Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 191956
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
256 PM CDT Tue Aug 19 2014

.SHORT TERM...(This evening through Wednesday)
ISSUED AT 255 PM CDT TUE AUG 19 2014

Short term models have trended slower with the front and precip that
is currently supposed to be moving into the area. But will still
have chance of precip starting in the northwest parts of the cwa
this morning. Then will progress the pcpn chances southeastward
across the cwa during the day. By this evening, most of the pcpn
will be in the eastern two thirds of the area with the highest pops
in the southeast. By overnight, the pcpn should have moved southeast
of the area so most of the area should be dry overnight, though will
keep a slight chance of pops in the southeast after midnight. Could
be some additional pcpn in the southwest late tonight, but models
keep most of pcpn west of the area through 12z.

Temps will begin the slow warming tomorrow, and am expecting mid to
upper 80s throughout the area today.


&&

.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 255 PM CDT TUE AUG 19 2014

Wednesday night after midnight had previously looked like our best
chances of storms over the next few days, but the 12z guidance has
sped up the shortwave/MCV by 6-12 hours and weakened it. Our area
will still remain along the storm track over the building upper
level ridge, so despite lowering PoPs below the likely category,
chances will remain in most areas, with lowest chances southwest of
Springfield to Effingham.

The theme of higher storm chances in N-NE Illinois will continue for
the balance of the extended forecast, as the upper ridge and dome of
hot air build from southwest to northeast. The storm track appears
to generally follow the 588dm 500mb height line into this weekend.
We kept a narrow channel of chance PoPs across our N-NE counties
from Thursday to Saturday, with minor shifts east and west during
that time. Slight chances could extend as far south as Rushville to
Lincoln to Mattoon, but the building dome of heat should provide
enough mid-level capping to limit the southward extent of storms.

Model differences in the Sunday to Tuesday time frame have prompted
a continuation of periodic slight chance PoPs as a cold frontal
boundary tries to push into the dome of hot air. The 12z runs have
limited the forward progression of the front into IL on Sunday night
and Monday, when previous runs indicated an airmass change for less
hot conditions on Monday. Now the heat may linger as long as Tuesday
with the only hints of relief coming for areas north of I-74.

Heat index readings from Wednesday to Sunday will climb to into the
95F to 102F range at peak heating, which could be locally limited by
any pop-up thunderstorms each afternoon. Heat advisory levels are
105F+, but conditions will still be very uncomfortable, and heat
precautions will be necessary each day.


&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 1244 PM CDT TUE AUG 19 2014

17z surface analysis shows cold front across eastern Iowa
approaching the Mississippi River. Earlier convection that pushed
into the Illinois River Valley ahead of the front continues to
diminish as it tracks toward the I-57 corridor. Based on latest
satellite/radar trends, it appears chances for additional
convection at KPIA are slim to none, so have gone with a dry
forecast there. Further southeast at the remaining terminals, will
carry either VCTS or a TEMPO group for thunder this afternoon.
Atmosphere has been temporarily stabilized due to clouds/showers
this morning, but as skies partially clear, think scattered
showers/storms will develop east of the Illinois River through the
afternoon. Any convection that fires up will push into Indiana by
early evening, followed by clearing skies tonight. Given clear
skies and light winds, think areas of fog will once again develop.
Have dropped visbys lowest at KPIA where quite a bit of rain fell
earlier, but have gone with 2-3 miles everywhere between 07z and
14z. After that, mostly clear skies with a light W/SW wind will
prevail by Wednesday morning.


&&

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

$$

SHORT TERM...BARNES
LONG TERM...SHIMON
AVIATION...BARNES






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