Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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969 FXUS63 KDVN 060849 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 349 AM CDT Sat Jul 6 2024 .KEY MESSAGES... - Turning unsettled once again with periodic showers and storms tonight 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 331 AM CDT Sat Jul 6 2024 Fairly tranquil conditions and seasonable temperatures are being found early this morning and will persist throughout today, as heights aloft undergo a bit of amplification between a Great Lakes upper trough and an approaching shortwave diving into the Northern Plains. Highs today should top out from near 80 to 85F with a SCT-BKN cumulus deck. PoPs are not zero with building instability and steepening lapse rates this afternoon, but the lack of a coherent trigger and rather shallow moisture profiles keep PoPs below mention. Tonight, cyclonic vorticity advection ahead of the approaching Northern Plains shortwave and moisture advection attendant to a veering 30+ kt low level jet will lead to chances (40-60%) for showers and storms by late evening and especially overnight, mainly north and west of the Quad Cities. Severe weather is not anticipated, but some gusty winds may be possible from a waning cool pool off decaying remnants of more organized convection to our west, as hinted at by some of the CAMs. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Issued at 331 AM CDT Sat Jul 6 2024 A quasi-omega block is forecast through early next week, with a series of shortwaves traversing along the SW to NE oriented mid/upper flow ahead of a mean upper trough over the Upper Mississippi Valley. This will keep the pattern unsettled owing to periodic showers and storms through at least Monday and possibly into Tuesday. PoPs will be high at times (60+%), but placement will vary pending the track of the shortwaves and 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 juxtapositioned 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 remant 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 /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1210 AM CDT Sat Jul 6 2024 VFR looks to be predominant through the TAF cycle, although periods of MVFR ceilings and/or visibility is possible toward daybreak and through Saturday morning mainly at KDBQ between valley fog and some advective potential of stratus from southern Wisconsin. Can`t also rule out a very brief MVFR ceiling at KMLI mid to late morning before mixing promotes lifting of cumulus bases. Late in the period we may see some convection approach eastern Iowa, but the better potential exists primarily after 06z-12z Sunday for portions of the area. Winds will remain light throughout generally favoring from a W/NW direction today, then becoming southerly tonight. && .HYDROLOGY... Issued at 1141 AM CDT Fri Jul 5 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 in timing. Major flooding is forecast along most of the Mississippi River. 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 Wapsipinicon River at Dewitt and minor flooding will continue at Conesville on the Cedar River. A flood watch remains in effect for the Cedar River at Cedar Rapids due to rises from routed flow and forecast rainfall. Wapello on the Iowa River is expected to drop below minor flood stage this afternoon. At Oakville, backwater from the Mississippi will keep the level high, in minor flooding, through July 11. Within banks rises are occurring on the English River at Kalona and on the North Skunk River at Sigourney. Over the next seven days widespread heavy rain is not expected. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...McClure LONG TERM...McClure AVIATION...McClure HYDROLOGY...Cousins