Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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062 FXUS63 KDVN 221816 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 116 PM CDT Wed May 22 2024 ...Midday Hydrology Update... .KEY MESSAGES... - Dry conditions for most today, with seasonable temperatures and comfortable humidity. There is a slight chance (15%) of a shower/storm along of north of Hwy 20 in Iowa this afternoon. - Active weather returns by Friday and again early next week with increasing shower and thunderstorm chances. There is a Marginal Risk (level 1 of 5) for severe weather on Friday. - The Cedar, Iowa, Skunk, and the Wapsi rivers are expected to rise with some sites going into flood in the next 3-4 days due to the recent 2-5 inch rainfall upstream. && .SHORT TERM /THROUGH THURSDAY/... Issued at 1205 PM CDT Wed May 22 2024 A beautiful early afternoon was unfolding across all of eastern Iowa, northwest Illinois and far northeast Missouri; a nice welcome after yesterday`s active weather. Skies featured mostly sunny skies with temperatures as of noon ranging from the mid 60s to near 70. It was breezy as well with west to northwest winds gusting around 20-30 MPH. 15z surface analysis showed a strong surface low just north of the arrowhead of Minnesota, with high pressure in place across the central Plains. The pressure gradient between the low and high was rather tight and, along with deep boundary layer mixing, was responsible for our gusty winds early this afternoon. Over the next 24 hours, our weather will be influenced by the the surface high as it slowly moves across the Plains into the mid- Mississippi River Valley. Gusty winds will subside late this afternoon and evening, becoming light & variable tonight into much of Thursday. Skies will feature only a few clouds, allowing for more of a diurnal swing to our temperatures compared to previous days. Look for lows tonight in the low to mid 50s (some upper 40s possible in valleys and low-lying areas), with highs Thursday recovering into the upper 70s to lower 80s ahead of strengthening ridging aloft. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Issued at 305 AM CDT Wed May 22 2024 Thursday...quiet and dry conditions will be seen with 850mb temps warming to 13C and southeast return flow boosting afternoon temperatures into the upper 70s and low 80s. Thursday night-Friday...00z models and their ensembles all show a strong upper level wave moving into the northern Great Plains, with diffluent flow developing over the Midwest. Another cold front will track east across Iowa with strong moisture transport expected ahead of it (PWs increasing to 1.5") into the local area. Sufficient shear and instability will present a risk for some stronger storms to develop in the warm sector which may again be over the local area. For this reason, SPC has a Day 3 Marginal (level 1 of 5) risk for severe weather across the entire outlook area. Timing of the fropa will be critical as to what impacts may be seen Friday. The 21.00z run of the Pas Ensemble shows a wide range of solutions ranging to a few storms, a large line of storms, and no storms. Needless to say more details need to be ironed on before Friday. Stay tuned. This Weekend and Memorial Day...00z ensemble data continues to show Saturday as a cooler and drier day across the CWA. Highs in the 70s and lows in the 50s are forecast. The latter half of the weekend and into the holiday is trending more active with two main waves moving through. Will maintain the daily chance PoPs through Monday night, but my confidence in each period seeing rainfall is low and some dry hours should be seen. One thing is for certain, it does not appear to be a hot and humid Memorial Day. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1205 PM CDT Wed May 22 2024 VFR conditions are expected for the upcoming TAF period. Gusty west to northwest winds around 20-25 kts will become light & variable with high pressure moving in this evening. && .HYDROLOGY... Issued at 115 PM CDT Wed May 22 2024 Watch/Warning Changes this Morning: Upgraded the North Skunk River at near Sigourney to Major flood and added the English River at Kalona to a warning with a secondary crest into Minor. Also went to a warning for minor flood category for the Wapsi at Anamosa. Discussion: Rainfall in the past 24 to 36 hours was highest in the Iowa and Skunk river basins near their headwaters where radar estimates and automated gauges reported 2 to 5 inches. The Cedar and Wapsi also received 1.5 to 3 inches in the upper portions of the basins. Because of this, the Iowa River at Marengo and the Skunk River near Sigourney have the best chances of reaching solid Moderate Flood by the end of the week. In fact with a projected run-off boost, there was enough confidence to upgrade the North Skunk to Major flood category. But still the idea that these sites will likely see some attenuation in the routed flow upstream and expect some changes to the forecast in the coming days. Because of this, confidence is lower at some other sites in reaching the currently modeled flood crest and Flood Watches were either continued or held off for one more shift to assess. A few examples are the potential crest into the Major category on the Wapsi near De Witt, and maintain the watch for the Cedar River at Conesville for now. Oakville on the Iowa River may eventually need a watch with crest projections near the flood stage by late Monday night. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...Speck LONG TERM...Gross AVIATION...Speck HYDROLOGY...12