Area Forecast Discussion
Issued by NWS Chicago, IL

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000 FXUS63 KLOT 261110 AFDLOT Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 610 AM CDT TUE JUL 26 2016 .SHORT TERM... 332 AM CDT Through Wednesday... Progressive westerly flow aloft will continue today, but with surface high pressure in place expect just some afternoon cumulus development today and some passing high clouds. Highs again will reach the mid to upper 80s with the lake breeze keeping conditions slightly cooler lakeside. A cold front across the Canadian/U.S. Border will move southeast tonight into Wednesday, reaching Central Wisconsin and adjacent Lake Michigan late Wednesday afternoon. An upper level disturbance across the Northern Rockies looks to trigger showers and thunderstorms across the plains, and also across Wisconsin closer to the cold front where a weak to modestly unstable atmosphere will exist. Locally, surface high pressure will still hold, and thus expecting somewhat of a repeat on Wednesday, with the exception being increased clouds, and possibly a shower or isolated storm sneaking into Northern Illinois late in the day. The cold front, aided by the frictionless lake, will move into the area Wednesday night. The aforementioned upper level disturbance will move east across the boundary during this time, possibly leading to a few showers and thunderstorms during the evening time frame, with areas north of I-88 favored as the upper forcing will mainly move east through Wisconsin. KMD && .LONG TERM... 332 AM CDT Thursday through Monday... Cooler conditions will be the rule Thursday through the upcoming weekend, and there could be a few periods of showers and isolated storms Thursday through Saturday as broad upper troughing takes hold of the region. Gradual drying out and warming will ensue into early next week as an upper ridge restrengthens across the Corn Belt. KMD && .AVIATION... For the 12Z TAFs... High pressure will lead to very quiet weather conditions. VFR cumulus will develop this afternoon and then dissipate this evening. Winds will remain light and variable away from the lake, while winds along the lake will be east less than 10 kt. Winds become variable again this evening and remain light and variable through Wednesday morning. Guidance hints at low cigs and fog overnight, but thinking we will dry out enough today that fog and low cigs will not develop overnight. JEE && .MARINE... 252 AM CDT High pressure currently over Iowa shifts east today. Onshore flow is expected across the southern end of the lake while winds will be southwest at 10-20 kt over the northern end. Winds veer and diminish into Wednesday morning. A cold front pushes down the lake Wednesday, and winds become north and northeast behind it. Guidance suggests winds may increase to 10-20 kt along the front Wednesday night. The pressure gradient tightens over the lake Thursday afternoon as low pressure shifts northeast over IL. Northeast winds will increase to 10-20 kt Thursday afternoon and night. The low passes south of the lake Thursday night through Friday morning. Winds remain northeast through Saturday and then become south or southeast as another high pressure system spreads over the lake over the weekend. JEE && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO

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