Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 141609
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1109 AM CDT Sun Sep 14 2014

.UPDATE...
ISSUED AT 1104 AM CDT SUN SEP 14 2014
High pressure dominates the Midwest and the mid level clouds just
out to the west are eroding quickly on vis sat imagery. Another
quiet and cool day for the region. A little bit of variability in
the relatively light sfc winds... but a mostly southerly component
throughout today. Minor updates to the hourly trends... maybe to
accommodate a few cu this afternoon...but no major updates
anticipated.

&&

.SHORT TERM...(Today)
ISSUED AT 250 AM CDT SUN SEP 14 2014

Another quiet, albeit cooler than normal, day is on tap across
central and southeast Illinois. Surface ridging remains in place,
and will continue to slowly drift east today. Upper level flow is
weakly cyclonic locally, and the compact short wave scooting east
along the U.S./Canada border to our north is too far away to have an
impact on our sensible weather. The local air mass continues to be
quite dry overall, and abundant sunshine is expected once again.
This insolation (and associated air mass modification) and weak
return flow on the back side of the departing surface/low level
ridge should produce high temperatures a few degrees warmer than
yesterday`s highs.

&&

.LONG TERM...(Tonight through Saturday)
ISSUED AT 250 AM CDT SUN SEP 14 2014

Not too much has changed with the storm system developing later
tonight. The evening models continue to sharpen a baroclinic zone
across Kansas northeast into Iowa overnight, linking up with a
shortwave that will be digging as it drops through the Dakotas and
Minnesota. The main front will be moving through the forecast area
during the day Monday, and much of the precipitation is
post-frontal. Thus, will keep most of Sunday night dry except very
late across the far northwest, with likely PoP`s over most of the
area during the day Monday. Precipitation should fade quickly during
the evening as the upper support from the wave shifts further east
in the Great Lakes region. With widespread clouds and rain, have
continued the trend of temperatures several degrees below guidance
values.

Midweek to be a quiet period as the upper ridge builds across the
Rockies, and a surface high drifts over the Midwest. The models do
try to develop an MCS along the periphery of the upper ridge, with
only the GFS bringing it into parts of Illinois, so have kept our
forecast dry.

Late week system looks to be more robust, with the longer range
models more in agreement on the evening run on a deepening wave
across the upper Mississippi Valley and a trailing cold front into
the southern Plains. Have added slight chance PoP`s to the Saturday
forecast, but these will likely need to be beefed up if the morning
models continue their agreement.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
ISSUED AT 651 AM CDT SUN SEP 14 2014

Predominantly quiet/VFR aviation weather expected across the
central Illinois terminals through the 12Z TAF valid time. High
pressure and the associated dry air will dominate to start the
period, but a gradual increase in cloud cover is expected for the
second half of the period as a frontal boundary approaches from
the west. There is a band of 6-8K foot clouds approaching Illinois
at the moment, and these are not very well handled by the current
guidance. If these clouds hold together, cigs may arrive sooner
rather than later. However, conditions would still be VFR in any
event.


&&

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

$$

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






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