Area Forecast Discussion
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000
FXUS63 KILX 182051
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
251 PM CST Thu Dec 18 2014

.SHORT TERM...(Tonight)
ISSUED AT 251 PM CST THU DEC 18 2014

Short-wave trough responsible for the light snow earlier today has
sheared out and pushed into Indiana this afternoon, leaving behind
cloudy skies and a few scattered flurries.  With another vigorous
wave noted upstream on water vapor imagery over the Desert
Southwest, short-wave ridging will begin to develop across the
Midwest later tonight into Friday.  This will ensure dry conditions
and perhaps some thinning of the overcast.  20z/2pm visible
satellite imagery already shows some breaks in the cloud cover
developing from the Bloomington area northwestward into Iowa.  As
synoptic subsidence increases in the wake of the departing Indiana
wave, additional breaks will develop further south and east as the
night progresses.  Will maintain mostly cloudy conditions overall,
but think some temporary clearing may occur from time to time.  HRRR
hints at this trend as well.  Meanwhile further west, a low overcast
will prevail across southern Iowa into Missouri.  Will have to keep
an eye on the low clouds and fog to the west, as several high-res
models try to develop fog eastward into the western KILX CWA after
midnight.  Will leave out of the forecast for now, as 18z NAM
forecast soundings show little or no restriction to visibility.  Low
temperatures will be similar to last night in the teens and lower
20s.


&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 251 PM CST THU DEC 18 2014

Morning vort max over northern MO that triggered morning south over
southern 1/2 of CWA has weakened and sheared to the east in
confluent upper flow through the day. Result is the end of light
snow for region in afternoon. Moisture channel data depicts next
wave that was over western AZ at 12z in upper air data, now moved
into eastern AZ. This wave to continue to track east into the
plains, but has weakened and models keep it south of area.

The main system of interest is the digging of the upper trough into
the midwest by late in the weekend. Both GFS and EUR similar in
closing off low into WI by Mon night. Pcpn still develops and
spreads into area Monday, with a brief early chance of a mix of pcpn
type at the onset. Warm advection ahead of the developing surface
low will then keep pcpn rain through Mon and then a light mix in the
northwest sections possible Mon night. Front to move through by
early Tues with cold air following. Therefore a mix of rn/sn in
grids for Tues, changing over to sn on Tues night. Chance of Sn in
the region Wed, but with the upper low in the Great Lakes, pcpn
amounts will be light and only wrapp around light pcpn. Sn amounts
will be light, ending Wed night.


&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1149 AM CST THU DEC 18 2014

The widespread light snow from earlier this morning has now
diminished to scattered snow-showers, primarily along and south of
a KSPI...to KDEC...to KCMI line. Will carry MVFR ceilings and -SN
at those 3 terminals through 20z accordingly. Further north, VFR
conditions will prevail at both KPIA and KBMI through the day.
Once the light snow completely ends, clouds will persist across
the entire area through Friday morning. NAM RH profiles show IFR
ceilings remaining in place across southern Iowa into Missouri
through the period, while MVFR/VFR ceilings prevail further east
across central Illinois. Winds will remain light/variable beneath
the surface ridge axis through 18z Fri.


&&

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

$$

SHORT TERM...Barnes
LONG TERM...Goetsch
AVIATION...Barnes






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