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fxus63 kilx 200324 

Area forecast discussion
National Weather Service Lincoln Illinois
924 PM CST Tue Nov 19 2019

issued at 326 PM CST Tue Nov 19 2019

Widespread fog will develop across central Illinois
tonight...resulting in reduced visibilities for the Wednesday
morning commute. Once the fog dissipates, a partly sunny and mild
day is anticipated on Wednesday with afternoon high temperatures
topping out in the lower to middle 50s.


issued at 924 PM CST Tue Nov 19 2019

Forecast looks OK for now, but thinking that dense fog is going to
develop tonight in the west and possibly spread east as low clouds
over the area push to the east. Already seeing some indications of
fog developing in obs and satellite loops in west central Illinois.
Satellite also showing clouds moving east as west. Light winds
over most of the area and clear skies appear to be setting the
stage for this, along with the light precip we had today. Believe
cross-over temp is mid to upper 30s and we are forecasting
overnight lows in the lower again another reason to think
dense fog will develop tonight. Going to issue a dense fog
advisory for tonight through 9 am tomorrow in west part of County Warning Area.
Concern will have to expand east...but will do as needed. Update
will be coming.


Short term...(this evening through wednesday)
issued at 326 PM CST Tue Nov 19 2019

21z/3pm satellite imagery continues to show overcast conditions
across much of central illinois: however, the back edge of the
cloud cover has advanced as far east as a kbrl to kmvn line.
Based on satellite loops and hrrr forecasts, it appears skies will
clear everywhere south of the I-74 corridor over the next 3-4
hours...while skies remain mostly cloudy further northeast. With
clearing skies and decreasing winds, the potential for fog
development tonight will be high...especially given the moist
boundary layer from today's light rainfall. Rap/hrrr/NAM/gfslamp
all suggest fog forming west of I-55 early this evening, then
spreading eastward across the remainder of the area overnight.
Given strong signal from model guidance, have gone with widespread
fog except across the far southeast kilx County Warning Area where rain did not fall
today. Overnight lows will be in the lower to middle 30s. Once the
morning fog dissipates, a partly sunny and mild day will be
observed on Wednesday with afternoon highs in the lower to middle

Long term...(wednesday night through tuesday)
issued at 326 PM CST Tue Nov 19 2019

The next significant storm system to impact the Midwest will come
into the picture late Wednesday into Thursday. As has been
advertised for the past several model runs, it appears the most
significant rainfall will occur across central Illinois late
Wednesday night and Thursday morning...followed by a lull in
precip chances Thursday afternoon as a dry slot works into the
region. Have carried categorical pops west of the I-57 corridor
after midnight Wednesday night, then everywhere Thursday morning.
Total rainfall will generally range from one quarter to one half
an inch.

Once the system passes to the east, the trailing frontal boundary
will stall in the Ohio River valley late Thursday into Friday.
Several weak impulses will interact with the front to keep precip
chances alive across central Illinois, with the best chances
focused south of I-70. The airmass will become cold enough to
support light snow or a light rain/snow mix on the northern edge
of the precip area late Thursday night and again Friday night:
however, little or no snow accumulation is expected. After that,
mild and dry conditions will be on tap Saturday through
Monday...with temperatures climbing back into the 50s by Monday.


Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 601 PM CST Tue Nov 19 2019

IFR cigs will remain at bmi and cmi through the night and into
tomorrow morning. Dec and pia are MVFR but should scatter out by
3-4z...while spi is VFR. The clearing that occurs across the area
will combine with light winds tonight, resulting in ideal
conditions for dense fog to develop across the central part of the
state and likely spread east toward morning. IFR and LIFR
conditions are also likely late tonight through tomorrow morning,
but then improving quickly during the afternoon. Winds will become
light and variable for the night and then as they increase
tomorrow to over 10kts, the direction will be southeast.


Ilx watches/warnings/advisories...


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