Area Forecast Discussion
Issued by NWS Central Illinois

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KILX 020452
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1152 PM CDT Wed Oct 1 2014

.UPDATE...
ISSUED AT 852 PM CDT WED OCT 1 2014

Latest surface analysis had an area of low pressure centered near
the central Kansas/Oklahoma border, with a frontal boundary
extending east-northeast across Missouri and Illinois.
Showers/storms have been firing for much of the day near the
strongest low level inflow into this frontal boundary across
Missouri, but they have been struggling as they have tracked
further east into the much drier airmass across Illinois. This dry
air has slowly been overcome as the low level trajectories turn
more southerly, a trend that should continue through the night.
Meanwhile, a vigorous upper wave moving out of the central Rockies
will help get the surface low/front moving toward the area over
the next few hours, a fact that should result in increasing
shower/storm chances overnight.

Going forecast is in reasonable shape, although have had to make
adjustments to tonight`s rain chances a couple times already.
Still expect chances to ramp up and will make some additional
hourly (mainly PoP) tweaks for the expected trends.

&&

.SHORT TERM...(Tonight)
ISSUED AT 259 PM CDT WED OCT 1 2014

Scattered showers and thunderstorms in west central IL will become
more numerous overnight as several ingredients come together. At the
surface a warm front extended from NW Missouri into south central
Illinois. This boundary, along with a shortwave trough lifting to
the northeast and plenty of upper level divergence will keep the
showers and isolated thunderstorms going from west central into
central Illinois this evening. Relatively drier air in eastern IL
will initially keep the eastward extent of the precipitation limited
to west of I-55 much of this evening.

The warm front will slowly continue to lift to the northeast
tonight, remaining the focus for additional convection to develop.
An increasing low level jet intersecting the front and higher low
level moisture levels in much of the forecast area will result in
widespread showers and thunderstorms in central IL toward midnight,
and eastern IL toward daybreak. Rainfall totals around 0.50-1.00
inch are possible overnight, with the highest amounts anticipated
along and west of the IL river valley.

&&

.LONG TERM...(Thursday through Wednesday)
ISSUED AT 259 PM CDT WED OCT 1 2014

Models are very consistent with the cold front refiring tomorrow
afternoon west of the area and then storms moving into the area late
tomorrow afternoon through tomorrow evening. Should be sufficient
moisture tomorrow ahead of the front to produce instabilities around
1500 J/kg. Models also forecasting strong low level winds and decent
wind shear. So storms are expected to become severe in the CWA,
mainly during evening hours. Agree with SPC with the slight risk
across the area tomorrow with the threat of large hail in the west
and damaging winds throughout the CWA after the storms become more
linear. In addition to the threat of severe weather, heavy rainfall
is also possible through tomorrow night west of I-55 where 1.75 to
over 2 inches is possible and just over 1.25 is possible in the
southeast parts of the CWA. Once the front moves through the area
cooler air will move into the area. However, the area will remain
controlled by an upper level trough. This will bring several chances
of scattered showers Friday and Friday night. The upper level trough
will remain over the area, but dry weather is expected for the first
part of the weekend.

The upper level trough will still be in control of some of the area
for the later part of the weekend and into the beginning of next
week. This will bring another shot of scattered showers to the area
for Sun through Mon night. However, the chances will be low enough
so that pops will just be slight chances; which means it will be in
the grids, but not in the worded forecast. A warm frontal system
will push into the area the beginning of next week, so will have
higher chances of pcpn for Mon night in the southeast only. As the
upper level flow becomes more zonal for middle of next week, dry
weather will return.

Temps will be warm one more day, tomorrow, and then cooler, below
normal temps are expected over the weekend and through most of next
week. By middle of the week, temps begin a slow trend of warming.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
ISSUED AT 1152 PM CDT WED OCT 1 2014

Periods of showers and some thunderstorms are expected through the
rest of the night across the central Illinois terminals, although
the thunderstorm threat should be more spotty at KPIA & KBMI. Have
covered thunder threat with a VCTS and/or a tempo group overnight.
VFR conditions should fall to MVFR or briefly IFR during steadier
rainfall. A break in the precipitation threat is expected early
Thursday as the warm front (responsible for tonight`s
showers/storms) lifts north of the area. Then, chances for
showers/storms return Thursday afternoon, and especially Thursday
evening, as a cold front pushes in from the west. For now, have
covered these storms with predominant showers and a VCTS. However,
expect thunder chances to increase in later TAF issuances as the
coverage is more clear. The heavier rainfall ahead of the cold
front tomorrow should eventually result in widespread MVFR and/or
IFR conditions by evening.

&&

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

$$

UPDATE...Bak
SHORT TERM...Miller
LONG TERM...Auten
AVIATION...Bak






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.