391 
FXUS63 KILX 042338
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
638 PM CDT Sat May 4 2019

.SHORT TERM...(This evening through Sunday)
ISSUED AT 316 PM CDT Sat May 4 2019

The main issues with today's forecast: clouds continue to impact
the southeast CWA...as boundary progression is slower than 
originally thought, and the issue of fog development overnight.

Low clouds are beginning to disperse and lift in locations across
southeast Illinois, as a weak trough is pushing eastward through
the region this afternoon. As the evening approaches, clouds will
continue to decrease from northwest to southeast, although
locations in northwest Illinois are already reporting clear skies.
Currently across central Illinois, from Springfield to
Bloomington, sunshine is starting to overpower the clouds as a
partly cloudy sky exists. Sunshine this afternoon and evening,
will allow some evaporation at the sfc level. This will work in
combination with the clearing skies and weak winds tonight to
bring fog development to the region. As of now, it does not 
appear to be widespread dense fog, however some rural areas could 
experience visby's reduced to 1 mile or less.

Sunshine and clear skies will rule Sunday, as High pressure shifts
overhead of the Midwest. This will allow for some additional
drying out...but not in the way the area needs. Temperatures
tomorrow will climb into the low 70s, as sunshine will allow for
much more spring-like conditions.

.LONG TERM...(Sunday night through Saturday)
ISSUED AT 316 PM CDT Sat May 4 2019

Heading into the start of next week: a frontal boundary approaches
the region from the north Sunday night, stalls out across the
region for the week, and more rainfall across land that does not
need it.

A west-east situated frontal boundary will slide into the region 
from the north late Sunday. This will once again hide sunshine
from the region through much of the upcoming week, as clouds will
dominate the skies. This boundary is associated with a Low
pressure system sliding into eastern Canada, with High pressure in
western Canada, and higher pressure in the southeast US. This will
flatten the boundary out across the Midwest. The other issue
working to help, is two High pressure systems will develop along
the Polar Jet Stream and hold any Low pressure systems in the US.

The first wave will come through Monday evening/overnight, as the
frontal boundary slides through the area. This will bring the
chance for rain showers across the region through Tuesday
afternoon. While this is ongoing, a Low pressure system in the
Rockies will linger during the first part of the week, gaining
moisture. Moisture ahead of the Low will be lifted into the region
from the Gulf, at this time though this appears to be more of a
widespread shower concern. The Low will finally eject from the
Rockies Wednesday morning, heading through the Plains and into the
Midwest by Thursday afternoon. Model uncertainty exists on the
exact track of the Low, but the idea is that it will track 
through some portion of central Illinois to southern Wisconsin.
Numerous models are hinting at a splitting rain core as it
arrives, with one band following the Ohio River Valley and the
other tracking through Wisconsin. With the already elevated rivers
and super-saturated ground, this rainfall will more than likely 
cause additional issues around the region.

The Low will slide northeast into Canada, splitting the two High
pressure systems. This will in turn drop the western High into the
Plains, bringing dry conditions back into the region Friday.
Behind frontal passage, temperatures will cool back to the 60s for
highs Friday and Saturday with lows in the 40s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 638 PM CDT Sat May 4 2019

VFR conditions will prevail across central and eastern IL for much
of the next 24 hours, except for a brief period around daybreak
when the visibility could drop to 4-5 miles in a few locations
east of a KBMI-KDEC line. 

MVFR ceilings remain across southeast IL, mainly south of I-70, 
and have been slow to clear out as low pressure in central KY and 
a mid-level shortwave trough axis from central IL to eastern MO 
slowly shift eastward. These lower clouds, and the associated high
clouds across central IL will eventually shift out of the region
tonight. 

The aforementioned lower visibility and patchy light fog will be a
result of a surface ridge axis replacing the cyclonic flow in the
Ohio Valley by early Sunday morning. The ridge will reside over
the region much of Sunday, with only a few high clouds and a light
wind.

&&

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

$$

SHORT TERM...Baker
LONG TERM...Baker
AVIATION...Miller