Area Forecast Discussion
Issued by NWS Chicago, IL

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000 FXUS63 KLOT 021744 AFDLOT Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 1144 AM CST Tue Mar 2 2021 .SHORT TERM... 216 AM CST Through Wednesday... After yesterday`s blustery and colder conditions, we`ll turn a bit milder today as southwesterly winds return with surface ridging departing to our east. Increased low-level flow at the northern flanks of the departing ridge will support the development of gusty winds later this morning and afternoon, perhaps towards 30-35 mph across northern Illinois, easing somewhat with southward extent. Otherwise, the only item of note during the short term forecast is the potential for a lake-enhanced cold front to approach or even move through a portion of the region on Wednesday. Questions remain, however, regarding the exact timing of the associated north and northeast wind shift, as well as the magnitude of low-level moisture present in the post-frontal airmass. A good portion of our available hires guidance is now suggesting quick saturation of the low-levels will take place through Wednesday morning and afternoon with this boundary surging down the lake and into northwest Indiana and northeast Illinois by early afternoon. Have trended temperatures in this area down a bit, while still holding onto low to even mid 50 degree highs into north-central Illinois where any frontal passage should hold off until after peak heating. The ECMWF remains pretty much cloud-free through Wednesday afternoon, allowing temperatures even near our lakeside locales to rise well into the upper 40s and lower 50s. A decent bust potential exists as a result, but electing to side a bit more with climatology here, while not totally biting on the coldest advertised solutions yet. Carlaw && .LONG TERM... 216 AM CST Wednesday night through Monday... Surface high pressure is forecast to dominate across much of the western Great Lakes Thursday and Friday. This will continue to support onshore winds with cooler temperatures over northeastern IL and northwestern IN both days. Expect lakeshore temperatures to top out mainly in the 30s, with inland areas reaching into the 40s. Thursday could also end up featuring more clouds than currently advertised, which could further knock high temperatures down a bit farther inland. Saturday will start our transition into a warmer pattern as southwesterly return flow re-develops. High temperatures will commensurately increase each day into early next week, with widespread mid and upper 50s becoming more of a possibility by Monday and Tuesday. We`re currently advertising precipitation-free conditions through the end of the official forecast period, but the weather pattern does look to trend more active, especially by the middle and end of next week. Carlaw && .AVIATION...
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For the 18Z TAFs... Quiet weather expected this afternoon with the only notable feature of interest being the breezy southwesterly winds. As these winds ease this evening there will be a marginal threat for LLWS tonight as winds a couple thousand feet off the surface increase into the 40-45 kt range. The best potential for this looks to be on the 03z-09z timeframe. A cold front will then shift southward across the area early Wednesday morning, resulting in a northerly wind shift across the area. While winds should remain light in the wake of this initial front, conditions across the Chicago area terminals could turn a bit more breezy from the northeast during the mid to late afternoon hours as a lake breeze pushes inland. KJB
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IL...None. IN...None. LM...Small Craft Advisory...Winthrop Harbor to Gary IN until 9 PM Tuesday.
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