Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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068 FXUS63 KILX 190044 AFDILX Area Forecast Discussion...Updated National Weather Service Lincoln IL 744 PM CDT Tue Jun 18 2024 .KEY MESSAGES... - Seasonably hot and humid weather will prevail this week. The hottest conditions will arrive Friday into Saturday when air temperatures climb into the middle to upper 90s and heat index values peak at 100-105 degrees. - Isolated thunderstorms will be possible from time to time over the next few days...with a better chance for thunderstorms arriving late Saturday into Sunday. && .UPDATE... Issued at 744 PM CDT Tue Jun 18 2024 Extensive cirrus shield remains in place across much of the forecast area, though is more sporadic across the Illinois River Valley. Rainfall has been next to non-existent so far, though a few showers are lifting northward toward the I-70 corridor in south central Illinois. Latest SPC mesoanalysis and HRRR forecast sounding for Effingham show some capping in this area, plus temperatures have been lower with the thicker cloud cover down there. Currently thinking thunder potential is minimal due to the weak instability, though a few showers remain possible in the eastern CWA through evening as a weak upper disturbance lifts northeast out of Missouri. Updated grids recently sent to reflect these thoughts, plus the usual minor tweaks to incorporate latest observational trends. Geelhart && .SHORT TERM...(Tonight through Wednesday Night) Issued at 329 PM CDT Tue Jun 18 2024 Deep-layer moisture continues to flow northward from the western Gulf of Mexico on the back side of a prominent upper high centered over the Carolinas. The corresponding thick cirrus shield has kept temperatures a few degrees cooler than they were yesterday and has limited instability. 20z/3pm satellite imagery shows mostly cloudy skies along/southeast of a Bloomington to Jacksonville line...with sunny skies to the northwest. Cannot rule out a stray shower or storm over the next couple of hours, but areal coverage will remain scant. CAMs are suggesting isolated showers may re-develop overnight across the Wabash River Valley...with showers/storms becoming a bit more numerous further west across Iowa/Missouri in association with a slowing cold front. Overall think most locations will remain dry as low temperatures only drop into the lower to middle 70s. The cold front will become stationary from Iowa into southern Wisconsin/northern Illinois on Wednesday. The strongest forcing and thus the greatest areal coverage of diurnal convection will remain focused just N/NW of the KILX CWA: however, the HRRR continues to suggest widely scattered convection along a pre-frontal trough perhaps as far south as I-72. Have therefore included slight chance PoPs as far S/SE as a Springfield to Paris line...but have focused better rain chances northwest of the Illinois River in closer proximity to the boundary. Otherwise Wednesday will be a hot and humid day with considerably less wind than has been experienced lately. S/SW winds will generally remain in the 10-15mph range as afternoon highs top out in the lower to middle 90s. Barnes .LONG TERM...(Thursday through Next Tuesday) Issued at 329 PM CDT Tue Jun 18 2024 As the upper high retrogrades westward and upper heights rise, rain chances will decrease and temperatures will increase by the end of the week. Latest guidance suggests the hottest period will be Friday and Saturday when high temperatures climb into the middle and perhaps upper 90s in a few spots. Corresponding heat index values will peak at 100-105 degrees...just shy of Heat Advisory Criteria. As has been advertised by the models for the past several runs, a significant short-wave trough is expected to traverse the country and push a cold front into central Illinois this weekend. 12z Jun 18 GFS and ECMWF are in relatively good agreement, showing the front arriving Saturday night. As a result, have included high chance to likely PoPs (40-60%) Saturday night into Sunday. Once the front departs, slightly cooler and less humid weather is expected early next week as highs drop back into the upper 80s to around 90 degrees by Monday. Barnes && .AVIATION... (For the 00z TAFs through 00z Wednesday Evening) Issued at 615 PM CDT Tue Jun 18 2024 VFR conditions expected the next 24 hours, with ceilings near or above 15,000 feet, primarily tonight. Gusty south winds will begin to diminish early this evening with loss of daytime heating. A gradual shift to the southwest is expected on Wednesday as a cold front approaches the Iowa/Illinois border, but speeds should be near or below 10 knots. Geelhart && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$