Area Forecast Discussion
Issued by NWS Central Illinois
FXUS63 KILX 191750
Area Forecast Discussion
National Weather Service Lincoln IL
1250 PM CDT Sat Jul 19 2014
ISSUED 1107 AM CDT Sat Jul 19 2014
High pressure and light winds. Forecast is doing well as areas of
light fog burned off earlier this morning. Hourly temps on track
for highs in the lower 80s. CU field already beginning to show up
on vis sat imagery. No updates anticipated at this time.
ISSUED 1248 PM CDT Sat Jul 19 2014
High pressure ridge keeping TAFs contained to diurnal cu and light
winds. Mostly easterly/southeasterly flow...though some variability with
winds less than 5 kts or so. Diminishing cu and light winds
continue into the overnight hours. With slowly increasing boundary
layer RH, will maintain a continuity forecast and keep some MVFR
vis in for the predawn hours.
ISSUED 236 AM CDT Sat Jul 19 2014
Lingering effects of high pressure keeping skies mostly clear
overnight, although some altocumulus clouds are approaching from
the west, from a weak wave advancing across Missouri and Iowa. A
deeper trough was tracking across Manitoba and North Dakota, while
the remnants of the earlier upper low across the Midwest open up
and lift northeast toward Lake Erie.
The main forecast challenge involves rain chances around mid week,
with the arrival of a cold front.
SHORT TERM...Today through Tuesday:
Not too much change from previous thinking for this period.
Gradual return to the heat and humidity will take place over the
next few days, peaking on Tuesday with highs in the lower 90s most
areas. An intense upper high will build across Colorado and
northern New Mexico, with the ECMWF showing 500 mb heights
reaching as high as 601 dm by late Tuesday. Any ripples of energy
along the northern periphery will track into the upper Mississippi
Valley through early Tuesday, before some digging of the northern
jet stream takes place over the north central U.S. The GEM, and
the ECMWF to a lesser extent, bring thunderstorms with the
associated cold front into far northwest Illinois by evening. Have
limited any PoP`s during the daytime hours to areas northwest of
the Illinois River during the afternoon, although the atmosphere
may be too capped to support anything until evening.
LONG TERM...Tuesday Night through Friday:
With the frontal passage itself, the GFS and its ensembles lag
behind the ECMWF and GEM by about 12 hours, before beginning to
catch up a bit late Wednesday. Have not made a lot of change to
the PoP`s for Tuesday night and Wednesday, when the greatest
chances are focused on our area. The front should be far enough
along by evening that the forecast west of I-55 is dry, and the
CWA should largely be dry by early Thursday.
The warm pattern starts to break down again by Thursday, as a
strong upper low comes onshore near Seattle and squashes the ridge
as it rides along the Canadian border. This should bring another
surge of cooler air southward, though not as cool as what we just
went through. High pressure should dominate the Midwest late week,
with any influence from this ridge rider beyond the current