Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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827 FXUS63 KDVN 061812 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 112 PM CDT Sat Jul 6 2024 ...Updated for Hydrology Section... .KEY MESSAGES... - Turning unsettled once again with periodic showers and storms tonight through at least Monday. - Near normal temperatures through much of next week. - Could Beryl have an impact on our weather next week? Time will tell. && .SHORT TERM /THROUGH TONIGHT/... Issued at 331 AM CDT Sat Jul 6 2024 Fairly tranquil conditions and seasonable temperatures are being found early this morning and will persist throughout today, as heights aloft undergo a bit of amplification between a Great Lakes upper trough and an approaching shortwave diving into the Northern Plains. Highs today should top out from near 80 to 85F with a SCT-BKN cumulus deck. PoPs are not zero with building instability and steepening lapse rates this afternoon, but the lack of a coherent trigger and rather shallow moisture profiles keep PoPs below mention. Tonight, cyclonic vorticity advection ahead of the approaching Northern Plains shortwave and moisture advection attendant to a veering 30+ kt low level jet will lead to chances (40-60%) for showers and storms by late evening and especially overnight, mainly north and west of the Quad Cities. Severe weather is not anticipated, but some gusty winds may be possible from a waning cool pool off decaying remnants of more organized convection to our west, as hinted at by some of the CAMs. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Issued at 331 AM CDT Sat Jul 6 2024 A quasi-omega block is forecast through early next week, with a series of shortwaves traversing along the SW to NE oriented mid/upper flow ahead of a mean upper trough over the Upper Mississippi Valley. This will keep the pattern unsettled owing to periodic showers and storms through at least Monday and possibly into Tuesday. PoPs will be high at times (60+%), but placement will vary pending the track of the shortwaves and location of a wavering surface frontal boundary. Deep layer shear looks generally marginal as typical for July and thus any organized severe weather threat appears low at this time. However, will have to keep an eye out for any augmentation of the deep layer wind fields by any shortwaves, which could foster a severe weather threat if juxtaposed with favorable diurnal timing and sufficient instability. The threat for widespread heavy or excessive rainfall also appears low at this time, with 00z GEFS indicating probabilities of >1 inch of total QPF through 12z Tuesday at 30-50% and ECE at just 20-30%. This would be good news for area rivers. We are monitoring the track of Tropical Storm Beryl, which is currently moving into the south central Gulf of Mexico. According to the latest NHC forecast it is expected to intensify into a Hurricane before reaching the lower and middle Texas coast late Sunday and Monday, then weaken to a Tropical Depression while reaching the Lower Mississippi Valley by Wednesday evening. The GFS Vertically Integrated Water Vapor Transport (IVT) plots does suggest the potential for at least some connection of moisture from the remnants of Beryl poleward into the existing moist conveyor ahead of the front in the region. That being said, the strongest IVT does show to remain disconnected and closer to remnant low center, but nonetheless this will be worth monitoring for any potential for a deeper connection leading to a more widespread heavy rain threat ahead of the frontal boundary draped across the area. Otherwise, the general consensus of the ensemble guidance beyond mid next week keeps the remnants of Beryl well south/east of the area into the Ohio/Tennessee Valleys. It is possible being on the northwest flank of this system that subsidence could increase enough to give us several days of dry weather from Wednesday through Friday and possibly deeper into next weekend. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1212 PM CDT Sat Jul 6 2024 A pleasant VFR day is expected the rest of today and through this evening, as high pressure controls the weather. Light winds will become southeasterly tonight, as warm advection begins to spread moisture over the region. Showers and a few thunderstorms will move east across Iowa overnight, reaching eastern Iowa after midnight, and into Illinois toward morning. These should not be strong, but could bring MVFR visibility at times, and lower cigs to around 3000-4000 ft. After rains end Sunday morning, we should see widely scattered activity through the day, with predominantly dry VFR conditions. && .HYDROLOGY... Issued at 110 PM CDT Sat Jul 6 2024 Rainfall amounts were less than expected. Therefore, the Mississippi River is currently cresting at and upstream of Bellevue, IA. The crest may take 1 to as much as 3 days to pass. Fulton and Camanche are forecast to begin cresting Sunday afternoon, with Le Claire, Rock Island, and Gladstone seeing the crest begin late on Monday. The remainder of the sites south of the Quad Cities are expected to crest Tuesday through Friday. Major flooding is occurring or expected to occur along the Mississippi River from Dubuque to Keokuk. Tributary Rivers: Moderate flooding will continue on the Wapsipinicon River at Dewitt through Tuesday. It is forecast to briefly drop into Minor Flood Category midweek, before rising back to Moderate Flood stage on Thursday. On the Cedar River at Conesville, minor flooding will continue. It will see a secondary crest near 14.5 feet late this coming week. The Iowa River at Oakville is seeing high water levels due to backwater affects from the Mississippi River. It is forecast to remain near 11.8 through midweek and then rise to near 12 feet. A flood watch remains in effect for the Cedar River at Cedar Rapids. It is forecast to briefly reach the 12 foot flood stage late Monday afternoon. Confidence remains low. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...McClure LONG TERM...McClure AVIATION...Ervin HYDROLOGY...14