990 FXUS63 KOAX 072318 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 618 PM CDT Mon Jul 7 2025 .KEY MESSAGES... - Line of strong to severe storms expected this evening. Primary hazard: damaging winds (70+ mph). Hail, brief tornado, and heavy rainfall also possible. - Additional chances for storms through the rest of the work week, with Thursday night looking like our next best chance for severe weather. - Drier, milder weather possible next weekend. && .DISCUSSION... Issued at 137 PM CDT Mon Jul 7 2025 Right now across our area we`re seeing partly cloudy skies with hazy conditions aloft, likely from a high smoke layer out of western Canada. Vis satellite shows a fairly active cu field across our area indicating a significant amount of instability, which models predict to be around 2000-2500 J/kg. This sets us up for potential severe weather this evening as an MCS is forecast to drop south out of eastern South Dakota, bringing a fairly good damaging wind threat as well as a low hail and tornado threat. In water vapor imagery, you can see the approaching shortwave over central South Dakota this afternoon. This is expected to trigger storms across southeast South Dakota sometime between 3-5 PM. These storms will then congeal, feeding off an ample amount of environmental CAPE to produce a broad MCS that will drop south across our area tonight. While CAMs indicate uncertainty in storm initiation time, based on current observations we would lean towards later arrival times for storms, more likely seeing storms move into northeast Nebraska between 6-7 PM, arriving in the Omaha Metro around 10-11 PM. While environmental shear isn`t remarkable, the orientation of 0-3km shear vectors indicates potential for a brief spin-up or two (tornadoes), which will be closely monitored. As the MCS progresses southward, it will be moving into an environment of weaker shear, which likely won`t support this system maintaining it`s strength lending toward a weakening trend as the line progresses southward. One additional hazard we will be monitoring is the potential for locally heavy rainfall, especially in the later stages of the MCS. PWAT values will be ranging from 1.5 to 1.75 across eastern Nebraska and western Iowa, lending toward efficient rain- producing storms. For the most part, storms should be moving well enough to keep from getting heavy enough rainfall totals for flooding, but as the MCS weakens and slows down we may see the boundary stall across southeast Nebraska/southwest Iowa. This could lead to storm training along the boundary and locally higher amounts in this area. Tuesday, a meso-high will be in place through most of the day as the atmosphere will be well worked-over from overnight storms. This should keep conditions dry. Temperatures will warm into the mid-to-upper 80s, with dew points in the upper 60s to low 70s making it feel muggy. For the second half of the week, the upper-level pattern remains active with a ridge over the Desert Southwest creating northwesterly flow across Nebraska and the Central Plains. This pattern is conducive for MCS development in the summertime, especially with a good enough moisture tap via the diurnal low- level jet, pulling in moisture from the Gulf each evening. This pattern remains in place through the end of the week, with our next MCS forecast for Wednesday night into Thursday morning (20-30% chance), and a higher chance for another MCS Thursday night into Friday(50-60% chance). WPC is already highlighting the Thursday night-Friday morning timeframe with a Slight Risk for excessive rainfall, due to the west-east orientation of the surface boundary, orthogonal to the low-level jet. This supports the potential for training storms with heavy rainfall. Temperatures through the end of the week will remain fairly steady with highs in the 80s and lows in the 60s to low 70s. Rain chances drop off Saturday and Sunday as we see the ridge over the Southwest retreat westward over the Coast of California. This will shift the storm track further south and bring in milder temperatures. Highs may only get into the low 80s on Saturday, though we see them warm back up into the upper 80s going into Sunday. && .AVIATION /00Z TAFS THROUGH 00Z TUESDAY/... Issued at 618 PM CDT Mon Jul 7 2025 Storms are still on track to push through the area this evening and overnight, though still some questions on exact timing at a given spot. A few could be strong to severe, with wind gusts of 50 kts and some hail, but the hail threat should diminish through the evening. Expect IFR to MVFR conditions as they push through with some lingering showers after. Things should clear out by early morning with some lingering clouds around 1500-4000 ft agl and light northwest winds. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...McCoy AVIATION...CA