Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 131740
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1240 PM CDT Sat Sep 13 2014

.UPDATE...
ISSUED AT 1038 AM CDT SAT SEP 13 2014

Surface MSAS analysis this morning shows high pressure main
feature to affect weather today, with high center over northern
half of MO. Aloft, broad sweeping west to northwesterly flow with
series of upper waves moving over the northern US region. First
wave noted in moisture channel satellite imagery over eastern
Great Laeks exiting region to the east, with second wave over
western ND to WY. This system progged to move east northeast
through Great Lakes, mainly north of forecast area, keeping the
cool, dry high pressure area in control of area through weekend.

For today, soundings this morning very dry aloft, with only
moisture very shallow in the lower levels. The early morning fog
and stratus this morning disipated and so expect light winds today
and clear skies. Temperatures should rise from cool morning low,
but continued cold air advection at 850mb/925mb should keep
temperatures around 60 to the lower 60s.

&&

.SHORT TERM...(Today)
ISSUED AT 220 AM CDT SAT SEP 13 2014

The center of a sprawling Canadian area of high pressure will build
into central and southeast Illinois today from the northwest, while
the upper level flow is expected to trend more neutral. The dry air
associated with this surface high is helping to rapidly scour out
the low clouds in place across the region, and see no reason this
trend will not continue. The air mass is too dry to support much in
the way of diurnal cloud development today. Expect high temperatures
today to be similar to, or a degree or two warmer than, yesterday.
This warming will be the result of nearly full sunshine today, as
there will be little/no warm advection taking place today given the
expected position of the surface high.

&&

.LONG TERM...(Tonight through Friday)
ISSUED AT 220 AM CDT SAT SEP 13 2014

Core of surface high to drift eastward across the Midwest Saturday
night and early Sunday, with mostly clear skies prevailing. Think
upper 30s/lower 40s will be widespread, but probably a few degrees
above records in most areas. Temperatures on Sunday should reach
the upper 60s with a few lower 70s southeast.

Upper riding just offshore of the Pacific coast to build inland late
this weekend, with a shortwave in the north central U.S. digging
southward on Monday. Next chance of rain will be focused with this
system. Have trimmed back the PoP`s late Sunday night and mainly
kept them northwest of the Illinois River, but have increased them
to the likely range (around 60%) across the northwest half of the
forecast area on Monday. The precipitation should die off quickly
Monday evening as the support from the upper wave pulls away.

Midweek pattern shows the upper ridge slowly building eastward, with
a large surface high dominating the Great Lakes. While temperatures
remain below normal for this time of year, some slow moderation will
take place as the ridge inches toward the Mississippi Valley. The
strong surface high will continue to influence us even as it moves
into New England late week, keeping the next rain maker to our west
until later next weekend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 1238 PM CDT SAT SEP 13 2014

With the high pressure center just to the west, low level flow
from the north will keep sct CU flowing over the region today.
Expect CU to disipate by early evening. Forecast soundings show
dry air over area Sunday morning in all be the lowest boundary
layer. With significant inversion, still some moisture trapped and
so still expect with nearly calm winds and clear skies, patchy
fog/some stratus to again develop toward sunrise. Expect that it
will be patchy and very shallow and so went with tempo group and 2
mile vis with sct status deck. Will need to watch this overnight
for development.

&&

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

$$

UPDATE...GOETSCH
SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...GOETSCH






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