Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 280927

Area Forecast Discussion
327 AM CST Wed Jan 28 2015

.SHORT TERM...(Today)

Latest surface analysis indicates high pressure just off to our east
which is expected to shift further away from our area during the
day. The next weather system is forecast to push into the central
Plains today and the tightening pressure gradient between the
departing high and approaching storm will help to increase surface
winds later this morning over west central Illinois and further east
into the remainder of the forecast area this afternoon. Models
indicating an increasing southeast to south flow today with the
better low level warm advection pointed towards west central
Illinois where afternoon temperatures will approach 50 degrees in
our far western and southwestern counties. Meanwhile, over far
eastern Illinois, with more of a southeasterly trajectory in the
surface flow, temperatures will struggle to reach 40 this afternoon.
RAP and HRRR forecasts showing gusts of 30 to 35 mph possible in the
west later this morning and this afternoon, and over all but far
southeast Illinois this afternoon.


.LONG TERM...(Tonight through Tuesday)

Surface low pressure close to 1005 mb tracks ENE near southern IA/MO
border this evening, into northeast IL by dawn Thu, and into eastern
lower MI by 18Z/noon Thu. This to bring a cold front east across IL
overnight and into central Indiana by midday Thu. Strong low level
jet with 850 mb winds 40-50 kts to continue gusty winds tonight, then
gusty south winds turn WNW behind cold front Thu. Not much moisture
to work with so still think just small chances of light rain over
central and eastern IL overnight into Thu morning. Lows tonight in
mid to upper 30s with coolest readings in eastern IL. Highs Thu in
upper 30s from I-74 north and mid 40s in southeast IL with temps
likely slipping behind cold front during afternoon.

1035 mb Canadian high pressure drops down into the western Great
Lakes region by sunset Friday and brings cooler and drier weather
from Thu night through Saturday morning as winds diminish. Highs
Friday 30-35F with coldest readings from I-74 north. Lows Thu night
and Friday night in upper teens and lower 20s (except mid 20s in
southeast IL Thu night).

00Z models continue to trend of phasing northern and southern stream
system and toward a potentially high impact and fairly long duration
weather event from Saturday night through Sunday evening. Surface
low pressure to deepen northeast from south Texas into the eastern
Ohio river valley Sunday night. Most of Saturday looks dry with just
small chances of light precipitation west of I-55 Sat afternoon. Best
chances of snow spreads ne across central/se IL Saturday night and
Sunday and then diminishes from the west during Sunday night. Added
a mix of precipitation in far southeast IL near highway 50 Sat night
and Sunday. Potential is there for several inches of snow over parts
of CWA especially se of the IL river with qpf of half to three
quarter inches and heaviest in southeast IL. Arctic air to follow
this low pressure system early next week with temperatures well
below normal, which we have not experienced since Jan 14th. Highs
Mon/Tue may stay in the teens over northern counties with lows
Monday night reaching near or just below zero from I-74 north.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)

Skies have cleared across much of central and southeast Illinois
late this evening, with MVFR ceilings persisting along/northwest
of a KBMI to KIJX line. IR satellite imagery continues to show
this area of clouds retreating to the northwest as light E/SE
return flow develops on the back side of departing high pressure.
Based on satellite loops and latest HRRR forecast, have removed
the ceiling at KBMI by 07z, then further northwest to KPIA by 09z.
Will need to keep an eye out for potential fog development, as
HRRR has been trying to develop areas of fog across the E/NE CWA
all evening. Latest obs show little or no obstruction to visby and
with dewpoints in the upper teens/lower 20s, do not think
widespread/dense fog will develop. Will however forecast slight
reductions in visby down to around 3-4 miles overnight. As the
high moves further away, strong southeasterly winds will develop
on Wednesday. Forecast soundings suggest gusts in the 20-25kt
range from late morning through the evening hours as the pressure
gradient continues to tighten. Next fast-moving storm system will
approach from the west late in the day, bringing an increase in
mid-level cloudiness but no precip through 06z Thu.





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