Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 241745
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1245 PM CDT TUE MAY 24 2016

.UPDATE...
Issued at 1052 AM CDT Tue May 24 2016

Morning surface analysis shows 1020mb high anchored over the
Southeast US...while frontal boundary remains stalled from the
Upper Midwest into the Plains. Aloft...southwesterly flow is
prevalent across the region...with one short-wave trough evident
over eastern Kansas. The Kansas wave is currently setting off
widespread showers and thunderstorms across central/western
Missouri...and this activity is slowly spreading eastward. Despite
the forward progress noted on radar imagery...the airmass across
central Illinois remains capped and quite dry as evidenced by the
12z KILX upper air sounding. Therefore any convection that forms
across Missouri will have difficulty moving into the more hostile
environment east of the Mississippi River. Most high-res models
keep the KILX CWA dry through at least early afternoon...with a
few showers/storms trying to work into the area later in the day.
Have updated PoPs to remove rain chances this morning, and have
limited slight chances this afternoon to locations along/southwest
of a Canton...to Taylorville...to Olney line. Have also made some
adjustments to hourly temps and afternoon highs...with readings
topping out in the lower to middle 80s.

&&

.SHORT TERM...(Today)
ISSUED AT 317 AM CDT Tue May 24 2016

For today, models are not depicting any coherent disturbance to
bring any substantial lift into central IL, as a shortwave over the
Dakotas and Iowa is expected to lift northeastward likely keeping
its influence out of our area, and another on over SE Missouri to
propagate eastward through southern IL, potentially grazing Clay and
Richland counties. Nevertheless, with increasing moisture resulting
in dewpoints reaching around 60 by afternoon...enough instability
will result with afternoon heating that isolated thunderstorms could
form along any leftover boundaries from convection in the region
overnight. Therefore, have trimmed thunderstorm chances to slight
category for today SW of a Bloomington-Effingham line. With several
hundred to 1500 J/KG CAPE progged west of the Illinois River, a
few of these could become strong with hail and gusty winds,
therefore SPC has outlooked these areas in a marginal risk for
severe thunderstorms.

Otherwise...highs today should reach the low 80s today, down
marginally since Monday due to increased cloud cover, and
southerly winds around 10 mph will continue through the day.

.LONG TERM...(Tonight through Monday)
ISSUED AT 317 AM CDT Tue May 24 2016

Upper level flow from the southwest expected to persist most of the
week, with the upper low currently just south of San Francisco
expected to only reach western Kansas by Friday evening in a weaker
state. Once that low lifts northeast into the northern Plains this
weekend, another will dig southward across the western U.S. and keep
the southwest flow continuing. Net result will be an extended period
of warm and somewhat humid conditions lasting into the holiday
weekend. Individual ripples in the upper pattern will enhance rain
chances periodically, as surface boundaries to our north will not
move much. While it will not be a continuous washout, such a pattern
makes it difficult to pin down any dry periods in the forecast.
Thus, most of the forecast periods will continue to have at least a
chance of showers and thunderstorms.

Currently looks like most of this evening will be dry over the
forecast area, with an uptick in rain chances after midnight as an
MCS organizes to our northwest. GFS tracks its remnants more or less
on top of us, while the ECMWF and NAM keep most of them to our
north. Another thunderstorm cluster more likely to affect the CWA
Wednesday night, and likely PoP`s were kept from about Havana-Paris
northward. Latest SPC outlooks have backed off on the severe weather
chances over our area the next few days, as while there will be
decent instability, shear parameters are rather week. However, with
precipitable water values rising to around 1.5 inches, some of the
storms will produce locally heavy rainfall.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1245 PM CDT Tue May 24 2016

An upper-level disturbance currently over western Missouri will
track eastward, triggering widely scattered showers and
thunderstorms across west-central Illinois late this afternoon and
evening. Most models indicate that a few thunderstorms may impact
the western KILX terminals, with higher-res solutions such as the
HRRR focusing on the 00z-05z time frame. Still quite a bit of
uncertainty concerning convective development, particularly given
lack of strong forcing and dry mid/low-level airmass, so will only
mention VCTS at this time. Given likely diurnal nature of any
storms that develop, will keep KDEC/KCMI dry through the entire
18z TAF period. Ceilings if they occur will remain in the VFR
category. Winds will initially be from the south gusting to
between 15 and 20kt this afternoon, then will decrease to less
than 10kt tonight.

&&

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

$$

UPDATE...Barnes
SHORT TERM...Onton
LONG TERM...Geelhart
AVIATION...Barnes



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