Area Forecast Discussion
Issued by NWS Chicago, IL
Issued by NWS Chicago, IL
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364 FXUS63 KLOT 062019 AFDLOT Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 319 PM CDT Sat Jul 6 2024 .KEY MESSAGES... - Mostly dry conditions are expected, but cannot completely rule out a brief pop-up shower early this evening. - Chance (25-45 percent) of showers and thunderstorms Sunday, mainly northwest of a La Salle to Lake County line. Slight chance (15-25 percent) southeast of that line. - Continued periods of unsettled weather Sunday night-Tuesday afternoon with periodic showers and thunderstorms, highest chance/coverage on Monday. - Seasonable temperatures will continue for the coming week. && .DISCUSSION... Issued at 316 PM CDT Sat Jul 6 2024 Through Sunday... Overcast skies have kept most locations in the upper 70s to around 80 early this afternoon, and a lake breeze pushing west through the metro area has supported some even slightly cooler temperatures. Sunday, with more sunshine expected, looks to be several degrees warmer with a bit more humidity as well. The exception would be toward the Rockford area where shortwave energy exiting the base of a shallow upper trough would support increased cloudiness and scattered showers or thunderstorms. It is possible that some of these showers could also work east toward the Chicago metro during the afternoon or evening. Elected to maintain just a slight chance mention in that region for now. However, more favorable mid-level lapse rates and low level moisture profiles do spread across the area later in the day as southerly surface winds turn southwesterly for a while and tap into the better moisture to our west. Sunday Night through Saturday... The weakly forced and seasonably mild pattern...at least by July standards...continues into the early part of the coming week. On Monday a frontal zone to our west makes very slow progress toward our area but increases the overall low level moisture convergence. Lapse rates don`t look overly impressive but should be enough to support scattered thunderstorms, especially by the afternoon. The lack of strong forcing along with generally unidirectional SW wind profiles would not appear to pose a severe threat, but the possibility of flooding may need to be monitored if storms manage to track repeatedly across the same area. As with Sunday, the greatest concern would be for the northwest half of the forecast area. The weak front...maybe more of a surface trough...moves through the area Tuesday. Surface winds turn west then northwest but copious low level moisture remains in place, which in conjunction with the upper trough trailing the front will support ongoing chances (25-45 percent) of thunderstorms into Tuesday evening. Wednesday presently looks quieter with subtle height rises aloft in the wake of the passing trough, but Thursday into next weekend are more of a question. The path of Beryl remnants may play some part in how the rest of the week evolves. Models suggest the low center passes to our south, which could provide the primary focus for convection late in the week. A different track might allow more of the moisture to work farther north. For now will maintain slight chance mentions of precip, with highs very gradually warming toward the upper 80s. Lenning && .AVIATION /18Z TAFS THROUGH 00Z MONDAY/... Issued at 1211 PM CDT Sat Jul 6 2024 Current satellite imagery shows a broad field of diurnal cumulus across the area creating scattered CIGs around 040. A lake breeze has been pushing inland through the late morning and will be across KMDW and KORD by 18Z bringing NE/E winds. Winds will shift to southeasterly tonight before becoming southwesterly tomorrow. Another lake breeze is expected to move across KORD and KMDW tomorrow afternoon. VFR conditions are expected at all terminals through the end of the TAF period although a shower can`t be ruled out tomorrow morning, especially for the Illinois terminals. Carothers && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at weather.gov/chicago