Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 270451
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1151 PM CDT Tue Aug 26 2014

.UPDATE...
ISSUED AT 845 PM CDT TUE AUG 26 2014

Band of strong/severe storms has been slowly trudging southward
along the frontal boundary roughly along the the I-72 corridor.
The models are generally handling this convection extremely
poorly, although the 21Z online HopWRF is doing a pretty decent
job, with the NamDNG5 also in the general vicinity. The HopWRF
shows a general push toward the I-70 corridor over the next couple
hours, and there is a lingering outflow that extends from near
Flora northwest toward Taylorville, so that could feed some
additional development. The front will not be moving too much
overnight, and the RAP and 18Z NAM show some redevelopment north
of it after 2-3am.

Have sent some updated grids/zones to significantly increase the
PoP`s this evening with this convection. Have not looked too
closely at the temperatures yet, so further updates may be needed
once that is evaluated.

&&

.SHORT TERM...(This evening through Wednesday)
ISSUED AT 316 PM CDT TUE AUG 26 2014

An outflow boundary is draped over the area this afternoon and this
could be the focus for more showers and thunderstorm development
this evening and into tonight. So will be keeping a chance pops in
the forecast for tonight, but mainly along and northeast of I-74. By
tomorrow, all models indicate a good chance of thunderstorms across
most of the area through tomorrow afternoon. Things will then shift
back to the west after that.

Temps and dew points are remaining high so will keep the heat
advisory and warning going through this evening. Temps will remain
warm through tomorrow, but with clouds and pcpn, advisory/warning
criteria for heat indices will not be met. Model guidance numbers
look to be too warm.

&&

.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 316 PM CDT TUE AUG 26 2014

Upper level ridging will be broken down, which will allow another
cold front to move into the area late in the week. Unfortunately
this means that the chance of showers and thunderstorms will
continue into the weekend. Most of the pcpn chances will remain to
the northwest or northern part of the CWA through Friday. Then when
the front drops into the area Friday afternoon, the chance of
thunderstorms will spread across the whole CWA for most of the
weekend. There could be a break in the pcpn over some of the area
Sunday night, but another frontal system will move into the region
for the beginning of next week...so chance pops continue.

Temps will cool through the period, but then warm back up during the
beginning of next week. Model guidance still looks to be too warm.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 1150 PM CDT TUE AUG 26 2014

Predominantly VFR aviation weather conditions expected across the
central Illinois terminals through the 06Z TAF valid time. Still
looks like a brief period of MVFR fog is possible later tonight,
although the convective debris cloud in the area make this a
little less certain than it seemed earlier tonight. Precipitation
for the period is likely to be quite tricky. Feel the bulk of the
night should be dry, and much of Wednesday may be as well.
However, with a weak cold front slipping south through the area,
and/or the presence of outflow boundaries, and expected arrival of
a weak upper wave Wednesday, feel a mention of VCSH or VCTS if
warranted. Confidence in timing of any precipitation is too low to
go with a tempo or predominant period. If convection were to
impact a terminal directly, lower than VFR conditions are
possible. Winds through the period should be light/variable away
from any convection with weak boundaries in the vicinity.

&&

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

$$

UPDATE...GEELHART
SHORT TERM...HJS
LONG TERM...AUTEN
AVIATION...BAK





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