Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 170753
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
253 AM CDT Thu Aug 17 2017

.SHORT TERM...(Today and tonight)
ISSUED AT 253 AM CDT Thu Aug 17 2017

Showers continue to spread into the western half of the CWA early
this morning, but little instability at the moment and there is
only a stray lightning strike or two on occasion with this area of
rain. Latest high-resolution models continue to indicate that this
area should be out of the CWA before noon. However, both the NAM
and GFS indicate CAPE`s east of I-57 reaching above 1000 J/kg by
midday, ahead of the actual cold front, which is currently back
across eastern Iowa and northern Missouri. With a secondary surge
of moisture ahead of the front, will keep showers over the
southeast third of the CWA through the afternoon, with a mention
of isolated thunder as well. Any lingering rain should end toward
sunset.

&&

.LONG TERM...(Friday through Wednesday)
ISSUED AT 253 AM CDT Thu Aug 17 2017

Main upper flow will be coming out of the northwest late this
week, as ridging strengthens along the western Rockies. Timing of
the sharpening shortwave over the upper Mississippi Valley late
Friday has not changed much, and the main focus for us will be
Friday night, with a bit of rain lingering across the far eastern
CWA into Saturday morning as the wave exits the state. Remainder
of the weekend looks dry, as surface high pressure is sprawled
over the Midwest.

Eclipse update (Monday): Weak shortwave should be approaching the
Illinois/Missouri border Monday afternoon. Gulf moisture surge
will be setting up on Monday. with cu-rule off the GFS forming
scattered cumulus by midday over our area. Concern may be more
with higher level clouds spreading in from Missouri due to
potential for thunderstorms in that area. However, summertime
patterns are a bit finicky, so such high resolution details 5 days
out are rather hard to pin down.

Beyond Monday, the western ridge starts to strengthen again,
setting up the storm track across the Great Lakes region. The next
system will be originating in this flow, with showers and
thunderstorms spreading in Monday night and continuing Tuesday.
This upper pattern looks to continue past mid week, bringing some
cooler weather beginning on Wednesday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1230 AM CDT Thu Aug 17 2017

Area of showers and isolated thunderstorms is advancing into
western parts of central Illinois, and should soon be at KSPI,
reaching the other TAF sites over the next couple hours. Bulk of
the rain appears to be in the period through about 10-11Z, and
isolated MVFR ceilings are expected to become more widespread in
the wake of the rain. A cold front will begin moving into central
Illinois late morning, resulting in improving ceilings from west
to east, as well as a period of gusty southwest winds in the
afternoon. These winds should subside toward 22-23Z.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Geelhart
LONG TERM...Geelhart
AVIATION...Geelhart



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