Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 140158

Area Forecast Discussion
National Weather Service Lincoln IL
858 PM CDT Sun Aug 13 2017

Issued at 855 PM CDT Sun Aug 13 2017

Another quiet night expected across the area as weak high pressure
slowly drifts off to our east by morning. A few more clouds around
this evening and that should be the case overnight, which should
tend to hold down any significant fog formation across the area.
Dew points from 60 to 64 degrees especially across our east and
southeast this evening and think that may be the area to watch
for some patchy ground fog development overnight as winds remain
very light.

The high will be off to our east on Monday as a weak frontal system,
currently along and just west of the Missouri River this evening,
shifts east into eastern Iowa northeast through central Wisconsin
by Monday afternoon. Widely scattered convection is expected to
redevelop tomorrow afternoon and evening to our northwest with the
main activity expected to remain just north of our area late in
the day and tomorrow evening. Temperatures will continue to inch
back close to where they should be Monday afternoon as readings
rise into the low to mid 80.

Minor adjustments made to the evening temperatures and added the
mention of patchy fog, mainly across east and southeast Illinois.
The updated zone forecast should be out by 910 pm.


.SHORT TERM...(This evening through Monday)
ISSUED AT 300 PM CDT Sun Aug 13 2017

High pressure is keeping mild and quiet weather in place for the
weekend in the Midwest...and the discussion feels similar today.
The highs are mainly in the upper 70s/near 80 yet again today with
fair weather cumulus clouds. Overnight, light and mostly easterly
winds as the ridge remains anchored in the region. Clear skies
and cool again tonight. Again, some patchy fog is possible, but
winds stay up a bit more and easterly flow should generally offer
some weak drying, so leaning against a mention. Tomorrow will
start to see a bit of a shift in the weather overall as more
southerly winds help the temperatures up a degree or two. A
shortwave passes to the north with limited moisture, but models
keep any precip out of Central IL at this time. Some partly to
mostly cloudy skies can be expected, however, as ILX is in between
precip to the north and the south.

.LONG TERM...(Monday night through Sunday)
ISSUED AT 300 PM CDT Sun Aug 13 2017

Mild warming trend continues through the remains of the forecast,
with highs generally rounding out in the mid to upper 80s, closer
to climatological norms. Overall, a surprising amount of agreement
on the sensible weather in the models considering the difference
between the ECMWF and the NAM/GFS solutions aloft. ECMWF a bit
drier longer into Tuesday, but the GFS persists in bringing in
precip for Tuesday afternoon. The NAM is almost a hybrid between
the two...but either way, going into Wednesday, the forecast
becomes dominated by periodic pops, even as the upper air patterns
diverge btwn the NAM/GFS and the ECMWF. Temps still remain near
normal and the latter half of the week periodically stormy. By
Friday, the forecast briefly dries out going into next weekend.


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 612 PM CDT Sun Aug 13 2017

VFR conditions are expected through most of this forecast period
with the possibility for some brief MVFR vsbys in fog in the 09z-
14z time frame. Quite a bit of high level cloud cover across th
area late this afternoon and that should continue into the evening
hours with short term models suggesting some lower cumulus clouds
in the 4000-5000 foot range may form towards dawn Monday. That
may hold back much in the way of any fog development late tonight
but will carry generally 5-6sm in fog just before dawn on Monday.
Otherwise, what fog that does form should quickly dissipate by
14z. with scattered cumulus and some high level cloud cover
expected through the afternoon. Winds will not be a factor again
this forecast period with light easterly flow tonight, 5 kts or
less, with winds become southerly on Monday with speeds of 10 kts
or less.




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