National Weather Service Raw Text Product

906 
FXUS63 KILX 281504
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1004 AM CDT MON SEP 28 2015

.UPDATE...
ISSUED AT 1000 AM CDT MON SEP 28 2015

Earlier fog has lifted, but a large expanse of lower clouds
remains present west of I-55. This has shown some signs of
contracting on the last few visible satellite images. There is a
fair amount of sunshine over the eastern CWA at present, but this
will become more filtered as high clouds move up from the south
this afternoon. Moisture continues to stream northward with a weak
upper feature moving into far southeast Missouri, with isolated
showers still expected in our area. We're already seeing a few of
these tracking northeast from the St. Louis metro, so some
westward adjustments were made to the existing 20% PoP's, as well
as to speed up the timing.

&&

.SHORT TERM...(TODAY)
ISSUED AT 329 AM CDT MON SEP 28 2015

The latest surface map indicates a narrow band of mid 60s dew
points stretching from the Gulf Coast northward through a good
portion of Illinois. Satellite and surface data showing a band of
mid clouds from northeast Missouri thru central Illinois with a
break in the clouds over southeast Illinois. With the clear skies
in the southeast and the high moisture content in the air areas of
fog have developed with a few locations reporting visibilities of
a quarter of a mile. As the band of mid clouds shifts further
north, we may see the fog expand north as well as many areas may
see a brief period of clearing early this morning which will allow
at least some patchy fog to form. May need a dense fog advisory
for parts of south central and southeast IL for a few hours early
this morning before the fog quickly dissipates between 8 and 9 am.

The water vapor loop indicates a weak shortwave over far northern
Arkansas drifting north away from a much large upper low over the
Gulf Coast states. This feature is progged to push into our area
today bringing the threat for isolated showers again to parts of
the forecast area. RAP-13 forecast soundings showing once we start
to warm up the lower levels of the atmosphere we should see a fairly
decent cumulus field develop, however, most of the forecast 
soundings were showing a decent subsidence inversion around 700 mb 
which should limit any instability from the 850-700 mb layer, so 
mainly an isolated shower threat with convective temperatures at or 
just above 80 degrees today. With a little better mixing expected 
today, afternoon temperatures should warm a few degrees from 
yesterday with most areas expecting highs in the 80 to 85 degree 
range, with the warmest readings in the west and south this 
afternoon.

.LONG TERM...(TONIGHT THROUGH Sunday)
ISSUED AT 329 AM CDT MON SEP 28 2015

Central IL will be in a squeeze play tonight as southern stream 
short waves push northward from mid MS river valley into southeast 
IL with 20-30% chances of showers by overnight. Meanwhile a cold 
front over central MN/NE to track SE toward the IL river by
12Z/Tue. Showers appear to be post frontal/behind the front and
have 20-30% chances of showers overnight especially late nw of
Peoria. Lows tonight in the low to mid 60s again.

Tuesday appears to be our best chances of showers with even isolated 
thunderstorms in southeast IL Tue afternoon as the cold front pushes 
through rest of CWA during the day Tue. Have chances of showers 
diminishing to slight chance over northern counties Tue afternoon 
while 40-50% southeast of I-70 with better instability present and 
giving isolated thunderstorms. A temperature gradient sets up on Tue 
with highs near 70F nw of IL river, to lower 80s southeast of I-70. 
Dewpoints in the low to mid 60s to start the day to slip into the 
low to mid 50s behind the front over northern counties Tue 
afternoon. Have isolated showers in southeast IL southeast of I-70 
Tue evening as front exists south of area. Then dry and cooler 
weather expected with decreasing clouds from north to south during 
Tue night, with clouds lingering longer in southeast IL. Lows Tue 
night range from upper 40s nw of IL river to mid 50s in southeast 
IL.

High pressure settling into the Great Lakes Region on  Wed to
bring dry and less humid weather with ne breezes and mostly sunny
skies. Highs Wed mostly in the lower 70s, with a few upper 60s
north of Peoria by Galesburg and Lacon. Lows Wed night in the mid
to upper 40s with Lawrenceville near 50F.

A weak upper level trof digs southward into the ohio river valley on 
Thu and ne winds to keep temps cooler. Highs Thu in the upper 60s 
and lower 70s with coolest readings ne CWA. 

Extended models diverge with upper level pattern late this week
into early next week, but generally show upper level trof
controlling our weather with temps a bit cooler than normal with
highs in the mid to upper 60s. GEM model is more aggressive with
qpf into eastern IL Thu night and across IL Fri but sided toward
the drier ECMWF and GFS models which are more consistent from
previous runs. These two models generally are dry over central/SE
IL from Wed through Sat and trended forecast in that direction.
Have slight chances of showers Sat night and Sunday with more
cloud cover.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z Tuesday MORNING)
ISSUED AT 600 AM CDT MON SEP 28 2015

LIFR/VLIFR conditions have developed just south of the TAF sites
and the lower cigs and vsbys were slowly drifting north and may
affect at least SPI, DEC and CMI for a couple of hours early
this morning. Otherwise, once the fog dissipates we expect any
lingering low cigs or vsbys to improve rapidly after 14z, with
mainly SCT-BKN VFR cigs late this morning into the afternoon
hours. A weak weather disturbance will move up from the south this
afternoon bringing a slight chance for a shower to parts of the
area, but coverage too limited to include in the 12z TAF issuance.
Any lingering shower activity should dissipate early this evening
with sct-bkn cigs at 4000-5000 feet with a layer above 20000 feet
indicated on the latest forecast soundings.

If we do see any clearing later tonight, fog and low cigs will
become a threat after 06z, similar to what happened late
last night. Surface winds will be out of the south to southwest
at 8 to 13 kts today and southerly tonight at 4 to 8 kts.


&&

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

$$

UPDATE...Geelhart
SHORT TERM...Smith
LONG TERM...07
AVIATION...Smith