SHORT TERM /THROUGH TONIGHT/
Issued at 401 AM CDT Sat Jul 27 2024

Today will be our last day of this stretch of quiet conditions, so if you have any outdoor plans, it looks to be a pretty good day for them. A large area of high pressure will linger over the central Great Plains region, which will help keep any showers and storms at bay. Southeasterly return flow around the high pressure system will stick with us through tonight. This flow regime will lead to increasing temperatures, with highs in the lower to middle 80s.

As we head into the evening and overnight hours, a southern stream mid-level trough will lift northwards from the southern Great Plains into our region. The leading PVA maxima looks to move into our southern areas after 00z/7 PM tonight. It might take some time for precipitation to develop, given there is plenty of dry air ahead of the trough, but eventually, some showers and perhaps a few isolated storms will take shape, mainly after midnight. Little, if any, noteworthy deep-layer shear will accompany the trough, so strong to severe storms are not expected. Overnight low should fall only to the upper 60s to near 70 for most locations.

LONG TERM /SUNDAY THROUGH FRIDAY/
Issued at 401 AM CDT Sat Jul 27 2024

Sunday starts off the long-term period on a more active note compared to the previous days, as the aforementioned trough continues to slowly move through the area. A cut-off low is progged to develop within the trough, which will translate south and east of the local forecast area. Shear continues to be very meager, but instability does appear to increase to around 1000 to 2000 J/kg, per the 27.00z GEFS ensembles, with the NBM giving between 40 to 70 percent chances of showers and storms Sunday afternoon. A secondary shortwave trough will quickly move through Nebraska into western Iowa Sunday night, with a strengthening 40 to 50 kt nocturnal low-level jet concurrent with this shortwave, which should support some additional chances of showers and storms. Deep-layer shear does appear to increase, but instability will take a tumble overnight, and ensemble soundings from the ENS, GEFS, and GEPS all indicate any storms that form to become more elevated.

For Monday through the end of the period, we will continue to have periodic chances of showers and storms as a large area of upper- level high pressure develops over the south-central CONUS, placing our region on the northern end of a large heat dome, which is depicted very well in the WPC ensemble cluster analysis. Zonal flow aloft will become established over our region, leading to a series of mid-level shortwaves to traverse the region. For Monday, one to perhaps two of these shortwaves will sweep through the region, but depending on how prior convection evolves, it will have great bearing on how subsequent convection develops. Monday looks to be the first day of our stretch of hot and humid conditions through Thursday, with highs Monday warming to the middle 80s to near 90, and dew points increasing to the lower to middle 70s. This should result in a very unstable air mass, characterized by MLCAPE around 2000 to 3000 J/kg. In fact, the GEFS ensemble probabilities of CAPE 3000+ J/kg are around 50 to 80 percent for our area! Additionally, mid-level flow is progged to increase to around 30 to 40 kts across our area, which should provide ample shear for storm organization.
However, uncertainty remains on how things will evolve due to prior convection, which has the potential to reduce the amount of instability to work with and lessen the severe storm threat, or if an MCS may result from the morning activity and move southward. It is possible that if prior convection staves off, the severe storm threat could be increased. With all of this said, SPC has introduced a Marginal Risk, or level 1 of 5, across our entire forecast area.
Stay tuned for more details on the upcoming severe weather threat as we get closer to Monday.

As far as the temperature forecast is concerned, it will be highly dependent on the timing of these storms as convection during the daylight hours will help keep conditions cooler than what the NBM is suggesting. If storms don't occur during peak heating, high temperatures could reach the lower to middle 90s Tuesday through Thursday. With increased humidity, heat indices of 95 to 100 degrees or more will be possible. Heat headlines may be needed.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/
Issued at 602 AM CDT Sat Jul 27 2024

VFR conditions are expected through the evening hours today before MVFR conditions move in from the south after midnight tonight. A daytime cumulus cloud field should develop later this morning and linger through the afternoon. Meanwhile, a trough of low pressure will lift northward, arriving tonight and bring increasing chances of showers and perhaps a few isolated thunderstorms with it. High-res models are in generally good agreement on the timing of precipitation, so confidence is fairly high on timing this far out. At least MVFR conditions are expected, but some IFR ceilings may also accompany the trough, so adjustments to the ceilings may be needed.

DVN WATCHES/WARNINGS/ADVISORIES
IA...None.
IL...None.
MO...None.