Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 141753
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1253 PM CDT Mon Aug 14 2017

.UPDATE...
Issued at 948 AM CDT Mon Aug 14 2017

A warm front lifting north from southern IL may bring a few
showers as far north Effingham to Robinson this morning. Lift
appears quite limited in that area, so we left thunder out for the
morning. Farther north, however, thunderstorms progressing into
eastern Iowa could affect our NW counties before Noon. The HRRR,
RAP and NAMnest all indicate a weakening trend with that wave, so
we added a few hours of slight chance PoPs towards Galesburg this
morning. Will monitor closely for continued convection this
afternoon, for possible extension of PoPs later.

Temps and dewpoints look on track. The morning KILX sounding
shows the airmass should support high temps primarily in the mid
80s. The remainder of the short term forecast elements appear on
track. Updated forecast info is already available.

&&

.SHORT TERM...(Today and tonight)
ISSUED AT 245 AM CDT Mon Aug 14 2017

Early morning water vapor imagery shows a well-defined swirl over
central Minnesota, with a trailing shortwave to near Omaha. This
wave will be pushing eastward today, but will have some difficulty
with any significant southward progress as the associated surface
boundary starts to get hung up in the upper flow. The tail end of
the RAP has the rain making it as far as Peoria by about 9 pm,
while the other high-resolution models have any showers and storms
in a decaying state by the time they arrive toward midnight or
later. Have continued with a mention of isolated showers/storms
over the far north tonight. Temperatures should be fairly close to
normal today, in the mid 80s, though Gulf moisture will start to
flow in and bring dew points up from where we`ve been enjoying
them the last couple days.

.LONG TERM...(Tuesday through Sunday)
ISSUED AT 245 AM CDT Mon Aug 14 2017

Upper level ridge currently just east of the Rockies will edge
eastward through mid week. While temperatures will only creep
upward a couple degrees, a more steady surge of Gulf moisture will
bring dew points back to the 70s Tuesday-Thursday. Heat index
values currently look to stay below 100 degrees though. Late week
into the weekend, a series of shortwaves will help to knock down
the northern extent of the warm air dome, bringing conditions back
closer to what we`re expecting for today.

With the current system loitering in the general vicinity, scattered
showers and storms will be possible Tuesday, mainly north of I-72.
The main focus remains mid week, as a strong wave digs just east
of the Rockies early Wednesday and lifts into the upper
Mississippi Valley by early Thursday. Leading wing of
showers/storms should spread from west to east across the CWA late
Tuesday night. Highest PoP`s still look to be Wednesday night
ahead of the cold front, with rain tapering from west to east
Thursday as the upper wave finally passes. While Friday looks dry,
model disagreement starts to pick up for the weekend with the
strength and timing of the next wave. The GFS is much stronger and
wetter due to a slower movement, showing widespread rain Saturday
and Saturday night, while the ECMWF keeps us dry as high pressure
drifts through the region. Will keep PoP`s fairly low during this
time frame due to the uncertainty.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1253 PM CDT Mon Aug 14 2017

VFR conditions will prevail through the entire 18z TAF period. A
weak cold front currently across western Iowa into Nebraska will
sink southward and eventually stall across central Illinois by
Tuesday morning. Well ahead of the front, a robust CU field will
lead to SCT-BKN conditions at around 5000ft through the afternoon.
Isolated convection will be possible from late this evening into
Tuesday as the front nears: however, questions regarding exact
areal coverage and timing of any storms lead to a dry forecast at
this time. Winds will be S/SW this afternoon and evening, then
will become light/variable later tonight...and perhaps turn to the
N/NE at KPIA by Tuesday morning as the front sinks toward I-72.

&&

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

$$

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



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