Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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480 FXUS63 KDVN 062356 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 656 PM CDT Sat Jul 6 2024 ...00z Aviation Update... .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 /SUNDAY 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 /00Z TAFS THROUGH 00Z MONDAY/... Issued at 650 PM CDT Sat Jul 6 2024 A VFR TAF period through late evening and into the over night with light and variable or light southeasterly sfc winds. Isolated to sctrd showers and thunderstorms, elevated in nature, are then expected to move in from the west after midnight, and get into the VCNTY of most of the TAF sites except maybe BRL. Have timed TEMPO and PROB30 groups for the most likely windows of activity into Sunday morning. The more substantial storms may still produce passing bouts of MVFR CIGs and rain-reduced VSBYs. Then much of the day Sunday may be VFR clouds with sctrd patches of MVFR CIGs with showers and possible thunderstorms. Southerly sfc winds should increase to 5-10 KTS, but still may show variable tendencies around the showers/storms. && .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...12 HYDROLOGY...14