Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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353 FXUS63 KDVN 250513 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 1213 AM CDT Sat May 25 2024 .KEY MESSAGES... - Strong to severe storms are possible through early evening as a cold front moves through the area. - Another round of strong to severe storms are expected late Saturday night into Sunday. - Northwest flow developing after the weekend will bring seasonal temperatures but the active weather pattern will continue. && .UPDATE... Issued at 652 PM CDT Fri May 24 2024 Convective trends continue a downward trend and thus the watch has been cancelled early for the area. The cold front has moved into eastern Iowa and is roughly located along a KIIB to KOTM line. The front looks to clear the Mississippi River around 9 PM and bring an end to the rain risk across eastern Iowa. Rain east of the Mississippi will slowly dissipate with the entire area dry by 1 AM. Once the cold front passes, dew points will drop fairly quickly into the mid 50s as the dry high pressure begins building into the area. && .SHORT TERM /THROUGH SUNDAY/... Issued at 257 PM CDT Fri May 24 2024 The cold front in central Iowa will move east during the late afternoon and evening hours. Ahead of the front scattered thunderstorms will be seen with the potential for severe storms. The better severe risk generally looks to be along and south of a line from Ottumwa, IA to Galesburg, IL. The primary risks look to be damaging winds and hail. However, given the numerous boundaries from the earlier storms, an isolated tornado cannot be ruled out. The overall rain and severe risk will quickly come to an end once the cold front moves through the area. Right now is appears the cold front will be very close to the Mississippi by 7 PM with it east of the area by 10-11 PM. Dry conditions will be seen after midnight. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Issued at 257 PM CDT Fri May 24 2024 Saturday night through Sunday night Assessment...medium to high confidence on seeing thunderstorms. Medium confidence for severe storms. This time period will be interesting as what occurs Saturday night will impact subsequent storm development Sunday afternoon. Late Saturday night a respectable upper level disturbance in combination with a strengthening surface low will likely result in an organized thunderstorm complex moving into eastern Iowa and then east of the Mississippi Sunday morning. Right now (as a rough estimate) there may be a 35-40 percent chance that this storm complex may produce severe storms. Boundaries left over from this storm complex combined with strong differential heating Sunday afternoon will result in another round of strong to severe storms developing that will continue into Sunday evening before ending. The current SPC enhanced outlook south of I-80 looks reasonable given the questions of storm evolution. Hail and wind appear to be the primary severe risks but a brief tornado cannot be ruled out. After sunset Sunday, storms will slowly dissipate during the evening hours with a few isolated storms lingering past midnight. Monday through Tuesday Assessment...medium confidence The global models vary considerably on timing and strength of features, but agree that an upper level disturbance will move through the area that may or may not include a weak frontal boundary. As a result of the differences in timing and feature strength, the model consensus has 20-30 percent chance of pops for Monday, a dry Monday night and then 15-25 percent chance pops for Tuesday. Temperatures should be close to normal. Tuesday night through Thursday Assessment...high confidence The model consensus has dry conditions for the area as an upper level high moves across the area. Temperatures look to be near or slightly above normal. Thursday night and Friday Assessment...low to medium confidence The model consensus has a 20-30 percent chance for rain as an upper level disturbance moves through the area. However, there are disagreements regarding the timing of the disturbance. Interestingly, the deterministic runs of the global models are mainly dry. The respective ensembles on the other hand have several members with some precipitation. Overall moisture availability will be the key as to whether or not precipitation occurs. If overall moisture is less than what is depicted by the models then there is a very real possibility that dry conditions would be seen. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1213 AM CDT Sat May 25 2024 VFR conditions are expected throughout the TAF period as high pressure builds into the region. Light and variable winds this morning will develop for a time before winds turn southerly around or after noon around 5 to 10 knots. && .HYDROLOGY... Issued at 1025 PM CDT Thu May 23 2024 The flood warning for the North Skunk River near Sigourney has been upgraded to Major flood category. Routed water from a sparse data area upstream where the heaviest rain fell a few days prior has led to a rapid rise in the last 6 hours and is now above Major flood stage. The forecast calls for a crest of 24.5 feet by Friday afternoon, but there is uncertainty in the amount of water that remains to move through the reach and the crest may need to be further adjusted. The Wapsipinicon River near DeWitt was upgraded to a Flood warning. Major flood stage is being forecast based on routed flow, and is supported in output from the Hydrologic Ensemble Forecast Service Model Simulation (HEFS), which places high confidence on reaching Major Flood stage (12.5 feet). The forecast has gone up this evening with a crest now over 13 feet next week. This fits near the most likely range from HEFS of 12.8-13.1 feet. Some attenuation is possible as the routed flow moves through the river system, but at the same time there will be additional rounds of rain Friday and Sunday of which could total over 1 to 2 inches. There will likely be changes to the forecast in the coming days as the rain lays out and the extent of the routed flow is better known, so stay tuned! Routed water and additional rain through the weekend is leading to rises on most other tributary rivers and the mainstem of the Mississippi, especially south. Flood warnings or watches are in effect for portions of the Cedar, Iowa, Skunk and southern sections of the Mississippi river so please refer to the latest Flood Statements and Flood Warnings for details. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ UPDATE...08 SHORT TERM...08 LONG TERM...08 AVIATION...Schultz HYDROLOGY...McClure