Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 152308
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
508 PM CST Sun Jan 15 2017

.SHORT TERM...(This evening through Monday)
ISSUED AT 307 PM CST Sun Jan 15 2017

Will continue the winter weather advisory from Fulton, Tazewell and
McLean counties northward tonight into Monday morning for light
icing up to a tenth inch possible along with some sleet. Latest
model runs are warming surface temps a bit quicker late tonight into
Monday morning, so the winter weather advisory might be able to end
sooner.

An area of light rain was along and south of a Macomb to Lincoln to
Terre Haute line at mid afternoon, with the northern fringe of
precipitation mixed with some light freezing rain and sleet. Surface
temperatures were mostly just above freezing over CWA, expect still
30-32F from Galesburg to Jacksonville west where mixed light
precipitation occurring. 1030 mb high pressure over the southern
great lakes was keeping northeast CWA from Lincoln ne dry so far
today with overcast mid level clouds around 10k ft. Light
precipitation was from overrunning of a warm front just south of TN
into central Texas to 1006 mb surface low pressure in sw Texas.
Aloft a 555 dm 500 mb low was spinning just east of El Paso Texas.

Hi resolution models like the HRRR and ARW (to a lesser extent with
the RAP model) lift the light precipitation ne across rest of
central IL late this afternoon and this evening. Then more
precipitation develops later tonight over western CWA and then
spreads ne across rest of area on Monday. Continued small chances of
thunderstorms late Monday afternoon sw of Springfield. The thermal
profiles still support best chances of light freezing rain north of
I-72 this evening, shifting nw of a Rushville to Bloomington line by
sunrise Monday, and nw of a Galesubrg to Henry line by 9 am Monday,
as temps rise above freezing. Lows tonight range from around 30F
over northern CWA where winter wx advisory is posted, to the mid 30s
from I-70 southeast and may be nearly steady or even rise slightly
later tonight. Milder highs Monday range from low to mid 40s over
northern CWA, to the low to mid 50s in southeast IL with southeast
winds 8-15 mph.

.LONG TERM...(Monday night through Sunday)
ISSUED AT 307 PM CST Sun Jan 15 2017

The upper low currently over western TX will eject northeastward
across the southern Plains reaching NW Missouri by Monday evening.
As it does so, warm moist southerly flow ahead of the low will
result in instability characterized by MUCAPE values around 200
J/kg, which should allow for isolated thunderstorms...continuing
after midnight east of I-55. Moderate rain amounts around 1/2 inch
to 1 inch should accompany this portions of the storm as the surface
low moves through northern IL. Low temperatures should only reach
around 50 near the Indiana border to the upper 30s in Galesburg as
the cold front sweeps across the state late in the night. As
temperatures remain above freezing and saturation depth decrease
dramatically behind the upper wave, precipitation type should remain
all rain with a loss of ice aloft. A bit cooler Tuesday with some
lingering drizzle/light rain toward the northeast, with highs
ranging from near 40 in Galesburg to above 50 in Lawrenceville.

Fair weather mid week as high pressure shifts east across the
central U.S. with highs in the mid 40s to lower 50s and lows upper
20s to mid 30s.

Pattern transitions to a longwave trough over the west and ridge
over the east for late in the week and next weekend. The result will
be a series of waves ejecting out of the southwestern U.S. toward
the Midwest. Although timing and track uncertainties remain, this
should bring mild temperatures with periodic chances for rain Friday
through the weekend. Current model consensus places a chance for
precipitation Friday and Sunday as indicated in afternoon forecast
package, however there will undoubtedly be refinements in the timing
and track of these systems in the upcoming days. As highs/lows
likely to be in the 50s/40s through this time, all rain expected at
this point.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 505 PM CST Sun Jan 15 2017

Latest surface observations indicate a large band of IFR to LIFR
cigs were located from Springfield to just south of Decatur and
are expected to edge north tonight. Latest forecast soundings
suggest our northern TAF sites (PIA and BMI) should see the IFR
cigs around midnight and once they arrive, it appears they will
be with us through the rest of the forecast period. A band of
light rain and sleet was track east across the TAF sites late
this afternoon and will continue to drift east early this evening
with most of the precip shifting away from our area in the 01z to
03z time frame. Surface temperatures around KBMI may slip a degree
below freezing for a time so we may see a brief period of -FZRA
and sleet early this evening before the precip moves out. Light
easterly winds of less than 10 kts tonight will turn more into
the southeast at 10 to 15 kts on Monday ahead of a approaching
storm system.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon CST Monday for ILZ027>031-
036>038.

&&

$$

SHORT TERM...07
LONG TERM...37
AVIATION...Smith



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