Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 162255
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
455 PM CST Mon Jan 16 2017

.SHORT TERM...(This evening through Tuesday)
ISSUED AT 243 PM CST Mon Jan 16 2017

Will need to extend the dense fog advisory through the rest of the
afternoon from I-72 north while letting it expire at 3 pm south of I-
72. Easterly winds are shifting southeast and advecting the dense
fog into area nw of the IL river. Peoria and Lacon have returned to
dense fog and Galesburgs vsbys is slowly dropping. Visibilites from
Jacksonville, Springfield, Decatur and Paris south have improved to
1-4 miles in past hour. Widespread dense fog caused in part by
mild/moist air moving over a cold ground (6 am frost depth at
Lincoln was 4 inches and 10 inches at Altona). The latest runs of
the HRRR and RAP models showing areas of fog and locally dense fog
lingering over northern CWA into this evening and lasting longest
over the IL river valley. Visibilities should improve during
overnight as a cold front moves east across IL.

20Z/2 pm surface map shows 1010 mb low pressure over east central KS
with a warm front lifting northward into central parts of MO and KY
and southern IL south approaching I-64. Bands of rain showers were
over IL with a few thunderstorms over eastern MO and lifting ne
toward the MS river. Temps currently range from mid 30s from Macomb
to Lacon northward to the lower 50s south of I-70.

Models deepen surface low pressure from east central KS northeast to
southern Lake MI by 12Z/6 am Tue with pressure down to 1007 mb. A
warm front will lift northward over central IL (especially se of the
IL river) during this evening, followed by the cold front sweeping
eastward across IL during overnight. Have likely to categorical
chances of showers along with isolated thunderstorms this evening,
then gradually diminish pops behind the cold front overnight with
highest pops in eastern IL where isolated thunderstorms still
possible til 3 or 4 am when cold front reaches near the IL/IN
border. Isolated light rain showers could linger over eastern IL and
areas from I-74 ne on Tue morning. Rainfall amounts through tonight
to range from 0.40-0.75 inches. Lows early Tue morning range from
upper 30s nw of the IL river to the lower 50s near the Wabash river
and these will also be the highs early Tue morning. Temps nearly
steady or slowly slipping during the day with WSW breezes.

.LONG TERM...(Tuesday night through Monday)
ISSUED AT 243 PM CST Mon Jan 16 2017

Models are in very good agreement that the modified southwest flow
will continue across the region through the week. Surface high
pressure will build into the area from the west as this past
weekends weather system finally moves off to the east. This high
pressure will keep mild conditions over the area with dry weather.
This will be a brief period of dry weather as another weather system
develops in the southern plains and lifts northeast, in the
southwest flow, through the Miss valley and eventually into the Ohio
valley. Models differ on the intensity of this system, but all agree
that the main low pressure area associated with the system will
remain southeast of the area through the period. The chance of
precip will run from Thursday in the southeast through Friday
morning. The best chance of pops will be in the southeast on
Thursday night. Despite being northwest of the track of the low,
temps overall will remain mild so all precip will be liquid and not
expecting any snow or freezing precip.

Another brief dry period is expected Friday night through Saturday
as the CWA will be in the warm sector ahead of the next weather
system expected for the latter part of the weekend. Models have some
differences with how and where this system first evolves, but agree
that the main low pressure area will come out of the southern plains
and lift northeast somewhere across the mid Miss valley. Location of
this track is where the models struggle with any agreement, but do
agree on the intensity of the system. Precip will move into the area
Sat night and then spread across the CWA for Sun and Sun night.
Temps will remain mild with this system and early look suggests it
will be quite windy as well.

Overall temps will remain warm/mild through the forecast period
with the warmest temps being Sat and Sat night.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 452 PM CST Mon Jan 16 2017

LIFR with occasional VLIFR conditions in fog will continue
through the evening hours with only a gradual improvement
after 02z as the warm front lifts across the area. However,
as the cold front associated with the storm system to our
west shifts across the area after 05z, we will see a return
to the dense fog and low clouds behind the front. We really
won`t see much of any long term improvement until after 16z
Tuesday as somewhat drier air advects in from the west and
northwest. Surface winds will be southeast this evening
with speeds 10 to 15 kts and then become southwest to west
in the 04z-08z time frame with similar speeds overnight.
West winds are expected during the day Tuesday at 10 to 15
kts.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 6 PM CST this evening for ILZ027>031-
036>038-040>048.

&&

$$

SHORT TERM...07
LONG TERM...Auten
AVIATION...Smith



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