![National Oceanic and Atmospheric Administration](/build/images/header/noaa.d87e0251.png)
![National Weather Service](/build/images/header/nws.4e6585d8.png)
![United States Department of Commerce](/build/images/header/doc.b38ba91a.png)
Area Forecast Discussion
Issued by NWS Omaha/Valley, NE
Issued by NWS Omaha/Valley, NE
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
178 FXUS63 KOAX 262322 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 622 PM CDT Fri Jul 26 2024 .KEY MESSAGES... - There will be a lower chance (25 to 40 percent) of thunderstorms Sunday evening. A few of these storms may be on the stronger side with gusty winds the primary hazard. - Another system will bring chances for storms (20 to 35 percent) Tuesday and Wednesday evenings. - Temperatures are expected to warm into the middle of next week, with Wednesday looking to be the hottest day of the forecast. The highest heat indices are expected across southeast Nebraska. && .DISCUSSION... Issued at 253 PM CDT Fri Jul 26 2024 Today and Tomorrow... A high-amplitude positively tilted ridge continues to persist across much of the western and central CONUS. This will keep skies clear and temperatures warm for the rest of the day. Hazy conditions are expected to persist today into tomorrow as residual smoke from wildfires in the Pacific Northwest and western Canada continues to linger. Tomorrow, a weakening mid-level disturbance will drift northeast into the central Mississippi River Valley. PVA on the north side of this system in combination with CAPE around 1500 J/kg will bring a very low end chance (10 to 20 percent) for a stray shower or thunderstorm south of I-80. Any convection that can initiate tomorrow afternoon will be diurnally driven, and as such will weaken and should dissipate shortly after sundown. Sunday and Monday... There is fairly good consensus amongst short term guidance in a weak low-amplitude disturbance ejecting out into the central and northern Plains Sunday afternoon. At the surface, a low-pressure system will develop in the vicinity of the Black Hills and track east-southeast through the evening hours into southeast South Dakota. South of the pressure center, a dryline will extend south through central Nebraska, with surface dew points in the upper 60s and low 70s to the east of the boundary. By late afternoon, isolated thunderstorms (25 to 40 percent chance of rain) are expected to initiate along the dryline and move to the east. These storms will likely have high LCLs, ranging from 1000 to 2000 feet. Low relative humidities in the boundary layer suggest that strong gusty winds will be the most likely hazard with these storms. The higher end gusts may range from 50 to 60 miles per hour, though any severe wind that does occur should remain very isolated at best. Thunderstorms will weaken as they move west and after sundown, with the strongest storms anticipated west of the Missouri River. Monday morning, a weak cold front will push south across the region. Moisture pooling along the front in conjunction with evapotranspiration will mitigate any cooling effect this will have, with the only noticeable change being a shift of wind direction from south to north. Furthermore, subsidence on the backside of the front may help bring smoke aloft to the surface, slightly reducing visibilities and air quality for a few hours after frontal passage. Winds are expected to become southerly again Monday night as a surface high pressure moves south and east of the area. Tuesday and Wednesday... Medium range guidance suggests that the high-amplitude ridge over the western and central CONUS will breakdown over the Plains, resulting in more zonal flow aloft. Embedded in this broader scale flow, embedded low-amplitude perturbations will traverse the northern CONUS. Though the exact timing and intensity of these disturbances is still uncertain, there is increasing agreement among models in low-end (20 to 30 percent) chances for thunderstorms Tuesday and Wednesday in the afternoon and early overnight hours. Tuesday, the primary mitigating factor to any thunderstorm development will be a strong capping inversion over the region. Wednesday, height falls due to a more robust disturbance will help erode this cap. However, the surface front may push south and east of the area before any convection can develop. As such, will continue to monitor trends the next few days. If thunderstorms are able to develop either of these days in our area, some may be on the stronger side with gusty winds and small hail as the primary hazards. These two days are also projected to be the warmest days of the forecast period as of now. Afternoon highs will range from the mid 90s (north of I-80 and east of US-77) to near 100 degrees (southeast Nebraska and Knox County). As such, heat indices will likely range from 100 to 110 both days later in the afternoon. However, there are several caveats to this. First, new wildfires out west may reintroduce smoke into our area which would keep temperatures a degree or two cooler than what we`re currently forecasting. Because these fires are new, there is some uncertainty in model guidance as to how much smoke will be generated and where this smoke will be transported. Also, if convection either day is able to develop, precip from these storms would locally bring down afternoon highs by several degrees. Thursday and Friday... Ridging will build out west by the end of next week with the return of northwesterly flow aloft over our area. At the surface, a high pressure is expected to move south into the northern Plains and Midwest from Canada. As such, temperatures are expected to cool down somewhat, with afternoon highs ranging from the upper 80s further north to the mid 90s near the Kansas border. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 622 PM CDT Fri Jul 26 2024 VFR ceilings through the TAF period. Isolated convection across southeast Nebraska has dissipated, though cannot rule out additional storms while daylight persists. Activity appears to be associated with low level diabatic forcing and H7 frontogenesis. Activity has remained south and east of TAF sites, and don`t plan to include. Otherwise, hazy skies persist early this evening across the forecast area with mainly high level smoke circulating around mid- level ridge axis. Area ASOS depicting visibilities 6 to 9 SM with HZ currently, thus some particulate trapped near ground. Decoupling will allow MVFR-low VFR visibility to persist during the overnight hours. Short- term ensembles gradually dissipate smoke concentration through early afternoon Saturday. As a mid-level disturbance lifts northward from lower Arkansas River Valley into lower Missouri Valley, there are small chances (10-15%) of isolated convection after 20Z Saturday, but will leave out of TAF for now. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Darrah AVIATION...Fortin