Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 260157
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
857 PM CDT Sun Jun 25 2017

.UPDATE...
Issued at 855 PM CDT Sun Jun 25 2017

Forecast looks on track tonight and only a few minor adjustments
done with the sky cover. Lows mostly in the lower 50s overnight,
with a few upper 40s by Knox and Stark counties. Scattered cumulus
clouds dissipate quickly at sunset leaving clear to mostly clear
skies over central IL at 9 pm. WNW winds have also diminished to
5-15 mph and will weaken a bit more during this evening. 1025 mb
Canadian high pressure over southern Saskatchewan and ridging
into the MO valley will remain in place through the night
providing another fair and cool night to central/southeast IL. A
short wave over northern MN has scattered to broken 7-11k ft
clouds spreading se into north central IA from MN. These clouds
will move into the IL river valley late tonight and early Monday
morning where clear skies to become partly cloudy.

&&

.SHORT TERM...(This evening through Monday)
ISSUED AT 243 PM CDT Sun Jun 25 2017

Breezy west/northwest winds continue to pump unseasonably dry air
into central Illinois this afternoon, with dew points only in the
mid to upper 40s at 2 pm. Southeast Illinois was a holdout
earlier, but recent passage of a weak surface boundary is allowing
the dry air to move in as well. Extensive diurnal cumulus field as
far south as I-72 has brought partly sunny skies to areas north
of Peoria, but most areas still enjoying abundant sunshine this
afternoon.

The relatively cool and dry conditions will continue into Monday,
as the broad longwave trough slowly edges eastward across the
Midwest. Main item of concern will be an upper disturbance
currently just north of Minnesota, which will slide southeast into
the Great Lakes region on Monday. Another weak boundary will drop
into central Illinois Monday afternoon. CAPE`s of up to 1000 J/kg
should be enough to trigger a few showers and thunderstorms
with this boundary, with the main focus by late afternoon closer
to the I-70 corridor.

.LONG TERM...(Monday night through Sunday)
ISSUED AT 243 PM CDT Sun Jun 25 2017

No significant pattern change expected until mid week, when the
western U.S. ridge flattens into a zonal flow. One more cooler/dry
day on tap for Tuesday until the warmer air spreads eastward, with
more typical temperatures and dew points for this time of year.

Second half of the weak will feature more of an active pattern, as
periodic waves traverse the country from west to east, while a
more substantial upper trough/closed low takes shape over the
Upper Midwest. Precipitable water values of 1.75 to 2 inches late
week will enhance some of the rains that occur over the area. Some
showers and storms will be moving in as early as Wednesday
afternoon west of I-55, with the arrival of the first wave. This
boundary will become stationary in a west-east fashion as it
becomes parallel to the upper flow, resulting in an extended
period of rain chances into the first part of the weekend. Severe
weather trends a bit difficult to pick out this far out, dependent
on various MCS`s and leftover mesoscale boundaries.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 653 PM CDT Sun Jun 25 2017

VFR conditions are generally expected to continue during this TAF
period through 00Z/Tue. Scattered diurnally enhanced cumulus
clouds with 6-8k ft bases will dissipate toward dusk/02Z as breezy
WNW winds diminish around sunset to 4-7 kts. 1026 mb Canadian high
pressure over southern Saskatchewan and ridging into KS/MO will
remain west of IL through Monday evening keeping WNW flow going
with winds picking up to 8-13 kts by 15Z/10 am Monday and a few
16-22 kt gusts Monday afternoon especially along I-74.

A northern stream short wave near the MN/Canadian border will drop
se into Lake MI and lower MI Monday afternoon while a deepening
upper level trof into central IL. Forecast soundings show CAPEs
of near 1000 J/KG available by Monday afternoon and this to
support isolated convection starting between 16-18Z Monday from nw
to se and diminishing from 22-24Z at PIA and BMI. Confidence too
low for a specific mention of thunderstorms (TS), but used VCSH
to address this for now.


&&

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

$$

UPDATE...07
SHORT TERM...Geelhart
LONG TERM...Geelhart
AVIATION...07



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