Area Forecast Discussion
Issued by NWS Central Illinois

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480
FXUS63 KILX 010150
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
850 PM CDT FRI SEP 30 2016

.UPDATE...
Issued at 845 PM CDT Fri Sep 30 2016

Large upper low which has been situated over northern Kentucky for
the past 24 to 30 hours appears to be inching its way north this
evening into extreme southern Indiana. This northward drift will
continue through Saturday which means another 24 hours of rather
dismal weather across the area with low clouds, patchy fog and
occasional showers. Models are in general agreement in lifting the
upper system and surface reflection across Indiana, and then north
through the eastern Great Lakes on Sunday which should result in a
gradual improving weather trend over our area to end the weekend
with.

With a weaker wind field over the area tonight coupled with nearly
saturated low levels of the atmosphere from the rainfall, some
patchy fog will develop, especially in the areas that had the more
persistent rainfall today. The current forecast has a good handle
on the expected weather trends for the overnight hours, as a
result, no ZFP update will be needed at this time.

&&

.SHORT TERM...(This evening through Saturday)
ISSUED AT 232 PM CDT Fri Sep 30 2016

No change in the location of the upper low since the last report,
still located near Louisville KY early this afternoon. Showers have
been increasing across areas east of I-55 this afternoon, with a few
thunderstorms tracking westward toward Danville and Champaign, as
well as just north of Lawrenceville. This low should finally start
drifting northward toward midnight, with most of the models
projecting it to reach the northeast Indiana area by late Saturday
afternoon. Until it exits the area, scattered showers will continue
into Saturday afternoon, most numerous over eastern parts of the
state. Overnight, this may trend toward more of a drizzle scenario
as cloud heights lower to a few hundred feet off the ground.
Temperatures will not be too far off of what we have been seeing,
with lows tonight mostly in the upper 50s and highs Saturday in the
upper 60s.

.LONG TERM...(Saturday night through Friday)
ISSUED AT 232 PM CDT Fri Sep 30 2016

A 5620 M cut-off 500 mb low remains nearly stationary over southern
Indiana and is expected to lift northeastward into northeast Indiana
by Saturday evening. Bands of showers wrapping around the system
into central/SE Illinois will taper off west to east Saturday
evening as it does so. Continued shower chances in areas roughly I-
55 eastward Saturday evening...then dry conditions forecast late in
the night.

High pressure will subsequently build into the region Sunday through
Tuesday producing fair and warmer weather. Highs will trend steadily
upward from the lower 70s Sunday to the upper 70s Tuesday...while
lows should be in the mid 50s through the period.

The next weather feature will be a large trough progressing eastward
via the western US. 12Z model runs are currently in relatively good
agreement through Tuesday...then details of the trough
evolution...associated surface low...and cold front diverge for
Wednesday and Thursday. Nevertheless...chances for showers and
thunderstorms develop Wednesday into Thursday as this feature
spreads in moist warm advection and an eventual cold front. Cooler
temperatures will ensue for late in the week following the cold
front. Highs should peak around 80 for Wednesday...then decrease
Thursday into Friday with highs ranging from the upper 60s to mid
70s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 550 PM CDT Fri Sep 30 2016

Upper low still located over northern Kentucky late this afternoon
is forecast to drift north through east central Indiana late
tonight and during Saturday. Cool temperatures aloft will bring
a continuation of the weather we have been having for the past
couple of days with scattered showers and low cigs. The lower
cigs will be most prominent late at night and thru the morning
hours before we see a gradual lifting of the cig bases to MVFR
or even low VFR conditions for a time in the afternoon and early
evening. Any TAF site that gets underneath any of the heavier
showers will see a brief lowering to IFR cigs and vsbys before
the vsbys quickly come back up. Looks as if the trend to low cigs
will once again come back over the entire area after 05z tonight
with rather low cigs into early Saturday afternoon. Surface winds
will be mostly out of a north to northwest direction during this
forecast period with speeds in the 8 to 15 kt range.


&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

UPDATE...Smith
SHORT TERM...Geelhart
LONG TERM...Onton
AVIATION...Smith



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