Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 221716

Area Forecast Discussion
National Weather Service Lincoln IL
1216 PM CDT Tue May 22 2018

Issued at 1035 AM CDT Tue May 22 2018

A weak surface front and upper level trough that were associated
with perhaps a few sprinkles earlier this morning in east central
IL has now exited the area into Indiana. Satellite imagery shows
that an area of fog and stratus associated with the frontal zone
near I-70 is diminishing rapidly. Dewpoints at 10 a.m. ranged
from near 60 in the NW near Galesburg to 70 in the SE near
Lawrenceville, and will trend downward toward the neighborhood of
60 across the area by afternoon, but this should still be enough
for scattered cumulus cloud cover across the area. Highs today
should range from the upper 70s at Galesburg, Peoria, and
Bloomington to the low to mid 80s in areas to the south. Current
forecast is in good shape with these features, so no significant
updates are needed this morning.


.SHORT TERM...(Today and tonight)
ISSUED AT 208 AM CDT Tue May 22 2018

A weak surface boundary continues to push across the forecast area
early this morning, generally located along a Quincy to Pontiac
line at 1 am. This should cross the CWA by about 9-10 am. Can`t
rule out a couple showers as it exits the area, but this should
largely be a dry passage in our area. Skies expected to be mostly
sunny over a large part of the area behind the boundary, though
the Cu-Rule suggests the cumulus may be harder to break out across
the north. With the more significant cloud over there,
temperatures likely will stay below 80 degrees north of I-74, with
mainly lower 80s elsewhere.

.LONG TERM...(Wednesday through Monday)
ISSUED AT 208 AM CDT Tue May 22 2018

Amplifying upper ridge over the Plains will build toward the
Mississippi Valley through Thursday. This should keep the
showers/storms away from the forecast area initially. However, the
ridge will break down late week, as an upper wave moves east
into the Great Lakes. Longer range guidance continues to keep us
dry into Friday night. Temperatures will slowly build as the ridge
drifts overhead, and highs should be in the 90 degree vicinity by

Forecast for the holiday weekend will be complicated by evolution
of potential tropical system in the Gulf of Mexico. Evening model
guidance has a fair spread on the track, ranging from a landfall
near New Orleans as early as Saturday morning (ECMWF solution) to
one near Tampa midday Sunday (GFS). Remnant system in either case
should be cut off from the upper flow over the Great Lakes, with
our area left in limbo. With no strong forcing in place, any
convection may be more diurnal in nature, but pinning it down at
this distance will be a bit tricky. Highest PoP`s both Sunday and
Memorial Day will be during the afternoon, but will be more
scattered in nature.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1217 PM CDT Tue May 22 2018

Mainly VFR conditions expected until around 09Z, then potential
for MVFR or worse vsby in fog through sunrise Wednesday. Scattered
cumulus cloud development should take place this afternoon into
early evening with cloud bases around 4000 ft AGL, although a few
patches of lower ceilings around 3000 ft AGL are possible early
in the afternoon. Slightly drier air advecting into the area today
along with just a light N-NE surface wind tonight bring some
doubt about potential for fog to form overnight, but opted to
include mention at this point pending further assessment of
afternoon crossover temperatures and model guidance. Winds NW 5-10
kts this afternoon, becoming N-NE up to 5 kts overnight into
Wednesday morning.




SHORT TERM...Geelhart
LONG TERM...Geelhart
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