Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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046 FXUS63 KILX 170757 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 157 AM CST Mon Nov 17 2025 .KEY MESSAGES... - Rain will spread west to east across the area this evening into tonight, with a few showers lingering through tomorrow. Most locations will see rain amounts between a tenth and half an inch (80% chance). - The next opportunity for beneficial rainfall arrives late Thursday into Friday. There is a 30-60% chance (highest south) for rain amounts greater than 1 inch. && .DISCUSSION... Issued at 156 AM CST Mon Nov 17 2025 ***** SHOWERS TONIGHT INTO TOMORROW ***** Early Monday morning, water vapor satellite imagery reveals an upper level trough spinning in the Great Basin, with shortwave ridging ahead of it in the Great Plains and Mississippi River Valley. Both features will shift east today, resulting in increasing cloud cover and, by tonight, rain showers along and in advance of a warm front. This still isn`t looking like a significant rainfall event, but PWATs climbing to around 0.75-1.00" (around the 90th percentile of climatology) per HREF/REFS mean could still favor some pockets of half inch or greater amounts with the heaviest cells given the deep layer of "skinny" CAPE apparent in forecast soundings. Through tomorrow morning, HREF`s 10-90th percentile range for rain totals spans roughly a tenth to half inch area-wide, though slightly higher south of I-70. With the upper level shortwave passing overhead and the surface low nearby, NBM and HREF suggest low level clouds are going to stick around most or all of the day tomorrow, with perhaps a couple light showers as well (20-30% chance). In addition, north of the surface low, cool advection by east-northeast winds will confine temperatures to the 40s. The exact low track is not quite nailed down at this time, but we did knock a couple degrees off of NBM`s forecast which had highs in the mid 50s to mid 60s. Surface high pressure will settle back into the region in the wake of that system on Wednesday, resulting in drier weather conditions, though we`ll still have some clouds around as we find ourselves near the northern periphery of weak ridging across the Ohio and Tennessee Valleys. Temperatures will run near or slightly above seasonable normals with forecast highs in the low to mid 50s. ***** RAINY END TO THE WORK WEEK ***** At some point Thursday into Friday, a cutoff low in the Southwest will meander northeastward across the Southern/Central Plains and into the Mississippi Valley. The dipole in EOF1 for 500mb heights suggests the primary source of forecast variance among the Low Resolution Ensemble Forecast (LREF) system`s members is coming from differences in the speed at which this trough moves east into our area, so unsurprisingly the NBM (and hence our forecast) has a long duration of PoPs beginning as early as Wednesday night. In general, the global models and their respective ensembles have trended slower with the storm`s arrival and hence later with the onset of rain locally, but low confidence precludes any big PoP adjustments at this juncture. One shouldn`t be surprised, however, if even a portion of the day Thursday winds up being dry and most of any rain we receive falls between Thursday night and Friday evening. Chances for rain totals over 1 inch generally range from 30-60% across the area, with the highest chances south of roughly the I-72 corridor given a recent slight southward shift in the low`s track. We may also wind up with a couple rumbles of thunder across our southern counties, but severe weather potential still looks limited at this time given poor mid level lapse rates and cloud cover mitigating surface heating. Temperatures are looking mild on Thursday as warm and moist advection overspreads much of the region in advance of the trough; NBM advertises a 40-70% chance for highs over 60 degrees southwest of a roughly Macomb to Paris line. Friday could still be on the mild side, though prolific cloud cover and ongoing rain in much of the area may limit surface heating. Temperatures look to trend closer to seasonable normals over the upcoming weekend, though, as we get a weak push of cool advection behind that system. Bumgardner && .AVIATION... (For the 06z TAFs through 06z Monday Night) Issued at 1035 PM CST Sun Nov 16 2025 Surface high pressure will keep winds light and variable overnight. As the surface high pushes off to our east on Monday, winds will veer to the southeast with sustained speeds up to 12 kt. Scattered mid to high clouds will slide through the area overnight with cloud cover more notably increasing later Monday ahead of an approaching weather system. Scattered rain showers become common late Monday evening continuing through the overnight hours. A few isolated storms are also possible, but chances of this occuring is only about 20%. NMA && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$