Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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309 FXUS63 KDVN 051014 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 514 AM CDT Fri Jul 5 2024 ...Updated for 12z Aviation... .KEY MESSAGES... - Isolated to scattered showers today (mainly PM). - Periodic chances for rain/storms through early next week with temperatures near to a little below normal. - Moderate to Major River Flooding continues. && .SHORT TERM /THROUGH TONIGHT/... Issued at 315 AM CDT Fri Jul 5 2024 Last of the low level WAA band of showers and storms is exiting our NW Illinois counties early this morning. Light winds and abundant moisture aided by recent rainfall will lead to some fog, dense in some areas particularly across portions of E Iowa north of I-80 and NW Illinois north of I-88 per obs, reports and Nighttime Microphysics satellite imagery. The fog may persist until winds begin to pick up from the west toward daybreak as the front passes. Otherwise, focus for later today will shift to an upper level low on water vapor imagery over Minnesota. As this low tracks eastward today it will usher in a surface cold front. Attendant wrap around cool advection and a bump in the surface gradient will contribute to at times breezy NW winds today and burgeoning stratocumulus. Cyclonic vorticity advection will also foster isolated to scattered showers, burgeoning this afternoon as steepening low level lapse rates coincident with peak diurnal heating allow parcels to tap the tall skinny SBCAPE profiles. This could lead to a few brief/pulse storms as hinted at in ECMWF lightning flash density forecast. With WBZ heights progged sub 10kft AGL can`t totally rule out some brief small hail with the strongest cores. The shower activity will diminish this evening with the loss of diurnal heating and NVA building in. Highs today will be modulated by the extent of solar insolation. The greatest duration is anticipated across our southern counties pushing highs in the upper 70s to lower 80s, while the lowest duration far north/west should limit highs there to around 70 or the lower 70s. Lows tonight under clear to partly cloudy skies will generally be in the upper 50s to lower 60s. A few mid 50s are possible portions of NE Iowa, with any duration of BL decoupling and clear skies being in closer proximity to surface ridging. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Issued at 315 AM CDT Fri Jul 5 2024 The active pattern is expected to continue through early next week. A developing broad longwave trough over the Northern Plains/Upper Midwest will shuttle several shortwaves through the region leading to periodic chances for showers and storms. Sunday into Monday looks to be the period that harbors the greatest shower/storm potential aided by diurnally building instability and a stronger mid level wave. At this time not seeing any anomalously high PWAT or excessive rainfall signal in NAEFS or ENS, which is good news given the ongoing moderate to major river flooding. There`s also signs that we could be looking at a drier pattern evolving mid month, as the deterministic and ensembles are starting to agree on a more amplified western CONUS ridge and an eastern CONUS trough. Between northwest flow and potential of the ridge spilling over at times into the central CONUS, a drier pattern may evolve while some periods of typical summer warmth/heat possible with any ridging episodes. This is eluded to in the very recent 8-14 day outlooks from CPC and also the most recent Weeks 3-4 outlooks. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 510 AM CDT Fri Jul 5 2024 IFR to patchy LIFR conditions predominantly in low clouds at DBQ may abate for a time through sunrise then redevelop with heating by mid morning before ceilings gradually lift to MVFR, and eventually VFR this afternoon. Elsewhere, VFR conditions are expected to start but stratocumulus with MVFR to lower VFR ceilings will develop with surface heating before eventually becoming all VFR this afternoon. In addition, isolated to scattered showers (20-50% chance) will develop toward midday and through this afternoon with diurnal peak heating and an approaching disturbance. This has largely been handled with VCSH and PROB30 mention. An isolated storm is possible, but too low of confidence to include. West winds will turn northwest and become gusty at 10-20+ kt today. Tonight, clouds should gradually dissipate and winds diminish with the loss of heating and passage of the disturbance. && .HYDROLOGY... Issued at 255 PM CDT Thu Jul 4 2024 The forecast crests along the Mississippi River have been delayed and are now showing a longer duration crest at several locations due to some rainfall and forecast rainfall upstream. Most of the crest values have been steady or only minor changes. Major flooding will be seen across much of the Mississippi River with long duration crests occurring after July 7th. Keokuk is expected to get to the Major Flood stage near the 7th or 8th, and Gregory Landing is expected to crest in its Moderate flood category. Tributary Rivers: Over the next 7 days, Moderate flooding will continue on the Wapsi at Dewitt and minor flooding will continue at Conesville on the Cedar River. Wapello on the Iowa River is expected to drop out of flood late Sunday. At Oakville, backwater from the Mississippi will keep the level high, in minor flooding, through July 11. Current projections for additional rainfall through July 10th appear to be spotty with widespread heavy rain not anticipated at this time. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...McClure LONG TERM...McClure AVIATION...McClure HYDROLOGY...14