Area Forecast Discussion
Issued by NWS Central Illinois
FXUS63 KILX 081143
Area Forecast Discussion
National Weather Service Lincoln IL
543 AM CST Sat Mar 8 2014
ISSUED 250 AM CST Sat Mar 8 2014
Initial cold front/wind shift has gone through about 3/4 of the
CWA as of 2 am, but colder air lingers further northwest, with
sub-freezing temperatures still back across Iowa and northern
Missouri. Band of light rain/sleet mix has pushed into the far
western parts of the forecast area, with radar presentation and
surface obs showing more of a snow signature in narrow bands from
southwest to east central Iowa.
General forecast concerns are threefold: the first being with
precip types this morning, secondly the much warmer weather early
next week, and the third and most significant being with potential
storm system at midweek.
SHORT TERM...Today through Tuesday:
For today, forecast soundings showing the sleet potential across
the western half of the CWA early this morning, changing to snow
north and rain south. Some very dry low levels across the
southeast half should hold off the precipitation until midday or
later, at which point it should be rain. Initial precip should be
in a weakening state ahead of an upper wave in the northern
stream, but a secondary surge will push out of southern Missouri
during the afternoon, where the southern stream starts to interact
with the northern one, and will linger some PoP`s into the evening
south of I-70.
Significant warming trend to start on Sunday as winds quickly
turn southwest, as high pressure pushes south into the lower
Mississippi Valley. 850 mb temperatures rising into the +10C range
early Monday. Have maintained highs in the upper 50s to lower 60s
on Monday ahead of a weak cold front, with slightly cooler
conditions on Tuesday but still well into the 50s most areas.
LONG TERM...Tuesday Night through Friday:
Main challenge remains with midweek system, due to phasing of
split upper flow near the central Plains. Medium range models in
good agreement with surface cyclogenesis over Oklahoma on Tuesday
with a general east-northeast track of the low into Kentucky
Wednesday morning. The GFS is much weaker with this feature than
the ECMWF or Canadian models, with just a glancing blow of some
precip Wednesday morning. It has had some inconsistencies in the
last few runs, so will lean away from that model for now. Precip
type will be critical, as 850 mb temps on these models are down to
around -6C by midday Wednesday. The resolution of forecast
soundings on these models is a bit on the coarse side, so it is
too difficult to fine tune the details that far out, but right now
will keep the southeast as all rain, with a rain/snow mix
elsewhere Tuesday night and Wednesday.
General upper flow to remain from the Pacific through the end of
the week, so temperatures should rebound again late in the week
following this storm system.
ISSUED 534 AM CST Sat Mar 8 2014
Northerly winds light behind the cold front that pushed through
the region this morning. Current mixed precip coming to an end
slowly and should be out of ILX terminals by 12z. MVFR cigs
building in from the NW...with obs reporting around 1300-1500ft.
IFR/MVFR vis...many sites down below 3, but not by much. Slow
drying out after this round will be stunted by approach of second
wave this afternoon. Majority of the showers should remain south
of ILX terminals, but will keep in a VCSH for DEC just in case.