Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 211716
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1216 PM CDT Sat Apr 21 2018

.UPDATE...
Issued at 1042 AM CDT Sat Apr 21 2018

Cloud shield associated with a storm system over north central
Texas continues to stream northeast across the area late this
morning. The further east the clouds get the more they tend to
thin out allowing some sunshine to peak through over parts of
central, east central and southeast Illinois. This has resulted
in temperatures warming up nicely this morning with most areas
now in the 55 to 60 degree range. Based on the current satellite
and temperature trends this morning, have bumped highs up a few
degrees across the forecast area for this afternoon.

The 12Z ILX sounding continues to indicate quite a bit of dry
air present in the mid and lower levels of the atmosphere helping
to keep the light rain/sprinkles well off to our west and north
and we expect that trend to continue this afternoon. We should
have the updated zones out by 11 A.M.

&&

.SHORT TERM...(Today and tonight)
ISSUED AT 323 AM CDT Sat Apr 21 2018

Predominantly easterly winds this morning across Central Illinois.
The high pressure ridge axis slips to the east and the ridge axis
remains expansive enough that the winds remain easterly through
the weekend. Next wave/storm system moves out of the Plains and
into the Ohio River Valley later today. So far, the first round of
precip in the forecast looks to remain south of the forecast
area...although some areas to the south may see a sprinkle or two
later this afternoon depending greatly on moisture that is looking
quite scant this morning. Dewpoints still in the 20s and winds
from the east instead of the south...keeping the forecast dry for
now. Guidance for today a little closer to climo, and on a warming
trend. Considering the flow at the surface, knocked down the
blended guidance a degree or so. Overnight lows pretty close to
seasonal normals for the end of April.

.LONG TERM...(Sunday through Friday)
ISSUED AT 323 AM CDT Sat Apr 21 2018

Extended forecast quiet for the most part. Models persist on
bringing the storm system through the Plains and into the Ohio
River Valley tomorrow. ECMWF is a little further north with the
spread of precip. Seems a bit far north considering the neutral
tilt and relative weakness of the low. Pops are confined to a low
chance in the far SE by tomorrow night. The low slows at the
surface as the upper low gets stranded over the region. Low
becomes an open wave at 500mb and the precip stalls more or less
over the southeastern section of the country. Best chances for
Monday as the low wobbles a bit to the north, but overall, precip
is a scattered threat into mid week. GFS produces a far stronger
wave midweek, but is much weaker in the ECMWF. This wave is a
series of shortwaves diving into the Midwest, effectively kicking
out the weaker open pieces of energy shearing out over the region.
The front/system to clear it out will come late in the week. The
ECMWF is open with the wave aloft, carrying much of the precip
with a cold front at the surface. The GFS is far more diffuse with
the precip, and better widespread ascent over the region with a
532dm height center/closed low at h5. Slightly cooler temps on the
way for next weekend as well as the pattern shifts and more
northwesterly flow aloft ushers in a cooler airmass.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1212 PM CDT Sat Apr 21 2018

VFR conditions are expected to prevail across the forecast area
through the period. Scattered to broken mid level clouds
(10000-15000 ft AGL) coupled with bkn-ovc cirrus will continue to
stream across the area through tonight as a storm system passes
south of our area this weekend. Precipitation chances will be
quite limited, other than possibly a few sprinkles across our far
southern areas on Sunday. Surface winds will continue from an
easterly direction at 10 to 15 kts, occasionally gusting up near
20 kts this afternoon, around 10 kts tonight with an east wind
continuing on Sunday at 10 to 15 kts.

&&

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

$$

UPDATE...Smith
SHORT TERM...HJS
LONG TERM...HJS
AVIATION...Smith


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