Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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193 FXUS63 KDVN 120518 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 1218 AM CDT Fri Jul 12 2024 .KEY MESSAGES... - Isolated to scattered showers and thunderstorms continuing this evening, with slow movement producing locally heavy rain and possible flooding. - Becoming very warm and humid this weekend and into next week, with heat indices in the upper 90s and low 100s. Heat headlines may eventually be needed Sunday and Monday. - Ring of fire pattern early next week may bring strong/severe thunderstorms close to the forecast area and temporary relief from the heat. - Moderate to major river flooding continues on the Mississippi River with most sites crested or cresting in the coming days. && .SHORT TERM /THROUGH SATURDAY/... Issued at 232 PM CDT Thu Jul 11 2024 Tonight...Upper level trof axis seen on water vapor(WV) imagery edging along and east of the local area still driving isolated to wdly sctrd showers and a few thunderstorms acrs the area until early to mid evening with low shear but buoyancy of 1000-2000 J/kg MUCAPEs. Locally heavy rain and ponding water possible out of these slow movers, and along lingering boundaries may still have to watch for funnels. Otherwise, clearing skies and light easterly sfc wind regime with moist sfc layer may foster at least some patchy fog development late tonight and will put mention in the grids. The southern CWA will look to be more favorable for fog but will place it area-wide. A cooler night with plenty of low temps in the lower 60s, and even some upper 50s possible acrs NW IL. Friday...Looking like a typical mid July day with some sunshine, although retreating elevated smoke layers from the southwest may filter the insolation some. Looks dry with no POPs warranted through 00z Sat. Friday night, more signals coming in for a convergent 10-20 KT southwesterly LLJ to produce sctrd elevated convection acrs the area later Friday night. Early signs of storm layer shear and thermodynamics suggest at least small hail may be possible with this activity, and possibly larger. With ongoing LLVL return flow, a milder overnight period as well with lows in the mid 60s to around 70. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Issued at 232 PM CDT Thu Jul 11 2024 Saturday and Sunday...While heat dome ridge continues to align up the western plains, steering west-northwesterlies aloft angle from the northern plains to the southwestern GRT LKS and northeastern OH RVR Valley. At the sfc locally, the main warm front continues to look to retreat northward acrs the local area Saturday, with ambient temps warming into the upper 80s to near 90. Some EML/capping may try to keep a lid for a mainly dry day, but still can`t rule out an isolated shower or storm. A better chance may come Sat night, either in the form of an upstream MCS dropping acrs the area out of the northern plains feed on thermal gradient of incoming high THTA-E pool. Another scenario is that a southwesterly LLJ may converge and blow up convection overhead and then bleed eastward into Sunday morning. Or the EML is firmly in grip acrs the local area and the warm front is far enough north to keep the storm clusters/systems off to the north acrs MN and WI. Depending on what occurs Sat night and rate of decay of resultant convective debris, Sunday is still shaping up to be a full tilt warm sector day with ambient temps in the low to mid 90s and low to mid 70 sfc DPTs for Heat Index`s worthy of heat headlines. Sunday night will continue to be the same story, if we are on the edge of the "Ring of Fire" and suspect to storms in or near the area, or very warm and breezy with the storm track shunted further to the north. With the extent of available CAPEs these storm complexes will have to utilize, damaging winds and heavy rainfall will be primary threats into early next week. Monday and Tuesday...Looking at the latest suite of ensembles continue to partial ring of fire pattern along and north of the CWA early next week, so a combo of heat in between the storm chances, with Monday looking like another possible Heat Advisory day if convective debris and storm outflow boundaries don`t get in the way for a long enough duration. Tuesday a low confidence day with the potential for a southward shunt Wednesday and next Thursday...Longer range jet stream patterns and synoptic scale feature flux trends suggest a western upper ridge retrograde, enough so for higher amplitude northwesterly flow aloft(to near meridional into the NW GRT LKS) to allow for Canadian anti-cyclone dumps into the upper Midwest mid to late next week. It may mean more showers/storms in the transition on Wednesday, but then the flood gates look to open for cooler and less humid Canadian air to infiltrate the region from the north. So a much needed pattern change and weather regime may be in store for later next week. && .AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... Issued at 1218 AM CDT Fri Jul 12 2024 A quiet day and evening are expected for aviators before some thunderstorm chances arrive overnight. High pressure over the area through daybreak with moist boundary layer conditions will allow for the likelihood of some fog. Spotty IFR visibility is possible (20% chance at TAF sites), though fog will not be as noteworthy in coverage or density as yesterday morning. Southeast winds will be primarily less than 10 kt today. && .HYDROLOGY... Issued at 232 PM CDT Thu Jul 11 2024 The Mississippi River continues a broad crest or just starting to fall from crest at major levels from upstream of Camanche, IA, and through Illinois City. The crest may take 1 to as much as 3 days to pass. From south of IL City to Burlington, the respective crests will commence within the next 1 to 2 days. Keokuk is now forecast to crest within Moderate Flood category Friday night into Sat. Gregory Landing is forecast to remain near 19.5 feet through the week. Tributary Rivers: On the Cedar River at Conesville, minor flooding will continue. It is starting to fall from it`s recent crest early this morning. The Wapsipinicon River at Dewitt is forecast to remain in moderate flooding category through late Friday. The Iowa River at Oakville continues to experience high water levels due to backwater affects from the Mississippi River. It is forecast to rise to near 12.1 feet into Friday. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...Friedlein LONG TERM...12 AVIATION...Haase HYDROLOGY...12