Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 250202
AFDILX

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

.UPDATE...
Issued at 902 PM CDT Tue May 24 2016

Most of current forecast looks ok and doesn`t need to be adjusted.
However, pops/wx need to be lowered over most of the area since
not seeing any development near the Mississippi river as some
short range models were showing earlier this afternoon. So have
lowered pops to slight chance or all the way to none. Still have
lots of high clouds over the area and these will continue the
remainder of the night. Will leave late tonight forecast as is
since lots of uncertainty as to what will be happening overnight
given the current ongoing convection in KS/OK and AR. Updated
forecast will be coming out shortly.

&&

.SHORT TERM...(Tonight)
ISSUED AT 240 PM CDT Tue May 24 2016

Mostly sunny, breezy, and warm conditions prevailed across central
Illinois this afternoon as the area remained under the influence of
surface/upper ridging.  A short-wave trough evident on water vapor
imagery over western Missouri will be the primary weather-maker over
the next 24 hours as it slowly tracks eastward.  Most models suggest
widely scattered thunderstorms will develop ahead of this feature
along the Mississippi River late this afternoon then will push into
west-central Illinois during the evening.  With plenty of dry air
evident at mid/low-levels, the environment will remain hostile to
widespread precip.  The HRRR has been consistently showing these
showers/storms dissipating toward midnight as they slowly track
toward the I-55 corridor.  Will therefore carry highest PoPs across
the Illinois River Valley tonight, with locations further east
around Champaign/Danville only seeing slight chance PoPs after
midnight.  Thanks to continued southerly flow and increasing surface
dewpoints, overnight low temperatures will remain in the lower to
middle 60s.

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 240 PM CDT Tue May 24 2016

Southwest flow aloft will prevail across the Midwest through this
forecast period bringing very warm and humid weather to the region
with the difficult part of the forecast trying to pin down rain
chances ahead of rather weak low amplitude shortwaves that are
forecast to eject northeast from the main longwave trof over the
western U.S.  With the persistent southwest flow aloft, any frontal
boundary and main forcing mechanism is expected to remain well west
and northwest of our area through the week. The next shortwave over
the southern Rockies is expected to push across the central Plains
tonight and into the northern Plains on Wednesday bringing another
round of convection to our west. Just how far east these storms
move towards the mid-Mississippi River valley and away from the
better forcing remains to be seen with most of the deterministic
models and even a few of the CAM solutions not doing very well
with the current convection to our west and south.

With the aforementioned shortwave approaching on Wednesday, we
should see a weak boundary/warm front develop and shift north across
the area during the day, with most model solutions having this
feature to our north by late tomorrow afternoon where the better
forcing/low level convergence will be located. Overnight, it still
appears convection will fire on the nose of the 850 mb low level jet
and along and just north of the 850 boundary which suggests the
better threat for more organized storms will be closer to the 850
front which with this model run is to our north. Based on the 1000-
500 mb thickness diffluence across our area, it appears the
storms may dive southeast into parts of our area early Thursday
morning where the better instability would be located. Still not
worth much more than 40 to 50 POPs at this point. Yet another
shortwave will approach the area from the southern Plains later
Friday and into Saturday possibly bringing another round of
convection to parts of the Midwest.

Warm weather is expected to continue through the holiday weekend
with daily chances for showers and storms. The 12z GFS ensemble
and ECMWF solutions indicate a transition to an increase in 500
mb heights over the Midwest, with the stronger flow and thunderstorm
chances shifting into the northern Rockies east thru the upper Great
Lakes during the first week of June.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 648 PM CDT Tue May 24 2016

Scattered CU and a blanket of cirrus is covering the TAFs this
evening. Believe this will continue this evening at all sites.
Short range HiRes models continue to show some scattered showers
developing early this evening out west of the sites and moving
east. Nothing seen on radar or in the IR satellite loop. So do not
have confidence that this will develop. So have removed any
mention of pcpn at PIA/SPI/BMI for this evening. If any thing
develops...then will amend and add...but for now VFR conditions
will prevail at all sites tonight and into the morning hours. NAM
model tries to bring scattered pcpn in again in the morning...but
not confident with this either. So no pcpn tomorrow either. Winds
will remain southerly through the period with an increase in speed
tomorrow.


&&

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

$$

UPDATE...Auten
SHORT TERM...Barnes
LONG TERM...Smith
AVIATION...Auten



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