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139 FXUS63 KDVN 242337 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 637 PM CDT Thu Apr 24 2025 .KEY MESSAGES... - Isolated showers/storms possible this evening, but the main round of showers and storms is expected later tonight into Friday morning. Severe storms are not anticipated. - Seasonable weekend with cool nights on tap - Severe storms are possible early next week. && .SHORT TERM /THROUGH FRIDAY NIGHT/... Issued at 254 PM CDT Thu Apr 24 2025 Tonight...The latest sfc analysis was indicating a weak boundary undulating acrs the northern and western CWA, with warm ambient temperatures in the mid to upper 70s/80. Some instability out there indicated by the cellular CU field, and there may be a chance for an isolated shower or storm developing in this field through early evening. But the MCV noted in current water vapor imagery acrs central/eastern NE will interact with a better pool of instability acrs the MO RVR Valley to spawn storm clusters or even an MCS type feature out that way this evening. As the MCV and 20-30 KT southwesterly LLJ gets induced ahead of it and migrates eastward acrs IA, so should the storm clusters. But weaker shear and mid layer MUCAPEs over this way should make for a general weakening trend as they arrive from west-to-east thus hopefully limiting much of any severe threat locally late tonight. However, still feel there could be some marginally strong cells in the southern CWA after midnight with hail and gusty winds. PWAT feed of an inch or more will fuel more locally heavy downpours, but the true heavy rain threat lies off to the west of the local area of concern acrs western into central IA in higher convergent/moisture feed zones. But still see many areas receiving 0.25 to 0.75 of an inch by Friday morning. Isolated 1 inch amounts on the IA side. Frontal placement will help low temps range from the upper 40s north, to the upper 50s south. Friday...Will walk out the lingering showers off to the east by late morning, with then increasing post-frontal north winds increasing to 10-20 MPH by the afternoon. Temps continue to range from north to south as the similar oriented LLVL baroclinicity slips southward. Friday night looks cool with cloud clear off and ongoing CAA. Lows in the 40s and even some upper 30s possible in the north. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Issued at 254 PM CDT Thu Apr 24 2025 Saturday and Sunday...Backdoor sfc high, along with incoming upper ridging will continue to a fair and rather seasonable Saturday with highs in the 60s. Sat night will look to be on the cool side in the low 40s and upper 30s. May have to watch areas that are under the influence of the ridge longer such as northwest IL where we may dip into the mid 30s and have possible patchy frost. On Sunday as we get on the other side of the progressing ridge axis, elevated return flow may spawn more showers and storms trying to spread in from the west. But the lingering ridge effects and dry air may erode incoming activity from the west until there`s better support later Sunday night. It may also shunt the better precip chances to the north and northwest, but we may still have to deal with decay debris/clouds in some portions of the local area. Still a warmer day Sunday with highs in the upper 60s to low 70s. Monday through Wednesday...Medium range ensembles continue to show a large piece of the upstream long wave acrs the western Rockies ejecting out acrs the plains and upper Midwest Monday into Tuesday. Plenty of conceptual synoptic scale features suggest this system may be a severe weather maker, but some of the trends such as positive tilt to the main upper wave and pre-system deep southwesterly uniform flow maybe not so tornadic looking at this time. Also like the previous shift stated, at this far out still plenty of phasing and timing issues to better define in the coming days, with the energy center still well off the west coast. Monday looks to be full blown warm sector with gusty south winds and strong WAA, pumping temps into the 80s and sfc DPTs in the 60s. So CAPEs will be there for the kinematics, again it`s timing and placement. This scenario will bleed into Tuesday with the frontal timing. Current ensembles that strike our area with Monday evening and overnight storms, then progress the front through eastward enough for Tuesday convective redevelopment east and southeast of the DVN CWA. System wake ridging following the cyclone would bring about dry cooler weather into the mid week period. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 633 PM CDT Thu Apr 24 2025 Isolated SHRA/TSRA will dissipate with sunset. A slightly stronger disturbance will initiate new SHRA/TSRA across eastern Iowa and into northern Illinois after 05z/25. Scattered nature of the convection has the potential to bring periodic rounds of MVFR conditions to TAF sites through 12z/25. After 12z/25 any lingering convection will move out with MVFR/IFR conditions overspreading eastern Iowa and northern Illinois. && .HYDROLOGY... Issued at 1022 AM CDT Thu Apr 24 2025 With recent bouts of heavy rainfall, and possibly more tonight with increased run-off especially in the upper basins of the Iowa, Wapsi, and Cedar Rivers, these rivers will likley experience significant in- bank rises. Some points and stretches of these rivers may also surpass action stage and even the flood stage into the weekend. But there is still some uncertainty with respect to tonight`s placement of additional heavy rainfall amounts, as well as associated extent of run-off. Since there is still some time to assess these factors before the potential crests occur, have issued river flood watches for the Wapsi at De Witt, and the Iowa River at Marengo. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...12 LONG TERM...12 AVIATION...08 HYDROLOGY...12 |
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