Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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860 FXUS63 KDVN 181810 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 110 PM CDT Sat May 18 2024 .KEY MESSAGES... - Scattered showers and storms will wane after sunset tonight. There is a Marginal risk (level 1 of 5) of severe weather today west of the Mississippi River. - Boundary stalls south of the area as temperatures again reach well into the 80s as chances for thunderstorms return late. - Active pattern returns early next week, with several rounds of storms Monday through Wednesday. Severe weather becoming more a concern on Tuesday.&& .SHORT TERM /THROUGH TONIGHT/... Issued at 109 PM CDT Sat May 18 2024 Temperatures well into the 80s today were found area-wide. Dewpoints in the upper 50s to low 60s made it feel somewhat nicer than the middle of July. To the west of the area, a cold front was located across the center of Iowa. A shortwave passing north of the area today will drag this front through the area this afternoon and into the evening. The boundary will then stall out across southern portions of the area. This boundary on Sunday will separate the higher moisture air from the drier air. Nonetheless, we will see highs again in the 80s, but with drier air than today. With that boundary in place across the south, we could see some thunderstorms redevelop along the front later in the day and move east towards us late. Most of the impactful weather will likely be ongoing at 00z tonight as the cold front moves through the area. Guidance has CAPE building ahead of the front to around 2000 J/kg this afternoon. Shear looks very weak, so updraft organization is not expected. Pulse like storms are expected if they develop. The main question today is forcing. The main upper level forcing is way north, so the front and daytime heating will be the main drivers for thunderstorm development. CAMs have either a broken line of storms or not much with the exception of the highway 20 corridor. Dprog/Dt of the HRRR shows run to run variability with some having convection down to highway 30 the rest further north. The NAMnest has convection all the way through the CWA. Think the best chance for storms is highway 20 north. In a nod to the NAMnest, did keep schc south through I80. Am not too big on severe today. Could see near severe wind gusts and hail, especially due to the steeper lapse rates, but don`t expect cells to have much longevity to really get going. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Issued at 329 AM CDT Sat May 18 2024 An active southwest flow weather pattern will develop early next week, with several waves moving through the local area. Timing and strength of these waves still differs from model to model and run-to-run. However, the 00z ensembles still suggest that Monday and Tuesday will have the potential for severe weather with plenty of CAPE/Shear for storms to work with. The 00z GEFS supercell composite parameter shows values of 3-5 for Monday/Tuesday. Additionally, the 12z ECMWF EFI also continues to show values around 0.7 for the CAPE/Shear combination for 00z Wednesday. These all point to a severe weather risk each day. SPC has now outlined our entire area in a Day 3 Marginal risk (level 1 of 5) on Monday. Strong capping aloft may prevent much activity locally until late Monday evening and overnight where an MCS may develop just to our west and propagate east into our CWA. Tuesday...this period is becoming more of one to monitor in the coming days. A warm front will lift north across the CWA in the morning, placing us in the warm sector. With a deepening surface low and trough lifting northeast, strong thermodynamics and kinematics will be in play by the afternoon and evening allowing for convection to rapidly develop possibly into a linear QLCS. All modes of severe weather will be possible and more details to come in later updates. In addition, some heavy rainfall will be possible with this event, with PWs around 1.5 to 1.7 inches, which would be above the 90th percentile for this time of year. Wednesday On...additional showers and storms will be possible late week. However, model timing differences in shortwaves moving through the flow precludes changing the PoPs, which are in the 15 to 30 percent range for each 6 hr period through Friday. There will be some dry hours, but when this will occur is still in question. Temperatures will return to more seasonable values by late week, with highs in the 70s and lows in the 40s. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 109 PM CDT Sat May 18 2024 VFR conditions are expected through the period. Winds will slacken tonight and then could become gusty again later in the period. There is a very low (<20%) chance for thunderstorms at CID and DBQ this afternoon. There are disagreements between guidance about this occurring. As such, have left out of the TAFs at this time. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...Gibbs LONG TERM...Gross AVIATION...Gibbs