Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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158 FXUS63 KILX 181043 AFDILX Area Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 543 AM CDT Thu Jul 18 2024 .KEY MESSAGES... - Seasonably cool and dry into the weekend, with high temperatures in the upper 70s to low 80s which is 5 to 10 degrees below normal. - Precip chances return throughout next week, with a 20-50% chance each day. && .DISCUSSION... Issued at 201 AM CDT Thu Jul 18 2024 An expansive 1024-mb sfc high pressure was centered over Minnesota early Thursday morning, and this sfc high will slowly shift southeast becoming centered over Illinois by Friday morning. With this broad sfc high pressure in control, conditions will be seasonably cool and dry through the weekend. Today will be the coolest day of the stretch, with highs peaking in the upper 70s, then gradual warming occurs through the weekend as highs return to the low 80s, which is still below normal. By the weekend, guidance continues to depict a slow-moving, closed upper low developing west of the area on Saturday. This upper low meanders about for a few days, with its associated forcing progged to stay far enough west that the ILX CWA stays dry through the weekend. Eventually though, that forcing shifts east and provides a chance for showers/storms (20-50% chance, highest south of I-70) early next week (Mon-Wed). The forecast PWAT values have trended higher, and are now progged to be near seasonable values (1.5") on Mon. Both PWAT and instability values gradually trend higher each day next week, but the instability values are still seasonably low, generally near or below 1000 J/kg each day Mon-Wed. Deep layer shear also looks weak, with 500 mb flow around or under 20 knots, and thus severe storms continue to appear unlikely. Given the increase in PWAT values and the potential for light flow in the cloud bearing layer, slow storm motions (less than 15 mph) could lead to localized instances of heavy rainfall. At any one location, the odds of heavy rainfall are low, with only a 10-20% chance of exceeding 1" of rain through next Thurs AM. Around mid-week, a stronger shortwave digs towards the upper Midwest, resulting in continued forcing for precip Wed night- Thurs. With continued upper troughing over the Great Lakes, temps are favored to stay near or below normal into the latter half of next week. Erwin && .AVIATION... (For the 12z TAFs through 12z Friday Morning) Issued at 542 AM CDT Thu Jul 18 2024 VFR conditions prevail through the period, with no precipitation expected. Light winds start off northerly but gradually turn to northeasterly today, with speeds below 10 knots. Scattered diurnal Cu is possible during the day, around 4-5kft. Tonight, winds will generally remain out of the northeast but fall below 5 knots, becoming variable at times. Erwin && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$