Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 241803
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
103 PM CDT Mon Jul 24 2017

.UPDATE...
Issued at 1039 AM CDT Mon Jul 24 2017

Low clouds have streamed into the area from the northeast early
this morning, although their southwest expansion has stalled. Much
of the model guidance does not have a very good handle on these
clouds. Even the short range models that have finally picked up on
them appear to dissipate them too quickly. 12Z ILX and area
forecast soundings do not suggest a terribly strong inversion that
would keep the clouds trapped all day. However, to this point, the
clouds have still been thickening up on satellite loops,

Updated forecast to account for the latest cloud trends, although
confidence in the break-up timing is low. In any event, went more
pessimistic than most guidance with the clouds. Also nudged
temperatures down a bit to account for the more widespread cloud
cover.

&&

.SHORT TERM...(Today and tonight)
ISSUED AT 238 AM CDT Mon Jul 24 2017

Some quiet and drier weather is on tap, as high pressure drifts
east across the Great Lakes region. The cold front that brought
the scattered storms Sunday afternoon and evening was about to
exit the extreme southeast CWA early this morning, and drier air
will be overspreading the forecast area today. Temperatures should
be a couple degrees normal for late July, with highs mainly in the
lower to mid 80s today. More pleasant sleeping conditions are
expected tonight, with some 60 degree lows near the I-74 corridor
and mainly lower 60s elsewhere.

.LONG TERM...(Tuesday through Sunday)
ISSUED AT 238 AM CDT Mon Jul 24 2017

Main concern in the longer term focuses on a brief return to the
heat and humidity around mid week.

A strong upper low seen on water vapor imagery over northern
Alberta this morning will be moving eastward early this week, and
will help keep the ridge over the western U.S. suppressed during
its eastward push across the country. 850 mb temperatures expected
to return to around 21C by Wednesday, which should bring back some
lower 90s in much of the CWA for highs. A cold front will
accompany an upper trough trailing southwest from the low. While
there remains reasonable model agreement in bringing the front
through the area late Wednesday night through Thursday, the GFS
and NAM continue to develop some scattered convection along the
periphery of the cap as early as Wednesday afternoon, while the
ECMWF and Canadian models keep it dry until the actual front
arrives. Am not completely dismissing this scenario, and will have
some low PoP`s mentioned Wednesday afternoon. The NAM and GFS
progs show precipitable water values as high as 2.50 inches along
and ahead of the front, near records for this area, so the
potential for heavy rain with some of the storms is high. The
front should exit the area Thursday evening, and a return to dry
and cooler conditions is expected again for late week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 101 PM CDT Mon Jul 24 2017

A sizable patch of MVFR CIGs persists across much of central
Illinois, impacting most of the local TAF sites. These low clouds
are not handled well by the model guidance, but recent satellite
imagery suggests they are beginning to mix out. Once these CIGS
dissipate, expect VFR condtions for the remainder of the period.

&&

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

$$

UPDATE...Bak
SHORT TERM...Geelhart
LONG TERM...Geelhart
AVIATION...Bak



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