 18 2025 .KEY MESSAGES... - A 50 to 60% chance for storms exists along our northern and eastern service area, with 30 to 40% chances areawide late tonight into early Saturday morning. Storms may be strong to severe, mainly north of a line from Platte to Shelby counties. - Another round of storms (20-30% chance) may develop Saturday afternoon and evening, with chances peaking early Sunday morning (30- 50%). Some of these storms could be strong to severe. Flood potential will also increase. - Active pattern continues into next week with some low end chances for evening and nighttime storms (15-30%). Dangerous heat will also return for much of next week. && .DISCUSSION... Issued at 319 PM CDT Fri Jul 18 2025 .SHORT TERM.../Today through Saturday Night/ H5 zonal flow continues across much of Nebraska and Iowa this afternoon, with a subtle shortwave seen across the Nebraska Panhandle region. This wave has resulted in a 1010 mb sfc low developing in the Panhandle area, with the warm front now draped across portions of eastern Nebraska. Low level moisture advection has kept the pesky stratus deck across the forecast area this afternoon, but do see a few peaks of sunshine. The clouds should mostly thin out by the late afternoon and early evening as the sfc low keeps moving to the east northeast. Aided by H8 warm air advection, should see highs today reach the mid to upper 80s across most of the CWA, with western Iowa slightly cooler in the low 80s. Our main concern for the short term forecast period is the threat for severe weather. As the warm front races to the north today, low level moisture advection will usher in low to mid 70s dew points, and coupled with midlevel lapse rates of 7 to 8 deg C/km, will most likely have an unstable airmass across much of the forecast area with MUCAPE around 1,500 to 2,500 J/kg. BUFKIT soundings seem to suggest capping remaining in place for much of the afternoon and evening hours, so if convection can develop late this evening, it will likely be rooted aloft. 0-6 km bulk shear looks favorable, primarily over northeast Nebraska at 35 to 40 kts by this evening. Forcing still seems to be rather weak in the midlevels as weak height rises are observed at H5. Forcing will largely by driven by any low level convergence along boundaries and also by a 25-30 kt LLJ at H8 which overspreads much of OAX this evening. Lots of questions remain though regarding the placement of convection, and if it will even spread into our forecast area. If we take a look at the 12z run of the HRRR, it ignites convection along the boundary in southeast South Dakota after 00z, with much of it either grazing far northern and eastern portions of the forecast area as it moves east southeast. A separate area of convection also develops along the cold front over north central Nebraska, but quickly dissipates as it moves into northeast Nebraska. The Hi Res ARW and NAM Nest seem to somewhat agree with this solution, although they tend to keep the convection along the cold front a bit more organized and track it just along our western border. The NSSL WRF and HiRes FV3 seem to be the most aggressive, developing discrete supercells early this evening across southeast South Dakota before congealing into an MCS and tracking east southeast into the Missouri River Valley. The SPC currently has a slight risk of severe weather, mainly along and north of a line from Platte to Shelby counties. The main hazards with this convection appear to be damaging wind gusts and some hail, but certainly can`t rule out a brief tornado if any supercells are able to develop and remain discrete before upscale growth. Given the myriad of solutions, have kept a general 30 to 40% chance of PoPs across much of the forecast area from 4z to 10z, with 50 to 60% chances mainly along the northern and eastern edges of our service area. Lows tonight will be in the mid 60s to low 70s. Showers and storms will exit the forecast area by mid morning on Saturday. A few of the CAMs suggest some lingering storms across northeast Nebraska in the late morning hours, so have added some light PoP mentions (15%) here. Highs for Saturday will be in the low to mid 80s north of I-80, and in the low to mid 90s south of I-80. Another shortwave will eject from the west toward central Nebraska on Saturday, with showers and storms forecast to redevelop in the afternoon across central Nebraska and track to the east in the evening hours (20-30% chance, peaking at 30 to 50% by late Saturday night into early Sunday). These storms could be strong to severe, but much of the severe potential will be dependent on how much destabilization can occur. 0-6 km bulk shear does seem to be a lot more favorable for severe storm development, with values at 40 to 50 kts. For now, the SPC has a marginal risk of severe weather across our service area, with higher chances of severe weather mainly to the west and east of the forecast area. Heavy rainfall and flooding will be of concern in the short term forecast period given we`ll see successive rounds of storms. HREF PWAT values suggest anywhere from 1.8 to 2 inches of water available in the atmospheric column Friday night, with slightly higher amounts for Saturday night into Sunday. Coupled with favorable warm cloud depths, should expect to see warm rain processes prevail. Storm total QPF from Friday to early Sunday suggests anywhere from a half inch of QPF across portions of northeast Nebraska, with up to an inch across west central Iowa. A slight risk for excessive rainfall has been issued for this evening and overnight across our far northeast and east, and again for Saturday, this time across east central Nebraska and much of western Iowa. .LONG TERM.../Sunday through Thursday/ Lingering PoPs will exit the forecast area by Sunday afternoon. H5 pattern will keep a quasi-zonal flow across the Northern Plains through at least Sunday, with another shortwave skirting through. This results in a 15 to 30% chance for PoPs across the forecast area Sunday evening into Monday morning. A few of these storms could be strong, with the SPC having issued a marginal risk of severe weather for the forecast area. The H5 zonal pattern will break down late Sunday evening as ridging across the southern and southeast US amplifies. This will result in more of a southwesterly flow closer to home, with several shortwaves forecast to ride this flow. This leads to at least some low end 15- 30% chances for evening and nighttime storms through at least Thursday. Some machine learning guidance suggests at least a low end severe chance with this activity. Will need to keep an eye on flood potential during this period, especially given that issues could arise if storms track across areas that have received heavy rainfall from earlier storms. Dangerous heat will return to the forecast area from Sunday through Thursday. NBM currently forecasts heat indices in the upper 90s to low 100s during this period, especially along and south of I-80. Monday through Wednesday could see heat indices reach up to 110 at times, mainly across southwest Iowa. Heat headlines appear likely during this timeframe, so those with any outdoor plans for next week should continue to pay attention to the forecast should any be issued and prepare to take necessary precautions to avoid heat related illnesses. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 627 PM CDT Fri Jul 18 2025 Main concern for this TAF period will be convective trends through Saturday. Models have been too aggressive with convective development early this evening, but generally expecting storms to develop over eastern SD and far northeastern NE late evening, then progress southeast late tonight into Saturday morning. Highest chance for TS appears to be at OMA early Saturday morning, with OFK and LNK likely a bit too far west. A front will stall in the vicinity of I-80 Saturday, which may allow additional TS to develop along it Saturday afternoon and evening. Overall, forecast confidence is low with this TAF set given the myriad of differing model solutions. Generally VFR conditions are expected, but some MVFR cigs are possible late tonight and Saturday morning, especially at OFK. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Castillo AVIATION...Borghoff