Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 122104

Area Forecast Discussion
National Weather Service Lincoln IL
304 PM CST Mon Feb 12 2018

.SHORT TERM...(This evening through Tuesday)
ISSUED AT 252 PM CST Mon Feb 12 2018

High pressure will drift east across the lower Great Lakes tonight
and be centered over the eastern Great Lakes by Tuesday morning.
Coldest temperatures will be across the snow covered areas of the
north where single digit lows will prevail while further south
early morning lows will drop to around 20. Another quiet day
expected on Tuesday with temperatures edging up across the entire
area, although the snow covered sites across the north will
struggle into the low and mid 30s, while further south, the
combination of sunshine and warming temperatures aloft should
yield afternoon temperatures in the middle 40s.


.LONG TERM...(Tuesday night through Monday)
ISSUED AT 252 PM CST Mon Feb 12 2018

Warmer temperatures will be the main story this forecast period
with several chances for mostly rain starting Wednesday morning
over southeast Illinois, then a better chance for more widespread
showers, possibly a few thunderstorms on Thursday as a northern
stream shortwave and attendant cold front push across the Midwest
with another threat for showers late next weekend. Upper level
heights will build across the Midwest in response to a trof digging
over the western U.S. over the next several days. This should result
in warming over the central portion of the country through most of
this week. Models continue to depict a weak disturbance passing
across our area late Tuesday night into Wednesday which may bring
some rain to southeast Illinois Wednesday morning. Surface
temperatures will be rather close to freezing on the northern
fringes of the precip. shield Wednesday morning, but at this
point, will keep mainly rain chances going in the southeast.

That minor wave and rain should shift off to our east later
Wednesday with a stronger shortwave tracking across the northern
Rockies on Thursday. A persistent southerly flow at the low levels
of the atmosphere will gradually advect higher dew point air
north over the colder ground (with a snow cover still remaining
across the north) on Wednesday and especially Wednesday night,
which should bring about the threat for some fog over areas
roughly north of the I-74 corridor. The stronger upper level wave
should track east across the upper Midwest on Thursday which
should bring a frontal boundary east into our area during the day
with low pressure forecast to track east-northeast along the
boundary across central Illinois Thursday afternoon and evening.
South winds ahead of the front should propel afternoon temperatures
into the middle 60s over parts of south-central Illinois Thursday.

Shower chances ramp up to likely across southeast and east central
Illinois Thursday into Thursday evening with a trend southeast
with the precipitation as the night wears on. 50+ dew points
advect northeast into central and southeast Illinois ahead of the
cold front on Thursday but instability parameters still look
meager at this point, but wouldn`t be surprised if we add the
mention of thunder, especially across southeast Illinois Thursday
afternoon into the early evening hours. As colder air filters in
Thursday night into Friday morning, we may see a mix or changeover
to light snow across southeast IL but any snow amounts will be on
the minor side. Temperatures will be quite a bit colder on
Friday, at least compared to our 50s and 60s on Thursday, but
overall, afternoon highs Friday will be a little below normal
with readings ranging from the mid 20s to mid 30s. As we head into
the weekend, warmer weather returns as the upper level flow
becomes southwest with model differences starting to show up with
respect to timing of our next threat for rain later next weekend.
Shower chances will increase again across the region either
Saturday night or Sunday ahead of a lead shortwave tracking
northeast out of the developing longwave trof to our southwest.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1115 AM CST Mon Feb 12 2018

VFR conditions are expected this forecast period. High pressure
will dominate the weather across the area through tomorrow. Other
than some high level clouds, no significant issues with cigs or
vsbys are expected thru tomorrow. Surface winds will be northeast
to east at around 10 kts and then become light easterly tonight
and a east to southeast flow on Tuesday at around 10 kts.




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