Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 150245

Area Forecast Discussion
National Weather Service Lincoln IL
845 PM CST Tue Nov 14 2017

Issued at 845 PM CST Tue Nov 14 2017

Only minor updates needed so far this evening as current model
trends continue to depict a rapid increase in precipitation
coverage after midnight tonight with increasing warm advection.
Trimmed PoPs down a bit for the late evening due to the absence
of any observations of rain or significant radar returns, however
cloud heights have been steadily decreasing over western Illinois
indicating a moistening trend. Lows generally in the mid 40s still
look good, although increased winds slightly for tonight, as obs
are showing predominantly 10 to 15 mph west of I-57.


.SHORT TERM...(This evening through Wednesday)
ISSUED AT 313 PM CST Tue Nov 14 2017

Clouds continue to slowly spread east through the CWA late this
afternoon, well ahead of the next weather system expected late
tonight through tomorrow. Small chance of showers will begin late
this evening in the west. However, the bulk of the precip will
begin after midnight and become more widespread and also spread to
the east through the overnight hours. The precip will also get
heavier as it moves to the east toward the morning hours.
Isolated/slight chance to chance thunderstorms will also occur
after midnight across the west and central parts of the CWA, but
then diminish and shift south during the morning hours. Southerly
winds ahead of this system should become a tad gusty with gusts
over 20mph possible at times especially once the front moves
through during the afternoon hours. Most of the precip will be
gone by noon with maybe some lingering showers in southeast IL
during the early afternoon...but by late afternoon dry and cooler
air will advect in behind the front.

.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 313 PM CST Tue Nov 14 2017

With high pressure building in Wednesday night, dry weather is
expected through Thursday and Thursday night. Temps will remain on
the cool side Thur as well but quickly get warmer for Fri and into
the weekend as strong waa will occur ahead of the next weather

Models are finally coming into better agreement as the GFS model
has finally slowed and come into better agreement with the ECMWF
and Canadian models. There is still some differences once the low
pressure tracks across the midwest/Great Lakes region, which
causes the GFS to be 6hrs quicker with the cold front. Will still
follow closer to the ECMWF and Canadian solutions with the front
not coming through the CWA til Saturday morning. This system does
appear to be stronger and deepens some as it passes through the
area. But given the timing of the front, convection will be
somewhat elevated and may not result in being as strong as first
thought. However, thunderstorms are still possible and have
continued the chance of thunder throughout the CWA for Friday
night. Models do show a tighter gradient ahead and even stronger
behind the front, so winds Friday will be gusty and then again n
Saturday behind the front. Precip will linger into Sat afternoon
but most of the area will be dry. Dry weather is then expected
rest of the weekend and into next week as a large area of high
pressure moves the area. Another weather system is possible on
Tuesday, but moisture looks to be lacking at this point and no
precip is forecast at this time.

Temps will be warmer ahead of the front Sat, so looking for
warmest temps on Fri and Sat. Sat high for the day will likely be
in the morning as colder air advects into the area during the
afternoon. Below normal temps are then expected rest of the
weekend and into next week.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 545 PM CST Tue Nov 14 2017

Ceilings and visibility will lower overnight as a cold front and
associated upper level trough approach the central IL terminals.
Expecting enough instability for a few thunderstorms after 06Z so
added VCTS to TAFS after 06-08Z with the onset of showers and MVFR
cigs. Cigs should continue to lower to IFR category by 12-14Z.
Improving conditions after cold frontal passage around 16-18Z,
becoming VFR around 18-20Z. Winds S-SE 10-12 kts until around
12Z...shifting to W-NW by 18-20Z behind the cold front, and
increasing to 12-15kts with typical gusts around 20-22 kts.




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