Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kilx 111844 

Area forecast discussion
National Weather Service Lincoln Illinois
1244 PM CST Mon Dec 11 2017

issued at 1104 am CST Mon Dec 11 2017

Clipper system continues to approach the area from the northwest.
It is currently nearly vertically stacked over Iowa. The upper
wave is showing signs of shearing out at the moment. The
associated weakening should largely account for the weakening in
the system's precipitation threat as progged my most of the high-
resolution models.

Updated forecast for the latest hourly trends, with the most
notable adjustments to cloud cover and precipitation chances. Also
boosted winds/gusts considerably into midday Tuesday as strong cold air advection
develops in the wake of the clipper.


Short term...(today and tonight)
issued at 330 am CST Mon Dec 11 2017
weak ridging moving through central Illinois this morning, resulting in
some variability in the winds, but generally more southerly flow
at the surface. Aloft however, the northwesterly aloft continues,
as it will for much of the forecast period. As a result, the
majority of the seven day forecast is a series of small clipper
waves, with many of them bringing the bulk of the precip threat
to the north. Central Illinois will likely see a series of chances for
flurries and variable temperatures through the week.

The first chance for flurries/sprinkles will come this afternoon
and evening as a quick wave moves through the region. Blustery
winds will accompany the wave as well. Not only an increased
pressure gradient to increase the sustained winds, but winds aloft
increase as well. Between some mixing and just adding enough
turbulence just off the surface, gusts should continue through the
overnight. Behind the wave, a cold air mass moves into the
Midwest, dropping the temperatures tonight into the upper
teens/lower 20s.

Long term...(tuesday through sunday)
issued at 330 am CST Mon Dec 11 2017

Northwesterly flow continues at the surface and aloft through the
first couple days of the work week. Tuesday, the cold air mass
will keep the highs in the upper 20s/near 30. Tuesday nights temps
drop into the teens, with the coldest air to the northeast as the
pattern shifts again. Next chances for snow now showing up in the
model blends Wednesday, mainly to the north, and flurries.
Remainder of the forecast is mainly dry, with the potential to see
some flurries added in subsequent runs as the pattern shifts from
a northwesterly flow to a quasi zonal by the end of the week. With
the moderating amplification, the temperatures moderate as well
through the weekend, milder across the board.


Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 1241 PM CST Mon Dec 11 2017

A strong cold front will cross the central Illinois terminals
later today, with winds shifting from southerly to northwesterly.
Gusty winds are anticipated through the period, especially in the
wake of the front. The passage of the front will also be
accompanied by a period of MVFR ceilings and possibly a few sprinkles
or flurries. Any precipitation is not expected to have much
impact on visibilities.


Ilx watches/warnings/advisories...


National Weather Service Glossary of Abbreviations