Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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264 FXUS63 KDVN 121038 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 538 AM CDT Sun May 12 2024 .KEY MESSAGES... - Today will be the warmest day of the next 7 with highs in the 80s. Scattered showers and isolated storms are possible late this afternoon into tonight. - Periods of showers and thunderstorms are likely on Monday with the heaviest rainfall amounts anticipated south of I-80. - Zonal flow aloft across the Western to Central U.S. will result in active weather continuing through the next week. && .SHORT TERM /THROUGH MONDAY NIGHT/... Issued at 245 AM CDT Sun May 12 2024 Today Warm and breezy today as low pressure tracks across Lake Superior. Steady SW winds, gusting near 25 mph, will advect much warmer air into the region with highs reaching the low to mid 80s. Humidity will remain comfortable with dewpoints reaching the upper 40s to lower 50s, which will limit afternoon/evening instability. We are still looking at chances for scattered showers and isolated storms late afternoon/evening into tonight. Coverage through the afternoon and evening may remain relatively low (20-30%) due to lack of a focused trigger. HREF has surface-based CAPE peaking around 1000 J/kg with deep layer shear under 30 kts. Therefore do not anticipate severe weather, but a few of the stronger cells could produce localized wind gusts over 40 mph due to a dry sub-cloud layer shown on forecast soundings. A weak cold front dropping in from the NW tonight may lead to slightly higher coverage of rain (30-50%), mainly across northwest and western counties. Monday An upper low on the northern periphery of the subtropical jet is forecast to slowly track from the Southern Rockies to the Lower to Mid Mississippi Valley early in the week. This will keep the local area on the cooler side of the surface low. However, a slower arrival of the system should allow temps to reach into the 70s across the east, with cooler 60s in the west. Occasional showers with isolated storms are expected from Monday morning into Monday night. Dewpoints will continue to trend upward from the weekend, reaching the lower 60s by Monday afternoon which will contribute to 1000-1500 J/kg of SBCAPE. So there is a potential for thunderstorms, especially in areas that can squeeze out some breaks in the clouds. Deep layer shear is weak, limiting the severe risk and SPC has kept the area in a general thunder outlook. NBM chances for measurable rain range from near 60% in the far NW corner of the outlook area to ~90% south of I-80. The 24 hour probability for 0.50" or more of rain has remained consistent, peaking between 50-70% south of I-80 and dropping down to 20-30% near Highway 20. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Issued at 245 AM CDT Sun May 12 2024 Tuesday: Shower chances will continue at least through the morning hours as the vertically stacked system tracks across central and southern Illinois. Otherwise, we`ll have breezy NE winds and seasonable temps in the upper 60s to low 70s. Wednesday - Saturday: Ridging aloft and surface high pressure is forecast to build in later Tuesday into Wednesday, leading to a break in the wet weather. The next system to impact the region arrives by late Wednesday into Thursday, bringing another round of widespread rain to the outlook area. Once again there is uncertainty on how quickly this system pushes to our east. The NBM has a chance for rain (30-40%) continuing through Friday which is reasonable given the model discrepancies. Forecast temperatures late in the week are near to slightly above normal. && .AVIATION /12Z TAFS THROUGH 12Z MONDAY/... Issued at 530 AM CDT Sun May 12 2024 VFR is expected today with SW winds increasing by mid/late morning. There is a chance for scattered showers and isolated thunderstorms this evening into tonight. Due to low confidence on areal coverage, mentioned showers in PROB30 groups for CID and DBQ late in the period. && .HYDROLOGY... Issued at 833 PM CDT Sat May 11 2024 Latest forecast this evening for the Wapsipinicon River near De Witt has a slower rise by several tenths of a foot. However, minor flooding is still expected but a little later now on Tuesday May 14th. Given how the initial crest was lower and attenuation of routed flow confidence is dropping, confidence is low in just how high above flood stage the river will get. Will continue the Flood Warning with this issuance. In addition, the forecasts on the Cedar and Iowa Rivers have lowered at Conesville and Marengo. Both sites now just touch flood stage on Wednesday. Will continue the flood watches for now, but if trends continue in the coming days the flood watches may need to be cancelled. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...Uttech LONG TERM...Uttech AVIATION...Uttech HYDROLOGY...Gross