Area Forecast Discussion
Issued by NWS Central Illinois

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS63 KILX 292304

Area Forecast Discussion
604 PM CDT Mon Sep 29 2014

.SHORT TERM...(Tonight)

Weak high pressure will continue fair weather into this evening as
few to scattered cumulus clouds with 5-7k ft bases away from the IN
dissipate around sunset. Patchy shallow ground fog will develop
again near rivers and streams in southeast IL during overnight.
A cold front over southeast WI and central IA will push south into
central IL overnight, reaching I-70 by sunrise Tue, and weaken over
southeast IL on Tuesday. Stratus clouds behind/north of the front
will move south into central IL during overnight and especially
affect areas from I-74 north while southeast IL likely stays clear
most of tonight. Light winds into this evening will become northeast
at 5 to 10 mph during overnight over central IL. Lows tonight will
mostly be in the mid 50s with lower 50s north of Peoria.


.LONG TERM...(Tuesday through Monday)

A dry front, located just north of the state is forecast to slowly
drop into the area tonight through tomorrow. NAM-WRF model has been
consistent with forecasting an increase in low clouds across the
northern half of the state tonight and tomorrow. It looks like it
could get to I-74 by morning and could progress further south
tomorrow. How far south it gets will depend on how much of the
southern edge of the cloud deck gets eroded away by the strong sun
during the day tomorrow. So, current thinking is it sill get past
I-74 and could get to I-72 in the eastern part of the CWA. During
the day tomorrow, the sunshine should dissipate a lot of the clouds,
like what is occurring in parts of SD/MN/and IA today. Then mostly
clear and dry conditions are expected tomorrow night through Wed.

A weather system in the western US will the lift northeast into the
northern plains and will have a trailing cold front that will extend
down into the southern plains. Showers and thunderstorms are
expected to develop along and ahead of this front Wed well west of
the CWA. However, these storms will advect eastward into the state
beginning Wed night. A second low pressure area will develop along
the front and will move northeast into the Midwest and bring the
cold front through the area Thur and Thur night. Additional
thunderstorms will develop along the front Thursday and move across
the area during the day and through Thur night. Conditions do not
look right for any of the storms to produce severe weather, but this
could change in the next couple of days. However, lightning and
brief heavy rainfall will be likely with any storms that move
through the area late Wed night and Thursday. Once the front and pcpn
pass, there could be some lingering showers behind the front, so
will be keeping some chance pops in the east for Friday.

Beyond Friday, conditions will improve as a drier and cooler air
mass pushes into the area for the weekend. There is one small, weak
wave that could bring some light showers to the northeastern parts
of the area, along and north of I-74, but its too far away to have
much confidence, so will just have slight chance pops for Sunday,
which will not be mentioned in the worded forecast.

Temps will remain above normal tomorrow, when the sunshine is able
to break through the clouds, and Wed as well. Then clouds and rain
for Thur will keep temps milder and around normal. Once the front
moves through at the end of the week, temps will become much cooler
and actually be below normal for the beginning of Oct.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)

Cold front expected to bring a period of MVFR and local IFR cigs
and vsbys with it as the boundary settles south into our area later
this evening across the north (KPIA and KBMI from 05z-07z). Models
suggest the southward surge in the front will lessen with time
overnight but still feel it will have enough momentum to pass our
southern TAF sites in the 07z-10z time frame. Along with the low
cigs moving in, there may be a period of drizzle and fog which
will bring vsbys down to between 3-5sm just behind the FROPA. The
MVFR and local IFR cigs are expected to gradually lift aftr 15z
Tuesday as drier air advects in. Surface winds will remain light
and variable ahead of the front with a shift into the northeast
aftr FROPA with speeds initially in the 10 to 15 kt range with a
few gusts around 20 kts possible, especially at KBMI for about an
hour after FROPA. Winds should then become easterly on Tuesday at
8 to 12 kts.




AVIATION...Smith is the U.S. government's official web portal to all federal, state and local government web resources and services.