Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 190828
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
328 AM CDT Wed Apr 19 2017

.SHORT TERM...(Today and tonight)
ISSUED AT 328 AM CDT Wed Apr 19 2017

08z/2am surface analysis shows a slow-moving cold front extending
from southern Wisconsin to just north of Kansas City.  Isolated
showers have developed along the front, with widespread convection
focused further west on the nose of a 45-50kt LLJ over eastern
Nebraska.  Some of this convection will track eastward along the
boundary and will spill into the far northern KILX CWA north of the
Peoria area toward dawn.  The storms will be outrunning the jet, so
they will be in a weakening stage as they arrive.  Will carry 40-50
PoPs across the NW counties early this morning accordingly.

As low pressure currently developing along the trailing end of the
front over eastern Colorado tracks northeastward, the boundary will
stall...then will lift back northward as a warm front this
afternoon.  Once the initial wave of early morning convection passes
to the north, a lull in precip chances will occur from mid-morning
through early afternoon before widely scattered thunderstorms
develop in the vicinity of the front later this afternoon.  Several
high-res models such as the WRF-ARW and WRF-NMM show little to no
convection firing along the warm front this afternoon, which seems a
bit unreasonable given dewpoint pooling in the mid-60s and CAPE
values of 1500-2000J/kg.  HRRR depicts a more reasonable
scenario...with a few storms developing along the I-80 corridor this
afternoon.  Have included low chance PoPs as far south as I-74 in
case front does not shift northward as quickly as expected, but
think main focus for strong to potentially severe storms will stay
to the N/NW of central Illinois today.  With partly to mostly sunny
skies and southerly flow, high temperatures will top out in the
lower to middle 80s across much of the CWA.  The exception will be
north of Peoria, where clouds/showers will keep temps in the middle
to upper 70s.

Strong to severe convection will also develop further west along an
advancing cold front late this afternoon and evening, mainly across
western Iowa into eastern Kansas.  These storms will advance
northeastward, but will weaken considerably as daytime instability
wanes further east.  Latest model guidance suggests they will remain
west of the CWA until after midnight, then will push into the
Illinois River Valley and diminish overnight.  As a result, will
confine PoPs to locations west of the I-55 corridor tonight.

&&

.LONG TERM...(Thursday through Tuesday)
ISSUED AT 328 AM CDT Wed Apr 19 2017

Low pressure will track into the Great Lakes on Thursday, pulling
the cold front eastward into Illinois.  Scattered showers and
thunderstorms will accompany the front during the morning hours,
then will become more numerous across east-central and southeast
Illinois as the airmass destabilizes later in the day.  As a result,
have focused likely PoPs along/east of a Paris to Effingham line
Thursday afternoon.  A few showers/storms will linger across the
E/SE CWA into the evening before the front clears the area and
cooler/drier weather returns across the board Thursday night into
Friday morning.

As has been advertised for the past several days, a stronger upper
wave is expected to cross the Rockies into the Plains by the end of
the week, causing a surface low to develop along the front.  Models
have been consistently shifting the low track further south and the
00z Apr 19 suite is no exception.  In fact, the GFS/ECMWF/GEM are
now in relatively good agreement with low pressure tracking from the
Texas panhandle Friday morning to eastern Kentucky Sunday morning.
With this more southerly track, central Illinois will be on the
cool/stable side of the system...with rain showers spreading across
mainly the southern two thirds of the CWA beginning Friday afternoon
and continuing through Saturday night.  It now appears areas
along/north of a Rushville to Bloomington line will remain
completely dry through the weekend...with the most significant
rainfall occurring along/south of I-70.  Once the low passes to the
southeast, dry weather will return for Sunday through Tuesday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1244 AM CDT Wed Apr 19 2017

VFR conditions will prevail through the entire 06z TAF period. A
band of mid-level clouds associated with a stationary frontal
boundary across eastern Iowa will spread across the northern
terminals over the next couple of hours: however, any showers that
develop will stay to the north/northwest. The front will edge back
northward later this morning into the afternoon, with only FEW-SCT
diurnal clouds at around 6000ft developing within the warm sector.
Winds will be southerly through the entire period...with gusts of
15-20kt from late morning through the afternoon.


&&

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

$$

SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Barnes



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