Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 220002
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
602 PM CST Thu Feb 21 2019

.SHORT TERM...(This evening through Friday)
ISSUED AT 310 PM CST Thu Feb 21 2019

High pressure dominates the short term in the Midwest, with light
and variable winds becoming more east/northeasterly in the
overnight hours. Midlevel clouds are streaming into the region
from the south/southwest and will likely continue through tonight
and tomorrow. Temperatures will be able to warm a couple degrees
over todays highs...just above climatological normals. Aloft, the
region is in southwesterly flow as a deep upper low digs into the
western CONUS, currently over Nevada. Over the next 24 hrs, that
low continues to amplify the pattern over the country, deepening
the warmer air over the Midwest. That same low will eventually
move out of the west and into the Plains, driving the weather
event expected this weekend for Central IL.

.LONG TERM...(Friday night through Thursday)
ISSUED AT 310 PM CST Thu Feb 21 2019

That upper low ejects out of the Southern Plains midday on
Saturday. The depth of the low at 500 mb at 18z already has a bit
of variation in the models. 500 mb heights come in between 544dm
and 536dm, a fact that actually continues out through the
remainder of the forecast, regardless of similarity of
shape/amplification of the pattern. Midday/Saturday evening, that
upper low takes on a negative tilt, and the surface system
responds accordingly with rapid development. The system wraps up
on itself and occludes quickly, and Central IL gets into the
precip Friday evening/night with the progression of the warm
frontal feature. Pops remain through Saturday night once the
system moves through entirely. Details are sketchy with the
potential for severe weather this far north and will depend
greatly on the track, with the better chances to the south of the
Ohio River Valley, where the cold front/warm sector interaction
is more distinct. One concern that is more likely to make an
impact either way is the rapidly deepening low and the
intensification of the pressure gradient. Blended MOS so far
under calculating the winds, and have collaborated higher winds,
and gusts to 40kts...with the potential to go higher, depending on
how this progresses. That same wind shear is a potential nudge to
the severe potential within the same time frame. Highest winds at
this point will be the southwesterly/westerly winds Sat night
through Sunday.

Beyond the weekend storm, colder air moving in with the low will
at least temporarily bring a cold blast in Sunday night/Monday
morning, dropping temps into the teens overnight. However, the
temps begin to come back up to near seasonal normals by Tuesday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 559 PM CST Thu Feb 21 2019

VFR conditions are forecast to prevail next 24 hours through
Friday across central IL airports. Mid/high clouds with bases of
12-25k ft will stream ne across central IL during this evening
with broad sw upper level flow, then shift se during overnight
into Fri morning and could become scattered for a time. A band of
lower clouds with bases of 5-10k ft will stream ne into central
IL from 21-24Z Friday as next wx system moves into the central and
southern Rockies. Light and variable winds this evening to become
ne 4-8 kts during overnight and veer easterly at 7-12 kts during
Friday.

&&

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

&&

$$

SHORT TERM...HJS
LONG TERM...HJS
AVIATION...07


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