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Area forecast discussion 
National Weather Service Lincoln Illinois
1042 am CDT Thu Oct 23 2014

issued at 1042 am CDT Thursday Oct 23 2014

Morning surface analysis shows weak frontal boundary across the
plains, accompanied by a band of clouds and light showers from
Missouri northeastward into western Wisconsin. Airmass ahead of
this system is very dry, as shown by the 12z kilx upper air
sounding. As a result, precip will have a difficult time
spreading/developing eastward. Latest radar trends continue to
show a decrease in precip areal coverage across northern/central
Missouri, so have updated pops to slow the eastward progression of
the rain chances. Will continue to carry just slight chance pops
west of I-57 this afternoon. Further east, precip will hold off
until evening. Rainfall amounts will be quite light, only
amounting to a couple hundredths of an inch at best.


Short term...(today)
issued at 307 am CDT Thursday Oct 23 2014

Main concern for today revolves around how much (if any) rainfall is
expected, as well as how soon it will arrive. Line of showers
upstream along a decaying cold front currently extends from the
upper Midwest into the Central Plains. The front and driving upper
wave have not been making very quick progress to the east due to the
blocking upper low along the East Coast and the weakening ridge
overhead it is trying to push into. This scenario should continue to
slow the arrival of the upstream front, as well as support its
continued weakening. With this thinking in mind, supported by a
strong consensus of the models, have removed all pops from this
morning, and limited them to slight chance for the afternoon across
northern 1/2 of forecast area (southern 1/2 of forecast area stays
dry). The slower arrival of the clouds and minimal precipitation
threat with this system should also allow temperatures to warm a bit
more than previously expected, with most locations able to make it
into the 60s.


Long term...(tonight through wednesday)
issued at 307 am CDT Thursday Oct 23 2014

Shower threat to diminish quickly this evening as the wave passes,
as forecast soundings near Champaign only show a moist layer about
2000 feet thick and quickly eroding from the top down. However,
clouds will be slower to exit as a weak wave moves in behind the
initial one.

Dry frontal passage expected Friday night, as what little
precipitation is shown by the models stays to our north. The cooler
air lags behind this front some distance, so highs 70-75 are still
anticipated for Saturday. While Sunday briefly cools off with the
arrival of a fast moving high, the warming trend kicks in again
early next week.

Main focus for rain in the longer term remains with a broad trough
that will be emerging from The Rockies Monday evening. Latest European model (ecmwf)
run is coming more in line with the GFS solution, with better
phasing of this trough in the northern/southern streams. However,
the GFS is a tad faster, spreading rain in most areas late Monday
night while the European model (ecmwf) is more during the day Tuesday. Both models
quickly end the rain from northwest to southeast Tuesday night.


Aviation...(for the 12z tafs through 12z Friday morning)
issued at 634 am CDT Thursday Oct 23 2014

A decaying frontal boundary will approach the central Illinois
terminal area today. Spotty showers will exist along/ahead of the
front. However, due to the weakening nature of the system and dry
airmass currently in place, precipitation coverage should
continue to decrease as the front moves east. With this in mind,
have only included a vcsh mention at kpia, with dry conditions
expected to prevail elsewhere. VFR conditions are likely until the
frontal zone arrives tonight, when MVFR cigs and patchy MVFR vsbys
in fog are likely.


Ilx watches/warnings/advisories...


short term...Bak
long term...geelhart

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