Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 110449
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1149 PM CDT Thu Apr 10 2014

.DISCUSSION...
ISSUED 859 PM CDT Thu Apr 10 2014

Latest surface analysis has cold front still across far southeast
portion of the forecast area, lying nearly parallel to and south
of I-70. A post frontal band of showers and a few thunderstorms
finally developed and continues to impact a portion of the area
along and just north of the I-70 corridor. This precipitation is
being forced by disturbances riding along and helping to slow the
cold front, and is residing in an axis of steep mid-level lapse
rates.

Expect the front, and band of showers/storms, to continue their
slow trek to the southeast for the rest of the night. Going
forecast was in pretty good shape overall. Updated grids to boost
PoPs in areas expected to be impacted by precip band overnight.
Also made hourly tweaks to most other parameters, but these
changes were not significant.

Bak
&&

.AVIATION...
ISSUED 1149 PM CDT Thu Apr 10 2014

Skies will continue to clear across the central Illinois terminals
overnight as drier air filters in behind the cold front that
passed through earlier today. As such, VFR conditions should
prevail through the 06Z TAF valid time.

Light/variable winds for the rest of the night will trend
southerly on Friday as return flow develops on the back side of
the surface ridge axis that is currently pushing into the area.

Bak
&&

.PREV DISCUSSION...
ISSUED 200 PM CDT Thu Apr 10 2014

Cold front continues to make steady progress southeast across our
area early this afternoon. Boundary as of 18z was located just east
of Peoria and Quincy with a gusty south to southwest wind ahead of
the front, while northwest winds were occurring to the northwest of
the boundary. Surface dew points were mostly in the low to mid 40s
ahead of the front with readings in the mid 20s to low 30s to the
west and north of the front. Despite the high level cloud cover
over the area, temperatures have had no problem warming into the
low to mid 70s just ahead of the front early this afternoon.

SHORT TERM...Tonight through Sunday

Main forecast concern this period will include convection chances
in our east and southeast tonight/Friday morning, and then
temperatures into Sunday as a more significant wave slowly pushes
out of the Rockies and heads for the Midwest.

Models fairly consistent with respect to the timing and position
of the cold front as it settles south of the area later tonight.
However, as far as moisture profiles are concerned, most of the
operational models have overdone the low level moisture forecasts
ahead of the front with several suggesting mid 50s to around 60
degree dew points. It appears the ARW core (U of I ensembles)
solutions have a much more realistic handle on the moisture
transport into southeast IL this evening so will tend to follow
their solutions, at least in the first period. Convective allowing
simulations suggest the highest POPs will continue to be along the
I70 corridor tonight into Friday morning before the front settles
south along with the precip chances by afternoon.

High pressure will then push across the area Friday afternoon and
night bringing quiet weather with a return flow already starting
to set up late Friday night into Saturday. A northern stream trof
will dig southeast while the southern stream upper low that was
out west of California will shift east to western Arizona by late
Saturday. In response, upper level heights will build this weekend
which will bring very mild air into the Midwest accompanied by gusty
southerly winds. Moisture transport will increase as well but as far
as a focusing mechanism for widespread precip is concerned, it appear
we will have to wait until late Sunday, more likely Sunday night into
Monday for widespread showers and thunderstorms to encompass our
forecast area. Precipitable water values of 1.2-1.4 inches Sunday
afternoon and night which is well above normal for this time of year
in our area. QPF totals in the Sunday afternoon through Monday
morning time frame could range from 1 to 2 inches, especially across
the northwest half of the forecast area.

Highest POPs will be Sunday afternoon far northwest, and over most
of the area Sunday night into Monday as the more consistent ECMWF
suggests the southern stream wave will get kicked northeast into
our area at this time. With the slower onset of precip, have gone
a bit above guid for highs on Sunday, especially across the east
and southeast where preip will probably hold off until Sunday
night.

LONG TERM...Monday through Thursday

A return to chilly weather is in store thru most of this period as
the upper trof edges slowly across the area on Monday accompanied by
rain chances before shifting off to our east later Monday night as
the colder air continues to filter southeast. Large trof will edge
slowly off to our east keeping us on the cool side thru Wednesday
night before we start to see temperatures moderate. Coldest mornings
will be Tuesday and Wednesday when we will see the mercury dip into
the upper 20s to middle 30s. Upper level ridging will begin to build
over our area midweek in response to another trof pushing into the
Rockies by the end of this forecast period. No real strong signal
for precip after our early week system shifts away so will keep the
extended period dry after Monday with the slow warming trend starting
on Wed.

Smith


&&

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

$$







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