Area Forecast Discussion
Issued by NWS Central Illinois

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498
FXUS63 KILX 301144
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
644 AM CDT MON MAY 30 2016

.SHORT TERM...(Today)
ISSUED AT 337 AM CDT Mon May 30 2016

08z/3am surface analysis shows a weak bubble of high pressure
over central Illinois, while a stationary frontal boundary remains
poised just to the west from southern Iowa into eastern Missouri.
Widely scattered convection continues to develop and move
southeastward along the boundary, with most of the activity thus far
remaining west of the Mississippi River.  Will need to keep an eye
on radar trends, as a few showers could potentially reach the far
W/SW KILX CWA from Rushville to Jacksonville southwestward over the
next couple of hours.  Airmass across central Illinois is drier than
it has been over the past few days, as evidenced by precipitable
water values on the 00z KILX upper air sounding of only 0.86.  This
dry air should keep most of the showers west of the area, similar to
latest HRRR forecast.  Have therefore maintained a dry forecast
through the morning, then have introduced slight chance PoPs across
the Illinois River Valley this afternoon as the airmass slowly
moistens and the stationary front begins to shift northward.
Elsewhere around the area...mostly sunny and dry conditions will
prevail with high temperatures reaching the middle 80s.

.LONG TERM...(Tonight through Sunday)
ISSUED AT 337 AM CDT Mon May 30 2016

Forecast still showery with thunderstorm activity off and on through
the middle of the week until another upper low digs in over the
Plains and drags a front through the region. Although the models are
showing some consistency...timing confidence remains problematic.
Temperatures in the forecast stay summer-like through the first
couple of days this week...several degrees above normal.  A few
degrees cooler behind the boundary, but not by much and not for
long...as southerly flow at the sfc reestablishes and sets up WAA
briefly going into next weekend. That being said, Tue/Wed high
temperatures will fall prey to any shower/cloud activity that could
dampen the diurnal curve.

Quasi-zonal flow sets up over the Midwest today and a weak flow
pattern aloft setting up as the next low digs in over the northern
Rockies. Main concern with the forecast surrounds the progression of
the low with the performance of the models lately with timing. Not a
distinct kicker on the horizon and yet the models steadily push that
wave across the country through the first half of the week. Would
prefer a slightly slower solution...and grids reflecting that for
now. GFS/ECMWF still together with the clearing of the frontal
boundary and associated rain by Thursday morning...with the possible
exceptions of the far east/SE. Until then...showery activity in the
forecast more often than not.  Dry on the other side of the front at
least for Friday...with warm weather lasting into next weekend.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 644 AM CDT Mon May 30 2016

VFR conditions will prevail through the entire 12z TAF period.
Isolated showers continue to develop in the vicinity of a
stationary frontal boundary extending from southern Iowa into
eastern Missouri early this morning. Models have not been handling
the evolution of the showers very well, so will have to keep an
eye on radar trends to see if they could potentially impact
KSPI/KDEC. At this point, will leave shower mention out of TAF as
areal coverage will be minimal due to a relatively dry airmass in
place. Winds will be light and generally from the south/southwest
through tonight.

&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

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



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