Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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631 FXUS63 KDVN 180805 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 305 AM CDT Wed Sep 18 2024 .KEY MESSAGES... - Above normal temperatures continue through Saturday. - Active weather returns to the area Thursday night through early next week. Confidence remains low in the timing of rain chances. - There is low risk of severe thunderstorms west of a Manchester to Fairfield Iowa line late Thursday afternoon into the evening. && .SHORT TERM /THROUGH WEDNESDAY NIGHT... Issued at 218 AM CDT Wed Sep 18 2024 Tranquil weather continues across eastern Iowa, northwest Illinois and far northeast Missouri through Wednesday night. Temperatures at 2 AM range from 53 degrees at Macomb to 61 degrees at Dubuque and Fairfield. At 500 MB, we continue to sit west of ridging centered over the eastern Great Lakes and a closed low anchored along the spine of the central Appalachians. This will bring quiet weather to the area through the period. High temperatures today will be very similar to the last several days and generally be in the mid to upper 80s. A 250 MB jet streak associated with a closed 500 MB low over Montana is forecast to move into Minnesota Wednesday night and may lead to increasing cloud cover Wednesday night as showers and storms develop to our west and move into central Iowa overnight. This will lead to slightly warmer low temperatures Wednesday night with temperatures dropping into the lower 60s. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Issued at 218 AM CDT Wed Sep 18 2024 The breakdown of the synoptic pattern that has been with us for several days begins on Thursday as the Rex Block to our east finally weakens and moves eastward and ridging across Texas rebounds northward across the Plains. This will be shortlived as a disturbance passing to our north will bring the risk of showers and storms to the area Thursday night. There is a substantial instability gradient across Iowa with quickly decreasing values as you to move into eastern Iowa and northwest Illinois. Models also show deep layer shear of around 30 knots. If storms develop to our west and move into our area they look to be weakening as they move into the lower instability environment. There are timing differences between the models and that could play a role in the severe threat. For now, SPC has a Marginal or level 1 out of 5 Risk of severe storms west of a Manchester to Fairfield line. The main threats will be hail and damaging winds. Active weather continues Friday into early next with zonal west to east flow across North America. There are two closed 500 MB lows that will bring chances of showers and storms to the area during this time period. The first passes to our north Saturday into Saturday night. The second will lift from the southern High Plains and cross the area Sunday into early next week. Models continue to disagree on the timing and placement of these storms and any interaction between the two late this weekend into early next week. This continues to result in broad brush POPS across the area through the period. This will also result in cooler high temperatures especially Sunday into early next week. && .AVIATION /06Z TAFS THROUGH 06Z THURSDAY/... Issued at 1214 AM CDT Wed Sep 18 2024 VFR conditions will continue through the TAF period with eastern Iowa TAF sites on the western edge of high pressure across the Great lakes and New England. Light easterly winds tonight will become southerly around 5 to 10 knots during the day and then become light and variable during the evening. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...Cousins LONG TERM...Cousins AVIATION...Cousins