Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 260002
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
702 PM CDT Wed Mar 25 2015

.SHORT TERM...(Tonight)
ISSUED AT 258 PM CDT WED MAR 25 2015

18z/1pm surface analysis shows 1007mb low over the Texas panhandle,
with nearly stationary frontal boundary extending northeastward into
the Ohio River Valley.  To the north of the front, another overcast
and cool day is underway across central Illinois with temperatures
hovering in the 40s.  Meanwhile south of the boundary, readings have
risen well into the 70s from the southern tip of Illinois to the
Gulf Coast.  As a vigorous short-wave trough evident on water vapor
imagery over Colorado/New Mexico ejects eastward and interacts with
the low, thunderstorms are expected to become widespread across the
Ozarks this afternoon.  Latest radar mosaic already shows convection
expanding across southern Missouri and expect this trend to continue
over the next several hours.  All models have slowed the northward
progression of precip into the area this evening, with the latest
Rapid Refresh keeping much of the rain W/SW of the KILX CWA until
closer to midnight.  The exception may be the development of a few
scattered showers along an advancing trough axis across the northern
CWA earlier in the evening.  Have adjusted PoPs to account for the
slower arrival of precip, with the best rain chances focused from
late evening through the overnight hours.  Will carry categorical
PoPs along/south of I-72, diminishing to just chance from the Peoria
area northward.  As expected, the 12z Mar 25 models have shifted the
low track a bit further south, now taking it along/just north of the
Ohio River.  This decreases the chance for strong thunderstorms
across the far southern CWA tonight, but keeps the threat for heavy
rainfall alive.  Latest QPF guidance still suggests 1 to 2 inches
of rain along/south of I-70, with higher amounts in excess of 2 inches
further south toward I-64.  Based on upstream convective trends and
the presence of a warm/moist airmass just south of the boundary,
think these amounts seem reasonable.  The heavy rainfall tonight
into Thursday morning will likely result in renewed flooding on many
creeks and streams across southeast Illinois: however, rainfall
rates will not be high enough to produce widespread flash flooding.
As a result, have opted not to issue a Flood Watch across the
southeast, but will instead re-issue the ongoing SPS.

&&

.LONG TERM...(Thursday through Wednesday)
ISSUED AT 258 PM CDT WED MAR 25 2015

Given the slower approach of the precipitation tonight, it will also
be slower to depart Thursday morning.  Model consensus places the
surface low near Louisville, Kentucky by 12z, with rain continuing
across the E/SE CWA at that time.  Have bumped PoPs up to likely
along/south of I-70 through mid-morning accordingly.  As the low
pulls further away, showers will come to an end by midday followed
by clearing skies from west to east during the afternoon.  High
temperatures will once again be on the cool side, mainly reaching
the middle to upper 40s.

The cool/dry weather pattern will continue through Saturday as a
deep upper trough develops over the Great Lakes.  Numerous weak
waves will drop through the region within the prevailing
northwesterly flow regime Thursday night through Saturday: however,
none of them will significantly impact the weather across central
Illinois.  The first feature is expected to track across Missouri
Thursday night, while a second wave will follow a similar path
Friday night into early Saturday.  End result will be dry conditions
with much below normal temps in the 40s both Friday and
Saturday.

A weak frontal boundary will swing through the Midwest on Sunday,
bringing clouds and perhaps a few showers.  Moisture will be
limited, so will only include low chance PoPs at this time.  After
that, the Great Lakes upper low will gradually shift eastward,
allowing a ridge to build across the central CONUS.  Rising upper
level heights will lead to a pronounced warming trend, with
temperatures returning to the 60s by Tuesday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
ISSUED AT 657 PM CDT WED MAR 25 2015

Low pressure, currently centered over Oklahoma, will track
northeast up the Ohio River Valley tonight. The passage of this
low across southern Illinois will spread rain across some of the
central Illinois terminals, mainly KSPI, KDEC, and KCMI. This
rainfall will also be accompanied by mainly MVFR conditions.
Condtions will improve to VFR Thursday morning as the low pulls
further away. Winds will be predominantly northwest through the
period, with gusts to around 20 kts common during the daytime
hours Thursday.

&&

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

$$

SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Bak





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