Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 172354

Area Forecast Discussion
National Weather Service Lincoln IL
654 PM CDT Mon Jul 17 2017

.SHORT TERM...(This evening through Tuesday)
ISSUED AT 310 PM CDT Mon Jul 17 2017

Will issue an excessive heat watch for CWA from Wednesday
afternoon through early Saturday evening. Highs in the low to mid
90s (upper 90s even possible sw CWA on Thu/Fri). Afternoon heat
indices are likely to peak from 100-110F during each of those 4
afternoons. Heat indices are expected to reach 100-105F over
southern half of CWA on Sunday afternoon so heat headlines may
need to be extended longer there. This will likely be our longest
heat wave of the summer for central and southeast IL.

A frontal boundary extending from Bloomington IN to near
Lawrenceville IL and just south of Flora, could develop an
isolated shower or thunderstorm this afternoon before shifting
south of CWA by 6 pm. Otherwise dry conditions expected tonight
and Tuesday across CWA as weak 1018 mb high pressure settles se
across the Great Lakes and ridges into central IL keeping winds
light. Lows overnight to range from the upper 50s and lower 60s
from I-72 north, to the mid to upper 60s in southeast IL where
airmass is more moist (dewpoints still in the lower 70s from
Charleston/Mattoon south). Highs Tue in the upper 80s to around
90F with warmest readings in western CWA with a fair amount of
sunshine expected across area. Dewpoints in the mid 60s to near
70F Tue afternoon to give afternoon heat indices peaking in low to
mid 90s Tue afternoon, warmest in western CWA.

.LONG TERM...(Tuesday night through Monday)
ISSUED AT 310 PM CDT Mon Jul 17 2017

12Z models continue to expand/build subtropical mid/upper level
ridge into the central and southern US during rest of this week
then starting to be suppressed southward during this weekend into
early next week. Disturbances/MCSs riding over top of upper level
ridge will initially pass north of central IL with hot and humid
conditions prevailing from Wed afternoon into this weekend. One
disturbance gets qpf close to far northern CWA later Tue night and
early Wed morning. Another disturbance/MCS to graze close to far
northern CWA again late Wed night and Thu morning. Feel most of
CWA will stay dry thru mid week though. Yet another one brings
slight pops to northern CWA overnight Thu night into Fri morning
and have 20-30% pops over central and ne CWA on Fri afternoon.
Have small pops over ne 1/3 of CWA Fri night then 20-30% over
areas north of I-70 on Sat afternoon. Better chances of convection
for CWA appear to arrive from Sunday afternoon thru Monday as a
frontal boundary moves thru central IL from late Sunday afternoon
and Sunday night and thru southeast IL on Monday. Temps to cool
closer to normal by next Monday along with heat indices coming
down to 85-95F range next Mon afternoon (highest in southeast IL).


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 652 PM CDT Mon Jul 17 2017

Predominantly VFR conditions expected across the central Illinois
terminals through the 00Z TAF valid time. High pressure building
across the area will provide light winds and minimal cloud cover.
Patchy MVFR fog is possible tonight, especially at KCMI, where
low-level moisture is more substantial.


Excessive Heat Watch from Wednesday afternoon through Saturday
evening for ILZ027>031-036>038-040>057-061>063-066>068-071>073.



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