Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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431 FXUS63 KDVN 070552 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 1252 AM CDT Sun Jul 7 2024 ...Updated for 06z Aviation... .KEY MESSAGES... - Showers and storms return later tonight and last 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 155 PM CDT Sat Jul 6 2024 A tranquil afternoon is taking place over the region, with widespread mid 70s to lower 80s in our area. Dewpoint temperatures are in the lower 60s, providing a summer feel to the air, without much of any heat stress. Some spotty sprinkles are taking place over northern Illinois today, in the cumulus field, but I`m inclined to keep the forecast dry given the very isolated and light nature of them. Looking to the west, there is an upper low pressure centered over north central South Dakota, with short wave trof locations in central Nebraska and eastern Montana. These two short waves will bring the forcing for two many chances for rainfall over the area through Monday, as they bring lift to a air mass that is forecast to have PWAT values of 1.5 to 1.75". The first short wave will move through Iowa tonight, with an elevated/high based shower and thunderstorms expected to move from eastern Nebraska into central Iow this evening, then gradually into eastern Iowa generally after midnight. The focus for storms appears rather diffuse, so this may be a festering area of weak convection and rain as it arrives, with QPF mainly under 0.40" With mostly cloud skies, temperatures will fall to the mid 60s area wide. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 155 PM CDT Sat Jul 6 2024 A quasi-omega block related to this Midwestern upper low will remain through early next week, with a the second of the main shortwaves traversing along the SW to NE oriented mid/upper flow ahead of a mean upper trough over the Upper Mississippi Valley Sunday night and Monday. PoPs will be high at times (60+%), with the main placement along the 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 /06Z TAFS THROUGH 06Z MONDAY/... Issued at 1238 AM CDT Sun Jul 7 2024 Predominantly VFR through the period, although there will be at times clusters of shra/tsra with MVFR/IFR conditions. Timing/location of these clusters is challenging, particularly further in the period. Based on current radar and trends the northern terminals (KCID, KDBQ) appear most favored to be impacted by convective clusters overnight and Sunday morning with transitory bouts of MVFR/IFR conditions (mainly for visibility) owing to TEMPO or prevailing mention at times 07z-16z. However, as the low level jet veers and a disturbance approaches convection is anticipated to develop further south perhaps close to KMLI by mid morning through early PM (14z-19z). Can`t rule out some convection lingering mid to late PM, but lack of forcing should limit to spotty coverage before a return of increasing shra/tsra coverage occurs by Sunday evening, which has been handled with PROB30 mention for now until we can refine the corridor of higher probabilities. && .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...McClure HYDROLOGY...14