Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 251116

Area Forecast Discussion
516 AM CST Thu Dec 25 2014

.SHORT TERM...(Today)

Latest surface analysis indicating high pressure across the lower
Mississippi Valley with the ridge axis extending north into extreme
eastern Iowa. Satellite data and surface observations to our west
indicate skies clearing just to the west of the ridge axis over
central Iowa and based on timing tools it appears our western areas
will see the clearing trend in the 12z to 15z time frame, with areas
over extreme east central Illinois seeing the decrease in clouds by
19z/1pm. Short term forecast soundings all showing this clearing
trend starting later this morning into the afternoon hours as drier
air erodes the low level moisture/clouds that have been present
across the area for the past 24 hours. Winds to back into the
southwest and south and become rather gusty today allowing some very
mild air to advect into the area. Afternoon temperatures expected to
range from the low 40s far northeast to within a few degrees of 50
in our southwest.


.LONG TERM...(Tonight through Wednesday)

00Z models continue to show a breezy and milder day Friday (after
lows tonight in mid to upper 30s) as dry conditions continue with
clouds over the IL river valley overnight and over rest of
central/eastern IL during Friday. SSW winds 10-20 mph and gusts in
the 20s to bring milder highs in the upper 40s and lower 50s. Upper
level trof digging into the southern Rockies to cause low pressure
to eject ne from nw Texas into eastcentral WI by noon Sat and pull a
cold front se through IL Sat. Have chance of light rain spreading
eastward across IL Friday night and have likely chances of light
rain over southeast IL Sat, while chances of light rain turn to
light rain/snow chances north of I-72 Sat afternoon. Little or no
snow accumulations expected Sat.  Lows Fri night in the lower 40s
then highs Sat range from lower 40s nw of IL river to upper 40s to
near 50F in eastern/se IL. Continue chances of light rain/snow over
areas se of I-55 Sat night and mainly in the evening before
precipitation chances shift se of Lawrenceville Sunday with cold
front pushing se through TN.

Extended models continue to show strong arctic high pressure of 1055
mb dropping southward from Canadian rockies into front range of US
Rockies by Tue. This to bring in colder air into central/se IL by
middle of next week and undercut SuperBlend temps and dewpoints. A
weak disturbance could bring light snow/flurries to IL river valley
later Mon night into Tue morning but models really do not show much
signals for precipitation from Sunday-Wed. Models do agree with
below normal temps arriving by middle of next week as some arctic
air ushers into the region.


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)

Improving conditions expected over central and east central
Illinois as the day wears on as the MVFR cigs are expected to
clear from west to east this morning. One concern will be right
at the backedge of the cloud band where we have had reports of
some IFR cigs, but the latest satellite data and surface obs to
our west were showing less coverage of the IFR cigs than a few
hours ago. Will continue to monitor and make a last minute
decision as to whether to include for a few hours early this
morning. Once the lower clouds move out, we expect VFR conditions
to prevail for the remainder of the forecast period. Surface
winds will back into the southwest and then south today with
speeds of 12 to 17 kts with gusts around 23 kts at times,
especially late this morning thru this afternoon. The gusts
should diminish this evening but expect winds to hold around 10
to 15 kts thru the night. If the winds do drop off for any period
of time late tonight, fog may become an issue but at this point,
am expecting the winds to hold up enough overnight to keep the
mention of fog out of this set of TAFs.




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