Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 231741

Area Forecast Discussion
National Weather Service Lincoln IL
1241 PM CDT Sat Sep 23 2017

Issued at 1056 AM CDT Sat Sep 23 2017

South/southeasterly winds continue in a very warm airmass,
resulting in high temperatures once again in the low 90s. Still a
little humid and heat indices add a couple degrees to the mid 90s
for the peak heating of the day. Some cu anticipated for Central
IL this afternoon, particularly the western half of the state.
HRRR is persisting in getting enough vertical growth on those cu
to result in isolated showers later in the afternoon. Comparing to
yesterday, instability above the mid levels is a little more
contained this morning, even with decent llvl lapse rates. Not
seeing enough to warrant a measurable pop just yet, but have made
a mention of sprinkles in the west/southwest. Will continue to
wave cu development through the morning. Only minor adjustments to
the forecast warranted at this time.


.SHORT TERM...(Today and tonight)
ISSUED AT 330 AM CDT Sat Sep 23 2017

The late season heat wave will continue a few more day across
central and southeast IL with high temperatures reaching close to
record levels. Below in the climate section are record highs for
today, Sunday and Monday for 10 of our larger cities in our CWA,
which are mostly in the lower 90s.

A 588-590 dm 500 mb subtropical ridge from Texas ne across IL and
into the eastern Great Lakes, will continue the summer like heat
wave through Monday (and over southeast IL thru Tue) as 592 dm
500 mb high over PA by 18Z/Sunday and ridges back into IL into
early next week.

Patchy fog possible over eastern IL until mid morning, otherwise
another hot day ahead with partly to mostly sunny skies. Highs of
90-95F today with afternoon heat indices in the 90s. A weak
disturbance that brought isolated convection to parts of IN and
east central IL yesterday afternoon and early evening appears to
shift west of I-57 today and this area will likely see more
cumulus clouds this afternoon. Most models keep our CWA dry today,
though HRRR shows isolated qpf western CWA into mid afternoon but
this model is also showing qpf currently where we have nearly
clear skies. Fair weather expected tonight as diurnally driven
cumulus clouds dissipate this evening. Lows mostly in the mid
60s, with some upper 60s over the IL river valley.

.LONG TERM...(Sunday through Saturday)
ISSUED AT 330 AM CDT Sat Sep 23 2017

The heat wave will likely continue through Monday with highs in
the lower 90s, except upper 80s Monday northern CWA from Peoria
and Bloomington north. Dry conditions expected through most of CWA
through Tue morning, though do have slight chance of convection
far nw CWA Tue morning as a cold front moves into far nw IL. This
front will bring 20-30% chance of showers and thunderstorms over
the IL river valley Tue afternoon mainly from I-55 nw. Highs Tue
range from lower 80s by Galesburg to near 90F from I-57 east. The
cold front to sweep thru rest of CWA during Tue night though lift
will be weak and pops are either slight or none going into Wed.
Much cooler air ushers in on Wed behind cold front with highs
ranging from lower 70s nw of IL river, to the lower 80s se of
I-70. Dry and seasonable temperatures expected Wed night thru
Saturday. Highs Thu in the low to mid 70s, and cooler upper 60s
and lower 70s Fri/Sat as a broad upper level trof digs south
across the Great Lakes and into the OH/TN river valleys.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1238 PM CDT Sat Sep 23 2017

Light winds south/southeasterly this afternoon, with VFR
throughout the forecast for ILX terminals. Only concern for the
forecast is vertical development of the cu in the west/southwest
potentially lending towards very isolated sprinkles this
afternoon. Not enough for a mention yet, and VFR sct cirrus with
light winds yet again tonight.


Issued at 330 AM CDT Sat Sep 23 2017

Record Highs Today through Monday:

Location        Today    Sunday   Monday
                Sep 23   Sep 24   Sep 25
--------       -------   -------  -------
Bloomington... 92/1937   94/1933  93/2007
Champaign..... 94/1891   94/1891  96/1891
Charleston.... 93/2010   93/1933  91/2016
Danville...... 91/2010   92/1939  94/1897
Decatur....... 92/2007   93/1933  91/1939
Galesburg..... 89/1937   90/2007  90/2007
Olney......... 94/1960   94/2010  92/2007
Peoria........ 92/1937   92/2007  92/1891
Springfield... 93/2007   93/2007  94/1891
Lincoln....... 92/1937   93/1935  92/1920




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