610
FXUS63 KILX 130753
AFDILX
Area Forecast Discussion
National Weather Service Lincoln IL
253 AM CDT Tue Aug 13 2013
.DISCUSSION...
ISSUED 253 AM CDT Tue Aug 13 2013
SHORT TERM...Today through Thursday
07z/2am surface analysis shows cold front settling southward
toward the Ohio River...with bulk of remaining convection now well
to the south across far southern Indiana into Kentucky. Despite
frontal passage and light northerly flow, airmass remains rather
humid across central Illinois. Surface dewpoints are still in the
middle to upper 60s across most of the area, with drier upper 50s
beginning to filter into the far north around Galesburg. Due to
mostly clear skies and light winds, this lingering low-level
moisture is producing some patchy fog around the area. Will
include fog mention in the forecast this morning, mainly for
locations south of I-72 where moisture will linger longest. After
any early morning fog dissipates, mostly sunny and cool weather
will be the rule today. Secondary cold front will allow very cool
airmass to pour southward into Illinois today, with 850mb temps
expected to drop into the 8 to 10C range. Numeric guidance is
suggesting highs only in the lower to middle 70s: however, based
on upstream readings yesterday afternoon and strength of mid-August
sun, think this is too cool. Will go several degrees above
guidance, with highs ranging from the middle 70s far north...to
the lower 80s along and south of I-70.
Clear skies and light winds will allow excellent radiational
cooling conditions to develop tonight, resulting in chilly
overnight lows in the upper 40s and lower 50s. With high pressure
remaining overhead, the cool/dry weather will continue on
Wednesday and Thursday as well, with highs in the middle to upper
70s and lows mainly in the 50s.
LONG TERM...Friday through Monday
Short-wave currently evident on water vapor imagery over Oregon
will track up and over the western CONUS ridge and into the
Midwest by the end of the week. This feature may trigger scattered
showers/thunder across Iowa and Nebraska Thursday night: however,
by the time it arrives in the drier airmass across Illinois, am
expecting only a slight increase in cloud cover on Friday. The
wave will act to amplify the existing long-wave trough in place
across the eastern CONUS this weekend into early next week. 00z
Aug 13 models continue to suggest the amplifying trough will
eventually lead to the development of an inverted surface trough
across the Ohio River Valley Sunday/Monday. This is the second
straight day models have latched onto this solution, so confidence
is growing that disturbed weather may develop to the E/SE early
next week. GFS/ECMWF spread a few showers into east-central/southeast
Illinois Sunday and Monday...however GEM tends to keep precip a
bit further east across Indiana. Will increase cloud cover and carry
a slight chance POP east of I-57 accordingly. Airmass will slowly
moderate through the period...with high temperatures climbing back
into the lower to middle 80s by Sunday.
Barnes
&&
.AVIATION...
ISSUED 1144 PM CDT Mon Aug 12 2013
Aside from some patchy MVFR fog overnight, quiet/VFR aviation
weather conditions expected across the central Illinois terminals
through the 06Z TAF valid time. Cloud cover should be minimal
through the period, with winds generally AOB 10 kts.
Bak
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$