Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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813 FXUS63 KDVN 081025 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 525 AM CDT Mon Jul 8 2024 ...Updated for 12z Aviation... .KEY MESSAGES... - Near daily shower and storm chances this week, but these chances will be low for most days and thus many dry hours expected. - Post tropical Beryl will bear watching for rain chances across portions of WC/NW Illinois Tuesday night. - Seasonable temperatures into late week, but then heat and humidity look to increase next weekend. - Moderate to major river flooding continues on the Mississippi River with most sites cresting or starting to fall this week, while flooding continues on parts of the Iowa, Cedar and Wapsipinicon Rivers. && .SHORT TERM /THROUGH TONIGHT/... Issued at 330 AM CDT Mon Jul 8 2024 A linear MCS with trailing stratiform rain was moving into portions of eastern Iowa early this morning, but is encountering a much less favorable kinematic and thermodynamic environment and subsequently weakening. That being said, weak elevated warm/moist advection atop the cool pool and convergence along outflows and with the MCV will continue to foster at least scattered showers and a few storms across portions of the area this morning. This afternoon, forcing is a bit nebulous but any residual outflow or differential heating boundaries could serve as foci for redevelopment of showers and storms. Coverage is anticipated to be fairly low (20-40%) and may favor areas east and south of the Quad Cities. Overall, the better forcing and subsequent greater coverage is suggested to be further north and east of the service area. Outside of the precipitation chances, look for seasonable temperatures and humid conditions. Tonight, not currently seeing much in the way of a trigger or focus for storms and as such anticipate a quieter night with weak west/northwest low level flow on the front flank of a Missouri Valley ridge axis. Will have to monitor for at least some patchy radiational fog, especially in the river valleys and areas that have received rain recently given lows in the 60s forecast near to a bit below crossover temperatures. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Issued at 330 AM CDT Mon Jul 8 2024 Early on in the period we`ll be keeping an eye on the remnants of post tropical Beryl. The latest NHC guidance and ensemble model guidance are in reasonable agreement on taking the center from south of St Louis to near Indianapolis to northwest Ohio from 06z Wednesday to 06z Thursday. Along and just northwest of the track will be a focus for heavy rain given the anomalously deep moisture and strong upward vertical motions aided by phasing or merging of the post tropical system with a synoptic upper trough, but the good news for area rivers this threat looks to remain well south of the area. In fact based on the GEFS and ECS ensemble mean QPF probabilities we either "beryly" get brushed by rain Tuesday night across the far southeast service area, or completely missed as there`s likely to be a sharp cut-off to the rain shield on the northwest side. Still we have to keep an eye for any adjustments to the track of this system given complexity/extent of the phasing, but it would appear as though the only impacts would be whether it rains or not... i.e. PoPs. In the wake of the departing post tropical Beryl through the Mid Mississippi and Ohio Valleys, a remnant and persistent broad upper trough will linger over the Upper Midwest and continue at least low near daily chances for showers and storms mid to late week. Heading into next weekend, the ensemble guidance supports ridging across the Intermountain West and Mid-Atlantic with weak troughing from the western Great Lakes to the Lower Mississippi Valley. This will keep some chances for precipitation around. There is also signs though that the western ridge /heat dome/ may also try to build toward the region leading to greater summer heat potential. && .AVIATION /12Z TAFS THROUGH 12Z TUESDAY/... Issued at 525 AM CDT Mon Jul 8 2024 We`ll continue to see chances for showers and storms today into early evening with a weak frontal boundary and various outflow boundaries draped across the region. Trying to time these out and determine the most favored TAF sites will be an exercise in nowcasting. In the near term it looks like the river sites will have the best chances for any shra/tsra. This will be handled with VCSH or prevailing shower mention for a time this morning. Additional shra/tsra development is possible this afternoon into evening, but currently looking like the better chances will be east and north of the terminals right now. Conditions in any stronger shra and tsra will drop to MVFR to IFR. Otherwise, predominantly VFR conditions expected although with heating and abundant low level moisture we could see periodic MVFR ceilings develop by mid morning through midday before lifting to VFR. Meanwhile, later tonight with light winds there is the possibility of patchy fog. However, with a light west/northwest wind and likely some higher level cloudiness around confidence is too low for mention at this time. && .HYDROLOGY... Issued at 1225 PM CDT Sun Jul 7 2024 The Mississippi River is currently cresting at and upstream of Camanche, IA. The crest may take 1 to as much as 3 days to pass. From Le Claire to Burlington, the respective crests will commence within the next 1 to 2 days. Keokuk is now forecast to crest within Moderate Flood category beginning Friday. The crest at Gregory Landing is forecast late Friday into Saturday. Tributary Rivers: Heavier rainfall overnight of near an inch upstream of Cedar Rapids has resulted in a slightly higher forecast for the Cedar River at Cedar Rapids. The Watch has been upgraded to a Warning for minor flooding with a forecast crest near 12.2 feet Monday evening. On the Wapsipinicon River at Dewitt, it is near crest around 11.8 feet. It is forecast to remain in moderate flooding category through late on Friday. On the Cedar River at Conesville, minor flooding will continue. It will see a secondary crest near 14.6 feet Wednesday night into Thursday. The Iowa River at Oakville is seeing high water levels due to backwater affects from the Mississippi River. It is forecast to remain near 11.7 or 11.8 feet through midweek and then rise to near 12.1 feet late Thursday into Friday. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...McClure LONG TERM...McClure AVIATION...McClure HYDROLOGY...14