423 
FXUS63 KILX 060312
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
912 PM CST Sun Mar 5 2017

.UPDATE...
Issued at 912 PM CST Sun Mar 5 2017

Lots of clouds over the area this evening and am expecting this to
continue during the overnight hours. Cloud cover and gusty winds will
keep temps from dropping too much more than what they have already
fallen to. Gusty winds will also continue overnight. Therefore
current forecast is handling current situation well. No update
planned at this time.

&&

.SHORT TERM...(This evening through Monday)
ISSUED AT 300 PM CST Sun Mar 5 2017

Strong southerly winds of 15-30 mph and gusts of 25-40 mph prevailed 
this afternoon across central IL and will continue Monday ahead of 
an approaching cold front. These strong southerly winds gave milder 
temperatures in the mid 50s to mid 60s, despite mostly cloudy skies. 
Weakening 1038 mb high pressure over central Quebec and ridging 
southward toward eastern VA/NC. Deepening 992 mb surface low 
pressure was over central MT. Latest forecast models deepen surface 
low pressure of 975 mb over ne ND by sunset Monday while bringing a 
cold front east across western IA and nw MO. Increasing low level 
moisture into IL ahead of this front with persistent strong 
southerly flow. This will bring small chances of light rain showers 
into southeast IL overnight and across CWA during Monday morning. 
Continued chances of thunderstorms over areas west of I-57 Mon 
afternoon, mainly late. Milder lows tonight in the upper 40s and 
lower 50s, which is a few degrees above normal highs for early 
March. Mild highs Monday in the mid to upper 60s with west central 
IL near 70F.

.LONG TERM...(Monday night through Sunday)
ISSUED AT 300 PM CST Sun Mar 5 2017

Showers and thunderstorms will be in the area to start the period 
ahead of a cold front that will be approaching western Illinois at 
00Z Tuesday. The showers and storms will be most widespread across 
the forecast area during the evening, but will begin to taper off 
from northwest to southeast overnight in the wake of the cold front. 
Recent model runs suggest a few severe storms are possible, mainly 
Monday evening, with pre-frontal bulk shear values of 50-60 kts and 
MU CAPE values possibly reaching 1000 j/kg or a little higher. The 
best chances will occur over west-central Illinois where the 
instability will be higher. Locally heavy rainfall is also a threat 
with precipitable water values of 1.25-1.5 inches ahead of the 
front. The rainfall threat will quickly come to an end Tuesday 
morning, if it has not already done so, as the front races to the 
east.

Gusty westerly winds are expected in the wake of the front Tuesday, 
with gusts to 40 mph possible by Tuesday afternoon. Forecast 
soundings suggest fairly deep mixing will develop to support these 
wind gusts, but this will also likely result in low Relative 
Humidity values in the afternoon. We'll have to watch the threat for 
high fire danger Tuesday afternoon if current model trends persist.

The models continue to struggle with the precipitation risk for the 
end of the week into the weekend. A fast west-northwest flow regime 
aloft will be in place for most of the week behind the early week 
storm. Model spread and run-to-run variability has been high with 
the low amplitude waves expected within this pattern. The best 
chance for organized precipitation (mainly rain) at this point 
appears to be Saturday. Although a risk also exists late 
Thursday/Thursday night, and possibly Friday. Numerous adjustments 
to the current forecast will likely be needed as the low amplitude 
waves are better resolved by the guidance.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 543 PM CST Sun Mar 5 2017

MVFR cigs have arrived at all sites except PIA and CMI. However,
CMI should get there soon given that other MTRs to the west are
already MVFR. Based on HRRR forecast, PIA should see MVFR cigs
starting around 02z. MVFR cigs will continue rest of the night and
through tomorrow as lots of low level moisture will advect into
the area from the south tonight and continue through tomorrow.
Models differ on if it will be continuous or have a period of
better cigs at SPI and DEC overnight. Have decided to stay
continuous at all sites with cig height dropping to around 1.5kft
overnight and continuing through tomorrow. Models show possible
light precip in the area tomorrow so will keep the VCSH already in
the TAFs. Winds will remain gusty out of the south overnight and
through tomorrow. Cig heights could improve tomorrow afternoon,
but models differ on this solution. Will decide how to handle for
next issuance. 


&&

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

$$

UPDATE...Auten
SHORT TERM...07
LONG TERM...Bak
AVIATION...Auten