Champaign, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

278
FXUS63 KILX 152302
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
602 PM CDT Tue Apr 15 2025

.KEY MESSAGES...

- Seasonably cold temperatures late tonight will result in frosty
  conditions across the region. Some areas are more susceptible to
  frost damage than others at this point in the spring with
  respect to vegetation, resulting in a non-uniform Frost Advisory
  across the state.

- Rain chances (30-60%) return by Thursday, though the better and
  more widespread rain chances (50-80%) come Friday evening. A few
  storms during this period have the potential to be strong or
  severe, particularly Friday evening with damaging thunderstorm
  wind gusts becoming the primary hazard.

- The stretch of wet weather will then continue through the
  weekend and into next week, particularly in areas near and south
  of I- 72/Danville. There is currently a low (30-50%) chance for
  2" or more of rain between Thursday - Tuesday in the defined
  area, and some degree of urban and small stream flooding is
  plausible if these probabilities increase with subsequent
  forecasts.

&&

.DISCUSSION...
Issued at 126 PM CDT Tue Apr 15 2025

The main concern in the near term remains the potential for patchy
frost to develop late tonight into Wednesday morning as skies
clear behind a departing upper-level trough. Temperatures are
still on track to crash into the mid 30s overnight as a ridge of
high pressure builds across central Illinois, rendering surface
winds light and variable. Ultimately, we decided to expand the
Frost Advisory a little further west into the Illinois River
Valley. Being mid-April now, we remain in a somewhat awkward
position with respect to vegetation, with some areas further along
than others. Thinking most areas across the CWA should exhibit at
least mixed susceptibility to frost by now, and with a fairly
uniform temperature forecast tonight, a case could be made to
expand the Advisory further. Our only pause is that favorable
conditions (RHs > 70%, sfc temps < 37 degF, and light winds) only
exist briefly for a good chunk of the area.

Temperatures will spike into the mid-to-upper 60s on Wednesday as
low-level flow veers southerly and increases behind the departing
ridge of high pressure. After a dry and breezy day, conditions
will turn wet and active to close the week, with a stretch of
unsettled weather extending through the holiday weekend and into
early next week.

Rain may return as early as Thursday morning as the flux of
moisture increases in the vicinity of a lifting warm front. These
potential showers would be high-based and light in nature, with
little or no instability to tap into from the ambient
environment. Rain/storm chances increase Thursday night across
western Illinois as a LLJ noses into the Mid-Mississippi Valley
ahead of an impending cold front. The SPC D3 outlook currently
clips our far northwest CWA for late in the Thursday night period,
most likely honing in on an isolated hail set- up near the nexus
of the LLJ axis and a mid-level cold pocket (steepening lapse
rates). Then, after a brief lull Friday morning when the LLJ
recedes and convective debris keeps much of the warm sector
stable, another opportunity for convective initiation along the
cold front returns Friday afternoon and Friday evening, primarily
in areas east of I-55 where a favorable CAPE/Shear parameter space
will evolve. As a result, SPC continues to outlook portions of
central and southeast Illinois for the D4 period. At this
juncture, the storm mode looks like it could be mixed. Bulk shear
exceeds 40 kts and the vectors are neither aligned parallel or
perpendicular to the front but rather somewhere in between. This
would therefore suggest all severe weather hazards may be a
possibility for Friday, but without strong upper-level forcing
present, coverage of severe weather could be limited.

Wet and unsettled weather then looks poised to continue through
this weekend as the cold front stalls out over or just south of
our CWA. Global deterministic guidance remains in reasonable
agreement with the general synoptic setup during this time which
features multiple upper- level shortwaves moving parallel to the
surface front, and with low pressure riding along it. The more
robust of the low pressures then lifts across the Mid-Mississippi
Valley Sunday afternoon, and depending on whether scenario A
(ECMWF/EPS) or scenario B (GFS/GEFS & Canadian) pans out, could
provide another chance for severe convection. Zooming out of the
severe weather potential and focusing on the hydro setup,
confidence is high that it will be a soggy end to the week, even
bleeding into next week. Current probabilistic guidance from the
latest LREF suggests only low probabilities (30-50%) of exceeding
2" between Thursday and Tuesday in areas near and south of
I-72/Danville, but it wouldn`t be a surprise to see these
probabilities increase over coming forecast cycles as convective
elements get better resolved.

MJA

&&

.AVIATION...  (For the 00z TAFs through 00z Wednesday Evening)
Issued at 602 PM CDT Tue Apr 15 2025

Gusty northwest winds will diminish with sunset, becoming light
and variable overnight into a good portion of Thursday. VFR
conditions prevail through the period.

Geelhart

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 2 AM to 8 AM CDT Wednesday for ILZ027>031-
036>038-041>046-048-051>057-061>063-066>068.

&&

$$