000
FXUS63 KILX 121546
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1046 AM CDT Wed Mar 12 2014

.DISCUSSION...
ISSUED 1045 AM CDT Wed Mar 12 2014

Will expire the wind advisory for our central and southeast IL
counties at 11 am, when the winter weather advisory expires at 11
am for counties along and east of I-55 and north of I-70.
Lawrenceville had wind gust of 43 mph in past hour while peak wind
gusts have generally been 30-40 mph over central and eastern IL and
sustained winds 20-30 mph. This is below the wind advisory
criteria of gusts of 45 mph or higher and/or sustained winds of 30
mph or more for an hour. Main batch of light snow has exit east of IL
over IN late this morning while a smaller area of light snow and
flurries was tracking sse from northern IL into the IL river
valley. Altona had about a half inch of snow in 4 hours from 6-10
am. Think any additional light snow accumulations to be less than
a half inch over ne counties into midday. Deepening low pressure
of 989 mb near the OH/PA/WV border to strengthen to 982 mb over NJ
by sunset. Light snow showers and gusty winds to diminish during
the afternoon from west to east as storm pulls away from IL.

07

&&

.AVIATION...
ISSUED 708 AM CDT Wed Mar 12 2014
Snowfall rapidly coming to an end across the area. Vis improving
from west to east with the loss of the snowfall. Cigs remaining
down this morning though slowly improving. Tightening pressure
gradient with deepening low as the storm pulls to the north and
east causing a major issue today with the winds. Winds gusting 30 to
45 kts through the morning before slowly backing down after mid
day. After the snow retreats to the east...MVFR cigs through the
day...very gusty northerly winds...VFR/MVFR break point expected a
few hours after sunset.

HJS

&&

.PREV DISCUSSION...
ISSUED 311 AM CDT Wed Mar 12 2014

Low pressure center was located just east of Lawrenceville at 2
am, and radar imagery showed the cold front roughly along a
Robinson to Flora line. Southeast CWA has only seen scattered
showers thus far, but most of the forecast area has had widespread
precipitation with scattered thunderstorms. Radar and surface obs
currently showing the rain/snow line roughly along I-55. A very
wet snow is falling to the west of I-55. Web cams around Peoria
showing about 1-1.5 inches has accumulated in a little over an
hour, although pavement conditions are more on the wet/slushy
side. Back edge of the deformation zone is generally along the
Illinois/Iowa border into central Missouri, near the position of
the upper wave.

The main forecast concerns are with the first 24 hours, with
precipitation, winds, and headlines.

SHORT TERM...Today through Friday:

Latest MSAS analysis showing 3-hr pressure changes around 7 mb
across southwest Missouri, and this will be tracking into south
central Illinois over the next few hours. This is the reason the
wind advisory was issued, as high-resolution model guidance was
indicating a period of 3-4 hours where wind gusts of 40-50 mph is
likely. Worst of the winds should be out of the area by about 10
am. Advisory is in effect until 1 PM, although this will likely
be cancelled early.

With regards to the snow, transition from rain to snow has been
pretty quick with little mixed precip in between. Forecast
soundings indicate most of the CWA should be all snow by sunrise,
with only the southeast CWA likely to see a more prolonged mixed
period. Have decided to downgrade the I-39 counties to a winter
weather advisory, as the later switchover time and the heavier
precipitation rates being tied to during the rain period, makes
reaching warning criteria less likely, although have kept snow
amounts of 4-5 inches there. The remainder of the advisory area is
being kept in place, although the ending time was moved up a few
hours. Western parts of the advisory will likely be cancelled
early as well, and will re-evaluate this in a few hours.

The snow will not be lasting long, as temperatures still progged
to reach into the 40s on Thursday and 50s Friday. Have brought
temperatures up a few degrees for today and tonight, as the amount
of cold air advecting in from the north has not been as much as
first thought.

LONG TERM...Saturday through Tuesday:

Illinois progged to be caught in the phasing area between the two
jet streams this weekend. Longer range models are struggling with
how to handle this, with the ECMWF forming a storm system along
the Gulf Coast, with the GFS much weaker in this regard, although
precip for our area in general will not be much. Beyond that, even
more significant differences are noted by Tuesday.

Geelhart

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY until 11 AM CDT this morning FOR ILZ040>057-
061>063-066>068-071>073.

WINTER WEATHER ADVISORY until 11 AM CDT this morning FOR ILZ038-
042>046-051>057-061.

&&

$$