Area Forecast Discussion
Issued by NWS Central Illinois

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871
FXUS63 KILX 271746
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1246 PM CDT Thu Jul 27 2017

.UPDATE...
Issued at 1042 AM CDT Thu Jul 27 2017

15z/10am surface analysis shows slow-moving cold front extending
from Lake Erie southwestward through central Illinois into
Oklahoma. Scattered showers are ongoing ahead of the boundary,
primarily along and south of a Jacksonville to Danville line. Due
to extensive cloud cover and cool temps, the atmosphere remains
stable across the KILX CWA...with latest LAPS data indicating CAPE
values of 600J/kg or less. With clouds holding firm for the
entire day, think instability will remain meager. As a result,
have only gone with isolated thunder across the area today. Best
rain chances will be focused across the southern CWA: however,
isolated showers/thunder will develop as far north as Peoria this
afternoon. High temperatures will only reach the lower 80s.

&&

.SHORT TERM...(Today and tonight)
ISSUED AT 300 AM CDT Thu Jul 27 2017

Latest surface map showing a weak boundary roughly draped along
the Illinois River valley. Much of the focus for showers and
storms has been further south the last several hours, with the
first round now exiting the southeast CWA and additional recent
development skirting the southwest CWA. This latter development is
in addition to the MCS that was already covering a good portion of
Missouri, and the latest short-range model guidance has been
focusing on the areas south of I-72 for periodic showers and
storms through the morning. The front will be making a slow push
southward during the day, reaching about a Springfield-Danville
line by early afternoon and I-70 very late afternoon. Decent
instability is progged immediately behind the front, and isolated
showers/storms are still possible in the afternoon over the
northern CWA, but gradual trend over the forecast area will be
for a weakening trend by late afternoon. Have kept healthy chance
PoP`s going into the evening from about Taylorville-Paris
southward, with only isolated showers lingering past midnight over
the far southeast.

.LONG TERM...(Friday through Wednesday)
ISSUED AT 300 AM CDT Thu Jul 27 2017

A fairly quiet weather pattern is on tap for this part of the
forecast. A shortwave currently near Lake Winnipeg will drop
southeast into the Great Lakes and begin to close off, loitering
near the mid-Atlantic states this weekend through Monday. This
will keep the hot western ridge from making any headway eastward,
with temperatures around here a tad below seasonal normals. The
GFS tries to punch a few showers through high pressure overhead
Monday and Tuesday, but this seems a bit unlikely at this point
and will maintain the dry forecast.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1246 PM CDT Thu Jul 27 2017

Widespread cloud cover blankets central Illinois early this
afternoon: however, latest visible satellite imagery is showing a
few breaks in the overcast developing across the northern KILX
CWA. Ceilings were initially IFR early this morning, but have
risen to MVFR/low VFR as of 17z. Based on satellite trends and NAM
forecast soundings, have gradually improved all sites to VFR by
20z. May see a few showers as well, especially at the I-72
terminals. Forecast soundings suggest skies will clear by early to
mid-evening, with some high-res guidance hinting low clouds may
re-develop across west-central Indiana then push westward to KCMI
and perhaps KDEC late tonight into early Friday morning. Have
brought ceilings back down to MVFR at KCMI after 09z, but have
kept the lower clouds out of KDEC at this time. Any early morning
low clouds will clear/dissipate by 15z...followed by mostly clear
conditions for the balance of the day.

&&

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

$$

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



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