Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 191147
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
647 AM CDT Tue Aug 19 2014

.SHORT TERM...(Today and tonight)
ISSUED AT 336 AM 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 through Monday)
ISSUED AT 347 AM CDT TUE AUG 19 2014

Models still pretty consistent with the development and lift of a
boundary through the Midwest on Wednesday. Boundary will have little
reflection at the sfc with very weak flow/weak wind shift, and
thermal gradient is better represented in the mid levels.  Boundary
will provide a weak focus for waves moving through the region as the
boundary lifts to the NE through the area for Wed/Wed night.  Though
Wed is lacking signif pop for now, the timing of the progression is
better for early evening and into the overnight on Wednesday
night/shifting to the northeast for Thurs. Position of the boundary
or the remnants thereof will be where the majority of the precip
chances will be...increasing to the north, particularly north of
Interstate 74 from Thursday to Saturday. Ample sfc based instability
in the form of hot and humid conditions as the ridge over the
southwest opens and spreads signif heat into the Midwest. Models
have also shown consistency with  850 mb temps in the 19-25C range
from Wednesday through Sunday.  This will drive the temps into the
upper 80s/lower 90s with heat indices in the upper 90s/approaching
100F.  A far more summer-like pattern than much of the season so far,
and well above normal for this time of year...with breaks from the
heat provided by any thunderstorms that may have the chance to form
from more diurnal instability with any frontal forcing further to
the north. Into the extended, day 7/just into day 8, models diverge
in solutions with major difference in breaking down the upper ridge
for the Midwest.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
ISSUED AT 609 AM CDT TUE AUG 19 2014

Cold front is still back northwest of the area, but still
forecasted to move through the area, affecting all TAF sites this
through afternoon. However, radar loops show a complex of
thunderstorms in northern MO that could move into central IL this
morning and effect some of the TAF sites, possibly SPI and DEC.
Short term models do show some pcpn moving through the area this
morning, but appears it will diminish as it moves into the area.
Then the front drops into the area a few hours later and this will
bring a chance of thunderstorms to the TAF sites for the afternoon
and early evening. The early stuff could be just showers, but
since the front will be right on the heels of the current complex
coming out of MO, will opt to just have VCTS for all TAFs to cover
both events. Believe t-storms will be more scattered as well. Also
VCTS will be in the TAFs longer than necessary, but only because
of two events. Not expecting cigs to go down today, but having
some light fog issues at mainly CMI, with some very light fog at
PIA and BMI. This fog will burn off quickly, like yesterday
morning. Winds will be south to southwest through the morning and
then become southwest just ahead of the front, and then westerly
or light and variable after FROPA.

&&

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

$$

SHORT TERM...AUTEN
LONG TERM...HJS
AVIATION...AUTEN





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