Area Forecast Discussion
Issued by NWS Central Illinois

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197
FXUS63 KILX 221145
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
645 AM CDT THU SEP 22 2016

.SHORT TERM...(Today and tonight)
ISSUED AT 321 AM CDT Thu Sep 22 2016

Well above normal temperatures and generally quiet weather is
expected across central and southeast Illinois through the period.
Southerly low-level flow between an area of high pressure centered
over the Ohio Valley and low pressure centered over the central
Plains will persist, with flat ridging building in aloft. Given this
scenario, would expect temperatures similar to yesterday with highs
near 90 and lows in the 60s. While dry weather is expected to
persist, we`ll still have to keep an eye on the ongoing convection
over the upper Midwest. A similar setup yesterday ended up kicking a
couple outflow boundaries, with spotty showers/storms, into the
forecast area. Nearly all current guidance keeps any convective
remnants north of the area today, which is better agreement than was
seen yesterday.

.LONG TERM...(Friday through Wednesday)
ISSUED AT 321 AM CDT Thu Sep 22 2016

As an overview, the forecast remains warm through the weekend as a
ridge keeps control over our area.  An upper low moving into the
west coast is resulting in increasingly southwesterly flow aloft,
and this is expected to continue through the first half of the
weekend.  Unseasonably warm and dry should continue, with the series
of small waves bringing precip mainly north of ILX.

The issues with the forecast are centered on the low/trof as it
moves across the country.  The GFS and the ECMWF have both been
inconsistent in handling the system aloft at 500mb with respect to
phasing or splitting it as an open wave in the northern stream...and
a cutoff low in the SW/Southern Plains.  Each run is different in
handling the synoptic system, regardless of the sfc fields
apparent relative consistency. The few things that seem to remain
a trend is a slower approach overall, and have no problems staying
dry through the weekend. However, with the difficulty in the
modeling, the low chance pops from Monday into Tuesday is actually
a preferred way to handle the forecast for now. Cooler air
accompanying the trof will drop the max temps in the first part of
next weak to more seasonable expectations.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 637 AM CDT Thu Sep 22 2016

Quiet/VFR aviation weather conditions expected across the central
Illinois terminals through the 12Z TAF valid time. Cloud cover
should be minimal, and winds generally light. However, will need
to keep an eye on convection to our northwest. While it is not
expected to push into the area, it may get close and/or push an
outflow boundary across part of the area.

&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...Bak
LONG TERM...HJS
AVIATION...Bak



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