Jerome, Illinois Weather Forecast Discussion

401
FXUS63 KILX 181947
AFDILX
Area Forecast Discussion
National Weather Service Lincoln IL
247 PM CDT Thu Sep 18 2025
.KEY MESSAGES...
- Very warm and dry weather will continue over central and
  southeast IL until Saturday, with  highs in the mid 80s to
  lower 90s. Temperatures look to cool down during next week with
  seasonably highs in the upper 70s to around 80 for middle of
  next week.
- Isolated showers and thunderstorms are possible west of highway
  51 through Friday, with a better chance of rain Friday night
  over central IL. The best chance (50-70%) for showers and
  thunderstorms comes Sunday into Monday evening.
&&
.DISCUSSION...
Issued at 245 PM CDT Thu Sep 18 2025
The mid afternoon surface map shows weak 1013 mb low pressure over
southeast SD with its frontal boundary extending southward over
eastern NE/KS. Aloft a 574 decameter 500 mb low was over northeast
MT and another one in central SD, embedded within a mid/upper
level trof over the northern High Plains and into the Central
Plains. An upper level ridge was over IL/IN with 500 mb heights
above 584 decameters over CWA. Patches of mid/high clouds was
over western CWA west of PIA and SPI while ample sunshine from PIA
and SPI east. Isolated convection was from Macomb northward to the
Quad Cities and lifting NNE. Better coverage of convection over
eastern half of Iowa into nw MO, southeast NE and eastern KS.
The occluding weakening front to push eastward toward far west
central IL by dawn Friday and to keep low chances of showers and
possible thunderstorms from Peoria and Springfield west tonight
into Friday morning. Have slight pops a bit further east on Friday
afternoon to BMI and MTO. Lows overnight mostly in the lower 60s,
with coolest readings around 60F east of I-57, with mid 60s over
the IL river valley where more cloud cover expected. Highs Friday
range from the mid 80s over the IL river valley and lower 90s in
eastern IL from I-57 east.
Latest CAMs shows a bit higher convection chances during Friday
night after sunset over central IL and into eastern IL overnight
Fri night as trof moves closer with weak short waves nearby.
Precipitation amounts still look fairly light (tenth to quarter
inch in spots). The forcing has trended weather on Saturday over
central IL as upper level low/trof weakens as it passes north of
IL. Mainly slight chances of convection with some areas likely
dry on Saturday. Highs Saturday range from lower 80s nw of the IL
river by Knox and Stark counties, to the upper 80s from I-72 south
with areas se of I-70 near 90F. Convection chances to increase
from west to east during Sat night and Sunday as upper level trof
moves into IL early next week. Best chances of convection still
appear to be Sunday into Monday and not quite as hot with highs in
the low to mid 80s, warmest in southeast IL.
Forecast models offer differing solutions with evolution of a
cutoff upper level low in central or southern plains by Wed.
Though Ecmwf, GEM and GFS all show a decent amount of qpf over
central IL Tue-Thu and temps closer to normal with highs in the
upper 70s to near 80F. We followed NBM pops ranging from 20-40%
but part of mid week could see higher chances of rain. We
definitely need the rainfall as the moderate to severe drought
continues to expand over central and southern IL (from Fulton,
Peoria and Woodford counties south) with burn bans as far north
as McLean county now.
07
&&
.AVIATION...  (For the 18z TAFs through 18z Friday Afternoon)
Issued at 1245 PM CDT Thu Sep 18 2025
VFR conditions should continue across the central IL terminals
through 18Z/1 pm Friday. Nearby weak high pressure ridge will
continue to influence central IL through Friday morning with
light and variable winds next 24 hours. A cold front over central
WI pushes into northeast IL overnight and lifts slowly back north
on Friday. Meanwhile a weak 1012 mb low pressure in east central
SD with a frontal boundary into eastern NE/KS to weaken as it
pushes eastward into far west central IL Fri morning. Its
convection should stay west of PIA and SPI through midday Friday,
though will likely see broken mid/high clouds affect those
airports especially overnight into Fri morning.
07
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$

NWS ILX Office Area Forecast Discussion