Severe thunderstorms producing damaging winds, hail, and a few tornadoes are expected through Tuesday across parts of the central Plains and lower to mid Missouri Valley. Heavy to excessive rainfall could produce flooding across portions of the Ohio Valley into the Central Appalachians through Tuesday. Read More >
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361 FXUS63 KDVN 170121 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 821 PM CDT Mon Jun 16 2025 .KEY MESSAGES... - Active weather pattern continues tonight through at least Wednesday evening, with some strong to severe storms possible at times - Confidence remains low on the timing and coverage of this activity, given that how showers/storms develop one day will impact the convective environment the following day - Very warm/hot conditions becoming more likely this weekend (highs in the 90s; heat indices near 100) && .UPDATE... Issued at 741 PM CDT Mon Jun 16 2025 We are currently watching a line of strong to severe convection northwest of the Des Moines metro area, which is generally moving east-southeast. If these storms are to continue over the next couple hours, they will be close to our forecast area. Current trajectory brings the line near our western border around 9-10 PM local time. The track of this line is difficult, as the northern portion of the line is moving more easterly, while the southern half continues east-sutheasterly towards the Des Moines metro. With that, the northern end of the line has been the area that has been dying off over the last few hours, while the strongest cores continue to build south. So, if that trend continues, areas along or south of Interstate 80 would see the best chance for any showers or storms if this line makes it. Confidence is low on it making it, but it will come close enough that mention is needed. This line has a history of winds around 60-70 mph and these winds cannot be ruled out as it continues over the next couple of hours. Although, it has been on a downward trend over the last hour or so. Thus, confidence is low overall. This line of convection may not be the only source of storms late this evening and into the night. We currently have discrete storms developing south of the Minneapolis Metro. Guidance hints that these will continue to move southeast through the night, with some coming close to our area as well. So, I just wanted to mention that areas north of Interstate 80 are not completely out of the threat yet. For both situations, short term guidance is not capturing these storms well at all. Thus, we have truly been relying on observational trends throughout the area, which would favor some longevity to at least the line of storms out west. Environment in place would favor the primary hazard in any storm being winds, but hail has also been seen and cannot be ruled out. && .SHORT TERM /THROUGH TUESDAY NIGHT/... Issued at 233 PM CDT Mon Jun 16 2025 Periodic chances of showers and storms will remain in the picture for tonight through late Wednesday as a few mid-level shortwaves crosses our region. Confidence remains lower as the forcing will be a bit more nebulous, at least at first, and with how daily showers and storms impact the convective environment the following day. Presently this afternoon, a cluster of strong to severe storms persists over our northwestern CWA from a weak convergence boundary and mid-level impulse. The convective environment is more driven by thermodynamic processes given fairly weak deep-layer shear (<30 kts), with SBCAPE values around 2000-3000 J/kg per the RAP/SPC mesoanalysis fields. Mid- and low-level lapse rates appear to be fairly modest in scope, but still should be sufficient to support some locally strong wind gusts and hail to the size of quarters. As such, SPC has maintained a Marginal Risk (level 1 of 5) for severe storms tonight along and north of a line from Sigourney, IA to Clinton, IA to Freeport, IL. For this entire period, confidence in thunderstorms remains highest for severe storm potential on Tuesday PM as a more robust mid-level impulse crosses the region during peak heating. CAMs are actually in decent agreement on the timing of storms in the afternoon, albeit a bit more spread out in terms of coverage. Initially, the deep-layer shear will be pretty meager, but instability will be pretty high, with SBCAPE values progged around 1500-2500 J/kg per the 16.12z HREF ensemble, and low-level lapse rates between 7-8 C/km. We will have to watch for additional convection Tuesday night as a southerly low- level jet develops, with the nose of the LLJ right over our region concurrent with large-scale forcing ahead of an upper-level trough. SPC has also maintained the severe risk for Tuesday, with a Slight Risk (level 2 of 5) for severe storms over our southwestern CWA, with a Marginal Risk elsewhere. The other thing to keep an eye on will be heavy rainfall with this convection as PWAT values are progged around 1.7 to 2.0+ inches. Values over 2 inches would be near the daily maximum for PWATs per the SPC sounding climatology, so very efficient rainfall can be expected with these storms. While the HREF LPMM QPF shows a pretty wide range of rainfall amounts due to the more scattered nature of the convection, the upper bounds of rainfall totals could reach around 2 to 3 inches, and if this occurs over an urban area, this could pose a flash flooding threat. WPC continues to have locations along and north of Interstate 80 in a Slight Risk (level 2 of 4) for excessive rainfall/flash flooding. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Issued at 233 PM CDT Mon Jun 16 2025 We`re not out of the woods with the severe storm threat Wednesday as the aforementioned upper-level trough translates through the area. The convective parameter space continues to indicate hefty amounts of instability, with perhaps some stronger deep-layer shear thanks to the nocturnal LLJ persisting into the morning hours. An attendant 850 low does appear to shift to the northeast early in the day Wednesday, which will likely keep the severe threat later on in the day to our east. SPC has also maintained the Slight Risk for severe weather across our southeast areas, with Marginal Risk for locations southeast of a line from Dubuque, IA to Sigourney, IA. Chances of showers and storms should remain in the wake of the 850 low as a few additional PVA impulses move through the area. Overall, the remainder of the extended period from Thursday through Sunday looks largely dry, but we can`t rule out a chance of showers and storms on Friday. Attention then turns to big-time upper-level ridging for the upcoming weekend, which will help push the heat dome farther northward over our area. Both the EC and GEFS ensembles indicate 850 mb temperatures around the 23 to 26 C range, which is near the daily maximum for the SPC sounding climatology on Saturday. Additionally, the ECMWF EFI indicates values between 0.7 to 0.9 for high temperatures, which increases confidence in a hot air mass settling in. High temperatures likely warming into the 90s both days, with heat indices possibly reaching 100 degrees F. The LREF exceedance probability of heat indices of 100 degrees is roughly around 30 to 50%, so we will need to keep an eye on some hot and humid conditions coming for the weekend. && .AVIATION /00Z TAFS THROUGH 00Z TUESDAY/... Issued at 616 PM CDT Mon Jun 16 2025 VFR conditions will remain through much, if not all of the TAF period. There will be the chance for brief MVFR conditions between 02-08z tonight, as a line of thunderstorms may move through the area. Our confidence remains low on how far this line would move into our area tonight, as guidance doesn`t have a good grasp on it. Either way, the environment currently in place would favor longevity in this line later into the evening. So, we opted to show this in TAFs right now as a PROB30 group for all sites but BRL. We will amend accordingly if confidence increases. With any storms that come through, we can see reductions in vis/cigs to MVFR conditions. Otherwise, winds will largely remain southerly at 5-10 KTs tonight, shifting southeasterly after 12-15z Tuesday. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ UPDATE...Gunkel SHORT TERM...Schultz LONG TERM...Schultz AVIATION...Gunkel |
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