Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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991 FXUS63 KDVN 071725 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 1225 PM CDT Sun Jul 7 2024 .KEY MESSAGES... - Active/unsettled through early week with periodic showers and storms. - Depending on the track, the remnants of tropical cyclone Beryl could bring rain to far south/east portions of the service area Tuesday night into Wednesday. - Temperatures generally near normal through much of next week. && .UPDATE... Issued at 947 AM CDT Sun Jul 7 2024 The weak upper wave helping trigger high based showers and a few thunderstorms over southern/southeast Iowa is also spreading extensive cloud cover over the entire CWA. This slow moving feature appears likely to bring at least some scattered showers over the entire area today, but also, seems to keep us from seeing daytime sun, except in the southeastern counties. I`m going to lower highs to the upper 70s in the central and northern CWA, on the next update, and continue pops in the 30-60 percent range as is. ERVIN && .SHORT TERM /THROUGH TONIGHT/... Issued at 333 AM CDT Sun Jul 7 2024 Broad mid/upper level troughing extends from the Northern Rockies to the western Great Lakes early this morning. Embedded within was a pronounced shortwave over eastern North Dakota and western Minnesota. Additional smaller perturbations with some convective augmentation were noted in water vapor imagery shifting east from the Missouri River Valley, and also lifting from south central to northeast Iowa. These lower amplitude waves will continue to foster chances for showers and storms today, initially greatest coverage north/west of the Quad Cities but evolving near QC metro to southeast Iowa later this morning into early PM. Sub-severe gusty winds are possible with outflows, and with convective augmentation of shortwaves we may have to also watch for some wake low potential. We could see a period of decreasing coverage of showers/storms by mid to late afternoon if timing of the waves holds. This evening/tonight, additional shortwave energy noted upstream across portions of eastern Colorado/ Nebraska will shift eastward through the mean trough axis bringing a renewed increase in shower/storm coverage aided by vorticity advection and a strengthening 20-30 kt LLJ and attendant warm/moist advection. Deep layer shear looks marginal at 20-25 kt 0-6km to preclude an organized severe weather threat, however given progged steep low level lapse rates and around 1000-1500 j/kg of CAPE 0-1km we may need to keep an eye out for some gusty winds potentially near severe especially if shear can be augmented by the approaching wave to foster more robust updraft potential. 00z HRRR neural network interestingly does highlight some very low probabilities of 50+ kt wind gusts south/west of the Quad Cities 22z-02z, and 00z HREF ensemble max gusts show potential for 50-60 kt. Low confidence on occurring but something to monitor for should the kinematic and thermodynamic environment become conducive. Localized heavy rain amounts of 1 inch or more are possible with any slower moving or repeated storms. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 333 AM CDT Sun Jul 7 2024 We continue with an unsettled/active early week period, as the positively-tilted mid/upper level trough progresses eastward toward the western Great Lakes by Tuesday. A series of shortwaves will continue to traverse the region along the SW to NE oriented flow aloft. These disturbances coupled with a SW LLJ and forcing along a slow moving cold front will foster periodic showers and storms, especially near and east of the Mississippi River into Tuesday. Locally heavy rains are possible with any repeated or slow moving activity, while the organized severe weather threat appears low. The progression of the broad mid/upper level trough will play a pivotal role in determining whether or not we see any rain and potentially gusty winds from the remnants of TC Beryl Tuesday night into Wednesday. The latest forecast from NHC and super ensemble mean track would take the remnant low from south of St Louis to northwest Ohio Wednesday into Thursday. The surface low tracks from the operational GFS, GEFS mean, and several members of ECMWF ensemble however, show a track further north/west, and closer to the western edge of the NHC forecast cone into northwest Illinois (not something we`re used to seeing!). To try and account for some potential of a more north/west track we`ve collaborated with eastern neighboring offices blending in some CONSAll guidance with NBM to give PoPs a bit of an increase across far SE portions of the service area Tuesday night into Wednesday, although staying in the chance (30-40%) category for now. We`ll continue to monitor the track of Beryl closely in the next 48+ hours, so stay tuned for updates. Heading into late next week and 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, although nothing too widespread/organized and perhaps more isolated diurnally driven. Temperatures should remain near normal into late next week, but by next weekend and just beyond there are some signs that the western ridge /heat dome/ may try to build toward the region leading to greater summer heat potential. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 1225 PM CDT Sun Jul 7 2024 VFR conditions will largely dominate, but there will be scattered shra/tsra throughout the TAF period accompanied by MVFR to IFR conditions (mainly for visibility). Outside of outflow near storms winds will generally be light from a southerly direction. The main period where showers and storms appear possible is during the late evening and overnight hours, after which, a period of MVFR cigs is more likely (50-70%). && .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. && $$ UPDATE...Ervin SHORT TERM...McClure LONG TERM...McClure AVIATION...Ervin HYDROLOGY...14