759 
FXUS63 KILX 060120
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
820 PM CDT Fri Apr 5 2019

.UPDATE...
Issued at 820 PM CDT Fri Apr 5 2019

Primary question will be with any kind of clearing overnight.
Latest GOES-16 nighttime microphysics combo showing the western
edge of the cloud deck from near the Quad Cities to south of
Quincy, but the clearing appears to be hitting a brick wall.
Evening sounding from our office shows the clouds to be about
2,000 feet thick, with an inversion at 850 mb at the top. RAP and
NAM try to make some slow progress with moving this cloud deck
east, but pessimism may be the way to go in this case. Have
maintained the mostly cloudy forecast overall, but showed a slight
short improvement west of the Illinois River for awhile late this
evening. Hourly temperatures needed some adjustments over the next
few hours, as they were running too warm. However, with the clouds
hanging around, a significant dropoff is not anticipated, and
went with lows fairly close to the earlier projections. 

&&

.SHORT TERM...(This evening through Saturday)
ISSUED AT 345 PM CDT Fri Apr 5 2019

Broken to overcast stratus cloud deck lingered over much of IL
especially south of I-88 at mid afternoon. Abundant low level
moisture/wet ground, along with a restrengthening low level 
inversion and weak wind flow will allow more lower stratus and fog
to set in especially overnight into mid morning Saturday. Lows 
overnight in the mid to upper 40s in central IL, with southeast 
IL near 50F. Skies to become partly sunny during Saturday 
afternoon, with low clouds lingering longer in eastern IL. SE 
winds increase to 8-15 mph by Saturday afternoon, with milder 
highs in the upper 60s to near 70F. 

.LONG TERM...(Saturday night through Friday)
ISSUED AT 345 PM CDT Fri Apr 5 2019

The 12Z forecast models continue to trend slower with arrival of
next wx system ejecting from the southern Rockies, with surface
low near the IA/MO border by dawn Sunday. Saturday evening should
continue dry, with chances of showers and isolated thunderstorms
spreading ne over CWA after midnight Sat night. Mild lows Saturday
night in the mid 50s. Good chance of showers and some
thunderstorms on Sunday and mild highs in the lower 70s with
breezy sw winds. SPC day3 outlook has slight risk of severe storms
in southeast IL later Sunday afternoon into mid Sunday evening
with marginal risk of severe as far nw as the IL river. Though 
latest models are not quite as strong with the instability and 
bulk shear parameters. Chance of showers and isolated
thunderstorms lingers Sunday evening, and over areas from I-55 se
overnight Sunday night. 

A surface low and upper level trof over the lower MS river valley
Monday could bring chances of showers into southeast IL yet on
Monday, while thunderstorms chances mainly closer to the Ohio
river on Monday. Mild temperatures in the lower 70s for highs
Monday across CWA. Dry wx expected across area Monday night thru
Tuesday evening with slightly cooler highs in the upper 60s north
of I-72 and lower 70s again from I-72 south. 

A much stronger surface low pressure system ejects from the
central Rockies into KS during Wed with a warm front extending
eastward over the mid MS river valley. Increasing chances of rain
showers mainly along and north of I-72 overnight Tue night into 
Wed. More of a north to south temp gradient on Wed with highs mid
to upper 50s northern CWA and upper 60s to near 70F in southeast
IL. 993 mb surface low pressure tracks into St Louis area by
midnight Wed night and travels near I-70 into west central IN by
dawn Thu. Good chance of showers and some thunderstorms over area
Wed night and lingering chances of showers Thu. Stronger winds on
Thu with cooler temps, highs Thu range from low to mid 50s 
northern CWA and low to mid 60s in southeast IL. Some light rain
showers linger Thu night and could mix with light snow showers
overnight Thu night into Fri morning. Highs Fri in the upper 40s
and lower 50s, mildest in southeast IL. Lows by next Friday night
to reach lower 30s over much of area especially from I-70 north. 

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 631 PM CDT Fri Apr 5 2019

Challenging forecast for this TAF set. Fairly widespread MVFR
cloud deck exists across central Illinois at 23Z, with ceilings
about to lower near the Indiana border. Some clearing is edging
into extreme western Illinois, but there is some question on how
much this is going to progress eastward. Any clearing would likely
result in a quick formation of very low clouds and fog. Went the
pessimistic route for now, and kept MVFR going until about 09Z,
with a few hours of IFR. Clouds may struggle again to scatter out
on Saturday, but will show some improvement by 18Z. 


&&

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

$$

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