Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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114 FXUS63 KILX 090135 AFDILX Area Forecast Discussion...Updated National Weather Service Lincoln IL 835 PM CDT Sat Jun 8 2024 .KEY MESSAGES... - A low chance (25% probability or less) that isolated thunderstorms develop this evening between 4pm - 9pm; severe weather and/or flooding not anticipated. - Heat stress returns Thursday and Friday as Wet Bulb Globe Temperatures (WBGT) climb to 82F-84F; risk level 4 of 5. && .UPDATE... Issued at 834 PM CDT Sat Jun 8 2024 A precipitationless front extending roughly across the I-72 corridor at 830 pm CDT continues its rather quick trek southeastward across central Illinois, winds veering quickly to northerly in its wake. Still can`t fully rule out a shower along it in the (south)east ILX CWA over the next couple hours, though the guidance which depicts such showers also suggested they would have developed along the cold front by now; in other words, it`s tough to believe the guidance that cried wolf. Pops have consequently been limited to ~15% at most (highest near and east of Champaign) near and south of I-72 with the evening update. Bumgardner && .DISCUSSION... Issued at 1227 PM CDT Sat Jun 8 2024 Afternoon water vapor imagery depicts an upper-level low positioned over Lake Superior with multiple shortwaves digging along its southern periphery. These features will ultimately help drive a surface cold front through central Illinois this evening. While large-scale forcing is better to the north and south of the area, there does appear to be enough moisture convergence along the front to support scattered showers, at least. The CAPE/Shear parameter space is somewhat underwhelming this evening, such that the severe storm risk is low, but there is enough support within CAMs (i.e. HRRR, RAP) to suggest we could see a feisty updraft or two anchored to the front where a few uncapped parcels (SBCAPE 1500 J/kg) coexist with 40 kts of effective- layer shear. While narrow CAPE profiles and straight hodographs should preclude a large hail and tornado risk, the threat for damaging wind is a little better. But again, coverage will be sparse since the more favorable forcing is displaced away from our region. Cooler and more stable air will build into the region Sunday through Monday as an upper ridge and its associated area of surface high pressure keep the pattern quiet. Overnight temperatures Sunday night and Monday night will be on the chilly side, with deterministic NBM guidance offering lows in the upper 40s in some spots. Low-impact weather will persist through the middle of next week, but an influx of heat and humidity is anticipated across the Mid- Mississippi Valley beneath increasing mid-level heights. Recent NBM guidance supports afternoon highs near 90 degF for both Thursday and Friday ahead of the next frontal system. Wet Bulb Globe Temperatures (WBGT), or simply the heat stress index, are forecast to be 82-84 degF which equates to a level 4 of 5 heat risk. Convective chances for next week are muted among blended and ensemble guidance, with PoPs generally below 20%. While we do appear to be entering a drier period, `tis the season for ridge- rider convection. And, with a series of diffuse synoptic fronts dropping through the area next week, it would not be wise for us to advertise a prolonged dry stretch. MJA && .AVIATION... (For the 00z TAFs through 00z Sunday Evening) Issued at 653 PM CDT Sat Jun 8 2024 2330z/630pm satellite/radar mosaic shows a cold front from near KPNT southwestward to KUIN. Winds ahead of the front will remain westerly at both KDEC and KCMI for the next hour or two, then will veer to NW and gust 15-20kt at all terminals through the evening. As the front settles south of the I-70 corridor, winds will further veer to N/NE and decrease to less than 10kt overnight. Patches of low clouds at 1500-2500ft will accompany the front: however, do not think MVFR ceilings will develop. Instead, a large mass of mid/high clouds upstream across Iowa/northern Missouri will stream eastward, resulting in mostly cloudy conditions through much of the night. Clouds will tend to thin/dissipate by Sunday morning, followed by just SCT high clouds through the day. Winds will return to NW and once again gust 15-20kt at the I-74 terminals after 17z/18z Sun. Barnes && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$