Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 211731
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1231 PM CDT Thu Sep 21 2017

.UPDATE...
Issued at 1054 AM CDT Thu Sep 21 2017

Rain and cloud cover NW of the IL river valley this morning is
keeping the temperatures down from expected diurnal swing. Have
made some adjustments to the highs as a result. Other than that,
warm and muggy yet again today. Highs still mainly in the low 90s,
with heat indices approaching 100F. Major updates are not
anticipated for the forecast at this time.

&&

.SHORT TERM...(Today and tonight)
ISSUED AT 222 AM CDT Thu Sep 21 2017

Backbuilding MCS has been persistent the last several hours across
southeast Iowa and far northwest Illinois, roughly about where the
cold front has stalled. Storms as of 2 am have crept about as
close to Knox County as possible without actually crossing the
border, though the associated outflow boundary recently went
through Galesburg. HRRR model shows a gradual diminishing trend
toward early morning. Will maintain the low PoP`s in the far
northwest CWA through about sunrise.

Extensive cirrus blowoff should thin out this morning, with
another unseasonably hot day following. Highs expected to be near
record highs in most areas, generally in the mid 90s, though the
heat index will be closer to 100.

.LONG TERM...(Friday through Wednesday)
ISSUED AT 222 AM CDT Thu Sep 21 2017

The first days of fall start off just as hot as the last day of
summer. Impressive upper ridge for late September will be anchored
over the Midwest into the weekend, keeping any rain away and
allowing temperatures to keep reaching the 90s. Odds of record
highs increase with time, as the weekend records are lower.

Some breakdown of the ridge takes place early next week, but the
northward movement of Hurricane Maria will slow its erosion.
However, by Wednesday, the blocking pattern finally gives way,
allowing a cold front to pass. This will allow temperatures to
ease back closer to normal.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1229 PM CDT Thu Sep 21 2017

Remains of overnight MCS is resulting in plenty of cirrus across
the area. A lack of well defined pressure gradient and a weak
ridge to the east is keeping the winds southerly for the most part
with a bit of variability. Overnight, southerly winds continue and
the cirrus will eventually mix out in the dry air aloft.
Location/existence of cu field tomorrow by late morning will vary
with mixing of dwpts this afternoon.

&&

.CLIMATE...
Issued at 222 AM CDT Thu Sep 21 2017

Record highs through the weekend:

Location         Thu       Fri       Sat       Sun
--------       -------   -------   -------   -------
Bloomington    94/1908   94/1930   92/1937   94/1933
Champaign      95/1891   95/1891   94/1891   94/1891
Charleston     95/1940   95/2005   93/2010   93/1933
Decatur        95/1955   94/2005   92/2007   93/1933
Galesburg      90/1940   92/1988   89/1937   90/2007
Olney         100/1940   96/2010   94/1960   94/2010
Peoria         93/1940   93/1930   92/1937   92/2007
Springfield    96/1931   95/2005   93/2007   93/2007

&&

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

$$

UPDATE...HJS
SHORT TERM...Geelhart
LONG TERM...Geelhart
AVIATION...HJS
CLIMATE...Geelhart



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