Area Forecast Discussion
Issued by NWS Central Illinois
FXUS63 KILX 101201
Area Forecast Discussion
National Weather Service Lincoln IL
701 AM CDT Thu Apr 10 2014
ISSUED 331 AM CDT Thu Apr 10 2014
Largely zonal wind flow from the Rockies to the Midwest... with a
deepening sfc low just south of Hudson Bay dragging a front
into the Great Lakes and Plains states this morning. Stretching
from Lake Superior through central WI and back through IA...this
frontal boundary will be the initial issue for the forecast.
Moderating temperatures through the weekend before another system
drives pops up again for Sunday and into Monday. On the other side
of the weekend system, the temps drop well below normal again for
the Midwest in April. Though the models are in agreement overall,
the colder ECMWF is backing off with the coldest air. Either way
though, colder weather expected for the first half of next week.
SHORT TERM...Today and tomorrow...
Frontal boundary moving into the Midwest this morning. Though GFS
is more aggressive with the QPF...minimal RH is in place and
little in the way of convergence expected as the boundary passes
through the state. Dropped the dewpoints a bit from guidance as
MOS is overdone already with current conditions. Pops are left
relatively low with minimal QPF. Will likely be showery...with the
best chances for precip in the north/northeast closer to the
system center. This evening however, 4km WRF and others hinting at
a small wave enhancement running along the boundary as it stalls
out over the Ohio River Valley. This wave/front interaction will
enhance showers/pops and the chance for thunder particularly in
the southeast. Tomorrow will see a dry out and slightly cooler temperatures
overall as highs move into the upper 60s...closer to normal.
LONG TERM...Saturday through Tuesday...
Forecast continues the warm temperatures on the back side of the
weak boundary and rather moderate spring like weather through
Saturday early evening...until another system spreads precip Sat
night and for the remainder of the weekend and through Monday as
a slow moving boundary makes its way across the region. Timing
issues diminishing with each run of operational models.
Temperature problems are starting to pile up behind this system
with the ECMWF dropping 850 mb temps from 10C Sunday afternoon...
to -5C to -7C in the wake of the precip through Tuesday night.
Mon night and Tuesday night guidance drops the temps to at or
below freezing, with a quick end to the warmer temperatures for
ISSUED 700 AM CDT Thu Apr 10 2014
Low Level Wind Shear conditions will start out this TAF period,
with SW winds just above the surface near 50kt at times. Surface
winds will gust to 20-25kt ahead of the front. As the cold front
arrives, surface winds will then diminish in the weakening
pressure gradient right near the front. Behind the front,
northwest winds will increase to 10-15kt for the rest of the
afternoon. Northerly winds will develop after sunset with speeds
diminishing to less than 10kt.
Scattered showers will develop, but the dry low layers will
prevent much in the way of rain accumulation today. Storm chances
will increase this evening as the front moves east of I-55. A VCTS
was included at DEC and CMI this evening with VFR cloud heights
near 5K ft. Precip should push east of the terminals by 06z as
clouds gradually clear out.