Area Forecast Discussion
Issued by NWS Central Illinois
FXUS63 KILX 301742
Area Forecast Discussion
National Weather Service Lincoln IL
1242 PM CDT Wed Jul 30 2014
ISSUED 954 AM CDT Wed Jul 30 2014
High pressure extending from the Northern Plains to the Ohio
River Valley is providing mostly sunny and cool conditions to
central Illinois this morning. Main question will be whether or
not any showers will develop within the cyclonic flow pattern
aloft. 14z/9am water vapor imagery shows deep upper low spinning
over Hudson Bay, with short-wave trough rotating around this
feature across southern Michigan. The influence of this wave will
likely remain NE of Illinois today, with scattered showers/thunder
developing across southern Michigan/Northern Indiana this
afternoon. Upper support will be weaker further W/SW, so am not
expecting much precip at all in Illinois. HRRR suggests isolated
showers may fire after 19z, mainly across northern Illinois.
Meanwhile, the NAM12 is completely dry. Have therefore scaled back
PoPs today, with only an isolated shower mention along/north of
I-74 this afternoon. Have also removed evening showers and gone
with a mostly clear forecast for tonight. Zone update has already
ISSUED 1242 PM CDT Wed Jul 30 2014
VFR conditions will prevail through the entire 18z TAF period. SCT
to occasionally BKN diurnal clouds at 4000-5000ft this afternoon
will rapidly dissipate toward sunset, with clear skies expected
overnight. The cycle will repeat on Thursday, with SCT diurnal
cloud cover once again developing by late morning/early afternoon.
Winds will be light from the NW this afternoon, then will shift to
the W/SW on Thursday.
ISSUED 317 AM CDT Wed Jul 30 2014
Forecast and overall atmospheric pattern slow to change right now
as an upper low remains parked over the southern tip of Hudson
Bay...with the trof dominating the eastern half of the CONUS. 500
mb ridge over the west, and sfc high pressure building into the
Midwest with northwesterly flow aloft. Forecast driven by slowly
warming temperatures, still below normal for late July, light
winds, and afternoon showers. Next chance for a slightly more
substantial chance for thunderstorms arrives on Friday, with a
wave diving into the upper trof and helping to enhance the
dynamics. Overall, very little in the forecast warranting more
than a chance/scattered mention, and not many changes expected
until the pattern breaks later in the weekend.
SHORT TERM...Today and tomorrow...
Partly cloudy afternoon skies with slight chance for some
afternoon showers and iso thunder... with the better chances to
the northeast. High temperatures upper 70s/low 80s...and overnight
lows dropping to upper 50s/near 60 with mostly clear skies. Upper
low anchored over southeastern Canada keeps the weather in a
pretty stagnant pattern and below normal temps in the Midwest.
LONG TERM...Friday through Tuesday...
Best chances for showers and thunderstorms moving in for Friday...
as a wave rotates through the trof and enhances chances for
scattered showers and thunderstorms. Models pretty consistent with
this feature...though coverage is not expected to be widespread
just yet. High pressure dominating into the weekend as the sfc
ridge axis moves into the region. Winds remain light and variable
and dry forecast as the upper trof finally starts to progress
across into the NE. Chances for more significant weather starting
to return Tues/Wed as a more active and progressive flow sets up
across the country.