textproduct: Springfield

KEY MESSAGES

- 15-40% chances for isolated to scattered showers and thunderstorms this today. There is potential for some storms to produce wind gusts up to 40-60 mph.

- Flood Watch to be in effect from 10 PM tonight to 10 AM Thursday morning along and northeast of a Warsaw to Gladden line. More numerous 50-80% chances for showers and storms north of Highway 60 will bring the potential for locally excessive rainfall and flooding. Wind gusts up to 60 mph and hail up to quarters to half dollars will also be possible.

- Additional chances for rain and storms exist through Friday night before an extended period of heat returns.

SHORT TERM /THROUGH TONIGHT/

Issued at 300 AM CDT Wed Aug 5 2026

Current water vapor imagery paired with RAP analysis depicts broad mid- and upper-level troughing and enhanced flow across the north-central CONUS as a mmid-level low churns away in the southeast CONUS. A few embedded shortwaves within the broad trough are noted in water vapor imagery. Most notably, is a wave moving out of the Colorado/Wyoming front range. Along the gradient of the broad trough is a rather stationary front extending from south Kansas, through northern Missouri, and into the Upper Peninsula of Michigan.

Isolated to scattered showers and thunderstorms today:

As the aforementioned shortwave moves across the Plains today, the surface front will sag to the southeast into west-central Missouri. During much of today, the greatest lift from the approaching shortwave should stay north and west of the area. However, convergence along the front and any pre-frontal convergence zones across our area may produce isolated to scattered showers and thunderstorms as somewhat uncapped 1500-3000 J/kg SBCAPE is forecast to be in place across the region, according to the HREF. CAMs suggest these may occur in bands, one closer to the front and one along pre-frontal convergence east of Highway 65. The band closer to the front may be more elevated given some greater capping in that region, but it may also occur anytime from this morning through the afternoon. Any storms east of Highway 65 should occur diurnally between 3 and 10 PM.

While instability will be plentiful this afternoon and evening, shear will be rather weak as the shortwave stays to the northwest during peak heating. Regardless, highs reaching the middle 90s today with mid-60s to around 70 F dewpoints will create a decent dewpoint depression and resulting inverted-V profile. The resulting steep low-level lapse rates along with elevated Vertical Totals will result in a pulse-like environment during peak heating. The Ozarks Pulse Severe Thunderstorm Index confirms this with values at 14-16 (moderately high) during peak heating. Therefore, any thunderstorm that does form in the afternoon may produce downdraft wind gusts up to 40-60 mph.

Flood Watch to be in effect from 10 PM to 10 AM Thursday morning:

More robust lift ahead of the shortwave moves overtop the frontal boundary later tonight. The resulting synoptic mass response is three-fold. First, the surface front will begin to slowly lift back north. Secondly, this will create a zone of strong low-level warm air advection aided by an increasing 25-30 kt low-level jet. And thirdly, large-scale synoptic ascent ahead of the shortwave will provide extra lift within a zone of 1000-2000+ J/of of MUCAPE. As a result, numerous showers and thunderstorms are expected to develop along this frontal boundary after 10 PM tonight. The exact corridor of these storms is still a bit uncertain, but the highest chances (50-80%) exist north of Highway 60 and especially north of Highway 54. The highest confidence areas are under a Flood Watch from 10 PM tonight until 10 AM Thursday morning.

RAP and HREF model forecasts suggest the frontal boundary will take on a more west-to-east orientation overnight, which will become parallel to the mean-layer flow aloft. Therefore, with lift persisting throughout the night, multiple rounds of training storms are expected to develop. The combination of storms training along with efficient rain rates from tall, skinny CAPE profiles and PWATs nearing 2 inches will bring the risk for locally excessive rainfall and flooding. Both the HREF and REFS LPMM QPF amounts narrow down a corridor in central Missouri with widespread 1-2 inches and localized values up to 3-5 inches.

Marginal Risk for severe thunderstorms continues through tonight:

In addition to the flooding threat, deep-layer shear will become more plentiful overnight, generally along and north of I-44. HREF and RAP forecasts suggest values of 30-35 kts, with upwards of 40 kts within the elevated 1-6 km layer. This is still on the Marginal side, but enough for a few strong to severe thunderstorms. The exact mode of resulting storms is also still a bit uncertain. Some CAMs show multiple line segments initiating and traversing the boundary, while others depict more cellular convection. Whichever mode occurs will dictate the main hazards, but given the environment, hazards would include damaging wind gusts up to 60 mph and hail up to quarter to half dollar size.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 300 AM CDT Wed Aug 5 2026

Additional chances of rain and storms exist through Friday night:

Medium-range models have the frontal boundary and broad trough lingering in the same area through Friday night. Shortwaves that move through the broad trough, along with surface convergence along the front, will promote additional chances for showers and thunderstorms through Friday night.

At the moment, 15-25% chances for isolated activity exists Thursday afternoon. There is currently no SPC risk for Thursday afternoon, however, given the proximity of the surface boundary, and environment characterized by 2500+ J/kg MUCAPE and 30-35 kts of 0-6 km bulk shear, would not be surprised to see another Marginal Risk come about.

Coverage of showers and storms then look to increase again Thursday night (40-70% chance) as the same pattern sets up with a nocturnal LLJ/WAA and shortwave support. Depending on where the frontal boundary is at this point in time, the Flood Watch may need to be expanded and/or extended to account for additional training and excessive rainfall potential. There is too much uncertainty at this time, though, to delineate any areas with enhanced risk.

The same pattern then occurs Friday and into friday night with isolated to scattered activity during the day, and focused more numerous coverage along the front overnight. Once again, we will need to monitor trends for any potential in heavy rainfall and/or strong to severe thunderstorms.

Extended period of heat build this weekend and into next week:

The longwave trough axis finally moves east of our region Saturday and Sunday, making way for rising heights and increasing temperatures. Highs over the weekend and into next week are expected to be in the 90s, some areas approaching 100 F. Current dewpoint forecasts keep heat a tad lower than "excessive" with LREF ensembles showing <10% chance for >105 F Heat Index values. However, they do show >60% chances for >100 F values Saturday through at least Tuesday. So, while around 100 F Heat Index is not terribly uncommon for Ozarkian summers, the expected extended nature of 100-105 F Heat Index values introduces a Heat Risk as there will not be much room for heat relief.

While heat will build, the jet stream across the northern CONUS will remain active. Some global models have the enhanced winds dropping south near our northern CWA. This may bring additional chances for rain and storms, but uncertainty in these types of patterns is too high for any appreciable mention above 15%. As an example, the EFI does show values of around 0.8 for CAPE- Shear combo in central and northern Missouri, which may highlight some potential for storms to come careening down the northwest flow of the jet stream sometime next week. Trends will continue to be monitored.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 655 AM CDT Wed Aug 5 2026

Current radar imagery shows some light and isolated showers across western Missouri, just outside the vicinity of JLN. These should continue through 18Z, with a 15-30% chance of impacting JLN. Following these showers, a frontal boundary is forecast to slowly sag into the region, which will bring 15-30% chances for additional scattered showers and perhaps a thunderstorm between 21-04Z. After 00Z, the front lifts back north, shifting winds back to southeasterly.

Greater chances for thunderstorms then exist between 08-12Z as additional storms develop along the lifting front. A TEMPO group has been added to SGF for the increased confidence, but there is lower confidence for it impacting JLN or BBG.

Otherwise, multiple cloud layers are expected through the period, but low-level cumulus will be above 5 kft unless a storm moves within the TAF site vicinity.

SGF WATCHES/WARNINGS/ADVISORIES

KS...None. MO...Flood Watch from this evening through Thursday morning for MOZ055>058-069>071-083.