Area Forecast Discussion
Issued by NWS Central Illinois

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541
FXUS63 KILX 191157
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
657 AM CDT Sat May 19 2018

.SHORT TERM...(Today and tonight)
ISSUED AT 230 AM CDT Sat May 19 2018

Upper low over Illinois should push east of the state today as
it lifts into the faster northern stream flow coming into the
Great Lakes. Shortwave ridging should keep much of Saturday dry.
Any residual showers should move east into Indiana by mid-morning.
Temps should respond to the increased sunshine and strong warm
advection to enable highs returning into the 80s.

Latest models in good agreement with regards to shortwave rapidly
ejecting out of the deep trough over the desert southwest today.
The energy should help trigger the development an MCS over the
Central Plains by late afternoon and early evening. Some
differences in the track is evident in the solutions, but the
majority of both synoptic-scale and convective allowing models
suggest the remnants of the MCS should move across at least a
portion of the forecast area late tonight. Although, the boundary
layer will likely be decoupled, elevated CAPE values are forecast
to remain above 1500 J/kg ahead of the linear system and will keep
the system strong as it moves through.

.LONG TERM...(Sunday through Friday)
ISSUED AT 230 AM CDT Sat May 19 2018

Convective evolution of the Saturday Night system will determine
whether convection will be able to impact the region again
Sunday. With a boundary expected to linger in the area, some
afternoon and evening convection seems a good bet, but coverage
and intensity will be heavily dependent on how rapidly the
atmosphere will recover from the Saturday Night system. The 00z
NAM, which is on the weaker side of the envelope with the Saturday
Night system, is more intense with convection Sunday afternoon
and evening with Sfc-based CAPE well over 3000 J/kg at KSPI around
22z.

Energy digging into the western trough early next week should pump
up the ridge over the plains reducing the coverage of convection
for the first part of the work week and allowing temperatures to
remain above normal. Toward the end of the week the overall
pattern retrogrades and allows some northern stream energy to
approach the Midwest from the Prairie Provinces. This should
enhance storm chances again as we approach the holiday weekend.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 657 AM CDT Sat May 19 2018

Areas of IFR fog and IFR clouds will affect portions of central
Illinois early in this 12z TAF period, with PIA the lowest in LIFR
at 1sm br and ovc003. The upper trough axis will continue to pull
east of Illinois this morning, allowing a brief push of drier and
more stable air during the day today. That should provide a
sizable break in the rain.

A warm front lifting north into central Illinois tonight, along
with low pressure progressing east along the front, will increase
storm chances after midnight. Elevated instability looks high
enough to support a few strong to severe storms, with strong wind
and large hail possible. Included a VCTS for later tonight to
account for storm chances, with clouds dropping to MVFR.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Barker
LONG TERM...Barker
AVIATION...Shimon



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