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fxus63 kilx 181731 

Area forecast discussion
National Weather Service Lincoln Illinois
1231 PM CDT Tue Jun 18 2019

issued at 1013 am CDT Tue Jun 18 2019

Mid morning satellite imagery and surface obs indicate that a
frontal boundary is draped from near Farmington, MO (kfam) through
Mount Vernon, Illinois (kmvn) and clipping the far southeast counties in the
forecast area going through near Lawrenceville, Illinois (klwv).
Meanwhile, a modest shortwave trough is also noted on satellite
imagery near klwv with drier and more subsident air overspreading
the mid Mississippi Valley in its wake. Despite increasing
instability late this morning into the afternoon and fairly weak
convective inhibition noted in forecast soundings, lack of any
large scale forcing for ascent in the wake of the shortwave will
keep precip coverage in check through the day. Best chance for any
afternoon pop-ups continues to be near the stalled surface front
over the far southeast counties today near and south of the I-70 corridor
where coverage may become widely scattered. Farther north, and
storms should remain more isolated.


Short term...(today and tonight)
issued at 311 am CDT Tue Jun 18 2019

Pretty much turning into a broken record for discussions, more
rain is on the way. Unfortunately, southeast Illinois Drew the
short Straw this morning. A stalled out boundary will continue to
linger along the I-70 corridor today, bringing more scattered
showers and isolated thunderstorms to that area. This line will
remain situated along and just north of the Ohio River, bringing
the chances for flash flooding throughout the early morning for
Illinois. The Flash Flood Watch will continue through 12z, with
additional collaboration with ind and pah occurring just before
12z to decide if extension is needed. At this time, rain totals
today are forecast upwards of 0.30 inches, which leads ME to think
the watch will be allowed to expire at 12z. Close monitoring of
this mornings rainfall will determine the final decision.

For locations in central and north central Illinois, fog will be
possible this morning as some clearing and light winds are
providing temperatures to fall to the TD. Many locations already
are reporting reduced visby's, which is expected to continue
through the early morning hours to the return of daylight, before
warming temps will quickly burn any fog off.

Once this wave finally moves eastward today, dry conditions will
overspread the entire area. However, this dry pattern will be
short lived, as another larger wave system arrives Wednesday.

Long term...(wednesday through monday)
issued at 311 am CDT Tue Jun 18 2019

Looking at models in terms of agreement for the mid-week system,
there remains some discrepancy in track and intensity of rainfall.
Track path is through Illinois, however at this time the
difference in path is either central Illinois or northern
Illinois. This difference is causing some uncertainty in storm
total rainfall, which creates a "landslide" effect for other
elements. With the current flash flood advisory ongoing through 12z Tuesday
morning, it was decided to hold off on any new issuance of
products, to limit confusion. Even though the path could shift
slightly northward, a new flash flood advisory will more than likely be issued
later today due to the already saturated soils across the region.
This wave will slide across the area starting Wednesday midday,
lasting through the overnight into Thursday morning, leaving
Illinois midday Thursday. As 500mb heights remain flattened, no
strong front will aid in movement, which is why heavy rainfall is
expected over the 24 hour period. Storm total rain for this event
is currently forecast between 0.75-1.50 inches, but could increase
based upon final track location. With the boundary in place over
the region and a disturbance riding along it, Storm Prediction Center has issued a
slight risk for severe weather across the east half of the County Warning Area.

After this wave, a quiet 24 hours will lead into Friday. A weak
ridge will develop across the Midwest, as a deepening low pressure
system digs into the northern rockies Friday. As this low lifts
back northeast into central Canada, it will lift moisture
northward on the backside of the ridge. This will bring another
chance for shower activity Friday afternoon, but the heaviest
precipitation will arrive during the upcoming weekend. Since
switching to the new nbm procedures, storm total accumulations
seem to be forecast slightly higher. Looking at the rest of this
week into the weekend, totals around the region are forecast to
range from 3-6 inches, however the values will likely change with
track determination and better atmospheric processes.


Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1228 PM CDT Tue Jun 18 2019

Light winds and VFR conditions will prevail through the rest of
today. There is a very small chance for a pop-up shower or
thunderstorms, especially for spi/Dec/cmi this afternoon and
evening, but much better chances for staying dry. Low pressure
will move across the region Wednesday. Mid and high clouds will
increase ahead, and precip chances will begin to ramp up by early
afternoon. Expect showers and thunderstorms to become more
widespread through the latter half of the afternoon into the
evening, and some of these storms could be strong.


Ilx watches/warnings/advisories...


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